Types of Airways
+ negative pressure breathing explained v2
+ two types of alveoli
Conducting airways: trachea, bronchi, and all but last few brancioles
Respiratory airway: respiratory bronchioles, alveolar ducts and sacs – lots of SA for exchange
Negative pressure breathing explained:
- Diaphragm and intercostal rib muscles contract and move downwards, expanding the cavity and causing a drop in pressure within the lungs (negative pressure)
- Air from the environment (positive pressure) rushes inwards to equilibrate pressure
- Tidal ventilation mixes fresh inhalation with stale air + Convective motion of air ceases inside alveoli – small diameter and single endothelium layer allows for sufficient diffusion of O2 and CO2
Specific naming of serous membranes in regards to the cavity / organ (5)
- Serosa: aka serise fluid; thin, double layered membrane that covers the walls of VENTRAL cavities and outer surfaces of organs
- Parietal serosa: lines cavity walls → contrast to Visceral serosa, which folds in on itself to cover organs WITHIN the cavity walls
- Parietal peritoneum: associated with lining of abdominopelvic cavities → contrast to visceral peritoneum, which covers the organs in the abdominopelvic cavities
- Parietal pericardium: lines the pericardial cavity → contrast to visceral pericardium, which covers the heart
- Parietal pleurae: line the walls of the thoracic cavity → contrast to visceral pericardium, which covers the lungs
Types of Alveoli (2)
+ Gas exchange
+ Gas diffusion
Alveoli:
- Type 1: make up bulk of membrane → has a membrane responsible for gas exchange
- Type 2: secrete the surfactant (mixture of lipids and proteins) that reduce surface tension in water (reduces the H bonding of water to reduce the heavy presence of water in the alveoli) → no water film to prevent gas exchange
Gas exchange:
- In alveoli, larger gradient for O2 vs CO2 yet amounts of gas exchanged are equal because O2 solubility is 1/20 of CO2 solubility
- At sites of gas exchange in the body tissues, O2 will diffuse from blood in the systemic capillaries into the body tissues (via interstitial fluid) and of CO2 in reverse direction
Gases always diffuse from high partial pressure to low partial pressure
- Total pressure of a mixture of gases is the sum of individual pressures exerted by each gas’ partial pressure (Px), which is proportional to its concentration → Therefore, in air, gases will always diffuse from [high] to [low], or from high Px to low Px
- BUT IN AN AQUEOUS SOLUTION, gases will differ in their solubilities, which will complicate the partial pressure and concentrations → Therefore, diffusion of a gas btwn the atmosphere and an aqueous solution may not move from [high] to [low] but ALWAYS from high Px to low Px
Types of Circuits for the Mammalian Cardiovascular System (2)
Pulmonary: pumps out O2 poor blood from the pulmonary artery to the right and left lungs → shorter pathway, therefore low pressure circuit
Systemic: pumping of O2 rich blood from the aorta to the systemic circuits / rest of body; can diffuse into respiring tissues → longer pathway, requires higher pressure
* also explains why left side of the heart is thicker in muscle than the right
Pulmonary and systemic circuits are completely separate in mammals and birds → closed circulatory system
– Circuits are in series (not parallel) → equal volumes of blood pumped BUT at different pressures (systemic is higher than pulmonary) bc of the locations that need to be oxygenated
Circulatory System
- functions (3)
- defining attributes
Functions:
- Transport nutrients, wastes, respiratory gases, hormones, lymphocytes
- Stabilize internal pH
- Regulate body temperatures
Defining attributes: transport of oxygen is most pressing / urgent, therefore minute to minute changes in tissue demand for O2 will drive changes in the rate of blood flow
DIFFERENTIATION OF BLOOD CELLS (2)
+ erythrocytes
All blood cells are derived from the same connective tissue source (Stem cells in bone marrow) → yield lymphoid and myeloid
- Lymphoid: lymphocytes → B and T cells
- Myeloid: everything else → basophils, eosinophils, neutrophils, monocytes, erythrocytes
