BIOL 228 Exam 3 (Ch 22, 25, & 26)
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: Where is the interstitial fluid the most concentrated?
Ascending limb is the most dilute so the interstitial fluid would be the most concentrated.
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: Which limb of the loop of Henle permeable to water?
Descending limb is permeable to water because water is reabsorbed into the medulla at that point
How is CO2 transported in the blood?
Dissolved in plasma (7%) Bound to globin (93%) Converted to HCO3 in plasma (70%)
How does behavioral modification help to maintain fluid and electrolyte balance?
Drinking fluids replaces fluid loss; low plasma Na+ levels stimulate cravings for salty foods which replaces the deficit in Na+; and avoidance behaviors can help prevent dehydration, such as desert animals avoiding the heat and seeking out shade.
Explain how Boyle's law is essential for describing ventilation.
During ventilation, inspiratory muscles contract, causing an increase in volume in the thoracic cavity. As the lungs stretch, volume in the lungs increases also, which lowers the pressure, so air flows into the lungs down the pressure gradient until it reaches an equilibrium. When inspiratory muscles relax, volume decreases in the thoracic cavity. As the lungs recoil, volume in the lungs also decreases, which increases pressure, causing air to flow out of the lungs down its pressure gradient until it reaches an equilibrium again.
What affect does fibrotic lung disease have on alveolar diffusion distance?
If the alveolar membrane becomes thickened, it increases diffusion distance and gas exchange rates are reduced. Loss of lung compliance may decrease alveolar ventilation.
When thinking of the integrated response to changes in blood volume and pressure: What behavior is initiated in response to low blood volume (ie. dehydration)?
Increased thirst, resulting in increased water intake
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: Is the fluid leaving the loop of Henle more or less concentrated than the fluid entering it?
Less concentrated
What 3 factors influence alveolar ventilation?
Lung compliance Airway resistance Rate/depth of breathing
What physical factors in the alveoli determine the rate at which gas exchange takes place?
Surface area and diffusion distance
Describe the functions of the pleural sac including the pleural fluid in the cavity? Where is the parietal pleura? Where is the visceral pleura?
The pleural sac lines the outer part of the lungs with the visceral pleura being closest to the lungs and the parietal pleura, closest to the thoracic wall. The pleural fluid is in-between the visceral and parietal pleura, creating the pleural sac. The pleural fluid lubricates, lowering friction between the membranes. It also holds the lungs tight against the thoracic wall, creating a pull on the lungs so that they move with the thoracic wall.
Describe Boyle's Law
The pressure of a gas is inversely related to its volume. If the volume goes up in a container of gas, pressure goes down and air rushes in down the pressure gradient. P1V1 = P2V2
Total lung capacity
The sum of all the lung volumes TLC = IRV + ERV + VT + RV male: ~5800 mL female: ~4200 mL
Functional residual capacity
The total amount of air remaining in the lungs after a normal exhalation breath ERV + RV male: ~2300 mL female: ~1800 mL
Vital capacity
The total amount of air that can be willfully moved in an out of the lungs VC = IRV + ERV + VT male: ~4600 mL female: ~3100 mL
PO2, PCO2, pH
The variables in the blood that are closely monitored because a deviation from the homeostatic range is enough to elicit a response by the respiratory system
Alveolar ventilation
The volume of air that reaches the alveoli. TV - Dead Space The more accurate way of calculating the amount of air that is available for gas exchange with the blood.
How does a pneumothorax disrupt intrapleural pressure? Why does this prevent proper ventilation?
There's usually negative pressure in the pleural space so if something punctures the pleural cavity, the pneumothorax pulls atmospheric air into the lung, causing the pressure to equalize. The equal pressure causes the lung to collapse, which prevents proper ventilation.
How do surfactants decrease the amount of effort needed for breathing?
They reduce the surface tension of the water molecules that line the alveoli, resulting in less energy needed to expand the lungs, also impeding collapse of the alveoli.
Describe Dalton's Law
Total pressure exerted by a mixture of gases is the sum of all partial pressures. Ptotal = PA + PB + PC
Atrial natriuretic peptide stimulus for release
atrial stretch due to increased BV
The chloride shift occurs when
bicarbonate ions leave the red blood cells.
