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Exam 4 Biol326 2025 FINAL EXAM LATEST
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gas exchange at both the pulmonary and tissue capillary levels, gas exchange involves simple diffusion of oxygen and carbon dioxide down partial pressure gradients - no active transport *ALWAYS diffuse down the gradient from high to low pressure partial pressure each gas exerts a different pressure within a particular space - the pressure exerted by one gas within a mixture Dalton's law pressure exerted by a particular gas in proportionate to the perfect of that gas in the atmosphere venous return where is partial pressure of carbon dioxide the highest? atmospheric exchange partial pressure of oxygen in alveoli is slightly lower than the atmosphere as inspired air becomes saturated with water vapor, which reduces the partial pressure of all other gases inspired air mixed with residual alveolar air alveoli will have higher partial pressure of carbon dioxide than atmosphere due to continued gas exchange with pulmonary capillaries
alveolar gas exchange systemic venous blood = partial pressure of carbon dioxide is 46mmHg and partial pressure of oxygen is 40mmHg partial pressure gradient FAVORS carbon dioxide movement into the alveoli, causing oxygen movement in the pulmonary capillary *blood leaving the pulmonary capillaries = alveolar space increased metabolic rate if systemic tissue metabolic rate increases, bigger gradients for oxygen and carbon dioxide exchange with alveoli more oxygen exchange occurs with alveoli and an increase in ventilation maintains alveolar partial pressure of carbon dioxide and partial pressure of oxygen tissue metabolism oxygen consumed in the mitochondria, which is the final electron acceptor in oxidative phosphorylation *oxygen is produced in the mitochondria, which causes TCA cycle and acetyl CoA formation systemic gas exchange partial pressure gradients favor oxygen movement out of the capillary and carbon dioxide movement into the capillary blood entering systemic capillary partial pressure of oxygen and partial pressure of carbon dioxide are exactly the same as when they left the lungs - exchange only in capillary beds
RBCs produced in red marrow of bones do not contain nuclei or mitochondria shape increases SA for oxygen and carbon dioxide exchange packed full of hemoglobin, glycolytic enzymes, and carbonic anhydrase hemoglobin partial pressure of oxygen is the main factor determining the percent of hemoglobin saturation (how much oxygen is on the surface versus bound to the hemoglobin) allows for extra loading of oxygen - pick up more oxygen in the blood and deliver more oxygen to systemic tissues lungs percent saturation of hemoglobin is high where? (hint: where partial pressure of oxygen is high) tissue cells percent saturation of hemoglobin is low where? (hint: where partial pressure of oxygen is low) true true or false: at tissue cells, oxygen tends to dissociate from Hb, the opposite of saturation concentration of dissolved oxygen what does blood partial pressure of oxygen depend on?
true true or false: oxygen bound to Hb does not contribute to blood partial pressure of oxygen (hint: not oxyhemoglobin) carbon dioxide, acidity, temperature, and 2,3-biphosphoglycerate what factors affect the percent of Hb saturation? (hint: promote loading of oxygen from hemoglobin) Bohr shift carbon dioxide, acidity, temperature, and 2,3-biphosphoglycerate shift the oxygen curve to the right *less carbon dioxide is bound to hemoglobin as blood passes through the lungs *increases Hb's affinity for oxygen true true or false: carbon dioxide, hydrogen ions, and temperature increase, which increase metabolic rate and drive of oxygen off of hemoglobin effect of carbon dioxide partial pressure of carbon dioxide in systemic capillaries is high - carbon dioxide diffuses into the blood - more carbon dioxide in the blood drives oxygen from hemoglobin (decreasing oxygen saturation) carbon dioxide binds to amino acids on polypeptide chains (does not bind to the heme group), which decreases affinity for oxygen = carbamino hemoglobin
hypoxia insufficient oxygen at the cellular level low arterial partial pressure of oxygen - inadequate Hb saturation ex: exposure to high altitude, suffocating environment, or carbon monoxide poisoning Haldane effect deoxyhemoglobin has high affinity for carbon dioxide and H+ - prevents venous blood from having a lower pH *more oxygen is bound to Hb as blood passes through the lungs *reduces Hb's affinity for carbon dioxide/H+ binding alveoli specific part of the lung has low partial pressure of carbon dioxide and high partial pressure of oxygen *gradient favors carbon dioxide flux into the alveoli and oxygen flux into RBCs oxygen-hemoglobin dissociation curve blood's normal partial pressure of oxygen is ~ 100mmHg at the alveoli due to an increase in water content as we move from the pulmonary capillaries to the systemic capillaries, ~ 25% of oxygen is dissociating from Hb venous blood going back to the heart is ~ 75% saturated - not dropping off all the oxygen bicarbonate
- carbon dioxide combines with water to form carbonic acid
- acid dissociates into H+ ions and bicarbonate ions
- carbonic anhydrase catalyzes this reaction - skips carbonic acid intermediary carbon dioxide transport carbon dioxide moves down its pressure gradient from tissue cells into the blood transported by:
- physically dissolved: ~ 10% blood total carbon dioxide content
- bound to Hb: ~ 30% - carbamino hemoglobin (HbCO2), which binds to the globin portion
- as bicarbonate: ~ 60% of carbon dioxide content cardiac muscle myogenic - generates its own signals for contraction (pacemaker) involuntary nerve signals modify rate and strength of contraction respiratory muscles neurogenic - requires stimulus from motor neurons for contraction subject to involuntary AND voluntary signals to modify rate and strength of contractions neural control
