1
Q
What do valves in the heart do?
A
prevent back flow of blood
2
Q
Myocardial muscle cell characteristics
A
- single nucleus
- branched
- connected to each other by intercalated disks
3
Q
What are the two pathways of blood through the heart?
A
- systemic
- pulmonary
4
Q
What is the endocardium?
A
- inner layer
- layer of endothelial cells
5
Q
What is the myocardium?
A
- middle layer
- cardiac muscle
6
Q
What is the epicardium?
A
- outer layer
- external membrane
7
Q
What protects the heart?
A
- the pericardium
8
Q
Characteristics of the pericardium?
A
- sac filled with fluid
- connected to the diaphragm
9
Q
What does pericardial fluid do?
A
-lubricates and allows the heart to move in a friction free environment
10
Q
How do we look inside the heart?
A
- echocardiogram
11
Q
What information does the echocardiogram give?
A
- the size and shape of the heart
- its pumping strength
- location and extent of any damage
- disease of the heart valves and cardiac hypertrophy (excessive development of the heart)
12
Q
Which ventricle is thicker in the heart?
A
- the left
13
Q
Why is one ventricle thicker than the other?
A
- to be able to deliver blood to the entire body
14
Q
Another name for the mitral valve?
A
- bicuspid valve on the left side of the heart
15
Q
Which valve remains closed in order to ensure back flow does not occur to the atria when ventricles contract?
A
- Atrioventricular valve (AV)
16
Q
Why do semilunar valves open and close?
A
- pressure differences
17
Q
Which valve prevents back flow of blood into the ventricles during ventricle relaxation?
A
- semilunar valves
18
Q
Where are coronary vessels located?
A
- on the surface of the heart
19
Q
What does systemic circulation include?
A
- arteries
- veins
20
Q
What do arteries do?
A
- carry oxygenated blood from the left ventricle to tissues
21
Q
What do veins do?
A
- carry deoxygenated blood back to the right atrium
22
Q
What does pulmonary circulation include?
A
- pulmonary arteries
- pulmonary veins
23
Q
What do pulmonary arteries do?
A
- blood from the right ventricle to the lungs
24
Q
What do pulmonary veins do?
A
- blood from the lungs to the left atrium
25
How does blood flow?
- Ohm's Law (General)
- The physiological Equivalent (specific)
26
What is Ohm's law equation?
- flow = change in pressure / resistance
27
What is the physiological equivalent equation?
- Q = MAP/ TPR
28
What is Q?
- cardiac output
- heart function
- The amount of blood leaving the ventricles every minute
29
What is MAP?
- mean arterial pressure
- blood pressure
- outward pressure exerted on the walls of the blood vessels
- NET driving pressure
30
What is TPR?
- total peripheral resistance
- blood vessels and their diameter
31
How is Q calculated?
- heart rate (beats/min) x stroke volume (mlblood/beat)
32
What is MAP directly proportional to?
- cardiac output x resistance
33
What is homeostasis equal to?
- physiological equilibrium
34
Define total peripheral resistance
- total resistance of all the blood vessels
- most impacted by arterioles
35
What is the average blood pressure of the systemic circulation?
- 93 mm Hg (millimetres of mercury) in aorta
36
Which blood vessels have low pressure?
- veins
- venae cavae
37
Define resistance
- the radius of the blood vessels determines resistance and is physiologically regulated
38
Characteristics of vasodilation
- r (radius) increases
- R (resistance) decreases
- Blood flow increases (assuming constant pressure)
39
Characteristics of vasoconstriction
- r (radius) decreases
- R (resistance) increases
- Blood flow decreases (assuming constant pressure)
40
How are flow and resistance related?
- inversely
41
If resistance increase, how does flow respond?
- decreases
42
If resistance decreases, how does flow respond?
- increases
43
What does resistance depend on?
- length of the tube
- radius of the tube
- viscosity of the fluid
44
How does length of the tube affect resistance?
- As R increases, L increases
45
How does radius of the tube affect resistance?
- As R increases, radius decreases
46
How does viscosity of the fluid affect resistance?
- As R increases, viscosity increases
47
Q refers to flow due to?
- central factors
48
R refers to resistances due to?
- peripheral factors
49
What type of cells spontaneously fire action potentials in the heart?
- autorhythmic
50
How does depolarization of the autorhythmic cells spread to adjacent contractile cells?
- gap junctions
51
How does the heart contract?
- it twists
52
What allows the heart to twist while contracting?
- the spiral arrangement of the muscle
53
How is force transferred from cell to cell?
- intercalated disks contain desmosomes that transfer force
54
What allows electrical signals to pass rapidly from cell to cell?
- gap junctions
55
Define desmosomes
- string protein that surrounds sarcomeres and bind neighbouring sarcomeres
- allow force to be transferred
56
Characteristics of cardiac muscle
- single nucleus
- distinctive short rectangular shape (are smaller compared to skeletal muscle)
- spontaneously contract
- branch and join neighbouring cardiac cells through intercalated disks
- depends partly on extracellular Ca2+
- T- tubular network is more extensive than skeletal muscle
- large volume of mitochondria
57
What controls heart rate?
