Physiology Final Review

Question 1

What is the short term adjustment for low arterial blood pressure?

Answer 1

Detection by the baroreceptors–> increased sympathetic activity which would increase CO–> generalized arteriolar vasoconstriction which would increase TPR–> both of these would increase the arteriole blood pressure

Question 2

What is the long term adjustment for low arterial blood pressure?

Answer 2

Detection by baroreceptors–> increase sympathetic activity–> generalized arteriolar vasoconstriction–> decreased glomerular capillary pressure–> decreased GFR–> decreased urine volume–> increased conservation of fluid and salt–> increased arterial blood pressure

Question 3

Distinguish between cortical and juxtamedullary nephrons.

Answer 3

Nephron is the functional unit of the kidney.
Cortical nephrons: 80% of the nephrons, glomerulus located in the outer cortex away from the medulla.
Juxtamedullary nephrons: 20% of nephrons. important in establishing the medullary vertical osmotic gradient. form hair pin loops like vasa recta, long loops of Henle plunge into the medulla glomerulus is located in the inner cortex.

Question 4

What are the vascular components of the nephron?

Answer 4

afferent/efferent arteriole
glomerulus
peritubular capillaries

Question 5

What are the tubular components of the nephron?

Answer 5

Bowman’s capsule
proximal tubule
loop of Henle
Distal tubule and collecting duct

Question 6

What is a part of the combined vascular and tubular component?

Answer 6

*Juxtamedullary apparatus: produces substances involved in the control of kidney function.

Question 7

Describe in sequence the tubular segments through which filtrate flows after it is formed at the Bowman’s capsule to when it enters the renal pelvis. Identify each structure as being located in the renal cortex or renal medulla.

Answer 7

Bowman’s capsule (cortex) –> proximal tubule (cortex)–> descending loop of Henle (medulla)–> ascending loop of Henle (cortex)–> juxtaglomerular apparatus (cortex)–> distal tubule (cortex) –> collecting duct (medulla)

Question 8

Describe in sequence the blood vessels through which blood flows when passing from the renal artery to the renal vein

Answer 8

renal artery –> afferent arteriole –> glomerular capillaries–> efferent arteriole –> peritubular capillaries/ vasa recta–> renal vein

Question 9

Identify the filtration barriers if any which impede the filtration of H2O, Na+,inulin, albumin and red blood cells.

Answer 9

FIltration:
fenestrated endothelium, more permeable, podocytes with filtration slits that can contract (less flow) and relax (more flow)

RBCs cannot make it past the fenestrations
The basement membrane prevents the passage of proteins that made it through the capillaries. Glycoproteins are negatively charged and repel the negatively charged proteins.
Inulin and sodium can pass through the glomerular membrane and water as well.

Question 10

Describe the processes of glomerular filtration, tubular reabsorption, tubular secretion and urine excretion.

Answer 10

Glomerular filtration is the non-discriminant filtration of a protein free plasma fro the glomerulus into Bowman’s capsule.

Tubular reabsorption is the selective movement of filtered substances from the tubular lumen into the peritubular capillaries

Tubular secretion is the selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen.

urine excretion is how urine is eliminated from the body.

*20% of the plasma that enters the glomerulus is filtered and 80% of the plasma that enters the glomerulus is not filtered and leaves through the efferent arteriole.

Question 11

Given the Bowman’s capsule hydrostatic and oncotic pressures, calculate the net filtration caused by increases or decreases in any of those pressures.

Answer 11

Glomerular capillary BP (major in, favors filtration): 55 mm Hg
Plasma colloid osmotic pressure (major out, opposes filtration): 30 mm Hg
capsule hydrostatic pressure (opposes filtration, out): 15 mm Hg

Net filtration is equal to 10 mm Hg, (in, favors filtration)

Question 12

Describe the relative resistances of the afferent and efferent arterioles and the effects on renal blood flow and GFR of selective changes in each.

Answer 12

vasoconstriction results in a decreased GFR.

pathologically the plasma colloid osmotic pressure and the capsule hydrostatic pressure can change.

Plasma colloid osmotic pressure decreases in protein deficiency or severely burned patients.

GFR decreases when it comes to kidney stones as well.

increase in pressure increases the blood flow which would ultimately increase the GFR.

Question 13

Describe the myogenic and tubuloglomerular feedback mechanisms that mediate the autoregulation of renal blood flow and glomerular filtration rate.