Erythrocytes:
- biconcave cell that is primarily made of hemoglobin (binds with O2 and Co2; helps to buffer pH)
- anucleate (NO NUCLEUS); also free of organelles (start off then rid themselves) → thus, cannot make proteins and will die pretty fast (120 days) → shredded to bits by macrophages in the SPLEEN and recycled for proteins / irons (toxic) / heme (transported to liver for bile production) / etc → Stercobilin: pigment of feces; derived from the breakdown of erythrocytes
Following the heart through a single cardiac cycle – pressure
+ ECG waves timeline
WHOLE HEART DIASTOLE: 0.4 seconds; AV valves open while SL valves closed bc P(atria) > P(ventricles); ventricles fill with deoxygenated blood
ATRIAL SYSTOLE and VENTRICULAR DIASTOLE: 0.4 seconds; AV valves open while SL valves closed bc P(atria) > P(ventricles); ventricles fill with deoxygenated blood
INITIAL OF VENTRICULAR DIASTOLE: P(ventricles) increase
- When P(ventricles) > P(atria), AV valves close = LUB SOUND
- When P(ventricles) > P(aorta), SL valves open
END OF VENTRICULAR DIASTOLE: P(ventricles) decrease
- When P(aorta) > P(ventricles), SL valves close = DUB SOUND
- When P(atria) > P(ventricles), AV valves open; ventricles begin to refill
(P) Signals from SA node spread throughout atria
(PQ) Signals are delayed at the AV node
(Q) Bundle branches pass signals to heart apex
(RS) Signals spread throughout ventricles via Purkinje fibers
(T) Relaxation as the signals stop contracting.
Heart anatomy
- auricles
- sides pathway
Valves maintain one-way flow of blood (no backflow)
1. Atrioventricular valves:
– Tricuspid: present in the right atrioventricular valve
– bicuspid: present in the left
⇒ “tri before you bi” make sure it’s “right before you leave (left)”
2. Semilunar valve: three flaps; bases of aorta and pulmonary artery
Right side receives venous return via VENA CAVA and pumps blood via PULMONARY ARTERY towards the lungs
– Veins will always return blood to the heart no matter the O2 content.
Left side receives oxygenated blood from lungs via PULMONARY VEINS and pumps blood into systemic circuit via the AORTA
Heart anatomy
- auricles
- sides pathway
Regarding venous return
Valves maintain one-way flow of blood (no backflow)
1. Atrioventricular valves:
– Tricuspid: present in the right atrioventricular valve
– bicuspid: present in the left
⇒ “tri before you bi” make sure it’s “right before you leave (left)”
2. Semilunar valve: three flaps; bases of aorta and pulmonary artery
Right side receives venous return via VENA CAVA and pumps blood via PULMONARY ARTERY towards the lungs
Left side receives oxygenated blood from lungs via PULMONARY VEINS and pumps blood into systemic circuit via the AORTA
Veins will always return blood to the heart no matter the O2 content. Venous return dependent on:
- Skeletal muscle pumps
- Respiratory pumps
- Sympathetic vasoconstriction of veins
Influences that affect SA node
- increase
- decrease
INCREASE:
- Intrinsic: higher temperatures – SA node sets pace; increases when atria stretched during venous return → think about the volume of blood that is returning to your heart. During exercise, the skeletal muscles are pushing large amounts of blood back, which will stretch the atria
- Extrinsic: sympathetic stimulation of SA node by norepinephrine, epinephrine, thyroxine
DECREASE: extrinsic only
- Parasympathetic stimulation via acetylcholine
- Ionic imbalances
Influences that affect SA node
- increase
- decrease
INCREASE:
- Intrinsic: higher temperatures – SA node sets pace; increases when atria stretched during venous return → think about the volume of blood that is returning to your heart. During exercise, the skeletal muscles are pushing large amounts of blood back, which will stretch the atria
- Extrinsic: sympathetic stimulation of SA node by norepinephrine, epinephrine, thyroxine
DECREASE: extrinsic only
- Parasympathetic stimulation via acetylcholine
- Ionic imbalances
Arterioles (2)
- equation
- sources of resistance (3)
Vasodilate in response to low [O2]m pH, high [CO2] and by release of nitric oxide from endothelial cells → local response
