Anatomy block 3 test ws questions

Explain what is meant by mucosa or mucous membrane

A mucosa, or mucous membrane is the name of the lining of all body cavities that open to the outside of the body - such as the hollow organs of the respiratory, digestive and urogenital tracts. These linings are wet or moist and consist of the epithelium that lines the lumen or cavity of the organ, and the connective tissue layer, or lamina propria just deep to the epithelium

What is a countercurrent mechanism

A countercurrent mechanism occurs when fluid flows in opposite directions through adjacent segments of the same tube - these segments are parallel to each other, usually because of a hairpin turn in the tube

Draw a diagram depicting a nephron and label the different regions. Or describe and list the parts of a nephron. Be sure to say which parts are located in the cortex and which are in the medulla

A nephron is made of a renal corpuscle and a renal tubule. The renal corpuscle is composed of the glomerulus (a capillary bed) inside a cup-shaped capsule called the glomerular capsule. The renal tubule is continuous with the renal corpuscle, and consists of a proximal convoluted tubule, a nephron loop (which is a U-shaped structure that dips down into the cortex), and a distal convoluted tubule. The distal convoluted tubule connects to a collecting duct. (The collecting duct isn't actually considered part of the nephron, but should be included every time you practice drawing a nephron.) The renal corpuscles, PCT and DCT are located in the cortex, the nephron loops dip down into the cortex. The nephron loop consists of a descending limb and an ascending limb

Which hormone increases water reabsorption by inserting aquaporins in the cells in the DCT/collecting duct

ADH (antidiuretic hormone)

Which hormone decreases Na+ reabsorption in the DCT

ANP (atrial natriuretic peptide)

How is oxygen transported in the blood? Why isn't more transported directly dissolved in plasma

About 98.5% of oxygen is transported bound to hemoglobin molecules. Each hemoglobin molecule is made up of 4 subunits, each of which has an iron-containing heme group that binds an oxygen molecule. Since there are 4 heme groups, each hemoglobin molecule can carry 4 oxygen molecules if it is fully saturated (100% saturated). Only 1.5% of oxygen is transported dissolved directly in the blood plasma because oxygen is poorly soluble in water (it has low solubility)

Which hormone increases Na+ reabsorption in the DCT

Aldosterone

Which hormone increases the secretion of K+

Aldosterone (K+ is secreted when Na+ is reabsorbed)

Which three hormones have roles in controlling water balance in the body, by acting on salt or water reabsorption at the distal convoluted tubule or collecting ducts? What do they do

Aldosterone increases reabsorption of NaCl - when Na+ is reabsorbed, water follows, so blood volume and blood pressure increases. Antidiuretic hormone (ADH) increases reabsorption of water in the distal convoluted tubules or collecting ducts. ADH inserts aquaporins (water channels) into the cells of the distal convoluted tubule and collecting duct, which increases water reabsorption (by osmosis). Atrial natriuretic peptide (ANP) reduces reabsorption of Na+, so it tends to decrease blood volume and blood pressure

How is carbon dioxide transported from the cells to the lungs

Approximately 7% of carbon dioxide is transported to the lungs dissolved in plasma. Another 20% is transported bound to hemoglobin forming carbaminohemoglobin. The binding site for carbon dioxide is not the same as the binding site for oxygen - while oxygen binds to a heme group, carbon dioxide binds to the globin part of hemoglobin. The remaining 70% of carbon dioxide is transported as a bicarbonate ion in the plasma. This transfer follows the following reaction, CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3- , which can be reversed in the lungs

What gases make up atmospheric air, and how does this differ from the alveolar air

Atmospheric air is composed mostly of (in order of greatest percent contribution) nitrogen, oxygen, water, and carbon dioxide. About 99% of atmospheric air is composed of the combination of nitrogen and oxygen, and carbon dioxide contribute less than 1% together. In alveolar air, the same gases contribute, but the partial pressures of water and carbon dioxide are much higher - because of the moisture added to air in the respiratory passageways, and because of the carbon dioxide produced by the cells during cellular respiration and eliminated in the alveoli (for exhalation)

Define and describe the inter-relationship between atmospheric pressure, intrapulmonary pressure and intrapleural pressure. Include how this relates to air movement into the lungs

Atmospheric pressure is the pressure of the air on the body. Intrapulmonary pressure is the air pressure within the lung air spaces, or alveoli, so its sometimes called the intra-alveolar pressure. Intrapleural pressure is the pressure within the pleural cavity. Relationships: Atmospheric pressure is the same as intrapulmonary pressure in between breaths, because the air in the lungs equilibrates with the outside air. When the intrapulmonary pressure is less than atmospheric pressure, air flows into the lungs. When intrapulmonary pressure is greater than atmospheric pressure, air moves out of the lungs. Intrapleural pressure is ALWAYS less than the intrapulmonary pressure (i.e. is a negative pressure) and this relationship helps keep the lungs (or alveolar spaces) inflated and keeps the lungs from collapsing. The intrapleural pressure is negative due to a combination of factors, including the tendency of the alveoli to recoil and get smaller, the tendency of the thoracic cage to expand, and the suction (or clinginess) created by the pleural fluid which makes the visceral pleura tend to cling to the parietal pleura, and causes the lungs to adhere to the thoracic wall.

Describe how the partial pressures of oxygen and carbon dioxide help regulate ventilation-perfusion coupling.

Both the bronchiole diameter (which determines air flow or ventilation) and arteriole diameter (which determines blood flow to the capillary beds) are controlled by local autoregulatory mechanisms that continuously respond to local conditions. The partial pressure of oxygen controls blood perfusion, where an increase in pressure increases perfusion and a decrease in pressure decreases perfusion. The partial pressure of carbon dioxide controls ventilation, where an increase in pressure increases ventilation and a decrease in pressure decreases ventilation. If the ventilation (air flow) isn't very good (could be due to blocked bronchioles, buildup of mucus), local O2 is low because the blood carries oxygen away faster than ventilation can replenish it. As a result local arterioles constrict, which redirects blood to capillary beds in other areas of the lung that are getting better airflow. If the air flow is good, the local levels of PO2 increases (fresh air). The high PO2 levels stimulate arteriole dilation, which increases blood flow to the capillary beds in this area with healthy alveoli. Bronchioles change their behavior based on local CO2 levels. Bronchioles servicing areas where alveolar PCO2 levels are high will dilate, allowing CO2 to be eliminated from the body more quickly (this corresponds to areas that have good blood supply, so are bringing lots of CO2 for elimination). Bronchioles serving areas where CO2 is low will constrict (corresponds to low blood flow)

Compare and contrast COPD and asthma. How are they similar? How are they different

COPD and asthma are both obstructive diseases. In obstructive pulmonary disease, it is very difficult to force air out of the lungs and air becomes trapped in the alveoli. Either because the airways are inflamed and tend to collapse during exhalation, or because of a loss of elastic recoil in the alveoli (emphysema). However, COPD is a chronic condition which is irreversible, while asthma occurs in acute attacks which are reversible (there are periods which are symptom free). COPD is associated with chronic bronchitis and emphysema leading to dyspnea (difficulty breathing), coughing, pulmonary infections, and eventually respiratory failure. Asthma results from an abnormal response to an allergen that enters into the conducting system. Clinical symptoms can be similar and include dyspnea, coughing, wheezing and chest tightness

How does carbon monoxide (CO) poisoning occur? Why is it so dangerous

Carbon monoxide (CO) is a colorless, odorless gas formed from the burning of fossil fuels or the incomplete combustion of any carbon source - like wood. Hemoglobin has a much greater affinity for CO than oxygen (~200X) - so CO binds very tightly to Hb and even very low levels of CO can outcompete oxygen for that binding site. When carbon monoxide is bound to Hb instead of oxygen, there is inadequate delivery of oxygen to the tissues, leading to hypoxia, which can be fatal. CO poisoning is very dangerous because it doesn't produce the normal signs of hypoxia such as cyanosis or respiratory distress. Instead, the victim is confused, nauseous and has headache - common symptoms of many illnesses and may go back to bed, instead of moving to fresh air. Victims of CO poisoning are treated by hyperbaric (high pressure) therapy if available or 100% oxgyen to try and increase the amount of oxygen in the blood. A simple solution for all households is to have carbon monoxide detectors in the home

A urinalysis is an analysis of urine, and consist of visual, physical, chemical and microscopic evaluation of a urine sample. What are some of the characteristics of urine that can be evaluated with a urinalysis? What are some of things that are normal to see in urine? What are some of the things you normally don't see in urine, and if you do, might be a sign of disease

Characteristics observed: pH - usually slightly acidic ~ pH 6; range 4.5 to 8.0 color - pale yellow (dilute urine) to deep yellow (concentrated) smell - may smell sweet in diabetes Don't worry about specific numbers in above characteristics - focus on what is being observed. Its normal to see water, nitrogenous wastes (urea, uric acid), electrolytes (Na + , K+ , Cl - , HCO3 - ), creatinine (breakdown product of creatine phosphate), drugs or metabolites of drugs. Things that aren't normally in urine and may be a sign of disease: glucose (due to high blood sugar in diabetes mellitus - overwhelms transporters), proteins (may indicate glomerular damage), blood cells (infection or injury

What causes cystic fibrosis?

