1
Q
Functions of the CVS
A
- Transport
- Homeostasis
- Protection (Immune Response)
2
Q
Structures of the CVS
A
- Blood,
- Heart,
- Blood Vessels (Arteries, Capillaries, Veins)
3
Q
Arteries
A
Carry blood away from heart
4
Q
Veins
A
Return blood towards the heart
5
Q
Capillaries
A
Exchange of gases, nutrients and waste products between blood and tissues
6
Q
Heart
A
Muscular pump that establishes pressure gradient for blood flow
7
Q
Heart Chambers
A
Left Atrium, Left Ventricle, Right Atrium, Right Ventricle
8
Q
Septum
A
Dividing wall between left and right sides of heart
9
Q
Pericardium
A
Double-walled sac containing the heart and major blood vessels
10
Q
True/False? - Deoxygenated and Oxygenated Blood Mix in a Healthy Heart
A
False
11
Q
Coronary Arteries
A
Wrap around the heart and transport oxygen to heart
12
Q
Coronary circulation
A
Provides blood to the heart to allow it to pump
13
Q
Functions of Pericardium
A
- Maintains heart position,
- Prevents heart from overfilling
14
Q
Layers of Pericardium
A
- Outer fibrous pericardium,
- Inner serous pericardium (parietal and visceral layer)
15
Q
Location of parietal cavity
A
Between the 2 serous layers
16
Q
Which ventricle has a thicker wall? Why?
A
The left ventricle as it operates at a higher pressure due to pumping blood to entire body minus the lungs
17
Q
Pulmonary Circulation
A
- Blood supply to Lungs
- Operatesat low pressure
- Right side of heart
- Low O2 in Arteries, High O2 in Veins
18
Q
Systemic Circulation
A
- Blood supply to the Rest of the body minus the lungs
- High pressure
- Left side of heart
- High O2 in Arteries, Low O2 in Veins
19
Q
Deoxygenated Blood Pathway
A
Blood enters via the inferior (lower body) and superior (upper body) vena cava where it then enters the right atrium. Blood flows through the tricuspid valve into the right ventricle. Right ventricle contracts and pumps blood through the pulmonary valve into the pulmonary artery, whereby it is carried from the heart to the lungs. In the lungs, the deoxygenated blood undergoes gas exchange in the capillaries where carbon dioxide is exchanged for oxygen.
20
Q
Oxygenated Blood Pathway
A
Oxygenated blood is carried by the pulmonary veins from the lungs to the left atrium. The oxygenated blood flows through the bicuspid/mitral valve into the left ventricle. The left ventricle contracts and pumps blood through the aortic valve into the aorta. The aorta carries the oxygenated blood to the rest of the body.
21
Q
Branches of the Aortic Arch
A
- Brachiocephalic Trunk (supplies blood to right arm and right side of head and neck)
- Left common carotid artery (supplies blood to left side of head and neck)
- Left subclavian artery (blood to the left arm)
22
Q
Papillary Muscles
A
Muscles in the ventricles to prevent valves from opening during contraction. Attached to Atrioventricular valves via chordae tendineae.
23
Q
Semilunar Valves
A
Pulmonary Valve and Aortic Valve
24
Q
Atrioventricular Valves
A
Tricuspid Valve and Bicuspid Valve
25
What is the direction of blood flow?
Unidirectional! Blood must flow through each circuit before returning to the heart
26
Arterioles
Smallest arteries branch into arterioles. Join the arteries to capillaries. Control blood flow and pressure.
27
Venules
Collect blood from the capillaries and join to veins which carry the blood back to the heart. Venules carry wastes from tissues.
28
Functions of the Heart
1. Pumping Blood
2. Oxygen Delivery
3. Nutrient Transport
4. Waste Removal
5. Circulatory Regulation
6. Hormone Transport
7. Immune Response
8. Thermoregulation
9. Gas Exchange
10. Homeostasis
29
Systole
When heart contracts to pump blood out.
30
Diastole
When the heart relaxes after contraction (filling).
31
Events in Cardiac Cycle
Closely integrated system of alternately contracting and relaxing in a rhythmic and coordinated sequence.