Constrict via sympathetic stimulation (and endothelin, a local paracrine) → basically control how much blood is passing through / at what pressure
Flow in mL/min = P(in) - P(out) / R
- pressure in minus pressure out, all over radius
Three sources of resistance:
- Blood viscosity → blood is v viscous; higher viscosity = higher friction
- - The more red blood cells, the more viscous, the more resistant it is to pumping - Vessel length → the longer the vessel, the more SA for friction
- Vessel diameter → the bigger the diameter of the vessel, the more SA for friction
- - Reduction of vessel radius increases resistance by power of four → eg. reduce by 2 of vessel radius = increase resistance by 16 (4^2)
Capillaries
- vessel types (2)
- fluid exchange
- Metarteriole: link btwn arterioles and capillary bed and venules; serves as vascular shunt when precapillary sphincters are closed
- True capillaries: actual site of exchange; has precapillary sphincters that act as a valve to regulate blood flow into the capillary
- - influenced by local chemical conditions and arteriolar nerve fibers (sympathetic)
* * every cell is within 10 microns of a capillary, allowing for optimum diffusion of necessary nutrients
Hydrostatic pressure pushes plasma out of the capillary via open clefts btwn endothelial cells (leakage) BUT osmotic pressure maintained by blood proteins (esp albumin) brings it back in
- NFP = net filtration / fluid pressure → In arteries, will have NFP of +9mmHg ;; In veins, will have NFP of -9mmHg
- No RBC or proteins bc cannot fit through the cleft, therefore remain in the capillary
Interrelationship of Blood Vessels, Blood Flow Velocity, and Blood Pressure
- water example
- compare to capillaries
- BP as it travels through the body
Water example: Water doesn’t compress under pressure THEREFORE volume of water moving through a hose exits from a narrow nozzle at a higher speed so that volumes remain equal
Compare to capillaries: Capillaries are NARROWER than arteries THEREFORE velocity in capillaries is the slowest (0.1cm / sec) → Slow velocity in capillary is good bc then allows for exchange btwn capillaries and interstitial fluid
– compare to that of arteries, which is 50cm/sec
Blood pressure highest nearest course of contraction (ie ventricles) and then dissipates due to the resistance generated by narrowing diameters of the tiny arterioles and capillaries → largest drop off in pressure is btwn the arteries and arterioles
Monitoring and maintenance of blood pressure
- Short term (3)
- Long term (2 ; 2sub2)
SHORT TERM REGULATION
- Baroreceptors: in carotid sinuses and aortic arch; detects changes in pressure; send impulses to cardiovascular center in medulla oblongata (aka brainstem) to adjust tension of arterial wall; FAST RESPONSE
- Chemoreceptors: Nearby baroreceptors; measure CO2 concentration and pH → the higher the concentration, the lower the pH
- - Also sent to the brainstem, which will send the electrical impulses to the SA node to beat faster in order to take in more O2, thereby increasing the pH - Hormonal controls: sympathetic stimulation of the SA node via norepinephrine, epinephrine, and thyroxine
LONG TERM REGULATION
- Direct = increased blood volume increases filtration rate of kidneys, increasing urine volume, and (eventually) reducing blood volume and pressure
- Indirect via hormones (at low pressures) to increase thirst
Hemoglobin
- composition and naming
- honorary enzyme
- solubility of O2 in water
Polypeptide bc has two alpha globin + two beta globin chains, each of which can carry one iron containing heme → each heme can bind one molecule of O2
– HbO2 = oxyhemoglobin, HbCO2 = carbaminohemoglobin
HONORARY ENZYME bc O2 attaches to the defined bind site via noncovalent interactions causing a conformational shift in the hemoglobin structure → cooperativity: affinity for O2 increases via shape change
– Once released, will start to revert to the original shape and thus lose the other O2 molecules more readily → called something
O2 is poorly soluble in water, therefore hemoglobin can increases the O2 carrying capacity of the blood by 50X
- 5 mL O2 per liter of blood VERSUS 200 mL O2 per liter of blood containing hemoglobin → wow!