Cystic fibrosis is caused by a gene mutation that affects a particular type of chloride channel that allows chloride to leave cells. If chloride can't leave cells, water can't follow - this makes the mucus that normally coats the respiratory mucosa stickier than usual - as a result the cilia of the muco-ciliary escalator get gummed up and can't move the mucus up and out of the air passageways. The mucus accumulates, which makes bacterial infections more common, and the increased infections and inflammation of the lungs cause permanent damage

How do Dalton's law and Henry's law relate to gas exchange

Dalton's law states that the total pressure of a mixture of gases is the sum of the pressures of the individual gases that make up that mixture, and the partial pressure of each gas within a mixture is proportional to the percentage of the gas in the mixture. The air that we breathe is made of a mixture of gases including the respiratory gases, oxygen and carbon dioxide. We can determine the partial pressure of oxygen and carbon dioxide in air based on the percentage they contribute to air. Henry's law states that when a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure and its solubility. How these laws help us understand gas exchange: Dalton's law helps us understand how oxygen and carbon dioxide will behave in a mixture of gases, and how their partial pressures are determined. Henry's law helps us understand how oxygen and carbon dioxide will move from the air of the alveolus to the blood (dissolve) based on their pressure gradients and their relative solubility. Both oxygen and carbon dioxide will move by simple diffusion and move from an area of high partial pressure to an area of lower partial pressure until they reach equilibrium. This explains how oxygen will diffuse from the alveolus (air) to the blood and carbon dioxide will diffuse from the blood to the alveolus (air) in the lungs and oxygen will diffuse from the blood to the tissue cells and carbon dioxide will diffuse from the tissue cells to the blood in the systemic capillary beds

What is the relationship between oxygen and hemoglobin? In your answer explain what is meant by saturation.

Each hemoglobin molecule is made up of 4 polypeptide chain subunits, each of which has an iron-containing heme group that binds an oxygen molecule. Since there are 4 heme groups, each hemoglobin molecule can carry 4 oxygen molecules if it is fully saturated (100% saturated). If hemoglobin is partially saturated, 1, 2, or 3 O2 molecules are bound. If 1 oxygen is bound, hemoglobin is 25% saturated, if 2 are bound, hemoglobin is 50% saturated. If 3 oxgyen molecules are bound, hemoglobin is 75% saturated. The binding of oxygen to hemoglobin exhibits cooperativity. This means that after the first oxygen molecule binds to hemoglobin, the hemoglobin changes shape and increases its affinity for oxygen - so the 2 nd, 3 rd and 4th oxygen molecules bind more easily. The opposite happens when hemoglobin is unloading (releasing) oxygen. After the first oxygen molecule is released, the next oxygen is more easily released, and so on. The affinity (binding strength) of hemoglobin for oxygen changes with the extent of oxygen saturation, and both loading and unloading of oxygen are very efficient

What is a bronchopulmonary segment and why is it clinically relevant

Each lobe of the lung contains a number of pyramid shaped bronchopulmonary segments that are separated from each other by connective tissue septa. These segments correspond to the regions of the lung that are served by tertiary (or segmental bronchi). In addition to receiving air from its own bronchus, each bronchopulmonary segment is served by its own artery and vein. This is important clinically because pulmonary disease is often limited to one or two segments of the lungs. Physicians typically move the stethoscope around when listening to breathing in order to detect abnormal sounds in any of the individual segments of the lung

Describe the relationship between the pleurae and the lungs

Each lung is surrounded by a double layered serous membrane sac called the pleurae or pleural sac. The pleural sac is like a balloon, and the lungs are like a fist that is pushed into the balloon. The layer of the pleural sac (balloon) that covers the surface of the lung including the fissures separating each lobe is called the visceral pleura. The layer of pleura that lines the inner surface of the thoracic wall, the superior face of the diaphragm, and the lateral wall of the mediastinum is the parietal pleura. The visceral and parietal pleura are continuous with each other at the hilum, the indentation on the medial surface of the lung where bronchi and blood vessels enter and leave the lung. In between the parietal and visceral pleurae is the pleural cavity that contains a small amount of pleural fluid. In addition to creating a slippery surface that allows the pleural layers to move freely during breathing, the surface tension created by this fluid makes the visceral and parietal pleural layers cling closely to each other (like the walls of a wet plastic bag) which is important in the mechanics of breathing (pulmonary ventilation).

Name the structures - in sequential order - through which urine flows after it leaves the kidney

Each ureter collects urine from one kidney and carries it to the urinary bladder. Since the kidneys are in the abdomen and the urinary bladder is in the pelvis, each ureter is a long, narrow tube spanning both compartments. The urinary bladder is a storage organ, holding the urine until the time of urination. At urination, the bladder contracts and expels urine through the urethra and out of the body

What are electrolytes and non-electrolytes

Electrolytes (like NaCl) are compounds that dissociate into ions when placed in a solvent like water. Because the ions are charged particles, they conduct electricity. Non-electrolytes are compounds that are formed by bonds (like covalent bonds) that prevent them from dissociating in a solution. Glucose is an example of a nonelectrolyte. It dissolves easily in solution, but it doesn't dissociate into its component parts

What are the primary functions of the respiratory system? You should be able to name 4-5 functions.

Exchange of gases between the atmosphere and the blood Helps regulate of body pH Protection from inhaled pathogens and irritating substances (dust, pollen, pollutants, bacteria etc) Vocalization or production of speech Sense of smell

What are extrinsic controls and why are they important

Extrinsic control mechanisms come into play when there are extreme fluctuations in blood pressure - for instance, when there is a need to maintain systemic blood pressure after blood loss. Extrinsic control mechanisms work to maintain systemic blood pressure even if it means sacrificing the activities of other organs such as the kidneys. Extrinsic control mechanisms include activating the sympathetic nervous system and activating the renin- angiotensin-aldosterone mechanism to maintain systemic blood pressure. When there are extreme drops in blood pressure outside the normal range, as observed during extreme blood loss or hypovolemic shock, the sympathetic nervous system is activated. Norepinephrine is released from sympathetic nerve fibers and epinephrine is released by the adrenal medulla to cause vasoconstriction in peripheral blood vessels, which helps to increase blood pressure. Blood flow to many organs, including the kidneys, is decreased in order to shunt blood flow to more critical organs such as the heart and brain. The afferent arteriole is also constricted, which decreases blood pressure in the glomerulus, and decreases GFR. Decreasing GFR helps conserve water and restore blood volume and blood pressure, but depending on the amount of blood loss, if GFR is decreased too much, and for too long, this can result in kidney failure.

What structures do water and solutes pass through in order to become filtrate

Filtrate is produced from plasma. In order to become filtrate, substances must first move out of the fenestrated capillary of the glomerulus, so must pass through gaps in the endothelium of the capillary wall. Only substances small enough to fit through those gaps cross the capillary wall. Then substances must pass through the basement membrane, which is a porous material that impedes the movement of negatively charged solutes; this layer adds a charge filter to the filtration barrier, rejecting the movement of large plasma proteins (anions). Finally, substances must pass between the slit diaphragms of the podocyte end feet; these podocytes are the visceral layer of the glomerular (Bowman's) capsule. Water, and some small solutes, ions and waste materials pass through the filtration membrane to become filtrate, while blood cells and most plasma proteins do not

Why is it important to regulate GFR (from the standpoint of the kidneys)? How can regulation of GFR help maintain blood pressure and blood volume in the body?

GFR is closely controlled in the body in order to allow the kidney to do its job filtering blood and maintaining extracellular homeostasis. If GFR gets too low, wastes accumulate in the blood, pH is not controlled well, and electrolyte balance may not be well controlled. An increase in GFR can be used to decrease blood volume and blood pressure by getting rid of more water in the urine. A decrease in GFR will increase blood volume and increase blood volume because less water is excreted in the urine (it is conserved)

What is glomerular filtration rate (GFR)? What anatomical or physiological variables modulate GFR?