- sinoatrial node
58
What are intercalated disks comprised of?
- desmosomes hold cells together
- gap junctions move ions
59
Where is Ca2+ stored in cardiac muscle
- Ca2+ is sequestered/ isolated in the sarcoplasmic reticulum like skeletal muscle but the SR is less voluminous
60
What does t - tubules do?
- allows rapid, synchronous excitation - contraction coupling
61
Why does the heart have so many mitochondria and how much of the heart does mitochondria make up?
- the heart depends on aerobic ATP production
- 1/3 of volume
62
Why is there a delay in the action potential of a cardiac contractile cell?
- filling time of the heart
63
How do you determine the amount of force generated by the heart muscle?
- The number of active cross bridges
64
In a cardiac muscle fibre, how long does the refractory period last?
- as long as the entire muscle twitch
65
What does a long refractory period in cardiac muscle prevent?
- tetanus
66
What determines the amount of active cross bridges in cardiac muscle?
- determined by how much calcium is bound to troponin
67
How do you determine the force generated in skeletal muscle?
- proportional to number and frequency of stimulations
68
What builds tension and what determines level of tension?
- tetanus and fused tetanus
- summation determines level of tension
69
How long is the refractory period in a fast twitch skeletal muscle fibre?
- very short
70
What is summation in skeletal muscles?
- muscles that are stimulated repeatedly
71
What effects force of contraction of cardiac muscle?
- sarcomere length
72
Action potentials in cardiac autorhythmic cells have a...
- unstable membrane potential
73
Since the membrane potential in cardiac autorhythmic cells is unstable, it is also called?
- pacemaker potential
74
What is the resting membrane potential of a cardiac autorhythmic cell?
- -60mV
75
What are If channels?
- funny (f) current (I) channels
- leaky channels that cause pacemakers to depolarize
- results in pacemaker potential
76
Where does the right atrium receive and send blood to?
- receive: venae cavae
- send: right ventricle
77
Where does the right ventricle receive and send blood to?
- receive: right atrium
- send: lungs
78
Where does the left atrium receive and send blood to?
- receive: pulmonary veins
- send: left ventricle
79
Where does the left ventricle receive and send blood to?
- receive: left atrium
- send: body except for lungs
80
Where does the venae cavae receive and send blood to?
- receive: systemic veins
- send: right atrium
81
Where does the pulmonary truck receive and send blood to?
- receive: right ventricle
- send: lungs
82
Where does the pulmonary vein receive and send blood to?
- receive: veins of the lungs
- send: left atrium
83
Where does the aorta receive and send blood to?
- receive: left ventricle
- send: systemic arteries
84
What is the primary function of the cardiovascular system?
- the transportation of nutrients, water, gases, wastes, and chemical signals to and from all parts of the body
85
What kind of system does the heart pump blood through?
- a closed system
86
blood vessels that carry blood away from the heart
- arteries
87
blood vessels that carry blood to the heart
- veins
88
Where does the pulmonary circulation take place?
- the right side of the heart to the lungs and back to the heart
89
Where does the systemic circulation take place?
- the left side of the heart to the tissues and back to the heart
90
How is pressure affected by fluid flowing?
- pressure decreases over distance
91
What is driving pressure?
- the pressure created when the ventricles contract
92
Which of the three factors that affect resistance have the greatest effect?
- radius
93
What type of muscle is cardiac muscle?
- striated muscle
94
What do contractile muscles contain?
- started fibres organized into sarcomeres
95
Where does the signal for contraction of the heart originate?
- autorhythmic cells (non contractile_
96
Where does coronary circulation originate?
- at the beginning of the aorta
97
Where does coronary circulation drain into?
- the chambers of the heart
98
Brief explanation to contractile cell excitation-contraction coupling
- action potential opens Ca2+ channels
- Ca2+ entry into the cell triggers the release of additional Ca2+ from the sarcoplasmic reticulum through calcium induced calcium released
99
The force of a cardiac muscle contraction is due to?
- how much ca2+ enters the cell
100
What is cardiac output (Q)?
- heart rate x stroke volume
- beats/min x mlblood/beat
101
Define stroke volume
- amount of blood pumped by one ventricle during a single contraction
102
How to calculate stroke volume?
- end diastolic volume (EDV) - end systolic volume (ESV)
103
What is end diastolic volume?
- heart is most full
104
What is end systolic volume?
- heart is most empty
105
How can one increase stroke volume?
- increase end diastolic volume (more blood in ventricle to be ejected: Preload)
- increase ejection fraction (more blood ejected from the ventricle: contractility)
106
Define ejection fraction
- the percentage of EDV ejected with a single contraction
- functional index of ventricular performance
107
How do you calculate ejection fraction?
- stroke volume/ end diastolic volume x 100
108
What is heart rate determined by?
- rate of depolarization in autorhythmic cells
109
What kind of innervation results in a decrease in heart rate?
- parasympathetic
110
What kind of innervation results in an increase in heart rate?
