Human Physiology Exam 3 Review Slides PDF

Exam 3 Review Lec 15 Respiration Mechanics General Flow during External Respiration KEY FUNCTIONS - Exchange of gases between atmosphere and body - Regulation of body pH (7.35-7.45) - Protect respiratory membrane from inhaled pathogens - speech 1. 2. 3. 4. Ventilation: atmosphere → lung Excha...

Exam 3 Review Lec 15 Respiration Mechanics General Flow during External Respiration KEY FUNCTIONS - Exchange of gases between atmosphere and body - Regulation of body pH (7.35-7.45) - Protect respiratory membrane from inhaled pathogens - speech 1. 2. 3. 4. Ventilation: atmosphere → lung Exchange: lung → blood Transport of gases in the blood Exchange: blood → cells Bicarb Equation!!! - Have this memorized - Useful in understanding how the respiratory system relates to body pH Structure Airway Epithelium -.Goblet cells secrete mucus -- traps inhaled particles and dust -.Ciliated epithelial cells push mucus out towards pharynx Alveolar Structure -.Increased quantity moving down, decreases diameter -.Cross-sectional area decreases down -.Specialized for gas exchange (~300 um diameter, 0.2 um thick, <1 um) -.Type I for gas exchange -.Type II synthesize surfactant (decreases surface tension) Pulmonary Circulation Inspiration: external intercostal and Important muscles to know: diaphragm contract active expiration, Expiration: external intercostal and inspiration, accessory diaphragm relaxes (passive muscles of inspiration process) Mechanics of Gas Exchange -- Gas Principles 1. Dalton’s Law: total pressure of mixture of gases is the sum of the pressures of the individual gases 2. Gases move from regions of high to low pressure 3. Boyle’s Law: volume and pressure are inversely related 4. Amount of gas that dissolves in a liquid is determined by the partial pressure of the gas, the solubility of the gas, and the temperature Note: importance of pleural sac -.Thin layer surrounding lungs -.Creates slight vacuum -.Pressure is less than atmospheric at the end of expiration -.Intrapleural pressure is always negative due to forces in opposite directions At the end of expiration, there is no air flow = no pressure gradient Inspiration -.Alveolar pressure decreases → air flows in (remember #2 mechanics of gas exchange) Expiration -.Alveolar pressure increases → air flows out Very important diagram to know! -.Make sure you understand the graphs and what is actually happening in the body Compliance: makes it easier for the lung to expand -.Intrinsic elastic properties -.Surface tension (surfactant) Surfactant -.Released from Type II alveolar -.Lowers surface tension of the water later at the alveolar surface (increases compliance) -.Greater effect in smaller alveoli -.Increased concentration when taking deep breaths Lec 16 Respiration Gas Exchange Divert blood flow away from alveoli that are not working well Systemic: send blood when you have a dec O2 Pulmonary: goal is to oxygenate blood, so you will decrease blood flow where there is a decrease in O2 Some factors that might influence gas exchange? ● ● ● ● O2 content of air Alveolar ventilation Surface area Diffusion distance More than 98% of the O2 in blood is bound to hemoglobin in RBCs, and <2% in plasma Hemoglobin has 4 subunits ● Positive cooperativity ● Percent saturation ● Synthetic heme group binds oxygen Hemoglobin-O2 binding curve ● ● ● Positive cooperativity Sigmoidal Shift to the right = lower affinity = more O2 delivery to tissue Hemoglobin-O2 binding curve Shift curve to right → O2 readily dissociates from hemoglobin → increase O2 delivery to tissues ● High Temperature ● Low pH ● 2,3 DPG CO2 Transport in Blood Lec 17 Respiration Regulation Lec 18 Renal Anatomy & Basic Mechanics BALANCE: Input = Output Functions of the Kidneys • • • • • • • • • Excretion of metabolic wastes Excretion of foreign substances (e.g., toxins, drugs) Regulation of body fluid osmolality Regulation of electrolyte conc. (like Na+, K+, Ca2+) Maintenance of water balance and electrolyte balance Contributes to maintenance of body pH Regulation of erythrocyte number (through erythropoietin) Regulation of blood pressure Glucose production 1,000,000 nephrons per kidney ~20% are juxtamedullary nephrons ● ● ● Whenever you see convolutions, think higher surface area, higher diffusion (if applicable) Bowman’s capsule is in series with peritubular capillary forming a portal system. Having the afferent and efferent arteriole allows for fine control of blood entering and leaving capillaries due to presence of smooth muscles in arteries. Juxtaglomerular cells: renin releasing cells (from angiotensin system) excreted < filtered excreted > filtered excreted = 0 Filtration = net filtration pressure X Kf 3 filtration layers: ● ● ● Capillary endothelial cells (highly fenestrated) Basal lamina (non-cellular protein matrix) Podocytes (filtration slits) The foot processes of podocytes make up the filtration slits GFR is tightly regulated across a large range of blood pressure. (80-180 mm Hg) due to the presence of arterioles in the portal system. MAP changes but Glomerular pressure is controlled through arterioles. Two mechanisms contribute to autoregulation: ● ● Myogenic control (Negative feedback - increased pressure causes arterioles to contract, generated by muscles) Tubuloglomerular feedback (Na delivery to distal tubule is ‘sensed’ in the macula densa, which influences the afferent and efferent arterioles) (Negative feedback) Tubuloglomerular feedback Consider a substance in blood that is filtered but neither reabsorbed or secreted; it is subsequently excreted (for example, inulin): GFR X Ps = Us X V (where Ps is the plasma concentration of the substance, Us is the urinary concentration of the substance, and V is the urine volume collected in some period of time) [This is stating that the amount filtered per unit time (the left side of the equation) is the same as the amount excreted per unit time (the right side of the equation.] so we could determine GFR by: GFR = V X Us / Ps (again, provided that the substance is filtered but neither reabsorbed or secreted) Inulin – polysaccharide, artificially administered, filtered by kidney but not reabsorbed or secreted; Creatine is another measure (some secretion, slightly overestimated, reasonable estimation for major kidney disease) Lec 19 Renal - General Processes & Water Handling How does the clearance and GFR relate to net reabsorption or secretion ● ● ● 66% of reabsorption occurs in the proximal tubule Anions get brought with the gradient Losing water causes other solutes concentrations (like potassium) to increase ○ This lets K+ move into across ● ● Movement across Na+ is down its concentration gradient Note the types of transport used to get the solutes to where they have to be Max amount of glucose that can be transported! Any more means you have maxed you can reabsorbed… so you excrete! ● ● ● ● ● The proximal tubule has a ton of aquaporins -> this is why there is a lot of water absorbed Other parts of the nephron do not have water Uptake of Sodium and Water is isotonic Concentration of glucose does not have an impact on the osmolarity. As long as there is not a lot of glucose, all of it will be absorbed. ● What happens when you drink water? ○ Plasma osmolarity stays the same ○ Flow goes up, while urinary solute stays the same ● Osmolality receptors are stretch indicated ○ As the cell shrinks, they will fire more frequently ● The descending loop and ascending loop are different ○ Descending is very permeable to aquaporins ○ Ascending is permeable to solute,not water ○ Note the red and green arrows on the diagram ○ Sodium Potassium is super important ○ Since the ascending tube in impermeable to water there is osmotic pressure that is created Lec 20 Renal - Ion Homeostasis