Glomerular filtration rate is the volume of filtrate formed by all the glomeruli in both kidneys per minute. Three variables can modulate GFR - net filtration pressure, surface area of all glomeruli, and filtration membrane permeability. Of the three NFP has the largest influence on GFR, and changes in NFP are directly proportional to GFR. Surface area can be adjusted by glomerular mesangial cells, and by any kidney disease which results in loss of functional nephrons. Filtration membrane permeability rarely changes outside of disease states, but if altered any decrease in permeability of the membrane will lead to a decrease in GFR

What are hydrostatic and osmotic pressure? How are they related to fluid movement? How does osmosis affect the volume of the ECF and ICF

Hydrostatic pressure is the pressure of a fluid exerted on a system. For example, the pressure of plasma exerted on the wall of a capillary, or the pressure of the filtrate in the capsular space. Osmotic pressure is the pressure exerted by the concentration of solutes in a solvent, which causes water to move into an area of higher solute concentration. These pressures control fluid movement by pushing a fluid out of one space and into another across a membrane (hydrostatic pressure) and drawing fluid out of a less concentrated environment into a more concentrated environment across a membrane (osmotic pressure). In the ECF and ICF, water will move to maintain osmotic equilibrium. If the concentration of solutes is high inside the ECF, water will leave the ICF (leave cells) to balance the osmolarity. This water movement will increase the volume of the ECF and decrease the volume of the ICF. If the concentration of solutes is low in the ECF, water will leave the ECF and enter the ICF (enter cells). This might lead to cell swelling

What is hyperventilation and how does this affect PCO2 levels

Hyperventilation is an increase in the rate and depth of breathing that exceeds the body's need to remove CO2. Usually hyperventilation results in PCO2 levels becoming lower than usual (hypocapnia), which can lead to other results, such as decreased stimulation to breathe

What are the partial pressure gradients for oxygen and carbon dioxide that facilitate external respiration

In the lungs, during external respiration or pulmonary gas exchange, the PO2 of alveolar air is ~104 mm Hg, while the PO2 in the deoxygenated blood arriving at the pulmonary capillary beds is ~40 mm Hg. At the same time, the PCO2 in the blood arriving at the pulmonary capillary beds is ~45 mm Hg (high from the tissues), and is only 40 mm Hg in the alveolar air. These pressure gradients favor the diffusion of oxygen from the alveolus to the blood, and carbon dioxide from the blood to the alveolus. Oxygen will diffuse into the pulmonary capillary until the PO2 in the blood reaches equilibrium with the PO2 in the alveolar air (104 mm Hg), carbon dioxide will diffuse until the PCO2 in the blood reaches equilibrium with the PCO2 in the alveolar air (40 mm Hg)

What are the partial pressure gradients for oxygen and carbon dioxide that facilitate internal respiration?

In the tissues, during internal respiration or tissue gas exchange, the PO2 of the blood arriving at the systemic capillary beds is ~100 mm Hg (usually slightly less than at the lungs because of a slight mixing of deoxygenated venous blood added to the oxygenated blood traveling in the pulmonary veins back to the heart). The PO2 in the tissue cells is ~40 mm Hg (and can be even lower in active tissues) because the tissue cells are using oxygen in the process of cellular respiration to make ATP as fast as it arrives. There is a strong gradient for oxygen to move from the blood to the tissue cells. Oxygen will diffuse into the tissue cells until the PO2 of the blood leaving the capillary bed is the same as the PO2 of the tissue cells (at equilibrium = 40 mm Hg). At the same time, the tissue cells are producing CO2 as a waste product of cellular respiration. The PCO2 in the tissue cells is ~45 mm Hg, and is only 40 mm Hg in the blood arriving at the capillary bed. Carbon dioxide will diffuse from the tissues to the blood, until it reaches equilibrium (~45 mm Hg in the blood leaving the capillary bed)

Draw and describe the pulmonary circulation

In your drawing, you should show that deoxygenated blood is pumped from the right ventricle through the pulmonary trunk and pulmonary arteries to the pulmonary capillaries of the lungs where it will pick up oxygen (and get rid of carbon dioxide). The freshly oxygenated blood leaves the pulmonary capillary bed and travels in the pulmonary veins to enter the left side of the heart at the left atrium. Blood then flows to the left ventricle, where it is pumped out to the systemic arteries through the aorta. The many branches of the aorta will distribute freshly oxygenated blood to all the organs and tissues of the body. One pair of branches from the aorta is the bronchial arteries which distribute oxygenated blood to the lung tissues (i.e. the tissue cells that make up the structure of the lungs and bronchial tree). The bronchial arteries aren't shown in the drawings below, but it's important to remember that ALL the tissues of the body need freshly oxygenated blood delivered by branches of the systemic artery supply (i.e. from the aorta). Once oxygen is delivered to the tissues in systemic capillary beds, deoxygenated blood returns to the heart either by way of the superior vena cava or inferior vena cava to enter the right side of the heart at the right atrium

Inulin is a plant compound that has a renal clearance of 125 ml/min. How is inulin handled by the kidneys, and how can its renal clearance be used as an indicator of kidney function

Inulin is a plant compound that is freely filtered at the glomerulus, and is neither reabsorbed or secreted. All the inulin that is filtered ends up in urine, so the clearance of inulin (the amount that shows up in urine) is the same as the glomerular filtration rate. Inulin can be intravenously infused at a known concentration, and its appearance in the urine over a 24 hour period can be used to determine GFR. A normal rate for the clearance of inulin is 125 ml/min, so GFR is 125 ml/min

What makes the lung tissues vulnerable to cancer? Why is lung cancer such a devastating disease

Lung cancer is the leading cause of cancer death for both men and women in North America. Nearly 90% of lung cancer cases result from smoking, so it is considered a preventable cancer. Because lung cancer is very aggressive and metastasizes rapidly and widely, most cases are not diagnosed until they are well advanced. Lung cancer seems to result when the normal respiratory system defenses are overwhelmed and can't protect the lungs from inhaled chemical and biological irritants. Smoking paralyzes the cilia that clear mucus from the airways, allowing irritants and pathogens to accumulate. The cocktail of free radicals and other carcinogens in tobacco smoke eventually can cause mutations in epithelial cell DNA can lead to uncontrolled division and growth that translates into lung cancer

Describe micturition. What is it and what triggers it? Which types of muscles are involved, and how are they innervated? Be sure to explain when the different muscles are stimulated and when they are relaxed, and by which types of nerves.

Micturition is the act of urinating, or voiding. Micturition, or the act of urination, is stimulated by the parasympathetic nervous system, but the sympathetic nervous system and somatic nervous system have roles in preventing micturition (i.e. during the storage or filling phase). The micturition reflex is a spinal reflex between sensory receptors in the wall of the bladder and nerve signals from the spinal cord that control the muscles involved in micturition. Even though there are some parts of this response that are reflexive, there is conscious control of micturition as well. In order for micturition to occur, the detrusor muscle must contract, and both the internal urethral sphincter and external urethral sphincter must relax. The external urethral sphincter is skeletal muscle and is controlled by the somatic nervous system (voluntary). The internal urethral sphincter is smooth muscle and is under the control of the autonomic nervous system. Both sphincters remain constricted (closed) until it is time to urinate. The detrusor muscle is the smooth muscle in the wall of the bladder. It is controlled by the ANS. When the bladder is filling, the sympathetic nervous system relaxes the detrusor muscle. At the same time, the sympathetic nervous system stimulates the internal urethral sphincter to contract (constrict), and the external urethral sphincter is contracted by conscious control of the CNS and somatic spinal nerves. When the bladder becomes full, sensory receptors in the wall of the bladder are activated, which send signals to the spinal cord.

Define minute ventilation and alveolar ventilation. Explain how understanding the difference between minute and alveolar ventilation can help you predict which types of breathing patterns result in the most effective ventilation

Minute ventilation is the ventilation rate (number of breaths per minute) times the tidal volume. Alveolar ventilation takes into account the anatomical dead space and is the ventilation rate times the tidal volume minus the anatomical dead space. The alveolar ventilation gives a better indication of the amount of fresh air that is flowing into the alveoli to participate in gas exchange. To get the most effective ventilation, you want to know how much fresh air is reaching the alveoli, and is not stuck in the dead space. Since the anatomical dead space is the same in a given individual, increasing the volume of breathing (i.e. deep breaths) enhances the flow of fresh air to the alveoli more than shallow, fast breathing. In shallow, fast breathing most of the inspired air never reaches the air spaces and is stuck in the dead space. In deep, slow breathing, a greater percentage of each inspired breath reaches the alveoli

Electrolytes are unevenly distributed between plasma, interstitial fluid, and intracellular spaces. What is the major cation in the ECF? In the ICF? Which two anions are highest in the ECF? Which anions are highest in the ICF? Why are HCO3- and HPO4- important

Na + is the major cation in the ECF, while K+ is the major cation in the ICF. In the extracellular fluid (both interstitial space and plasma, Cl - and HCO3- ions are the most predominant anions. The predominant anions in the ICF are HPO4- and negatively charged proteins (protein anions). HCO3- (bicarbonate) and HPO4- are important because they are weak bases that will participate in the chemical buffering systems to resist changes in pH

How do the anatomical features of the respiratory system allow humans to live in dry climates

One of the principal actions of the conducting passageways that make up the respiratory system is to warm, humidify, and filter the air. This action is facilitated by superficial blood vessels that allow for heat exchange, seromucous gland secretions that create a humid environment, and the mucociliary escalator that allow trapped pathogens to be trafficked to the digestive system for destruction. These anatomical features of the respiratory system allow us to live in many different climates because no matter what the surrounding atmosphere looks like, when the air enters the alveoli it is warm, humid, and clean

Why are renal clearance tests done?

Renal clearance tests of certain substances can be used to assess kidney function - they can be used as an indicator of GFR, which can allow us to detect damage to the glomerulus, and they can be used to follow the progress of kidney disease. Any compound that is completely cleared (eliminated) by the kidneys can be used to assess kidney function

What is renal clearance?