- sympathetic
111
Define pulse rate (different then heart rate)
- time between pressure waves in an artery
112
Define systolic pressure
- highest pressure in the ventricles and arteries
- occurs during ventricular systole
113
Define diastolic pressure
- lowest pressure in the ventricles and arteries
- occurs during ventricular diastole
114
Define pulse pressure
- difference between the systolic and diastolic pressures
115
How to calculate pulse pressure
- systolic pressure minus diastolic pressure
116
What is heart rate?
- time between two R waves and two P waves
117
What is a P wave?
- atrial depolarization
- SA node depolarizes then the atria
118
What is a P-R segment?
- conduction through AV node and AV bundle
- time between end of atrial depolarization and onset of ventricular depolarization
119
What is a QRS complex?
- ventricular depolarization
120
What is a T wave?
- ventricular depolarization
121
What is an electrocardiogram divided into?
- waves
- segments between the waves
- combinations of segments and waves
122
Electrical events of the cardiac cycle
Start
- p wave
- P-Q or P-R segment
- Q wave
- R wave
- S wave
- S-T segment
- T wave
End
123
When does atrial contraction begin?
- during the latter part of the P wave
- through the PR segment
124
When does ventricular contraction begin?
- just after the Q wave
- continues through the T wave
125
What comes first, electrical events or mechanical events?
- electrical events
126
What is the Q wave?
- the SA node depolarizes and then the bundle branches lasted in the septum
127
What is the R wave?
- the purkinge fibres depolarize loaded in the apex and outer walls of the heart
128
What is a wave?
- deflections above or below baseline
129
What are segments?
- sections of baseline between waves
130
What are intervals?
- combinations of waves and segments
131
What is a ST segment?
- Time between end of ventricular depolarization and onset of ventricular repolarization
- continuing ventricluar contraction
132
What is a PR interval?
- time between onset of atrial depolarization and ventricular depolarization
- AV blocks
133
What is a QT interval?
- time between onset of ventricular depolarization and end of repolarization
- long QT syndrome
134
What is systolic?
- contraction
135
What is dystolic?
- relaxation
136
Autonomic control of heart rate: Parasympathetic control
- decreases heart rate
- Ach on muscarinic receptor
- K+ permeability increases
137
Autonomic control of heart rate: sympathetic control
- increases heart rate
- beta one adrenergic receptors in node
- Na+ and Ca2+ permeability increases
138
Events of the cardiac cycle
- late diastole
- atrial systole
- isovolumic ventricular contraction
- ventricular ejection
- isovolumic ventricular relaxation
139
What is late diastole
- both sets of chambers are relaxed and ventricles fill passively
140
What is atrial systole
- atrial contraction forces a small amount of additional blood into ventricles
141
What is isovolumic ventricular contraction
- first phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves. Maximum blood volume in ventricles = end-diastolic volume
142
What is ventricular ejection
- as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected
143
What is isovolumic ventricular relaxation
- as ventricles relax, pressure in ventricles falls. Blood flows back into cusps of semilunar valves and snaps them closed. Minimum blood volume in ventricles = end systolic volume
144
What factors affect stroke volume?
- Preload
- contractility
- afterload
145
What is preload?
- The longer (more stretch) the muscle fibre and sarcomere when contraction begins, the greater the tension (more force) developed
146
What is Frank-Starling law of the heart
- Stroke volume is proportional to EDV
147
How can we increase the blood volume in the ventricles ?
- increased venous return
148
What is venous return?
- the amount of blood that returns to the heart from venous circulation
149
What is venous return affected by?
- skeletal muscle pump
- respiratory pump
- venous constriction
150
What is skeletal muscle pump?
- contraction of skeletal muscle that compresses veins and pushes blood towards the heart
- enhanced venous return
151
What is respiratory pump?
- decreased pressure on inferior vena cava allowing it to draw in more blood from the abdomen
- enhanced venous return
152
What is venous constriction?
- increased sympathetic activity causes veins to contract
- decrease in volume of the veins
- result is more blood "squeezed" out of them
153
What are sympathetic nervous system effects on contractility?
increased sympathetic activity =
- increased epinephrine release
- increase strength of contraction
- increate rate of both contraction and relaxation
- decreased duration of contraction
154
What do catecholamines do?
- increase cardiac contraction
155
What is afterload?
- is the combined load of EDV and arterial resistance during ventricular contraction
- "ventricular force must exceed the resistance created by blood filling the arterial system"
- blood must be pushed through the semilunar valves and into circulation
156
157
What happens during aerobic exercise to decrease afterload?
- peripheral vasodilation
158
What clinical condition is associated with increased afterload?
- hypertension
159
Where do action potentials originate in the heart?
- sinoatrial node (SA node)
160
What follows action potentials in the heart?
- a wave of contraction
161
Pathway that electrical signal moved through the heart?
- from the SA node through
- the internal pathway to the atrioventricular node
- then to the AV bundle
- to the bundle branches
- to the terminal purkinje fibres
- to the myocardial contractile cells
162
What sets the pace of the heart beat?
- SA node
- if SA node malfunctions, other autorhythmic cells in the AV node or ventricles take over
163
What does an ECG provide information on?