Acid in the ECF is usually combined with ________ to prevent large changes.
buffers
The kidneys regulate water balance by ___________
conserving water
Abdominal and internal intercostal muscles
contracting causes the volume of the thorax to decrease
Angiotensin converting enzyme (ACE)
converts angiotensin I to angiotensin II
The drug acetazolamide is an inhibitor of carbonic anhydrase. How would this affect the body?
decrease blood pH
metabolic acidosis
decreased pH in blood and body tissues as a result of an upset in metabolism **does not include a CO2 imbalance
Anaemic hypoxia
decreased total amount of oxygen bound to hemoglobin
Boyle's Law
describes the relationship between pressure and volume. It states that pressure is inversely proportional to volume.
ACE inhibitors
drugs that target angiotensin converting enzyme (ACE) to block its activity
metabolic alkalosis
elevation of HCO3- usually caused by an excessive loss of metabolic acids **does not include a CO2 imbalance
Ventilation
exchange of air between atmosphere and lungs (respiratory system)
External respiration
exchange of gases between lungs and blood
Histotoxic hypoxia
failure of cells to use O2 because cells have been poisoned
atmospheric pressure
force that air exerts on the surface of the body (760 mm Hg at sea level)
Bicarbonate is produced
from CO2 released during cellular respiration
How is partial pressure of a gas related to gas diffusion?
gases diffuse along partial pressure gradients until they reach equilibrium
carbon dioxide
has the strongest effect on regulating respiration rates
Carbaminohemoglobin
hemoglobin that has carbon dioxide bound to its amino acids
Oxyhemoglobin
hemoglobin that has oxygen bound to its heme group
If a person is dehydrated, would you expect the osmolarity of their urine to be high or low?
high
Chemical levels during respiratory acidosis
high PCO2 high H+ low pH high HCO3
Generally, PO2 in arterial blood is ________ than PO2 in venous blood.
higher
pH
hydrogen ion concentration (acidity/alkalinity of the blood) 7.35-7.45
Vasopressin origin
hypothalamic neurons in posterior pituitary
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: Where are water and solute permeability actively regulated by hormones?
in the collecting duct
Angiotensin is always __________ in the blood
inactive
Hypoxia
inadequate oxygen delivery to body tissues
A student in your lab volunteers to enter a hyperbaric chamber for 10 minutes. The chamber becomes pressurized and his alveolar PO2 climbs to 150 mm Hg. What other change should occur?
increase in arterial PO2
When blood pressure decreases, baroreceptors in the aorta and carotid bodies sense the change and signal to the hypothalamus to
increase vasopressin (ADH) secretion
Hypercapnia
increased concentrations of carbon dioxide
Diuresis
increased output of urine/removing excess water in urine
What effect would be produced by active reabsorption of sodium in the distal portion of the nephron?
increased passive reabsorption of water
Aldosterone effect on target cells
increases Na+ reabsorption and K+ secretion
Main function of angiotensin II
increases blood pressure by promoting vasoconstriction, increasing sympathetic stimulation to the heart, and stimulating aldosterone production
Vasopressin effect on target cells
increases renal water reabsorption
Atrial natriuretic peptide effect on target cells
increases salt and water excretion
Main function of aldosterone
increases sodium and water reabsorption by regulating Na+/K+ pumps, sodium channels, and potassium channels
How does vasopressin (ADH) affect nephrons in the kidneys?
increases water permeability in the collecting ducts
Main function of vasopressin (antidiuretic hormone)
increases water reabsorption by inserting aquaporins
Atrial natriuretic peptide target cells/tissues
kidney, brain, adrenal cortex primarily
How is the renin angiotensin system activated?
kidneys sense low BP so juxtaglomerular cells cause release of renin
In the absence of vasopressin, is urine leaving the collecting duct more or less concentrated than if vasopressin is maximally present?
less concentrated
Aldosterone stimulus for release
low BP, high K+
Chemical levels during respiratory alkalosis
low PCO2 low H+ high pH low HCO3
Hypoxic hypoxia
low arterial partial pressure of oxygen/low O2 overall in blood
Generally, PCO2 in arterial blood is ________ than PCO2 in venous blood.