32
True/False? - Blood always flows from a region of higher to lower pressure
True
33
True/False? - Heart valves are either open or closed depending on relative pressures on either side of the valve
True
34
Heart Sounds
S1: Closure of the bicuspid and tricuspid valves
S2: Closure of aortic and pulmonary valves
S3: Marks end of filling phase
S4: Atrial contraction but normally not heard
35
End diastolic volume (EDV)
Volume of blood in the ventricle IMMEDIATELY BEFORE ventricular contraction
36
End systolic volume (ESV)
Volume of blood in the ventricle IMMEDIATELY AFTER ventricular contraction
37
Stroke Volume (SV)
Volume of blood pumped per heart beat
38
Formula for Stroke Volume
End diastolic volume (EDV) - End systolic volume (ESV)
39
Cardiac Output (CO)
Volume of blood pumped by each ventricle per minute
40
Formula for Cardiac Output (CO)
Heart Rate (beats/min) x Stroke Volume (ml/beat)
41
Preload
- Volume of blood received by heart
- The amount of stretch during diastole
42
Afterload
Pressure or resistance the heart must overcome when ejecting blood
43
Venous Return
1. Volume of blood returning back to the heart each minute
2. Increased venous return increases EDV
3. Causes stretching of heart muscles
4. Increased venous return stretches the ventricle and makes the next contraction stronger
44
Frank-Starling Law
The greater the end diastolic volume, the greater the force of contraction during systole
45
Effect of increased venous return
1. Increased EDV
2. Stronger Contraction
3. Increased Stroke Volume
46
Two Cell Types in Heart
1. Contractile
2. Non-contractile (Pacemaker)
47
Generation of action potentials in pacemaker cells
Action potentials are generated by pacemaker cells, also called auto-rhythmic cells. These action potential initiate and regulate the heart's rhythmic contractions. An action potential is generated by;
1. A membrane potential drift: due to an influx of sodium ions
2. Threshold Potential: Membrane becomes more positive, reaching its threshold point where calcium channels are activated, allowing calcium to flow into the cell.
3. Upstroke of Action Potential: Triggered by influx of calcium ions, results in a steep increase in membrane potential, depolarising the cell.
4. Repolarization: Potassium channels open, allowing potassium ions to exit the cell. This causes repolarization and the membrane becomes more negative.
5. Pacemaker Potential: After repolarization, cells return to threshold, initiating another action potential.
48
Contractile Cells
1. Composed of tubular myofibrils (repeating sections of sarcomeres)
49
Function of actin and myosin
Bind together and contract for heart contractions to take place
50
Excitation contraction coupling
Conversion of electrical stimulus (pacemaker cells) to mechanical response (cardiac contraction).
51
Gap Junction
Allow electricity/depolarization to travel from cell to cell and these cells contract in coordinated fashion which is important for heart to pump
52
True/False? - Cardiac Pacemaker cells generate impulses spontaneously
True
53
Where does electrical activity mainly occur?
Sinoatrial node
54
Spread of excitation through the heart
- Involves specialised 'conducting tissues'
- controlled by electrical impulses
- originated in the sinoatrial node; this is the heart's natural pacemaker
- Consists of the following process:
1. SA node generates electrical signals spontaneously causing contraction of atria
2. electrical impulse rapidly travels across atria and forces blood into ventricles.
3. impulse reaches atrioventricular node (cells in bottom of right atrium). AV node acts as gatekeeper and delays impulse, allowing ventricles to fill completely. this ensures atria contract before ventricles.
4. After AV node delay, electrical impulse travels down bundle of his (muscle fibres extending from AV node and branch into left and right bundle branches)
5. these bundle branches extend down interventricular septum towards heart's apex.
6. at Apex, branches give rise to purkinje fibres.
7. impulse travels to ventricular walls causing contraction of ventricles from bottom to top - leading to ejection of blood into pulmonary artery and aorta
55
What are the three criteria of spread of excitation of the heart
1. heart chamber must pump as a unit
2. atria should contract together, ventricles should contract together
3. atrial excitation and contraction must be complete before ventricular contraction
56
Is propagation through the AV node fast or slow?
Slow
57
Is conduction along the bundle of his and purkinje fibres slow or fast?
Fast
58
How does ANS change heart rate?