- heart rate
- rhythm
- conduction velocity
- condition of the cardiac tissues
164
What speeds up the rate of the pacemaker depolarization?
- norepinephrine and epinephrine act on beta one receptors
165
What hyper polarizes the pacemaker of the heart?
- acetylcholine activates muscarinic receptors
166
What makes the first heart sound?
- closure of the AV valves
167
What happens during isovolumeic ventricular contraction?
- pressure rises but ventricular blood volume does not change
168
When do semilunar valves open?
- when ventricular pressure exceeds arterial pressure
169
When does most of the blood enter ventricles?
- when the atria is relaxed
170
What creates the second heart sound?
- the semi lunar valves closing
171
What is the average cardiac output at rest?
- 5L/min
172
How are homeostatic changes accomplished in cardiac output?
- varying heart rate
- stroke volume
- or both
173
What does epinephrine and norepinephrine do when they bind to beta one adrenergic receptors?
- increase the force of myocardia contraction
- shorter the duration of cardiac contraction
174
What enhances contractility of the heart and what kind of effect do they have?
- catecholamines and certain drugs
- inotropic effect
175
What is poiseuille's law
- R=8Ln(weird n)/pir^4
176
What does the weird n stand for?
- viscosity
177
What is viscosity?
- the thickness of the fluid of blood
178
What determines the thickness of blood?
- the amount of plasma, RBCs, and the amount of proteins
179
How does blood flow?
- down pressure gradients, from regions of high pressure to low pressure
- blood only flows if there is positive pressure
- depends on the pressure gradient not on the absolute pressure
180
What are arteries?
- measure pressure
- act as pressure reservoir
- thick layers of vascular smooth muscles
- lots of elastic and fibrous connective tissue
181
What are arterioles?
- site of variable resistance
- part of the microcirculation
- less elastic and more muscular
182
What are metarterioles?
- branches of arterioles
- partial smooth muscle layer
- Pre capillary sphincters open and close to direct blood flow to capillaries or venous circulation
183
Which blood vessels are more easily changeable, less muscular, and accepts blood?
- venules
- veins
184
When is the velocity of blood flow the slowest?
- where the cross sectional area is the greatest
185
What blood vessel acts as volume reservoir?
- veins
- at rest they "hold" the majority of the blood volume
186
When does redistribution occur?
- when Q (cardiac output) increases
- as tissues demand more oxygen and nutrients (like during exercise)
187
Where do venues receive blood from?
- from capillaries
188
How is blood pushed through veins?
- by skeletal muscles contracting
189
Where does blood flow to in veins?
- to the heart
190
Which type of blood vessels are more numerous?
- arteries
191
Which blood vessel is closer to the surface of the skin?
- arteries
192
What are capillary beds?
- site of gas exchange
193
What is exchanged in capillaries?
- plasma and cell exchange
194
What are capillaries made of?
- a single layer of flattened endothelial cells
- supported by basal lamina
195
What is capillary density related to?
- metabolic activity of cells
196
Define Angiogenesis
- Angiogenesis is development of new blood vessels
197
What does angiogenesis do?
- necessary for normal development
- enhanced heart and skeletal muscle blood flow
198
How can blood pressure be estimated?
- sphygmomanometer
199
Define systolic pressure?
- highest pressures in the ventricles and arteries occur during ventricular systole
200
Define diastolic pressure?
- lowest pressures in the ventricles and arteries occur during ventricular diastole
201
Define pulse pressure?
- difference between systolic and diastolic pressures
202
What does MAP (mean arteriole pressure) = ?
- diastolic pressure + 1/3 (pulse pressure)
203
How is mean arterial blood pressure determined?
- blood volume
- effectiveness of the heart as a pump
- resistance of the system to blood flow
- relative distribution of blood between arterial and venous blood vessels
204
How is blood volume determined?
- fluid intake
- fluid loss
205
How is the effectiveness of the heart as a pump determined?
- heart rate
- stroke volume
206
How is resistance of the system to blood flow determined?
- diameter of the arterioles
207
How is the relative distribution of blood between arterial and venous blood vessels determined?
- diameter of the veins
208
What system has the a rapid response to control blood pressure?
- cardiovascular system
209
What system is slower to respond to control blood pressure?
- the kidneys
210
How does the cardiovascular system respond to increased blood pressure?
- by vasodilation
or
- by decreasing cardiac output
211
How does the kidneys reduce blood pressure?
- excretion of fluid in urine
212
What happens when blood volume increases?
- increased blood pressure
213
Which organ is responsible for removing excess fluid from the body?
- the kidneys
214
What if blood pressure is too low?
- lost fluid volume compensated through drinking (slow)
- intravenous infusion (rapid) - IV
- vasoconstriction (rapid)
- sympathetic stimulation of the heart?
215
What is heart rate determined by?
- rate of depolarization in autorhythmic cells
216
What is stroke volume determined by?
- force of contraction in the myocardium
217
Define hyperaemia
- hyperaemia is a locally mediated increase in blood flow
218
Active hyperaemia is like?
- exercise
219
Reactive hyperaemia is like?