lower
Lung compliance
lung's ability to stretch
Lung elastance
lungs ability to recoil to resting volume when stretching force is released
Bicarbonate
most CO2 transported by the blood is converted to ____________ (the most abundant ECF buffer)
Atrial natriuretic peptide origin
myocardial cells
Pleural spaces
negative pressure in this structure helps to increase lung volume during inspiration
Chemical levels during metabolic alkalosis
normal or high PCO2 low H+ high pH high HCO3
Chemical levels during metabolic acidosis
normal or low PCO2 high H+ low pH low HCO3
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: If the collecting duct becomes more permeable to water, what will happen to the osmolarity of the final urine?
osmolarity will decrease/filtrate becomes more dilute
Why is pH in the ECF so closely regulated?
pH changes can denature proteins
Alkalosis
pH of arterial blood above 7.45 neurons become hyperexcitable
Acidosis
pH of arterial blood below 7.35 neurons become hypoexcitable
PCO2
partial pressure of carbon dioxide
PO2
partial pressure of oxygen
Main function of atrial natriuretic peptide
promotes sodium and water excretion
If CO2 levels in the blood increase
rate of breathing would increase
Ischemic hypoxia
reduced blood flow/impaired or blocked circulation
osmolality
regulating the total volume of water in the body and the total concentration of solutes in that water
Vasopressin target cells/tissue
renal collecting duct
Aldosterone target cells/tissues
renal collecting duct - principal cells
What do granular cells of the juxtaglomerular apparatus secrete?
renin
Flow of pulmonary circulation
right ventricle - pulmonary trunk-pulmonary arteries - lungs - pulmonary veins - left atrium
Type II alveolar cells
secrete surfactant
Causes of metabolic alkalosis
severe vomiting, diuretics, excessive NaHCO3 (antacids)
Type 1 alveolar cells
simple squamous cells where gas exchange occurs
What allows the kidneys to make urine with varying concentration (between 50-1200 mOsm)?
the concentration gradient in the renal medulla
Anatomic dead space
the conducting respiratory passageways that consist of the volume of inspired air not involved in gas exchange
filtration fraction
the fraction of blood plasma in the afferent arterioles of the kidneys that becomes glomerular filtrate
Air moves out of the lungs when
the gas pressure in the lungs is greater than outside atmospheric pressure
Passive expiration is possible mainly due to
the relaxation of the expiratory muscles
Trachea
the structure between the larynx and the primary bronchi
Lung capacities
the sum of 2 or more lung volumes
Primary function of surfactants
to help prevent the alveoli from collapsing
Most water is lost from the body through the __________ system
urinary
Collecting ducts function in regulating water reabsorption and urine osmolarity
use the renal medullary gradient to adjust urine concentration
Total pulmonary ventilation (minute ventilation)
volume of air moved in and out of lungs per minute
Does vasopressin (ADH) increase water reabsorption or water excretion?
water reabsorption
Alveoli
where gas exchange takes place between the lungs and blood in the capillaries
When a body is dehydrated, water that has made its way to the urinary bladder
will still be expelled from the body in the urine
Increased pH
would make oxygen more likely to stay bound to hemoglobin (left shift in the oxyhemoglobin disassociation curve)
Aldosterone origin
zona glomerulosa of adrenal cortex
When thinking of the changes in osmolarity of the filtrate as it moves through the nephron: Salts are actively pumped out from which limb of the loop of Henle?
Salts are actively pumped out from the ascending limb because that's where solute is removed and ions are reabsorbed.
Describe the structure of the alveoli. What cell types are present and what are their functions (both epithelial and immune cells)?What connective tissue is found in the basement membranes?
Simple squamous
Causes of metabolic acidosis
Starvation, dehydration, diarrhea, shock, renal failure, and diabetic ketoacidosis (DKA), consuming too much alcohol
Alveolar ventilation (alveolar ventilation rate (AVR)
an index of respiratory efficiency; measures volume of fresh air that flows in and out of alveoli
Renin release activates
angiotensin, converting it to ANG I
Vasopressin regulates water balance by inserting __________ into the apical membrane (facing the duct lumen).
aquaporins
What are the main muscles of inspiration and how do they contribute to ventilation?