Answer 13

Intrinsic:
myogenic mechanism is the physical stretch of the arteriole (smooth muscle automatically constricts when stretched).
tubuloglommerular mechanism: juxtamedullary apparatus (regulates BP and filtration rate) comprises of the macula densa which are cells that sense the salt amount and the granular cells which release renin.

increased salt triggers ATP and adenosine for vasoconstriction and decreased salt signals for NO release and vasodilation.

extrinsic: sympathetic stimulation- arteriolar constriction
* macula densa cells release vasodilators if the flow is too slow and vasoconstrictors when the flow is too fast

Question 14

Describe the cellular mechanisms for the transport of Na+ , Cl- , K+ , Ca2+ , phosphate, organic solutes (e.g., glucose, amino acids, and urea), and water by the major tubular segments

Answer 14

Sodium reabsorption:
80% of the kidneys energy is used for sodium transport, this explains how important it is.
It is also involved in glucose, amino acid, water, chloride and urea reabsorption. In the DCT, that is where it is under hormonal control and can be changed in the amount (RAAS and ANP), this is important in ECF volume control, think BP
It is reabsorbed everywhere except the descending loop of Henle because it only absorbs water there.
Transport maximum: yes

Question 15

To be reabsorbed a substance must pass through 5 distinct barriers:

Answer 15

luminal membrane–> cytosol–> basolateral membrane–> interstitial fluid–> capillary wall

Question 16

Describe the cellular mechanisms for the transport of Cl- , K+ , Ca2+ , phosphate, organic solutes (e.g., glucose, amino acids, and urea), and water by the major tubular segments

Answer 16

Chloride reabsorption is passive along with sodium through a leak channel.

Potassium reabsorption: actively reabsorbed in the PT and the ascending LOH

Urea reabsorption: reabsorbed at the end of the PT, 50% excreted and an increase in urea in plasma= kidney failure

Ca2+/ Po34- reabsorption: reabsorbed in the PT
Tm= normal plasma concentration of each, parathyroid hormone can alter Tm, increase calcium means decreased potassium

glucose/ amino acid reabsorption: glucose–> reabsorbed in the proximal tubules through secondary active transport, Tm= 375 mg/ min, normally 100% reabsorbed

water reabsorption: through AQP-1 and 2, descending LOH

Question 17

Predict the change in renal blood flow and glomerular filtration caused by: increased synthesis of angiotensin II,

Answer 17

Increased angiotensin II:
arteriolar constriction
causes the release of aldosterone
stimulates thirst
causes the release if ADH/ vasopressin
decreases GFR

Question 18

Describe the role of the renin-angiotensin-aldosterone systems in the regulation of sodium balance and arterial pressure with emphasis on the actions of angiotensin II on renal hemodynamics and tubular transport.

Answer 18

granular cells of the juxtamedullary appartus secrete renin in response to low NaCl or low volume
- renin activates angiotensinogen (liver) to angiotensin I (kidney) and by way of ACE it becomes angiotensin II which causes the release of aldosterone to reabsorb Na+ and adds Na+/K+ in DCT

Question 19

Predict the change in renal blood flow and glomerular filtration caused by increased release of atrial natriuretic peptide

Answer 19

Increased ANP:
inhibits the reabsorption of sodium
lowers BP
released when heart muscles in atria are stretched from high ECF
inhibits renin, aldosterone and ADH Secretion
increases GFR
decreases sympathetic NS activity and the smooth muscle of afferent arterioles

Question 20

Predict the change in renal blood flow and glomerular filtration caused by: increased nitric oxide formation.

Answer 20

increases the GFR

NO is a vasodilator so it will result in increased BF and ultimately increased GFR

Question 21

Describe the mechanisms for tubular secretion of hydrogen ion, potassium ions and organic ions.

Answer 21

Hydrogen ions:
never reabsorbed
important in maintaining the acid/base balance
H+ secretion takes places in the PT and DCT
active process
urine is normally acidic

Organic ions:
non selective
secreted from PT via secretory carriers

K+ secretion:
important in maintaining RMP
secretion takes places in the DCT and is highly regulated
secreted to absorb more Na+ (aldosterone)
basolateral Na+ /K+ pump
leak channels on the luminal membrane

K+ and H+ secretion from intercalated cells:
K+ and H+ are secreted from intercalated cells in the DCT
normally mostly K+ is secreted
when pH is too low, H+ secretion causes the retention of K+

Question 22

Describe the anatomy of the respiratory system

Answer 22

gas exchange is the primary function of the resp system.

nasal cavity
pharynx
larynx
trachea
bronchi (primary, secondary, tertiary), bronchioles, alveoli
*there is a gradual thinning in columnar epithelium as you go down the system.