- after measuring blood pressure
220
What influences arteriolar resistance?
- influenced by both local and systemic control mechanisms
221
What is myogenic auto regulation?
- adjusts blood flow
222
What do paracrine signals influence?
- vascular smooth muscle
223
Local factors?
- can have greater impact on vessel diameter than catecholamines like during exercise hyperaemia
224
What chemicals mediate vasoconstriction?
- norepinephrine (alpha receptors)
- vasopressin
- angiotensin II
225
What chemicals mediate vasodilation?
- epinephrine (beta 2 receptors)
- nitric oxide
- adenosine
- decreasing O2; increasing CO2, H+, K+
- natriuretic peptides
226
What happens to distribution of blood during physical activity?
- majority (88%) goes to skeletal muscles
227
What does homeostatic regulation of the cardiovascular system aim at maintaining?
- adequate blood flow to the brain and heart
228
What is the desirable blood pressure?
- 120mmHg (systolic)
- 80mmHg (diastolic)
229
What are blood vessels comprised of?
- smooth muscles
- elastic and fibrous connective tissue
- endothelium
230
What is blood composed of?
- Plasma (water, proteins, organic molecules, ions and dissolved gases)
- Cellular elements (red blood cells, platelets, white blood cells)
231
What are red blood cells also called?
- erythrocytes
232
What are platelets also called?
- megakaryocyte
233
What are white blood cells also called?
- leukocytes
234
What are the functions of plasma?
- transports materials around the body
- solvent for cellular elements
235
What manages plasma?
- primarily the kidneys
- Involves the absorption and excretion of water
236
What does the presence of proteins in the plasma do?
- makes the colloid osmotic pressure of the blood higher that that of the interstitial fluid.
237
What does colloid osmotic pressure do?
- pulls water from the interstitial fluid into the capillaries and offsets filtration out of the capillaries created by blood pressure
238
What protein is most prevalent in blood?
- albumins
239
What does the protein albumins do?
- transport free fatty acids
240
What do plasma portend do generally?
- act as carriers, participate in blood clotting, and defend against foreign invaders.
- create colloid osmotic pressure
241
What are the two divisions to white blood cells?
- phagocytes
- granulocytes
242
What are all the white blood cells? (LMNOP)
- lymphocytes
- monocytes
- neutrophils
- eosinophils
- basophils
243
Define hematocrit?
- percentage of total blood volume that is occupied by packaged red blood cells
244
What is the normal range of hematocrit in a male and female?
- males: 40 - 54%
- females: 37-47%
245
Define hemoglobin?
- the oxygen-carrying capacity of red blood cells
246
What is the normal range of hemoglobin in males and females?
- 15
247
Where is hemoglobin located?
- inside a red blood cell
248
How much oxygen can on hemoglobin bind?
- 4 oxygens
249
How much oxygen can be transported in a fully saturated (1 gram) Hb?
- 1.34ml of O2
250
What does a RBC not have which allows for biconcave shape?
- a nucleus
251
What is a downsize to RBCs?
- they live 120 days (no DNA to replicate)
252
What is a hemoglobin made up of?
- 2 beta chains
- 2 alpha chains
253
Define anemia
- occurs when you do not have enough red blood cells OR when your red blood cells do not function properly
254
What value of hemoglobin does a person have to be diagnosed anemic?
- men: less than 13.5gm/dl
- woman: less than 12.0gm/dl
255
What are the types of anemia?
- sickle cell disease
- iron deficiency anemia (female athletes)
- hemolytic anemia
256
How to calculate O2 content in red blood cells per 100ml of blood
- amount of hemoglobin (mass) x amount of O2 bound to hemoglobin x % saturation at a given PO2
257
What is the typical hemoglobin mass/ 100ml blood?
- 15g
258
What is the saturation of arterial blood?
- 100%
259
What is the saturation of venous blood?
- 75%
- 1.00ml of O2
260
What is O2/L of blood for individuals with normal Hb?
- 201ml
261
What is O2/L of blood for individuals with anemia?
- 134ml
262
Where are blood cells produced?
- in bone marrow
263
What bone produces the most RBCs?
- the femur
264
What is hematopoiesis?
- production of blood cells
- 25% RBCs
- 75% WBCs
265
What is hematopoiesis controlled by?
- cytokines --> interleukins
266
What are cytokines?
- are peptides or proteins released from one cell that affect the growth or activity of another cell
267
What is erythropoietin?
- regulates red blood cell production
268
What is trhomboepoietin?
- regulates platelet production
269
What are colony stimulating factors?
- regulates leukopoiesis
270
What cytokines are involved in hematopoiesis?
- erythropoietin
- thrombopoietin
- colony stimulating factors
271
Sites of production for erythropoietin?
- kidney cells
272
Sites of production for thrombopoietin?
- liver
273
Sites of production for colony stimulating factors?
- endothelium and fibroblasts of bone marrow, leukocytes
274
Why don't RBCs live as long in athletes?
- mechanical factors
275
Define hematocrit or "CRIT"
- ratio of red blood cells to plasma
- expressed as a percentage
276
Define mean corpuscular volume?