(Inspiratory muscles contract which increases the thoracic volume) ° External intercostals - elevate ribs, lift sternum, and expand the thoracic cage ° Diaphragm - descends and flattens out (most important) ° Sternocleidomastoids - pull up on ribs, clavicle, and sternum ° Scalenes - pull up on ribs
What are the main muscles of expiration and how do they contribute to ventilation?
(Inspiratory muscles relax, diaphragm rises, ribs & sternum are depressed, and thoracic volume decreases) ° Internal intercostals - create recoil for thoracic cage Abdominal muscles - help push into organs and decrease thoracic volume
Why is potassium important?
- (Na+/K+ pump) It is important for resting membrane potential , transmission of nerve impulses, and normal cardiac rhythms. - It is also important for skeletal and smooth muscle contraction. - It's metabolic importance is seen in its ability to regulate ICF osmolality, intracellular neutrality, and it is required for glycogen deposition in the liver and skeletal muscle. -It also changes the ability of the kidneys to concentrate urine.
When thinking of the integrated response to changes in blood volume and pressure: How does the cardiovascular system respond to a decrease in blood pressure?
- Rapid, sympathetic response - Increased cardiac output - Vasoconstriction
When thinking of the integrated response to changes in blood volume and pressure: How do the kidneys respond to a decrease in blood pressure?
- Slow endocrine & neuroendocrine response - Conserve salt and water to minimize further volume loss
Causes of respiratory alkalosis (hyperventilation)
- anxiety, stress, pain, sepsis, asthma, PE, DKA, infection, stroke, toxins, lung disease
Angiotensin II acts on
- arterioles - CV center in medulla oblongata - hypothalamus - adrenal cortex - proximal tubule
Type A intercalated cells
- cells of the nephrons responsible for acid removal from the body - active during acidosis, secrete H+, reabsorb HCO3- and K+
Type B intercalated cells
- cells of the nephrons responsible for base removal from the body - active during alkalosis, secrete HCO3- and reabsorb H+
Acids enter the body via
- diet (fatty acids, amino acids) - metabolism (CO2, lactic acid, ketoacids)
Bases enter the body via
- few dietary sources - few metabolic sources but main one is HCO3
What is the stimuli for the release of renin in the RAS system?
- granular cell sensitivity to blood pressure - sympathetic stimulation from cardiovascular center - paracrine feedback from macula densa cells of distal tubule
Angiotensin II initiates responses that will
- increase BV - maintain osmolarity - increase BP
Stimuli for the activation of the renin-angiotensin system (RAS)
- low BP - paracrine signaling from macula densa of distal tubules - increased sympathetic activity from the cardiovascular control center
Causes of respiratory acidosis (hypoventilation)
- narrow breathing or impeded gas exchange - aspiration, abdominal distention, drug overdose, CNS disease, pleural/lung disease, trauma
kidney functions
- regulate osmolality - regulate ion concentrations - ensure long-term acid-base balance - excrete wastes & foreign substances - produce erythropoietin & renin - convert Vit.D to active form - carry out gluconeogenesis during prolonged fasting
Respiratory cycle
1 inspiration followed by 1 expiration
4 functions of respiratory system
1. Exchange of gases between atmosphere and blood 2. Homeostatic regulation of body pH 3. Protection from inhaled pathogens and irritating substances 4. Vocalization
Shape of hemoglobin
3D protein that can be slightly altered by the chemical and physical conditions of the blood
Normal blood pH range
7.38-7.42
Respiratory acidosis
A drop in blood pH due to hypoventilation (too little breathing) and a resulting accumulation of Co2.
Respiratory alkalosis
A rise in blood pH due to hyperventilation (excessive breathing) and a resulting decrease in CO2. CO2 is removed from the body faster than it can be produced.
What effect to ACE inhibitors have on blood pressure?
ACE inhibitors decrease blood pressure
Water input and output
Amounts are balanced. Input (2.5L/day water gain): - food/drink 2.2L/day - metabolism 0.3L/day Output (2.5L/day water loss): - skin/lungs (insensible) 0.9L/day - urine 1.5L/day - feces 0.1L/day
Breathing
Another term for ventilation
How does low PCO2 affect vasoconstriction in pulmonary arterioles?