Renal clearance, C, is the volume of plasma from which the kidneys clear a particular substance in a given time, usually a minute. Renal clearance is calculated by multiplying the concentration of a substance in the urine (U) by the flow rate of urine formation (V) divided by the concentration of the substance in plasma (P), or C = UV/P. You don't need to know the equation, but you do need to know why it is used. The renal clearance of a substance is a reflection of how long it takes for the kidney to clear the substance out of a particular volume of plasma

What is the Bohr effect and how does it impact the oxygen hemoglobin relationship

The Bohr effect is a weakening of the hemoglobin-oxygen bond caused by declining blood pH (increased H+ levels) and increased PCO2, which are all typical of actively metabolizing tissues. This causes the oxygen- hemoglobin dissociation curve to shift to the right, which allows hemoglobin to release more of its oxygen where its needed (in active tissues). Increasing temperature, PCO2 and hydrogen ion levels all shift the dissociation curve to the right. (Decreased temperature, increased pH and decreased PCO2 all shift the dissociation curve to the left and cause hemoglobin to hold on to more of its oxygen - because its not needed at less active tissues)

What are the blood vessels associated with the renal corpuscle

The afferent arteriole (a branch of the cortical radiate artery) brings blood into the glomerular capillary bed (glomerulus) inside the renal corpuscle. The glomerulus is a fenestrated type of capillary, which means that solutes and liquids can leave the capillary through pores (fenestrations) in the wall. The glomerulus empties into another arteriole, which is called the efferent arteriole. The blood from the efferent arteriole drains into another capillary bed called the peritubular capillaries

What is the Haldane effect

The amount of carbon dioxide transported in blood is affected by the degree to which blood is oxygenated. The lower the PO2 and the lower the saturation of hemoglobin with oxygen, the more CO2 that blood can carry. This is the Haldane effect and reflects the greater ability of reduced hemoglobin to form carbaminohemoglobin and to buffer H+ by combining with it. The Haldane effect encourages CO2 exchange in both the tissues and the lungs. In the tissues, as hemoglobin releases its oxygen, carbon dioxide binds to hemoglobin, forming carbaminohemoglobin. In the pulmonary capillaries, hemoglobin uptake of oxygen facilitates the release of CO2. As hemoglobin becomes saturated with O2, the H+ released combines with HCO3-, helping to unload the CO2

What is the anatomical dead space and why is it important to consider when discussing respiratory efficiency

The anatomical dead space is the volume of the conducting zone structures. It is important to consider when discussing respiratory efficacy because it means that not all of the air moved in the tidal volume participates in gas exchange. Approximately 150 mL of air moved during the tidal volume is within the anatomical dead space, which means that only 350 mL of air is actually participating in gas exchange. By taking the dead space into account when you consider pulmonary ventilation, you will have a better understanding of how much air is reaching the alveoli for gas exchange

What is the functional difference between the conducting and respiratory zone? What is the anatomical feature that delineates the transition from conducting to respiratory zone?

The conducting zone structures primarily are responsible for moving air from the atmosphere toward the respiratory zone. Along the way the air is humidified, warmed, and cleaned (filtered). The respiratory zone is where gas exchange occurs. The respiratory zone is defined by the presence of the alveoli. So, the presence of the first alveolus marks the transition from conducting to respiratory zone

How does the puncturing of the parietal pleura of one lung result in a pneumothorax in only that lung

The puncturing of the parietal pleura allows for the intrapleural pressure to equilibrate to the atmosphere. In this situation the intrapleural pressure would be equal to the intrapulmonary pressure and the transpulmonary pressure would drop to zero resulting in a collapsed lung. However, this only effects the lung with the punctured pleura, as each lung is encased in its own pleural cavity allowing each lung to operate somewhat independently

Using the same chart (above), list the four respiratory capacities, explain what each represents, including which respiratory volumes are combined for each of the capacities

The inspiratory capacity is the total amount of air that can be inspired after a tidal volume or normal expiration. It is a combination of tidal volume plus inspiratory reserve volume. The functional residual capacity represents the amount of air remaining in the lungs after a normal tidal volume expiration. It is the combination of expiratory reserve volume and residual volume. The vital capacity is the total amount of exchangeable air. Vital capacity is the combination of tidal volume, inspiratory reserve volume, and expiratory reserve volume. The total lung capacity is the sum of all the lung volumes, and just like it sounds, is the total amount of air that can fit into the lungs

What is the juxtaglomerular complex (or juxtaglomerular apparatus)? What are the cells in this region and what do they do

The juxtaglomerular complex (JGC) or juxtaglomerular apparatus is a specialized region where the last part of the ascending nephron loop interacts with the renal corpuscle. The juxtaglomerular complex monitors blood pressure and filtrate concentration. The JGC consists of macula densa cells, granular cells, and extraglomerular mesangial cells. The macula densa cells are located in the wall of the ascending limb of the nephron loop, and have chemoreceptors that monitor the amount of NaCl in the filtrate entering the distal convoluted tubule. The granular cells are modified smooth muscle cells in the wall of the afferent arteriole that monitor blood pressure and can release renin if the blood pressure gets too low. The extraglomerular mesangial cells lie between the tubule and arteriole and pass signals between granular and macula densa cells

Describe the anatomy and primary functions of the larynx, including the vocal ligaments

The larynx is a composed of a series of cartilages connected by membranes and ligaments. The most prominent cartilage is the thyroid cartilage that can be found on the anterior side of the larynx. The epiglottis is the only elastic cartilage in the larynx; movement of foodstuffs into the pharynx moves the epiglottis over the opening into the larynx, inhibiting the movement of food into the lower respiratory system. The larynx performs three functions - providing a patent airway, inhibiting the entry of food into the lower respiratory system, and voice production. The open space that allows the movement of air between the upper and lower respiratory system is the glottis. Crossing the glottis are two ligaments called the vocal cords (vocal folds). Muscles that draw the true vocal cords together (adduct them) narrow the glottis and reduce air flow to the trachea and lungs; muscles that pull the true vocal cords apart (abduct them) open the glottis and increase air flow to the trachea and lungs. In addition, there are muscles of the larynx that tense the vocal cords to raise the pitch of sound produced by air moving through the narrow glottis

Which 2 structures are responsible for the formation and maintenance of the osmotic gradient

The long nephron loops of the juxtamedullary nephrons (and the countercurrent flow of filtrate between the descending and ascending limbs) are responsible for establishing the osmotic gradient. The vasa recta and the countercurrent flow of blood through the descending parts and ascending parts of the vasa recta are responsible for maintaining the osmotic gradient - in other words, it ensures that the osmotic gradient doesn't wash away.

What (and where) is the medullary osmotic gradient?

The medullary osmotic gradient is an increase in the concentration of solutes (osmolarity) in the interstitial space as you go deeper in the renal medulla. This increasing osmotic gradient extends through the renal medulla. The gradient starts at the cortical-medulla junction at 300 mOsm (isotonic to the blood) and increases in osmolarity as you move deeper in the medulla (toward the apex of the renal (medullary) pyramid).

What stimuli can modulate the activity of the brainstem respiratory centers?

The most important factors that regulate breathing rate and depth are changing levels of CO2, O2 and H+ in arterial blood. Chemoreceptors for these are found in the brainstem (central chemoreceptors) and peripheral chemoreceptors are located in the carotid arteries and aortic arch. Levels of carbon dioxide are the most potent in regulating breathing and therefore are the most closely controlled. As CO2 levels rise (hypercapnia) in the brain, H+ is formed which stimulates central chemoreceptors and stimulate the respiratory centers to increase the depth and rate of breathing, in order to blow off excess CO2. When CO2 levels are low, respiration is inhibited, and breathing becomes shallow. Peripheral chemoreceptors are sensitive to low O2 levels, but normally blood PO2 affects breathing only indirectly by influencing peripheral chemoreceptor sensitivity to PCO2 levels. Low PO2 augments PCO2 effects, but high PO2 levels diminish the effectiveness of CO2 stimulation. When PO2 levels fall below 60 mm Hg, it becomes the major stimulus for respiration, and stimulates the respiratory centers to increase ventilation. Decreases in arterial pH can stimulate respiratory centers to increase ventilation in order to blow off CO2 to restore blood pH.

Describe the gross anatomy of the nasal cavity. How do these structures facilitate the primary functions of the respiratory system

The most interesting feature of the nasal cavity is the nasal conchae, which rise like scrolls from the lateral walls. The nasal conchae are made of bone, and they are covered by respiratory mucosa. There are spaces called nasal meatuses between the 3 conchae (superior, middle, and inferior). The conchae increase the surface area of the cavity and create turbulent wind tunnels, maximizing contact of the air with the mucosa lining. This movement of the air ensures efficient conditioning of the air entering the nasal cavity and facilitates the removal of particles from the air. The nasal cavity contains two different types of mucosa. The olfactory mucosa and the respiratory mucosa. The olfactory mucosa lines the superior part of the nasal cavity and contains the olfactory neurons that form cranial nerve I and convey the sense of smell. The respiratory mucosa is a pseudostratified ciliated columnar epithelium with Goblet cells. The cilia beat the mucous toward the back of the throat and toward the digestive system. Seromucous glands produce mucus and enzymes that help trap and kill pathogens found in the air. Blood capillaries in the lamina propria help warm incoming air and reclaim heat in outgoing air

What is the mucociliary escalator? Where is it found? Why is it important for respiratory system function