- size of red blood cells
277
What is the stimulus for erythropoietin release?
- low O2 levels in the tissue
- hypoxia
278
What is stimulated after hypoxia is detected?
- hypoxia - inducible factor 1
279
What does HIF-1 do?
- increases EPO synthesis in the kidneys
280
What is required for hemoglobin synthesis?
- iron
281
What is a Heme
- a ring with an Fe atom in the centre
282
Where does Iron for hemoglobin come from?
- diet
283
Where is excess iron stored?
- in liver by ferritin
284
What are remnants of heme groups converted to?
- bilirubin --> excreted as bile
285
What is jaundice a result of?
- elevated levels of bilirubin
286
What are platelets?
- cell fragments from megakaryocytic
287
What are life spans of platelets?
- 10 days
288
What do platelets do?
- stop blood loss, immunity, and inflammation
289
What kind of feedback is platelet plug formation?
- postive feedback
290
Steps in a platelet plug formation?
- exposed collagen binds and activates platelets
- release of platelet factors
- factors attract more platelets
- platelets aggregate into platelet plug
291
How are platelet plugs restricted to the site of injury?
- prostacyclin
292
What do intrinsic and extrinsic pathways lead to?
- generation of thrombin
293
What does coagulation do?
- converts a platelet plug into a clot
294
What is the clotting protein?
- fibrinogen
295
How does all blood cells develop?
- from a pluripotent hematopoietic stem cell
296
What triggers platelet adhesion and platelet aggregation?
- exposed collagen
297
What do anticoagulants limit?
- the extent of blood clotting within a vessel
298
define mean corpuscular hemoglobin?
- amount of hemoglobin per RBC
299
define mean corpuscular hemoglobin concentration
- amount of hemoglobin per volume of one red blood cell
300
define thrombus?
- a blood clot that adheres to the undamaged wall of a blood vessel
301
Respiratory system functions
- exchange of gases between the atmosphere and the blood
- homeostatic regulation of body pH
- protection from inhaled pathogens and irritating substances
- vocalization
302
Total pulmonary ventilation value
- 6L/min: resting
303
Total alveolar ventilation value
- 4.2L/min: resting
304
Maximum voluntary ventilation value
- 125 - 170L/min
305
Resting respiration rate
- 12 breaths/min
306
Resting tidal volume
- 500ml
307
Define eupnea
- normal quiet breathing
308
Define hyperpnea
- increased respiratory rate and/ or volume in response to increased metabolism
- ex: exercise
309
Define hyperventilation
- increased respiratory rate and/ or volume without increased metabolism
- ex: blowing up ballon, or emotional
310
Define hypoventilation
- decreased alveolar ventilation
- ex: asthma
311
Define tachypnea
- rapid breathing
- usually increased respiratory rate with decreased depth
- ex: panting
312
Define dyspnea
- difficulty breathing
- ex: various pathologies, or hard exercise
313
Define apnea
- cessation of breathing
- ex: holding breath
314
What does the respiratory system to do air?
- warms it
- adds water vapour/ humidify
- filters out foreign material
315
What does the upper respiratory system include?
- pharynx
- voal cords
- esophagus
- nasal cavities
- tongue
- larynx
- trachea
316
What does lower respiratory system include?
- right lung
- left lung
- left bronchus
- right bronchus
- diaphragm
317
How many lobes does the left lung have?
- 2
318
How many lobes does the right lung have?
- 3
319
Define bronchoconstriction?
- increases resistance
- parasympathetic
320
Define brochodilation?
- decreases resistance
- sympathetic
321
What is pleural fluid?
- lowers friction between membranes
- holds lungs tight against the thoracic wall
322
What encloses the lungs?
- pleural sacs
323
What does the respiratory cycle include?
- one inspiration and one expiration
324
What is used to measure pulmonary function?
- spirometer
325
What are the four lung volumes?
- tidal volume
- inspiratory reserve volume
- expiratory reserve volume
- residual volume
326
What is vital capacity?
- tital volume + IRV + ERV
327
What is total lung capacity?
- VC + RV
328
What is inspiratory capacity?
- Tidal volume + IRV
329
What is functional residual capacity?
- RV + ERV
330
Define tidal volume
- volume that moves during a respiratory cycle
331
Define inspiratory reserve volume (IRV)
- additional volume above tidal volume
332
Define expiratory reserve volume (ERV)
- forcefully exhaled after the end of a normal expiration
333
Define residual volume (RV)
- volume of air in the respiratory system after maximal exhalation
334
Where does flow take place?
- from higher to lower pressure
335
What creates pressure gradients?
- a muscular pump
336
How does air flow into the lungs?
- when pulmonary (alveolar) pressure is lower than atmospheric pressure
337
When does inspiration occur?
- when alveolar pressure decreases
338
When does expiration occur?
- when alveolar pressure increases
339
What does Boyle's Law describe?
- describes pressure-volume relationships
- the inverse relationship between pressure and volume
340
What does Dalton's law describe?
- total pressure equals sum of all partial pressures
341
What is the normal sub atmospheric intrapleural pressure?
- -3mmHg
342
What happens when alveolar pressure = atmospheric pressure?