Type I alveolar cells are thin, flat, squamous and form the structure of the alveoli. Type II cells secrete alveolar surfactant.

lungs occupy most of the thoracic space. Pleural sac separates the lungs from the thoracic wall and the interior of the sac contains the pleural cavity.

interpleural fluid is found in the pleural cavity and is secreted by surfaces of the pleura and lubricates pleural surfaces.

Question 23

Diagram how pleural pressure, alveolar pressure, airflow, and lung volume change during a normal quiet breathing cycle. Identify on the figure the onset of inspiration, cessation of inspiration, and cessation of expiration. Describe how differences in pressure between the atmosphere and alveoli cause air to move in and out of the lungs. Identify the forces that generate the negative intrapleural pressure when the lung is at functional residual capacity, and

Answer 23

Mechanics of respiration: increased volume leads to decreased pressure.
PV= nRT
As volume in the thoracic cavity increases, the pressure in the cavity decreases.
Expiration deals with the abdominal and internal intercostal muscles.
Inspiration deals with the sternomastoid, scalenus, diaphragm and the external intercostal muscles.

Atmospheric pressure= 760 mm Hg= intraalveolar pressure
intrapleural pressure is less than alveolar pressure= 756 mm Hg
Transmural pressure gradient along the lung wall= intraalveolar pressure- intrapleural pressure= 4 mm Hg
transmural pressur egradient across the thoracic eall= atmospheric pressure- intrapleural pressure
760- 756 mm Hg= 4 mm Hg

As you breathe in, pressure is decreased.

Question 24

predict the direction that the lung and chest wall will move if air is introduced into the pleural cavity (pneumothorax).

Answer 24

Spontaneous pneumothorax (in lung) and the traumatic pneumothorax (in chest wall )will lead to collapsed lung because the pressure will try to equalize with the intrapleural pressure.

Question 25

Define surface tension and describe how it applies to lung mechanics, including the effects of alveolar size and the role of surfactants. Define atalectasis and the role of surfactants in preventing it.

Answer 25

Surface tension is the interaction of water molecules to each other. It opposes lung expansion and helps with recoil.

surfatant is produced by the type II alveolar cells.

Surface tension is reduced by surfactant- allows for an increased radius.
P= 2T/r
- increased pressure= increased tension
- increased radius= decreased pressure

atelectasis: collapsed lung due to deflated alveoli.

Question 26

Describe the effects of airway diameter and turbulent flow on airway resistance

Answer 26

flow= pressure/ resistance
flow is primarily affected by the radius.
parasympathetic stimulation: muscarinic–> bronchioconstriction
- acetylcholine causes constriction of the smooth muscle around the bronchi
sympathetic stimulation: beta 2–> bronchiodilation
COPD- diseases that are due to increased resistance ( hard to breathe)
- bronchitis: thick mucus, decreased radius, decreased diffusion
- asthma: allergies-> histamine release-> pulmonary edema–> thickened walls-> excessive mucus-> spasm
- emphysema: excessive irritation-> release of protein digesting enzymes–> destroy alveolar walls-> collapsed lung

Question 27

Draw a normal spirogram, labeling the four lung volumes and four capacities. List the volumes that comprise each of the four capacities. Identify which volume and capacities cannot be measured by spirometry

Answer 27

TV= 0.5 L
IRV= 3.0 L
Inspiratory capacity: TV+ IRV
ERV= 1.0 L
* air expelled after tidal volume
FRC= ERV+RV
Residual volume= 1.2 L
Vital capacity= 4.5 L (ERV+IRV+RV)
TLC= 5,700 ml (everything)

FRC, RV, TLC cannout be measured by spirometry.

Question 28

Differentiate between the two broad categories of restrictive and obstructive lung disease, including the spirometric abnormalities associated with each category

Answer 28

Obstructive lung disease: “the floor up disease”
-increased airway resistance
- more difficulty emptying the lungs [than filling]
increased RV- more air staying in the lung
decreased ERV- can’t expire well
decreased VC
increased FRC

Restrictive Lung disease: “ ceiling comes down”
(reduced normal lung capacity)
- reduced lung compliance
- causes: pneumonia, pulmonary edema, obesity, neuromuscular issues
same TV, ERV, RV, FRC
- decreased VC. TLC, IRV, IC
trouble breathing in due to loss of elasticity

Question 29

Define and contrast the following terms: anatomic dead space, physiologic dead space, total minute ventilation and alveolar minute ventilation.