The mucociliary escalator is created by the respiratory mucosa, and can be found in any structures lined by respiratory mucosa, such as the nasal cavity, nasopharynx, lower larynx, trachea and upper regions of the bronchial tree. Secretions from the seromucous glands and goblet cells create two layers of fluid that cover the apical surface of the pseudostratified epithelial cells. A deep watery layer allows the cilia to move freely. The superficial mucus layer traps and inhaled particles or pathogens. The constant beating of the cilia moves the mucus and any trapped particles toward the pharynx where they will be swallowed and directed into the esophagus (digestive system). The mucociliary escalator cleans inhaled air and helps ensure that no foreign particles reach the lower delicate parts of the respiratory system (alveoli)

What is the function of the nephron

The nephron is responsible for filtering blood and processing the resulting filtrate into urine. The nephron is the structural and functional unit of the kidney, which means that it is the smallest structure that can carry out the function of the kidney (which is to filter blood and make urine)

Why is the number of transport proteins expressed in the plasma membrane important for the effective reabsorption of solutes in the kidney

The number of transport proteins in the membranes of tubule cells establishes the maximum concentration of a solute that can be effectively reabsorbed from the filtrate in a given time. We call that the transport maximum for a particular substance. Tubular reabsorption for particular solutes depends on how many transport proteins for that solute exist in the plasma membranes of tubule cells to move that solute from the filtrate into the interstitial fluid. If the concentration of the solute in the filtrate is greater than the number of transporters available, then the transport maximum is exceeded - the transporters become saturated and some of that solute will be lost in the urine

What is the oxygen-hemoglobin dissociation curve? What does it tell you about the relationship between the partial pressure or oxygen and hemoglobin

The oxygen-hemoglobin dissociation curve is a plot that describes the relationship between the partial pressure of oxygen and the percent saturation of the hemoglobin. In other words, the curve describes the binding affinity of hemoglobin for oxygen at different partial pressures of oxygen. In general, the curve demonstrates that as the partial pressure of oxygen decreases the percent hemoglobin saturation also decreases. The relationship however, is not linear. At partial pressures above 80 mm Hg hemoglobin is near 100% saturation. When the pressure drops below 80 mm Hg the curve becomes more exponential, decreasing rapidly. This exponential property suggests the oxygen release is cooperative in nature and explains the rapid loading and unloading of hemoglobin in the lungs and at the tissues respectively. At high partial pressures of oxygen, such as in the lungs, hemoglobin has a high affinity for oxygen and is nearly 100% saturated. At lower PO2, such as 40 mm Hg, the binding affinity is lower, which allows hemoglobin to release some of its oxygen molecules, as would be necessary at the tissues. Because hemoglobin has such a high affinity for oxygen at PO2 = 100 mm Hg, it is very easy for hemoglobin to pick up oxygen in the lungs, and it will hold on to its oxygen as it is traveling through the systemic arteries (you don't want oxygen released until it reaches the tissues). At the tissues, when PO2 is 40 mm Hg or less, hemoglobin has a lower affinity for oxygen, so is able to release oxygen where it is needed

What are paranasal sinuses? Where are they found? What do they do?

The paranasal sinuses are air filled spaces in some of the skull bones that surround the nasal cavity. Sinuses form a ring around the nasal cavity and are found in the frontal bone, sphenoid bone, ethmoid bone and maxillary bones. The sinuses are named according to the bone where they are located (i.e. frontal sinus). Sinuses are lined by respiratory mucosa, and they have holes that drain directly into the nasal cavity. Sinuses lighten the skull and may help to warm and humidify the air.

How do the partial pressures of oxygen and carbon dioxide regulate respiratory rate? Which gas has more control

The partial pressure of oxygen and carbon dioxide in the blood influence the activity of central and peripheral chemoreceptors and therefore regulate respiratory rate. The partial pressure of carbon dioxide has a more dominant role. Carbon dioxide can easily cross the blood brain barrier. Once in the brain extracellular fluid, carbon dioxide and water form carbonic acid, which dissociates into a hydrogen ion and a bicarbonate ion. The hydrogen ion can bind to central chemoreceptors that directly affect the medullary respiratory centers. An increase in partial pressure of CO2 will trigger hyperventilation, while a decrease will trigger hypoventilation. Peripheral chemoreceptors are sensitive to low O2 levels, but normally blood PO2 affects breathing only indirectly by influencing peripheral chemoreceptor sensitivity to PCO2 levels. Low PO2 augments PCO2 effects, but high PO2 levels diminish the effectiveness of CO2 stimulation. When PO2 levels fall below 60 mm Hg, it becomes the major stimulus for respiration, and stimulates the respiratory centers to increase ventilation

Describe the anatomy of the pharynx. Be sure to compare and contrast the different regions

The pharynx is muscular tube that serves as a conduit between the nasal, oral cavity and the lower respiratory system. It is the anatomical region commonly known as "the throat." There are three regions that make up the pharynx - the nasopharynx, the oropharynx, and the laryngopharynx. The nasopharynx is the most superior region and is posterior to the nasal cavity. This region only allows for the movement of air and so has a pseudostratified ciliated epithelium (respiratory mucosa). The oropharynx is posterior to the oral cavity and therefore allows for the passage of both air and food, so we observe a stratified squamous epithelium here. The laryngopharynx is the more inferior region and is posterior to the larynx. The laryngopharynx is where food is directed into the digestive system (esophagus) and air into the respiratory system (larynx). Because food (as well as air) passes through the laryngopharynx, the epithelium is stratified squamous

What is Boyle's Law? How does it relate to pulmonary ventilation

The pressure of a gas within a container is inversely related to the volume of the container. In a container that contains a gas, if the volume of that container is reduced, the pressure of the gas increases. If the volume of the container increases, the pressure decreases. This law can be described mathematically as P1V1 = P2V2, where P is pressure and V is volume. In pulmonary ventilation, the thoracic cavity and lungs act like a container. The pressure within the lungs and alveolar air spaces is the intrapulmonary pressure (or intra-alveolar pressure). When the inspiratory skeletal muscles contract, the thoracic cavities and lungs enlarge, so the intrapulmonary pressure decreases. Since intrapulmonary pressure is now less than atmospheric pressure, air flows down its pressure gradient and enters the lungs. When the inspiratory skeletal muscles relax, the thoracic wall and lungs recoil back to their original size (get smaller), and the intrapulmonary pressure increases. Since intrapulmonary pressure is greater than atmospheric pressure, air moves out of the lungs, down its concentration gradient

Briefly describe the reabsorption capabilities of the proximal convoluted tubule, descending limb of the nephron loop, and ascending limb of the nephron loop

The proximal convoluted tubule is responsible for reabsorption of most water and sodium (~65%) and practically all glucose, amino acids, bicarbonate ion, vitamins, and other nutrients. The descending limb of the nephron loop is permeable only to water - some reabsorption of water occurs here. The ascending limb of the nephron loop is responsible for the reabsorption of sodium, chloride, and potassium by active transport (some passive reabsorption of Na+ occurs too). The ascending limb is not permeable to water, so no water reabsorption can occur here

Two separate sets of arteries bring blood to the lungs. Name these two arteries and compare and contrast their functions

The pulmonary arteries (branches of the pulmonary trunk leaving the right ventricle) carry deoxygenated blood to the lungs to pick up fresh oxygen in the pulmonary capillary beds. These pulmonary arteries are part of the pulmonary circuit that brings low pressure, low oxygen blood to the lungs. This circuit is also high volume, because all of the body's blood has to come to the lungs for re-oxygenating. Because of this, enzymes that need to work on material in the blood can be located in the lungs. The bronchial arteries are branches of the aorta, and bring freshly oxygenated blood to the lung to supply oxygen to lung tissue cells to use for cellular respiration. The bronchial arteries are part of the systemic circulation which carries oxygenated, high pressure blood to tissues in the body

What can the renal clearance of a particular substance tell you about that substance, and why is this useful clinically

The renal clearance, C, of a substance tells you how the substance is handled by the kidney, when it is compared to the clearance of a standard, such as inulin. If a substance has a C less than inulin, that suggests the substance is at least partially reabsorbed. If a substance has a C equal to inulin, there is no net reabsorption or secretion. If a substance has a C greater than inulin, then the tubule cells are secreting the substance into the filtrate. This is the case with most drug metabolites. If the renal clearance of a substance is zero, then none of the substance ends up in the urine. There are two situations that account for a substance not appearing in urine. The first is that the substance isn't filtered, so it stays in the blood. An example of this is plasma proteins - they don't get filtered, so don't show up in urine. The other situation is that the substance is freely filtered, so it ends up in the filtrate, but then all of it is reabsorbed. A common example of this is glucose which has C = 0. Under normal circumstances, glucose is fully reabsorbed from the filtrate, so no glucose ends up in the urine. Knowing the clearance of particular drugs can help determine correct dosing - if a drug has a high clearance value, then a lot is secreted into the filtrate and is quickly eliminated from the body - knowing this will help adjust dosage levels and dosing frequencies to keep the appropriate amount of drug in the blood

Draw or describe the components that make up the renal corpuscle

The renal corpuscle is composed of the glomerulus and the glomerular capsule. The glomerulus is a tuft of capillaries, and the glomerular capsule forms a hollow cup-shaped structure surrounding the glomerulus. The glomerulus is composed of a fenestrated endothelium. The glomerular capsule has an outer parietal epithelial layer composed of a simple squamous epithelium and a visceral epithelial layer that lies directly on the glomerulus. The visceral layer of the capsule is composed of podocytes and their foot processes