- no air flow
343
What happens when alveolar pressure is less than atmospheric?
- air flows in
344
What happens when alveolar pressure is greater than atmospheric?
- air flows out
345
What do type one alveolar cells do?
- gas exchange
346
What do type two alveolar cells do?
- produce surfactant
347
What are other features of alveolar cells?
- compliance: related to connective tissue and elastin and collagen
- ventilation perfusion matching association with capillary blood flow and alveolar ventilation
348
What does surfactant do?
- reduces surface tension and this increases compliance, which decreases the work of breathing
349
Where is more surfactant present?
- in smaller alveoli to equalize pressure between alveoli
350
What is Newborn respiratory distress syndrome?
- premature babies born with inadequate surfactant
351
What is alveolar ventilation?
- the amount of "fresh" air that reaches the alveoli each minute
352
How is gas exchange maximized?
- perfusion of blood past alveoli is matched to alveolar ventilation
353
What is bronchiole diameter mediated by?
- CO2 levels in exhaled air
354
What is VE?
- Total pulmonary ventilation
355
How to calculate VE?
- Tidal volume x breathing frequency
356
How to calculate alveolar ventilation?
- ventilation x (tidal volume - dead space)
357
What determines breathing efficiency?
- rate and depth of breathing
358
What is the thoracic cavity bound by?
- ribs
- spine
- diaphragm
359
What is hypoxia?
- too little oxygen
360
What is hypercapnia?
- increased concentrations of carbon dioxide
361
What do you have to do when calculating partial pressure of gas in humid air?
- subtract the water vapour pressure from the total pressure
362
How do you calculate VO2 (fick equation)?
- Q x A-VO2difference
363
What does the fick equation calculate?
- the ability to intake, transport, and utilize oxygen
364
What is the typical oxygen consumption rate at rest?
- 250ml/min
365
How is oxygen transported in the blood?
- bound to hemoglobin on RBCs
- dissolved in plasma
366
At rest how much oxygen can a fully saturated hemoglobin carry?
- 20mlO2/L
367
At rest how much oxygen can plasma carry?
- 0.3mlO2/L
368
What factors affect O2-Hb binding?
- anything that changes the conformation of Hb:
- pH
- Temperature
- CO2
- 2,3 - diphosphoglycerate
369
How does exercise affect HbO2 saturation curve?
- shifts the curve downward and rightward
370
How is CO2 transported?
- dissolved in blood
- combined with bicarbonate ions
- bound to Hb
371
How is ventilation regulated?
- respiratory neurons in the medulla control inspiratory and expiratory muscles
- rhythmic pattern of breathing arises from a neural network of spontaneously discharging neurons
- continuous modulation by chemoreceptor and mechanoreceptor linked reflexes and higher brain centres
372
What is the primary stimulus for changes in ventilation?
- primary stimulus for changes in ventilation
373
What are the ventilation changes initiated by the medulla oblongata caused by?
- changes in cerebrospinal fluid pH
374
What pressure must O2 fall below to stimulate the peripheral chemoreceptors?
- 60mmHg
375
How is pH affected by increased CO2?
- decrease in pH
376
How is pH affected by decreased CO2?
- increase in pH
377
What is the most important function of the kidneys?
- the homeostatic regulation of the water and ion content of the blood
- balancing intake of ions and water with their excretion in the urine
378
How much of the fluid that enters the kidney is returned to the blood?
- 99%
379
How much plasma does the kidneys filter each day?
- 180 litres
380
What is the average volume of urine leaving the kidneys per day?
- 1.5 liters
381
How much kidney function must you lose before homeostasis is affected?
- 75%
382
What does the afferent arteriole do?
- controls inflow
383
What does the glomerulus do?
- filtration
384
What does the efferent arteriole do?
- controls outflow
385
What does the peritubular capillaries do?
- reabsorption
386
What does the vasa recta do?
- reabsorption
387
How are the kidneys arranged?
- outer cortex (80%)
- inner medulla (20%)
388
What are the vascular components of the kidney?
- afferent arteriole
- glomerulus
- efferent arteriole
- peritubular capillaries
- vasa recta
389
What are the tubular components of the kidney?
- Bowmans capsule
- proximal tubule
- loop of henle
- distal tubule
- collecting ducts
- distal nephron
- juxtaglomerular apparatus
390
What does the bowman's capsule do?
- is the site of plasma filtration with the glomerulus
391
What is the bowman's capsule and glomerulus referred to?
- renal corpuscle
392
What is the loop of henle do?
- descending and ascending limb
393
What does the collecting duct do?
- converge and drain into the renal pelvis
394
What is the distal nephron?
- distal tubule and collecting ducts
395
What is the juxtaglomerular apparatus?
- ascending limb passes between afferent and efferent between arterioles at the glomerulus
396
What is the kidneys function?
- filtration
- reabsorption
- secretion
397
Filtration in the kidneys
- about 20% of plasma is filtered in the nephron
- remaining 80% flows into the peritubular capillaries
- less than 1% of filtered fluid is eventually excreted
- takes place in the renal corpuscle
398
What is the filtration fraction?
