Vasculature
Name 2 main differences between arteries and veins.
* veins have bigger lumen
* arteries have thicker tunica media (smooth muscle layer)
* arteries have more elastic fibers, greater pressure
What happens in the larynx when we swallow?
the entire larynx is elevated, which pushes the epiglottis over the glottis so that food may only enter the esophagus (and not the trachea)
1. Dissolved in the plasma (7%)
2. Bound to hemoglobin (23%)
3. Converted to carbonic acid (70%)
What are the 2 medullary control centers for respiration?
Dorsal Respiratory Group: regulates inspiration for every cycle
Ventral Respiratory Group: only active in forced breathing, expiratory and inspiratory centers
What are the three processes involved in urine formation?
1. Filtration: small solutes from the blood filter through glomerulus like a sieve into tubular lumen
2. Reabsorption: water and solutes return to blood through epithelial cells
3. Secretion: adding solutes from blood into tubules (after filtration, directly into tubules)
Name and describe the 3 layers of the vascular wall
Tunica intima: closest to lumen, endothelial cells
Tunica media: smooth muscle cells - mediate vasodilation/vasoconstriction
Tunia adventitia: connective tissue surrounding whole vessel
Describe the difference between the conducting vs. respiratory zone.
conducting = anatomical dead space, air not participating in gas exchange
respiratory = gas exchange occurs here (in alveoli - also includes respiratory bronchioles)
What does shifting the oxyhemoglobin dissociation curve to the left or right mean?
Right: affinity for oxygen decreases, P50 increases, easier for oxygen to come off of hemoglobin (more acidic pH, higher T)
Left: affinity for oxygen increases, P50 decreases, harder for oxygen to come off of hemoglobin (more basic pH, lower T)
Describe the central chemoreceptors involved in respiratory control.
found in CNS, sensitive to pH changes through carbonic acid (H+ cannot cross BBB)
- CO2 diffuses into CSF, where carbonic anhydrase converts it to H+ ions
- H+ ions there stimulate central chemoreceptors, ventilation increases
Describe paracellular vs. transcellular transport.
Paracellular: movement between the cells through tight junctions (ex. sodium, water)
Transcellular: movement by passing through apical and basolateral membranes using transporters on both surfaces (active or passive) (ex. glucose)
What are the effects of ANP on BP?
Baroreceptors in R atria detect stretch --> ANP release --> vasodilation, renal Na+/water excretion, blocks ADH/norepinephrine/aldosterone
How does surfactant work?
How can oxygen be transported in the blood?
1. physically dissolved (2%) - this is responsible for pO2, dictates gas exchange
2. bound to hemoglobin (98%) (functionally how we actually deliver oxygen to tissues)
Describe the role of peripheral chemoreceptors in respiratory control
- increase ventilation in response to hypercapnia and hypoxemia
- directly sensitive to pH and O2, found in aortic body and carotid bodies
- when CO2 levels elevated, H+ levels are increased --> signal to medulla to increase ventilation
- also get tachycardia
Describe the permeabilities in the different parts of the Loop of Henle.
Descending: permeable to water, not to NaCl --> water leaves, urine gets highly concentrated
Ascending: permeable to NaCl, but not to water --> solutes are reabsorbed, urine becomes less concentrated
Describe how pressures drive exchange across the capillary bed at the arterial and venule end.
At arterial end: HSP > OP, fluids/solutes driven into interstitial fluid
At venule end: OP > HSP, solutes/fluids drawn into capillary bed
Describe the relationship between Patm and Pia at each stage of the breathing cycle.
bottom of exhalation: no airflow, Pia = Patm
inhalation: volume of thoracic cavity increases, alveolar pressure drops (Pia < Patm)
top of inhalation: no airflow, Pia = Patm
exhalation: Pip increases as volume decreases (Pia > Patm)
Describe external respiration.
between lungs & plasma
in alveoli: pO2 = 100, pCO2 = 40
in capillaries: pO2 = 40, pCO2 = 45
oxygen moves into capillaries and CO2 into alveoli --> oxygenates blood and send waste to alveoli to exhale
inflation: prevent over-expansion of the lungs during forced inhale (inhibit DRG, activate expiratory VRG)
deflation: prevent over-deflation during forced exhale (inhibit expiratory VRG, activate inspiratory centers)
both signal via vagus nerve!
acidosis on left side, alkalosis on right side
metabolic alkalosis & acidosis: maintain normal PaCO2 (i.e. not a respiratory issue) but still demonstrate pH issues
respiratory: note abnormal PaCO2 values (too low = alkalosis, too high = acidosis)
Explain the renin-angiotensin-aldosterone system.
low BP triggers renal renin release --> triggers angiotensinogen release from liver, converted to angiotensin I by renin --> ang. I accumulates in lungs, converted to ang. II by ACE --> ang. II increases vasoconstriction, CO, aldosterone release, ADH release --> BP increases
Calculate alveolar ventilation if the tidal volume is 700 mL and the respiratory rate is 17 bpm.
AV = (TV - dead space) x RR
= 9350 mL/min
Describe internal respiration
between plasma and peripheral tissues
in capillaries: pO2 = 95, pCO2 = 40
in tissues: pO2 = 40, pCO2 = 45
oxygen moves into tissues, CO2 moves into blood --> delivers oxygen to tissues and removing waste to bring back to lungs
How does the body adapt to high altitude?
Kidney: releases carbonic acid to counteract alkalosis from decreased pCO2; also secretes EPO to make more RBCs
RBCs: increase production of 2,3-BPG so that easier to unload O2 at tissues (shift curve to right)
Describe the major buffer systems involved in acid-base regulation in the blood and urine.
1) dihydrogen phosphate contributes to phosphate buffering system in urine and ICF
2) amino acids contribute to protein buffering system in ICF/ECF - can receive or donate H+
3) carbonic acid can dissociate into H+ and bicarb or convert to CO2 for excretion in lungs (acidosis: bicarb is reabsorbed; alkalosis: bicarb is secreted)
4) PT generates ammonia (NH3+) through glutamine breakdown, which can buffer H+ in lumen