Compare and contrast quiet inspiration, quiet expiration, forced inspiration, and forced expiration. Include the role of skeletal muscles involved in each phase

The repeating pattern of quiet inspiration and quiet expiration is commonly referred to as ventilation or breathing. The amount of air moved during this process is the tidal volume (usually around 500 mL). Quiet inspiration is an active process and requires the contraction of the diaphragm and external intercostal muscles, which cause an increase in the thoracic cavity volume, a decrease in intrapulmonary pressure and air flow into the lungs. Quiet expiration is a passive process and therefore only requires the relaxation of the diaphragm and external intercostal muscles. The natural recoil of the lungs and the thoracic wall cause an increase in intrapulmonary pressure and air flows out of the lungs. Forced inspiration is an active process that requires the recruitment of additional muscles including the sternocleidomastoid, scalenes, serratus anterior. These muscles help increase the volume of the thoracic cavity beyond what is seen in quiet inspiration, thus allowing for the movement of more air. Forced expiration is also an active process that requires the recruitment of the internal intercoastal muscles and the abdominal wall muscles. Contraction of these muscles help decrease the volume of the thoracic cavity beyond what is achieved with quiet expiration, again allowing for a greater movement of air

What is the respiratory membrane and how is it formed? Where do we observe this membrane

The respiratory membrane is formed by the very thin wall of the alveolus and wall of the capillary across which respiratory gases cross. The respiratory membrane is typically about 0.5 um and is formed by a squamous Type I alveolar cell, the endothelial cell of the pulmonary capillary and the fused basement membranes (or basal lamina) between these two cells. This ultra-thin membrane allows for diffusion of gases between the alveolar air space and the blood. The respiratory membrane is found in the respiratory zone structures in between the walls of the alveoli and the pulmonary capillaries that surround the alveoli

Describe the respiratory mucosa and list where it can be found

The respiratory mucosa lines most of the upper respiratory tract (nasal cavity, paranasal sinuses, nasopharynx) and some of the lower respiratory tract (larynx below the vocal cords, trachea, upper parts of bronchial tree). The respiratory mucosa is responsible for conditioning the air that comes into the respiratory system through the nasal cavity. The respiratory mucosa consists of ciliated pseudostratified columnar epithelium with goblet cells and a lamina propria that contains seromucous glands and a rich network of blood capillaries. Seromucous secretions include a watery solution, and a sticky mucous; these secretions pass through ducts to reach the lumen surface. Mucous secretions on the surface of the epithelium capture inhaled particles and the gently beating cilia sweep the mucous and trapped particles toward the pharynx for swallowing. Watery secretions from seromucous glands help to humidify the air, Blood vessels in the lamina propria warm incoming air, and help to recapture heat in outgoing air

Describe the anatomical features of the respiratory zone

The respiratory zone contains respiratory bronchioles, alveolar ducts, alveolar sacs, and individual alveoli. By definition, the respiratory zone is where the alveoli are located because this is where gas exchange can occur. The respiratory bronchiole is the smallest type of bronchiole and it is the first part of the bronchial tree where we start to see alveoli - it's actually the last part of the bronchial tree too, because bronchioles will transition into alveolar ducts. Bronchioles are considered respiratory bronchioles if they have alveoli in their walls. Respiratory bronchioles transition into alveolar ducts, which are long hallways lined by alveoli. Alveolar sacs are clusters of alveoli at the ends of alveolar ducts. The alveolar sacs are analogous to a cluster of grapes, while an individual alveolus is analogues to a single grape. The alveoli are surrounded by elastic fibers which impart elasticity to the air spaces - the elastic fibers allow them to inflate easily when they fill with air, and they recoil to their original shape during exhalation. The alveoli are also surrounded by pulmonary capillaries which carry blood that needs to be oxygenated

What are extrinsic controls and why are they important

The second extrinsic mechanism is the renin-angiotensin-aldosterone system (RAAS). RAAS is the body's main mechanism to control blood volume and blood pressure. Low blood pressure is sensed by the granular cells in the walls of the afferent arteriole (part of the juxtaglomerular complex), and they release the enzyme renin. Once renin is released, it converts angiotensinogen to angiotensin I. Angiotensin I is converted to angiotensin II, when it encounters angiotensin converting enzyme (ACE) in the lungs. Angiotensin II has many effects that increase systemic blood pressure, including causing release of aldosterone from adrenal cortex, which leads to Na reabsorption in the distal convoluted tubule of the kidney. Increased Na reabsorption leads to increased water conservation (water follows solutes). This helps restore blood volume and blood pressure.

Describe three (3) physical factors that affect the efficiency of pulmonary ventilation

The three factors that can impact the efficient of pulmonary ventilation include airway resistance, alveolar surface tension, and lung compliance. • Airway resistance is controlled by smooth muscles that line the bronchioles. Contraction of the smooth muscles causes bronchoconstriction which decreases the diameter of the airway, increases resistance and therefore decreases airflow. Relaxation of the smooth muscles produces bronchodilation, or increased diameter of the airway. Bronchodilation decreases resistance and therefore increases airflow. • Alveolar surface tension is created by the thin layer of fluid on the inner surface of the alveoli. The molecular attraction between the water molecules creates high surface tension which make the alveoli tend to collapse, just like a plastic bag with a few drops of water in it. Collapsed alveoli are extremely difficult to inflate, limiting gas exchange. However, surfactant secreted by the type II alveolar cells decreases surface tension, keeping the alveoli open. • Lung compliance refers to how easy it is for the lungs to stretch or expand at a given transpulmonary pressure. Things that can decrease lung compliance are increasing alveolar surface tension (which makes the alveoli hard to inflate), limiting chest wall movement (broken ribs or weak muscles), or inhibiting lung movement within the thoracic cavity. Decreased lung compliance leads to decreased pulmonary ventilation.

Describe the anatomy of the bronchial tree including structural changes that occur in the various branches

The trachea branches into two primary or main bronchi which enter each lung on their medial surface. The primary bronchus quickly branches into secondary or lobar bronchi that serve each lobe (2 on the left and 3 on the right). Secondary bronchi branch into tertiary or segmental bronchi. Bronchi continue dividing into smaller divisions. Larger bronchi are lined by the typical respiratory mucosa - ciliated pseudostratified columnar epithelium with goblet cells with a lamina propria, which is responsible for conditioning the air entering the lungs. The bronchi also have hyaline cartilage plates in their walls for structural support. The larger bronchi have more cartilage, and the cartilage plates start to get smaller and are replaced by smooth muscle cells in smaller bronchi. Once the cartilage plates disappear, the branching air passageways are called bronchioles. Bronchioles are about 0.5 - 1 mm in diameter, have no cartilage in their walls, but do have smooth muscle cells. There is also a change in the epithelium as the passageways get narrower. The epithelium transitions from a pseudostratified columnar to a cuboidal cell type with fewer mucus secreting cells and cilia. Smooth muscle in the walls of the bronchioles help control air flow by constricting (bronchoconstriction) or dilating (bronchodilation) the lumen of the bronchiole

Compare and contrast the transcellular and paracellular pathways of reabsorption

The transcellular pathway describes the movement of water and solutes from the filtrate through the tubule cells into the interstitial fluid and then into the peritubular capillaries. Most solutes will be reabsorbed by the transcellular pathway for reabsorption which requires specific transport proteins that are expressed on the apical and basolateral membranes of the tubule epithelial cells. The paracellular pathway describes the movement of water and solvents from the filtrate between the tubule cells (through the leaky tight junctions) into the interstitial fluid and then into the peritubular capillary. Transport proteins are not required for the paracellular pathway, because water and solutes simply diffuse down their concentration gradients in the spaces between cells

What is tranpulmonary pressure and why is it important

The transpulmonary pressure is the difference between the intrapulmonary pressure and the intrapleural pressure. (Ppul - Pip) It is usually expressed as an absolute value. If the intrapulmonary pressure is 760 mm Hg, and the intrapleural pressure is 756 mm Hg, or -4 mm Hg relative to the intrapulmonary pressure, then the tranpulmonary pressure is 4 mm Hg. The transpulmonary pressure is the pressure that keeps the lungs from collapsing. The size of the transpulmonary pressure will dictate the size of the lungs. The greater the transpulmonary pressure, the more inflated the lungs become. If the transpulmonary pressure falls to zero the lungs will collapse. Sometimes the descriptions of intrapleural pressure and transpulmonary pressure sound similar. They are both critical to preventing lung collapse, but are different ways of expressing the same concept. Because of this, I would never ask you to distinguish between these two on an exam

Draw a diagram of the respiratory system and define the structures in the upper and lower respiratory systems

The upper respiratory system includes the nose, nasal cavity, paranasal sinuses, and the pharynx The lower respiratory system includes the larynx, trachea, bronchial tree, alveoli, lungs, and pleurae

Describe the layers of the ureter and urinary bladder. How are they similar, how are they different? Describe the function of the smooth muscle layer in each. Make sure you include a description of the epithelium

The ureters are composed of 3 distinct layers. The layer closest to the lumen is the mucosa, which is composed of transitional epithelium and a connective tissue layer called the lamina propria. Outside the mucosa is a muscularis composed of a couple layers of smooth muscle fibers. The outermost layer is the adventitia composed of dense fibrous connective tissue. When urine stretches the ureter wall, the smooth muscle is stretched, which stimulates its muscularis to contract. This propels the urine forward in the ureter toward the bladder. This type of alternating waves of contraction is called peristalsis. The urinary bladder is also composed of 3 layers: The mucosa with transitional epithelium and lamina propria; a very extensive muscularis layer composed of 3 very thick muscle layers. This muscularis layer is called the detrusor muscle. The outermost layer is adventitia for most of the bladder, except for the most superior region which is covered by peritoneum and thus displays a serosa. The detrusor muscle in the wall of the bladder relaxes when the bladder is filling with urine, but it contracts when emptying the bladder (during micturition). The mucosa of the bladder is thrown into folds called rugae when the bladder is empty. The folds flatten out when the bladder is full, which allows for distention of the walls allowing for an increase in storage without an increase in pressure. Transitional epithelium is a special type of stratified epithelium that lines the ureter and urinary bladder. Its surface cells, sometimes called "dome cells" are rounded up when the bladder is empty, but the surface cells can stretch and flatten out when the bladder is full.