- the percentage of total plasma that enters the renal corpuscle and filters into the tubule
399
Reabsorption in the kidneys
- most reaborsptlon occurs in the proximal tubules
- reabsorption can occur by active or passive transport
400
Secretion in the kidneys
- at distal convoluted tubule
- is the transfer of molecules from the extracellular fluid into the lumen of the nephron
- depends mostly on membrane proteins for transport
- is an active process moving against concentration gradients
401
What causes filtration?
- capillary pressure
402
What two factors have to be overcome in order for filtration to occur?
- colloid osmotic pressure
- hydrostatic pressure
403
What are 3 filtration barriers?
- pores in endothelium
- foot process of podocyte
- basal lamina
404
What increases membrane permeability?
- hormones
405
How do hormones increase membrane permeability?
- by changing the size of the filtration slits or contraction of the mesangial cells
406
How does glomerular filtration rate (GFR) increase or decrease?
- changing renal blood flow
- changing blood pressure
- changing permeability of Bowmans capsule
407
What hormone influences GFR?
- angiotensin II --> vasoconstriction
408
How is GFR regulated?
- inflow ad outflow
- afferent and efferent arteriole
409
What is the myogenic response?
- intrinsic ability of vascular smooth muscle to respond to pressure changes
- similar to auto regulation in other systemic arterioles
410
What is tubuloglomerular feedback?
- a local control path where fluid flow through the tubule influences GFR
- paracrine control
411
What is the average hydrostatic pressure in glomerular capillaries?
- 55mmHg
412
What is maintaining ECF osmolarity equilibrium essential to?
- mining cell volume hemostasis
413
What is law of mass balance?
- mass balance = existing load + intake or metabolic production - excretion or metabolic removal
414
What is water movement driven by?
- the osmotic gradient between the tubule and the interstitial fluid
415
What part of the loop of henle is impermeable to ions?
- the descending section
416
What part of the loop of henle is impermeable to water?
- the ascending section
417
What happens at the vasa recta?
- reabsorption of water and some ion in a countercurrent flow
418
Define diuresis
- removing excess water in urine
419
What does vasopressin control?
- water reabsorption
420
Where is ADH secreted from?
- posterior pituitary gland
421
What is the result of maximal vasopressin?
- urine is highly concentrated
422
What happens when vasopressin is not present?
- urine is dilute
423
What does vasopressin act on?
- on the collecting duct
424
Vasopressin is secreted in response ti three physiological changes:
- increased plasma osmolarity
- decreased blood pressure
- decreased blood volume
425
What is the Na+ stimulus closely related to?
- blood volume and blood pressure
426
What hormone regulates Na+ reabsorption in the distal portions of the nephron and collecting duct?
- aldosterone
427
What type of hormone is aldosterone?
- a steroid hormone
428
Where is aldosterone synthesized?
- in the adrenal cortex (outer part of adrenal gland, on top of the kidney)
429
What is aldosterone secretion regulated by? (wanting more)
- increased extracellular K+ concentrations
- decreased blood pressure
- decreased plasma Na+
430
What is aldosterone secretion regulated by? (wanting less)
- increased ECF osmolarity
431
What two effects does aldosterone have when combining with a cytoplasmic receptor?
- in the early repose, Na+ and K+ channels increase permeability, intracellular Na+ concentrations rise and the Na+-K+-ATPase pump speeds up, and results in increased Na+ reaborsptlon and K+ secretion
- in the slower phase, new ion channels and pumps are inserted in the epithelial cell membranes, and allows for a quicker response and greater capacity for Na+ reabsorption
432
How does your body respond to a drop in blood pressure?
- Renin - angiotensin - aldosterone (RAAS)
433
When do granular cells produce and secrete Renin when?
- they directly detect low blood pressure
- sympathetic neurons that terminate on the granular cells are activated by the cardiovascular control centre when blood pressure decreases
- they receive paracrine feedback from the macula dense cells to increase secretion due to decreased fluid flow in the distal tubule
434
What are the many effects of angiotensin II?
- stimulates adrenal cortex to produce aldosterone
435
What is the pathway of ANG II to increase blood pressure?
- ANG II increases vasopressin secretion
- ANG II stimulates thirst
- ANG II is one of the most potent vasoconstrictors
- Increases sympathetic output to the heart ad blood vessels
- ANG II increases proximal tubule Na+ rweaborption
436
Define natriuresis
- urinary Na+ loss
437
What does natriuresis do?
- decreases blood volume
- dilates affernt artioles, increasing GFR
- decreases Na+ reabsorption in the collecting ducts
- suppress RAS
438
Define atrial natriuretic peptide
- produced in atria myocardial cells
439
Define brain natriuretic peptide
- produced in ventricular myocardial cells and certain brain neurons
440
How is thirst triggered?
- by hypothalamic osmoreceptors
441
Why do people have a salt appetite?
- triggered by aldosterone and angiotensin
442
How is aldosterone inhibited?
- aldosterone can be inhibited when there is high osmolarity and low blood volume despite the presence of ANG II
Kin 101 - Physiology
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