- - Good to have the hemoglobin in a cell because if just in the plasma, will make the blood incredibly viscous
Dissociation Curve for Hemoglobin
+ Bohr shift, defined sub 3
functional relationship btwn P(O2) and percent saturation of hemoglobin
- At rest, modest use of O2 at rest leaves a large venous reserve
- During exercise: slight decrease in P(O2) causes a large release of O2 to match metabolic demands
- During vigorous exercise with rapid blood flow (ie P(O2) in lungs reaches only 80 mmHg), blood leaving the pulmonary capillaries is still saturated
Bohr shift, defined: change in hemoglobin’s affinity due to different pH values; triggered by H+ and CO2 binding to globin chains of hemoglobin (cooperativity)
- Allosteric effect at low ph environments will have H+ bind to globin chains causing a conformational shift in hemoglobin structure, reducing its affinity for O2
- Binding of H+ to hemoglobin buffers against blood pH from falling to low
- lower pH, shift right – higher pH, shift left
CO2 Exchanges in systemic and pulmonary capillaries – the science-y bits
Two exchanges happen concurrently
Loading of CO2 and release of O2 from blood in systemic capillaries:
1. 8% of CO2 released from tissues dissolves in plasma; 20% binds to globin chains; 72% diffuses into RBC
2. Carbonic anyhydrase converts CO2 and H20 into H2CO3
3. Chloride shift reduces [HCO3-] inside RBC, which favors diffusion of even more CO2 into RBC
RESULT = binding of H+ to globin chains reduces affinity of hemoglobin to O-
Release of Co2 and loading of O2 into blood in pulmonary capillaries:
1. REVERSE chloride shift allows HCO3- to diffuse back inside RBC where carbonic anhydrase converts it back to CO2
2. CO2 will diffuse into alveoli
RESULT = Loss of H+ binding to hemoglobin increases its affinity for O2
Homeostatic control of breathing
- Set basic ventilation rate and respond to chemosensors in the aorta and carotid arteries
- - Eupnea: basic ventilation at rest → usually 10 - 12 breaths / min but if people know they’re being measured, can fluctuate
- - Hyperpnea: increase of ventilation during exercise → increase by 10x to 20x - pH, P(CO2), and P(O2) sensors monitor blood in aorta and carotid arteries; afferent sensory input to respiratory centers in medulla
- - Afferent: towards the brain
- - Efferent: from the brain
* * Increasing P(CO2) or falling pH (PO2 < 60 mmHG) increase ventilation - Three neural factors involved
- - Psychological stimuli (conscious anticipation)
- - Cortical motor activation of respiratory centers in brain stem
- - Excitatory impulses from proprioceptors in moving joints, muscles, and tendons
Tidal ventilation
vs countercurrent
vs crosscurrent
Tidal ventilation: normal amount of volume inhaled and exhaled; allows for exchange of fresh air with stale air BUT v inefficient bc P(O2) blood exiting respiratory organ < P(O2) in exhaled medium = very inefficient system
– versus X-current exchanges where its the opposite, therefore more efficient
Countercurrent: opposing directions
– Fish: gill arch → water passes through gill filaments allowing for countercurrent gas exchange
Crosscurrent: same direction
– Bird: air passes through posterior air sacs, pick up oxygen in the lungs; air passes through anterior air sacs → two cycles of inhale, exhale to move through both air sacs
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Lab Exam 133
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Lecture Exam 176
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Lab Exam 212
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Lecture Exam 270
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Lab Final64
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Lecture Final: Chapter 2120
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Lecture Final: Chapter 1917
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Lecture Final: Chapter 2017
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Lecture Final: Chapter 2212
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Lecture Final: Chapter 2312
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Lecture Final: Chapter 2414
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Lecture Final: Chapter 2512
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Lecture Final: Chapter 268
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Lecture Final: Chapter 2712
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Lecture Final: Chapter 2813