As PCO2 decreases, systemic arterioles constrict, pulmonary arterioles dilate (weakly), and bronchioles constrict
How high PCO2 affect vasoconstriction in systemic arterioles?
As PCO2 increases, systemic arterioles dilate, pulmonary arterioles constrict (weakly), and bronchioles dilate
How does low PO2 affect dilation?
As PO2 decreases, systemic arterioles dilate, pulmonary arterioles constrict, and bronchioles dilate (weakly)
How does high PO2 affect bronchoconstriction?
As PO2 increases, systemic arterioles constrict, pulmonary arterioles dilate (weakly), and bronchioles constrict (weakly)
What functions do the airways provide other than simple conduits for air.
As air is inspired, the airways warm the air to body temperature, humidify it by adding water vapor, and filter out foreign substances.
Where does vasopressin (ADH) act on the nephron?
At membrane receptors on cells of the collecting duct
Why is alveolar ventilation a better estimate of the amount of air available for gas exchange than total pulmonary ventilation?
Because total pulmonary ventilation does not take into account the dead volume
You and a friend are sitting on the floor after a birthday party, using balloons filled with helium to change the sound of your voice. It is hilarious! However, after about ten minutes you notice your friend present with a blank stare, and then slump over, unconscious. You initially panic but notice that they are breathing at a normal rate. Which two things probably occurred? (Helium is an inert gas, it is unlikely that the gas itself is directly reacting with the body.)
By inhaling a high percentage of helium gas, there is a high partial pressure of helium in the lungs which displaces oxygen. Your friend's alveolar PO2 is most likely lower than normal. By inhaling helium for an extended period of time, your friends arterial PO2 is most likely lower than normal.
Long nephron loops of juxtamedullary nephrons function in regulating water reabsorption and urine osmolarity
CREATE the renal medullary concentration gradient
You expose a beaker full of water to an artificial atmosphere that has equal partial pressures of oxygen and carbon dioxide (100mmHG-oxygen and 100mmHG-carbon dioxide). The gasses dissolve into the water until the pressure of each gas reaches an equilibrium between the artificial atmosphere and the water. Would there be more molecules of oxygen or carbon dioxide dissolved in the water?
Carbon dioxide
What is the difference between external and internal respiration?
External respiration is the exchange of gases between the lungs and blood and is a function of the respiratory system. Internal respiration is the exchange of gases between the blood and cells and is a function of the cardiovascular system.
How does the respiratory system use bulk flow to move air in and out of the body?
Flow moves from areas of higher pressure to lower pressure. Without a pressure gradient, no air will flow in or out of the lungs. A muscular pump creates the pressure gradients. Air flow resistance is mainly affected by the diameter of the respiratory tubes.
Vasopressin stimulus for release
High osmolarity, decreased BP, or low BV
When thinking of the integrated response to changes in blood volume and pressure: If BV decreases, what happens to BP?
If BV decreases, BP decreases.
When thinking of the integrated response to changes in blood volume and pressure: If BV increases, what happens to BP?
If BV increases, BP increases.
What affect does emphysema have on alveolar surface area?
If alveoli are destroyed, there's less surface area for gas exchange, resulting in hypoxia
What affect does pulmonary edema have on alveolar diffusion distance?
If fluid in the interstitial space increases, it also increases the diffusion distance and gas exchange rates are reduced. Arterial PO2 may be normal due to higher CO2 solubility in water.
An extreme example of an electrolyte imbalance occurs when a high concentration potassium chloride (KCl) is injected into a person. What might result from this homeostatic imbalance?
Membrane potentials become more positive leading to cardiac arrhythmias and possibly cardiac arrest (KCl dissolves into K+ and Cl-)
Pleura
Membrane surrounding the lungs
Trace the movement of air inhaled from the mouth down the upper and lower reparatory tract until it reaches the alveoli. What structures will the air pass?
Nasal cavity/mouth -> passes sinuses/tongue -> through pharynx -> passes epiglottis -> through larynx/vocal cords -> into trachea -> into bronchi -> into bronchioles -> into alveoli
Track the movement of carbon dioxide and oxygen in internal respiration.
O2 diffuses from blood to tissue cells and CO2 diffuses from the tissue cells to blood.
Track the movement of carbon dioxide and oxygen in external respiration.