1. heart is innervated by sympathetic and parasympathetic neurons
2. ANS can change rate of depolarisation in SA node (can change heart beat)
3. Can CHANGE action potentials but NOT initiate them
59
How does the PNS regulate heart rate
1. decreases HR via acetylcholine
2. does this by opening potassium channels
3. this causes hyperpolarisation followed by SLOWER depolarisation
60
How does the SNS regulate heart rate
1. stimulated by noradrenaline
2. increases HR
3. does this by opening Na channels
4. this causes rapid depolarisation
61
Three layers of arteries and veins
1. Tunica intima
2. Tunica media
3. Tunica externa
Note: capillaries only have tunica intima
62
Difference in structure of arteries and veins
1. arteries have smaller lumen
2. arteries have a muscular wall
3. veins have smooth muscle
4. arteries have thicker tunica media
5. veins have thicker tunica externa
6. arteries contain elastic lamellae to withstand higher pressure
7. arteries are a pressure reservoir
8. veins are a volume reservoir
63
Coronary sinus
- collection of veins that join together to form a large blood vessel
- drains DEOxygenated blood from heart muscle into right atrium
64
Major blood vessels
Major arteries:
1. Aorta
2. coronary arteries
3. carotid artery
4. renal arteries
Major Veins:
1. Superior Vena ceva
2. inferior vena ceva
3. Pulmonary
4. renal
65
Blood composition
- fluid connected tissues
- composed of erythrocytes (red blood cells)
- Leukocytes (WBC)
- platelets
- ECM (plasma)
66
Function of blood vessels
1. oxygen delivery
2. nutrient delivery
3. waste removal
4. hormone messenger
67
Blood flow formula
Blood flow = pressure gradient/resistance to blood flow
68
Pressure gradient
difference in pressure between the two ends of a vessel
69
Resistance to blood flow
Due to three factors:
1. blood viscosity
2. vessel length
3. vessel radius
70
What is Blood viscosity
thickness of blood which affects its flow
71
Two effects of turbulance
1. increases resistance
2. slows blood flow
72
Regulation of blood flow through organs
Control of blood flow through arterioles
- Regulates blood flow to tissues
- amount of blood delivered can be adjusted determined by arteriolar resistance and organ vascularisation
- arteriolar resistance can be changed by contraction (vasoconstriction) and relaxation (vasodilation)
control of blood flow through capillaries
- Pre capillary sphincters are smooth muscle cells that spiral capillaries which are sensitive to metabollic factors.
- if metabolic activity increases = sphincters relax = increases flow (and vice versa)
control of blood flow through venules
- little to no resistance
- chemically communicate with arterioles to match inflow and outflow
control of blood flow through veins
- returns blood towards heart
- low resistance
- less elastin so less recoil
73
Mean arterial blood pressure
- The driving force of blood flow through organs and tissues
- determined by 2 factors
1. cardiac output
2. total peripheral resistance (sum of resistance of all blood vessels, mainly determined by arterials)
Formula 1 : Cardiac output x total peripheral resistance
Formula 2: diastolic pressure + 1/3 of pulse pressure
74
Systemic blood pressure
1. pumping action of heart to generate blood flow
2. highest in Aorta and declines through the pathway
75
Diastolic pressure
lowest level of aortic pressure when heart is at REST
76
Pulse pressure
difference between systolic and diastolic pressure
77
Arterial Blood Pressure
Determined by two factors:
1. Elasticity (compliance or distensibility) of arteries close to heart.
2. Volume of blood forced into them at any time. Blood pressure near heart is pulsatile (Rises and falls with each heartbeat)
78
Systolic pressure
pressure exerted in aorta during ventricular contraction.
79
Pulse
Throbbing of arteries due to difference in pulse pressures
80
Does the heart spend more time in systole or diastole?
Diastole
81
Intrinsic controls of blood flow
- uses paracrines or properties of muscle tissue
- also known as autoregulation
- eg metabolic or chemical (eg O2 or CO2)
- eg myogenic or physical (eg stretch)
82
extrinsic controls of blood flow
- uses nerves or hormones
- eg neural (sympathetic stimulation)
- eg hormonal (adrenaline/ noradrenaline)
83
Measuring blood pressure
- using a sphygmomanometer
1. wrap cuff around arm superior to elbow
2. increase pressure in cuff until exceeds systolic pressure and brachial artery
3. pressure released slowly and examiner listens to sounds of korotkoff with a stethoscope
84
Short term regulation of blood pressure
- neural controls
- baroreceptors (detect pressure changes, and send info to CCM)
- cardiovascular centre of medulla (CCM)
Baroreceptor reflexes
- located in carotid synosis, aortic arch, and walls of large arteries in neck and thorax
- monitor and detect pressure changes, and send the info to CCM
- the reflex response is an AUTOMATIC response to changes in blood pressure (eg a rise above normal causes reflex to decrease HR and vascular resitance)
cardiovascular centre of medulla (CCM)
- located in medulla
- divided into cardiac centre and vasomotor centre
- receives input from baroreceptors + other afferents
- integrates information
- issues commands to heart, arterioles, and veins via ANS
85
Haemorrhage
decrease in blood volume = decrease in venus return = decrease in stroke volume - decrease in cardiac output = decrease in arterial pressure - decrease of firing baroreceptors = increases HR