- generating of altering inspiration and expiration
- regulation of magnitude of ventilation (to meet needs)
- modification of respirator activity for other purposes how? medulla and pons
if carbon dioxide increases, does alveolar ventilation increase or decrease? decrease if oxygen increases, does alveolar ventilation increase or decrease? increase if hydrogen ions increase, does alveolar ventilation increase or decrease? hypoventilation alveolar ventilation is less than metabolic demands increases partial pressure of carbon dioxide and decreases blood pH hyperventilation alveolar ventilation exceeds metabolic demands decreases partial pressure of carbon dioxide and increases blood pH hypercapnia elevated partial pressure of carbon dioxide in the blood hypocapnia lower partial pressure of carbon dioxide in the blood
respiratory acidosis decreasing blood pH respiratory alkalosis increasing blood pH peripheral chemoreceptors located in the carotid bones and aortic bodies triggered by H+, carbon dioxide, and oxygen *not part of normal respiration (weak influence) central chemoreceptors located in the medulla and inform respiratory control center triggered by H+ generated by CO2 crossing the blood brain barrier *strong influence and easily triggered decreased arterial PO peripheral chemoreceptors increased ventilation PO2 must fall below 60mmHg before peripheral chemoreceptors increase firing rate (this is when O2 saturation really begins to drop off) no
channel closure depolarizes the cell, causes dopamine release, causes afferent neuron to increase impulses sent to the medullary respiratory center 70% what percent of high PCO2 increase in ventilation is central chemoreceptors responsible for? 30% what percent of high PCO2 increase in ventilation is peripheral chemoreceptors responsible for? increase with an increase in high intensity exercise, does PO2 increase or decrease? decrease with an increase in high intensity exercise, does PCO2 increase or decrease? respiratory changes with exercise
- reflexes from body movement
- body temperature increase
- epinephrine release
- impulses from cerebral cortex urinary system consists of urine forming organs (kidneys)
structures that carry urine from the kidney to the outside for elimination from the body: ureters, urinary bladder, and urethra ureters carry urine from the kidney to the bladder urinary bladder muscular sac in the pelvis that stores urine, allowing urination to be infrequent and controlled urethra eliminate the urine from body retroperitoneal position where is the kidney located? (hint: renal fascia, fibrous capsule, perirenal capsule) renal fascia connective tissue that anchors the kidneys fibrous capsule helps the kidneys keep shape and provides connection perirenal capsule
one renal artery and one renal vein what supplies the kidneys? nephrons functional unit of the kidney - the smallest unit that can perform all kidney functions (responsible for urine formation) originate in the cortex of the kidney - contain a long hairpin loop and eventually drains into the collecting ducts that contain urine cortical nephrons 80% of nephrons where the loop barely penetrates medulla-SHORT juxtamedullary nephrons 20% of nephrons where the loop of Henle goes down to the innermost regions of medulla-LONG outer region the renal cortex of the nephron inner region the renal medial of the nephron vascular component contains the afferent arteriole, glomerulus, and efferent arteriole
afferent arteriole supplies blood to the glomerulus (blood ARRIVES here) glomerulus tuft of capillaries that filters protein-free plasma to tubules efferent arteriole carries blood away from the glomerulus and forms peritubular capillaries/vasa recta (blood EXITS from here) tubular component contains Bowman's capsule, proximal tubule, loop of Henle, distal tubule, and collecting duct Bowman's capsule collects glomerular filtrate proximal tubule huge amount of reabsorption and secretion occurs here loop of Henle establishes the osmotic gradient - necessary for varying urine formation
descending limb moves from the cortex to the medulla ascending limb moves from the medulla to the cortex epithelium variation mostly simple cuboidal but exception in thin segments of the lop of Henle and Bowman's capsule (simple squamous) functions of various nephron segments match up with epithelial cell types squamous what type of epithelium does the glomerular capsule and loop of Henle contain? cuboidal what type of epithelium does the proximal convoluted tubule cells, distal convoluted tubule cells, and collecting duct cells contain? glomerular formation, tubular reabsorption, tubular secretion what are the 3 processes in urine formation? glomerular filtration
blood flows from the renal arteries to the afferent arterioles into the glomerulus - from the capillaries of glomerulus, the filtrate moves into the Bowman's space of the glomerulus tubular reabsorption fluid moves from renal tubules into the peritubular capillaries - peritubular capillaries carry the reabsorbed filtrate into venous circulation tubular secretion fluid moves from the peritubular capillaries into the renal tubules and drains into collecting tubules - renal tubules carry the fluid, which eventually leaves the body in the form of urine *requires active transport in form of Na+/K+/ATPase pump *important molecules secreted: H+, K+, and organic ions true true or false: you filter (almost) everything, and take back what you need amount filtered (F) - amount reabsorbed (R) + amount secreted (S) = amount of solute excreted (E) write the equation that is used to calculate the amount of solute excreted given amounts filtered, absorbed, and secreted glomerular filtration indiscriminate - all constituents of blood enter the tubule during filtration (water, wastes, electrolytes, nutrients) only things that do not enter are blood cells and plasma proteins