O2 diffuses from the lungs to the blood and CO2 diffuses from the blood to the lungs.
How is the PO2 related to hemoglobin binding and unloading?
PO2 increases as O2-binding affinity increases, and vice versa
Vasa recta function in regulating water reabsorption and urine osmolarity
PRESERVE the renal medullary concentration gradient
The two organ systems responsible for controlling acid base balance?
Renal and respiratory systems
Organ system that handles the majority of acid base control?
Respiratory system. Ventilation corrects 75% of disturbances
Inspiratory capacity
The amount of air inhaled during an active (forced) inspiration TV + IRV male: ~3500 mL female: ~2400 mL
Compare and contrast the anatomy of the left and right lung.
The left and right lungs are surrounded by pleurae and connected by the lung root. Each has an apex at the superior tip, and a flatter base at the inferior surface, near the diaphragm. Each lung has an indentation (the hilum) where blood vessels, bronchi, lymphatic vessels, and nerves enter and leave the lungs. The left lung is smaller than the right, with a "cardiac notch" where the heart sits. The left lung is divided into 2 lobes, but the right is divided into 3 lobes. Each lung also has multiple smaller subdivisions (lobules) and has a "stroma" of mostly elastic connective tissue. The lungs are soft & spongy and weigh a total of about 2 lbs. together.
Type I alveolar cells
allow rapid diffusion of gases through their thin membranes
Describe Henry's Law
When a gas is in contact with a liquid, the gas will dissolve in the liquid in proportion to its partial pressure.
Water leaves the permeable descending limb of the loop of Henle because of ______________
a steep concentration gradient that creates an osmotic pull.
Active expiration
actively exhaling or blowing air from the lungs
Passive expiration
air subconsciously expelled from lungs at rest
Like the cardiovascular system, resistance in the respiratory system dependent on the length of the airways, viscosity of the air, and diameter of the airways. Describe how each of the factors affect resistance and which of these factors can be modulated to increase or decrease airway resistance.
· Airway resistance is inversely proportional to air flow. ° Length of the airways remains constant in adults. Resistance is not a factor. ° Viscosity of the air usually remains constant. Altitude and humidity can have a slight affect, but it is not a major contributor to resistance. ° Diameter of the airways will be the main contributor to resistance. ° Physical obstruction in upper airways, mediated by mucus or other ways. ° Bronchoconstriction, mediated by parasympathetic stimulation, histamines, and leukotrienes, if you are experiencing an asthma attack or in a smoky room, for example. ° Bronchodilation can be mediated by carbon dioxide & epinephrine, if you are running, for example.
Where is ventilation regulated in the brain?
· Medulla - Respiratory neurons control inspiratory and expiratory muscles · Pons - Neurons integrate sensory information and interact with medullary neurons to influence ventilation
Compare and contrast obstructive vs restrictive lung disease.
· Obstructive lung disease is just as it sounds - a blockage or constriction in an airway. Restrictive lung disease is also as it sounds - restriction...the lungs cannot stretch. · With obstructive, there's increased airway resistance and decreased flow. You can move the same amount of air, but it will be slower (low FVC/fast FEV1). With restrictive, you cannot move as much air, but it can be fast (FVC can be high/slower FEV1).
Factors affecting the amount of O2 that can be carried in the blood
· Plasma O2 - Hemoglobin saturation · Oxyhemoglobin - Amount of Hb that is present - Total number of Hb binding sites
Factors affecting diffusion of a gas into a fluid
· Pressure gradient of the gas · Solubility of the gas in liquid · Temperature
Tidal volume
· The amount of air taken in during a single normal inspiration ° ~500 mL in both males & females
Inspiratory reserve volume
· The amount of air that can be inhaled after a normal inspiration ~300 mL in males & ~1900 mL in females
Expiratory reserve volume (ERV)
· The extra amount actively (forcibly) exhaled after a normal exhalation ~1100 mL in males & ~700 mL in females
Residual volume
· The minimum amount of air always present in the respiratory system, after blowing out all you can ° ~1200 mL in males & ~1100 mL in females
4 factors that can modify the shape of hemoglobin, causing a change in its affinity for O2
· pH · PCO2 · Temperature · 2,3-BPG