Briefly describe the functions of the ureters, urinary bladder and urethra

The ureters collect the urine from the renal pelvis and transport it to the urinary bladder for storage. The urinary bladder stores urine until it is voided. During micturition or urination, the urethra conveys the urine from the urinary bladder to the outside of the body

Describe the anatomy of the urethra. How is this structure different in males and females

The urethra is a thin walled tube that drains urine from the urinary bladder out of the body. The epithelium is transitions to a protective stratified squamous (similar to skin) near the opening to the outside. Fluid flow through the urethra is controlled by the involuntary internal urethral sphincter and the voluntary external urethral sphincter. The urethra is much longer in males compared to females. The male urethra is about 20 cm long and passes through the prostate gland and penis. The male urethra is also involved in the reproductive system and carries semen out of the body (but not at the same time as urine). The female urethra is only about 3-4 cm long

What are the three physiological variables that can affect external respiration? Briefly describe these variables

The variables that can affect the efficiency of external respiration or pulmonary gas exchange, include partial pressure gradients and gas solubility, thinness and surface area of the respiratory membrane, and ventilation- perfusion coupling. The partial pressure gradients of oxygen and carbon dioxide dictate the direction of gas flow. In external respiration the partial pressure of oxygen is around 104 mm Hg in the alveoli and 40 mm Hg in the pulmonary capillary. Because of this pressure gradient, oxygen will diffuse from the alveolus (air) into the capillary (blood). The partial pressure of carbon dioxide in the alveolus is around 40 mm Hg and 45 mm Hg in the pulmonary capillary. This pressure gradient facilitates the diffusion of carbon dioxide from the capillary into the alveoli. The respiratory membrane adds to the efficiency of pulmonary gas exchange due to its thinness and the large number of alveoli in the lungs (millions). Simple diffusion is most efficient over short distances and over a large surface area. Any disease that decreases the number of healthy alveoli (surface area available) such as emphysema, or increases the thickness of the respiratory membrane (fibrosis, pneumonia, scarring) will decrease the efficiency of gas exchange. Ventilation-perfusion coupling is the process by which the ventilation of air into the alveoli is matched to the perfusion of blood through the surrounding pulmonary capillary.

What structures act as countercurrent exchangers? What does it do, and how does it do that?

The vasa recta act as countercurrent exchangers and preserve the osmotic gradient. The vasa recta are capillary beds that are formed from the efferent arteriole from the juxtamedullary nephrons. They follow the long nephron loops deep into the medulla and are very permeable to both water and solutes, so the blood that travels through the vasa recta is isosmotic with the extracellular fluid around it. This means that stuff moves in and out of the vasa recta to maintain osmotic equilibrium between the blood and the interstitial fluid. When the blood in the vasa recta first starts encountering the higher osmolarity - it picks up some NaCl, and loses some water, in order to maintain osmotic equilibrium. This continues to happen as the blood flows down - so as the blood is losing water and picking up salt, it becomes very concentrated to match the fluids around it. At the hairpin loop, the osmolarity of the blood is the same as the filtrate. As the blood starts to flow up the vasa recta, and encounters areas of less osmolarity, the NaCl flows out of the blood and water flows in, again to create osmotic equilibrium with the surrounding fluids. In this way, the vasa recta are able to reabsorb water and solutes, without undoing the osmotic gradient

Provide an overview of the 4 processes required for exchange of gases between the atmosphere and the blood. Be sure to include relevant terminology.

There are four important events that need to happen in order for gases to pass from the atmosphere and the blood. These events include - pulmonary ventilation, external respiration, transport of respiratory gases, and internal respiration. Pulmonary ventilation is the processes of breathing, or the cycling between inspiration (bringing air into the lungs) and expiration (moving air out of the lungs). External respiration happens in the alveoli where oxygen diffuses from the alveoli (air spaces) into the blood in the pulmonary capillaries and carbon dioxide diffuses from the blood into the alveoli. Transport of blood is the movement of blood from the lungs to reach the tissues and movement of blood from the tissues back to the lungs. During this transport, the blood moves through both the systemic and pulmonary circuits of the cardiovascular system (and the heart). Internal respiration is the process of gas exchange between the blood and the body's cells - oxygen leaves the blood and enters the cells while carbon dioxide leaves the cells and enters the blood

Why is the partial pressure of oxygen and carbon dioxide in the atmosphere different from the partial pressures of the same gases in the alveoli

There are three primary explanations for this mismatch. First, gas exchange is constantly occurring in the alveoli, such that oxygen is always diffusing out and carbon dioxide is always diffusing in. This is not an activity normally observed in the atmosphere at large. Second, humidification occurs along respiratory passageways. The humidification allows for the development of water vapor pressure, which becomes part of the total gas mixture modulating the ratio of each gas partial pressure to the total pressure. Finally, gases mix in the respiratory passageways such that not all of the oxygen inspired enters the alveoli and not all of the carbon dioxide expired escapes the conducting system

How do groups of neurons in the medulla and pons control normal respiratory rate and rhythm (eupnea)

There are two groups of neurons in the medulla that help regulate respiratory rate and rhythm - the ventral respiratory group (VRG) and the dorsal respiratory group (DRG). The VRG generates inspiration and expiration, so is called the rhythm generating center. It contains groups of neurons that fire during inspiration and others that fire during expiration. When inspiratory neurons fire, they activate phrenic nerve and intercostal nerves to stimulate the diaphragm and external intercostal muscles. When expiratory neurons fire, output from phrenic and intercostals stops, inspiratory muscles relax and the lungs recoil, causing expiration. Cyclic on/off activity of inspiratory and expiratory neurons repeats continuously and produces a respiratory rate of 12-16 breaths per minute. This normal rate and rhythm is called eupnia. Breathing stops when VRG neurons are suppressed, as can occur during an overdose of opiates or alcohol. The DRG acts as in integrating center - it collects sensory information from chemoreceptors and peripheral stretch receptors and communicates this information to the VRG. The pons contains the pontine respiratory group which helps to smooth the transitions between inspiration and expiration. This helps us breath appropriately during exercise and vocalization (speech production)

What intrinsic controls does the kidney use to regulate GFR? These intrinsic controls are also called renal autoregulation. Explain how each mechanism works

There are two intrinsic controls that the kidney uses to regulate GFR - the myogenic mechanism and the tubuloglomerular feedback mechanism. In the myogenic mechanism, smooth muscle cells reflexively contract when they are stretched, and relax when they are not stretched. When there is a high blood volume entering the afferent arteriole (high blood pressure), the smooth muscle cells feel the stretch, and they automatically constrict, decreasing the diameter of the afferent arteriole. This decreases the amount of blood entering the glomerulus, so GFR is decreased. When blood volume is low entering the afferent arteriole, the smooth muscle cells aren't stretched, so they relax or dilate. This allows more blood flow into the glomerulus and results in increased GFR. The second intrinsic mechanism is the tubuloglomerular feedback mechanism. This mechanism involves the macula densa cells of the juxtaglomerular complex (JGC). The macula densa cells monitor the sodium concentration of the filtrate entering the distal convoluted tubule. The sodium content of the filtrate varies depending on filtrate flow rate. If sodium concentration is too high, this suggests that the GFR is too high and filtrate is flowing through the tubule too fast for sufficient sodium reabsorption to occur. In this case, the macula densa cells release vasoconstrictor chemicals which constrict the afferent arteriole and decrease GFR (less blood entering glomerulus). If macula densa cells sense Na levels in the filtrate that are too low, this suggests too much Na reabsorption is occurring because filtrate is flowing too slow. The macula densa releases less vasoconstrictor molecules, the afferent arteriole dilates, and GFR is increased.

Describe the anatomy of the lung

There are two lungs within the thoracic cavity. The lungs are surrounded by the thoracic cage which is formed by the ribs, sternum, and vertebral column posteriorly. The lungs are located on either side of the mediastinum and fill the space between the rib cage, the diaphragm, and the lateral surface of the pericardium. The left lung contains two lobes, a superior lobe and an inferior lobe separated by the left oblique fissure. The right lung contains three lobes, a superior, middle, and inferior lobe. The right superior and right middle lobe are separated be the horizontal fissure, while the right oblique fissure separates the right middle and right inferior lobes. Each lung is served by a primary or main bronchus that enters at the hilum. The hilum is the area on the medial surface of the lung where the blood vessels, bronchi, nerves and lymphatics enter and leave the lungs. The lungs are surround by the pleurae or pleural sacs which are described below

What is tubular secretion and which types of substances are generally secreted into the tubule?

Tubular secretion is the process by which the body gets rid of substances it doesn't want by moving them from the blood to the filtrate in the lumen of the tubule. As long as the substance doesn't get reabsorbed back into the blood, anything that remains in the tubule will be excreted in the urine. Things that the kidneys secretes are excess ions (K+), drugs or their metabolites, toxins, H+ (acid-base balance) and nitrogenous wastes such as urea

What are the two types of sleep apnea? How are they similar? How are they different

There are two types of sleep apnea, obstructive or central. In obstructive sleep apnea, the soft tissues of the pharynx sag and obstruct the airways. Obstructive sleep apnea can be worse in obesity. In central apnea, there is a reduced stimulation to breathe from the respiratory centers in the brainstem. This can be made worse when patients are taking opiate pain relievers, or when a person is in medication-assisted treatment for substance abuse disorder. Both types of sleep apnea are characterized by periods in which the patients stops breathing while they are sleeping. These periods of apnea, or breathing cessation, can occur up to 30-50 times per minute and result in decreased blood oxygen levels and excessive daytime sleepiness. In most cases, a person with is not aware of these repeated awakenings because they occur below the level of consciousness. As a result, people with sleep apnea frequently complain of daytime sleepiness, fatigue, and/or insomnia. This poor sleep may also cause problems with memory, concentration, and mood changes. Also, in people with sleep apnea, repeated episodes of falling oxygen levels lead to a variety of physiological changes that can lead to cardiovascular disease and high blood pressure.

How is the Haldane effect related to the Bohr effect?

These two effects are synergistic. As CO2 enters the blood at the tissues, it causes more oxygen to dissociate from hemoglobin (the Bohr effect). The dissociation of oxygen allows more CO2 to bind (the Haldane effect)

Describe in detail the process of tubular reabsorption in the proximal convoluted tubule. What proteins are necessary? What molecules are transported?

Tubular reabsorption includes both passive and active types of transport. Active transport mechanisms involve both primary active transport and secondary active transport. Because these methods involve a little more detail, they are describe first. Passive transport mechanisms will be described at the end of the answer. Tubular reabsorption utilizes sodium gradients to facilitate the movement of other ions. The sodium gradient is established by the Na+/K+ ATPase on the basolateral surface of the tubule cell. The Na/K ATPase moves 3 Na+ ions out of the cell for each K+ ion moved into the cell. This occurs by primary active transport because an ATP molecule is used to do this. This establishes the Na-K gradient so that Na+ is high outside the cells and K+ is high inside the cells. The reabsorption of Na by active transport provides the energy and the means for reabsorbing almost every other substance, including water. (why water? Because water follows solute movements). The result of this is that Na+ will now be able to move down its concentration gradient and bring things along with it - by co-transport. Na+ moving down its concentration gradient (on a carrier or transport protein in the apical membrane) will co-transport glucose, amino acids, some ions and vitamins. This is secondary active transport.

What is tubular reabsorption, and what materials are absorbed in the distal convoluted tubule and collecting duct

Tubular reabsorption is the process of moving materials from the filtrate across the tubule wall, putting the substance in the interstitium where it can be picked up into the capillaries and thus returned to the bloodstream. The most important substances reabsorbed at the DCT and collecting duct are regulated by hormones, and include sodium, chloride, calcium and water

What is tubular secretion

Tubular secretion is the process by which the body gets rid of substances it doesn't want by moving them from the blood to the filtrate in the lumen of the tubule

List the cell types that are found in the alveoli, and describe their functions.

Type I alveolar cell - flat squamous cells that form most of the wall of the alveolus. It forms part of the respiratory membrane across which gas exchange occurs. Type II alveolar cell - cuboidal shaped cell that secretes surfactant which coats the inner surface of the alveoli and decreases surface tension. Alveolar macrophage - these cells are phagocytes that keep the respiratory zone of the lung free from debris. They clean up and dust or pieces of dead cells that end up in the alveoli

Name the structures - in sequential order - through which urine flows within the kidney

Urine is produced in a microscopic structure in the kidney called the nephron. Each kidney contains close to a million nephrons. After leaving the tubule system of the nephron, urine flows through the collecting duct; collecting ducts collect urine from multiple nephrons. Multiple collecting ducts all empty into a single minor calyx. Several minor calyces empty into a major calyx. All the major calyces (there are 3-5 total) empty into the renal pelvis. The renal pelvis leads into the ureter. Note that urine is created by the nephron and the collecting ducts, with water, ion and solute concentrations adjusted according to the needs of the body. Once urine flows into the calyces, its composition will not change further

How does changing the diameters of the afferent and efferent arteriole affect GFR

Vasoconstriction of the afferent arteriole decreases the blood flow into the glomerulus, so decreases hydrostatic (blood) pressure, or HPgc in the glomerulus. This decreases NFP and GFR. Vasodilation of the afferent arteriole increases blood flow and blood pressure in the glomerulus, which increases NFP and GFR. Vasodilation of the efferent arteriole decreases the resistance to blood flowing out of the glomerulus. This decreases glomerular blood pressure, or HPgc, so also decreases NFP and GFR. Vasoconstriction of the efferent arteriole increases the resistance to blood flow out of the glomerulus. This increases the blood pressure inside the glomerulus, so increases HPgc, increases NFP and increases GFR

What is diuresis

Water excretion (getting rid of water in the urine)

What are the names of the 2 main fluid compartments? One of these can be broken down into 2 other fluid compartments. What are these two divisions called? (Hint: one of them is in blood) Which of these contributes the greatest percent to the fluid in our body

Water exists in two main fluid compartments - the intracellular fluid (ICF) and extracellular fluid (ECF). The ECF can be further broken down into the plasma (in blood) and the interstitial fluid (IF), which is between cells. Most of fluid in the body is in the intracellular fluid compartment (ICF)

How can carbon dioxide influence blood pH? How does respiratory rate effect these changes

When carbon dioxide enters the blood, hydrogen ions are produced, as described in the equation: CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO - Carbon dioxide combines with water to produce carbonic acid. The carbonic acid rapidly dissociates to hydrogen ion plus bicarbonate ion. Changes in respiratory rate or depth can alter blood pH dramatically by altering the amount of carbon dioxide and therefore, carbonic acid in the blood. Slow, shallow breathing (hypoventilation) allows CO2 to accumulate in the blood. As a result, carbonic acid levels increase, and blood pH drops. Conversely, rapid, deep breathing (hyperventilation) quickly flushes CO2 out of blood, reducing carbonic acid levels and increasing blood pH.

How do the kidneys form concentrated urine? What are the triggers (body conditions) that signal the body to form concentrated urine? What is the role of the osmotic gradient?

When the body is dehydrated, osmoreceptors in the hypothalamus detect high levels of blood osmolality (high concentrations of solutes). This stimulates neurons in the hypothalamus to make more ADH (anti-diuretic hormone) which is released from the axon terminals in the posterior pituitary. When ADH is present, it causes aquaporins to be inserted into the principal cells of the collecting duct, so the collecting ducts are more permeable to water. This allows water to be reabsorbed by osmosis - water is conserved, which results in a more concentrated urine. The osmotic gradient is important because it is the driving force for water movement by osmosis. Even if aquaporins are present, there won't be any net water movement through them unless there is a high concentration of solutes (high osmolarity) in the interstitial space. In osmosis, water wants to move from an area of high water concentration (low osmolarity) to an area of low water concentration (high osmolarity). The osmolarity must be high in the interstitial space in order for enough water to be reabsorbed to concentrate the urine

How can measuring respiratory volumes and capacities help determine your patient's respiratory disease status? In your answer, mention the difference between obstructive and restrictive respiratory diseases

While respiratory volumes and capacities won't diagnose a specific disease, they can be useful for evaluating loss of respiratory function and following the progression or recovery from a respiratory disease. Knowing which volumes or capacities are impaired or deviate from expected normal can help distinguish between obstructive pulmonary diseases or restrictive pulmonary diseases. Obstructive pulmonary diseases are often diseases in which patients experience increased airway resistance. In obstructive disease, it's harder to push air out of the lungs. Obstructive diseases include chronic bronchitis, emphysema, asthma and cystic fibrosis. Patients with obstructive disease might exhibit increased total lung capacity (TLC), increased functional residual capacity (FRC) and increased residual volume (RV). In other words, more air stays in the lungs because it's hard to push out. The lungs might hyperinflate, but its harder to push air out. Restrictive pulmonary diseases usually involve a decrease in total lung capacity. Examples of restrictive disease include tuberculosis, pneumonia or fibrosis where there is an increase in non-elastic tissue in the lungs, so its harder to inflate the lungs. In these diseases, the vital capacity (VC), total lung capacity (TLC), functional residual capacity (FRC) and residual volume may decline (RV). In these diseases, it's harder to expand the lungs - in other words, there is a decrease in overall compliance