Answer 29

pulmonary ventilation: volume of air breathed in and out in one minute ( minute volume ventilation)
PV= TV*RR
greater than alveolar ventilation due to the dead space

alveolar ventilation is how much fresh air enters the alveoli in one minute
AV= (TV-DS)RR

anatomic DS: parts of the respiratory system that don’t undergo gas exchange
ADS=150 ml

Physiologic DS: ADS + poorly perfused alveoli that are are not exchanging gas

Question 30

List the normal airway, alveolar, arterial, and mixed venous PO2 and PCO2 values. List the normal arterial and mixed venous values for O2 saturation.

Answer 30

PO2: atm- alveoli- blood (160-100- 40)
PCO2: blood- alveoli- atm (46- 40- 0.23)

Alveolar air: PO2:100 mm Hg PCO2: 40 mm Hg
Arterial blood: PO2: 100 mm Hg PCO2: 40 mm Hg
Venous blood: PO2: 40 mm Hg PCO2: 46 mm Hg
Tissue level: PO2: 40 mm Hg PCO2: 46 mm Hg

Atmospheric air: PO2: 160 mm Hg
PCO2: 0.23 mm Hg

Question 31

Name the factors that affect diffusive transport of a gas between alveolar gas and pulmonary capillary blood.

Answer 31

Ficks law of diffusion: QxAxB/ square root of MW x X
B= solubulity: CO2 is 20x more permeable than O2 through the plasma membrane
SA: increased in exercise (both the capillary and alveoli)
decreased with emphysema
greater rate of diffusion in exercise
membrane thickness: increases in pulmonary edema, fibrosis and pneumonia which decreases diffusion as it increases

Question 32

Ventilation/ Perfusion

Answer 32

For small blood flow and large air flow…
Decreased CO2 in the area will lead to an increase innt he contraction of smooth muscle and constriction of the airways and increased airway resistance and decreased airflow
Increased O2 in the area leads to relaxation of the pulmonary smooth muscle and dilation of blood vessels which leads to increased vascular resistance and increased blood flow

Question 33

Draw an oxyhemoglobin dissociation curve (hemoglobin oxygen equilibrium curve) showing the relationships between oxygen partial pressure and hemoglobin saturation. Compare the relative amounts of O2 carried bound to hemoglobin with that carried in the dissolved form.

Answer 33

Hb saturation depends on PO2, this gives rise to the dissociation curve which is not linear.

60 mm Hg is the PO2 where it starts to drive respiration ~90% saturation

Hb+4O2 HbO2
increased PO2 drives the equation right
decreased Po2 drives the equation left

Question 34

Show how the oxyhemoglobin dissociation curve is affected by changes in blood temperature, pH, PCO2, and 2,3-BPG, and describe a situation where such changes have important physiological consequences.

Answer 34

a moderate shift to the right is ok. Too right of a shift, Hb is too generous and it doesnt load oxygen in the lungs. any left shift is bad (pathological)

increased Co2, increased [H+], increased Temp, ** all are indicative of metabolic activity** and increased 2,3- BPG all move the curve to the right

increased CO, decreased temp, decreased [H+], decreased CO2, and decreased 2,3 BPG all move the curve to the left.

when the curve is shifted to the left, Hb becomes greedy and O2 is not released, tissues do not get oxygenated.

Question 35

List the forms in which carbon dioxide is carried in the blood. Identify the percentage of total CO2 transported as each form. Identify the enzyme that is essential to normal carbon dioxide transported by the blood and its location. Describe the importance of the chloride shift in the transport of CO2 by the blood.

Answer 35

O2
physically dissolved= 1.5%
all that contributes ti the PO2
bound to hemoglobin= 98.5%

CO2
physically dissolved= 10%
bound to hemoglobin= 30%
as bicarbonate= 60%

Chloride shift is it helps with the acid/base balance. The chloride shift is an exchange of ions that takes place in our red blood cells in order to ensure that no build up of electric change takes place during gas exchange. Within our tissues, the cells produce a bunch of carbon dioxide molecules that are ultimately expelled by the cell and travel to the blood plasma. Once inside the blood plasma, the majority of carbon dioxide moves into the red blood cells, where they are converted into bicarbonate ions with the help from carbonic anhydrase. Unlike carbon dioxide, bicarbonate is very soluble in the blood plasma and therefore must return there by moving out of the red blood cell. However, as it moves across a special ion-exchange membrane protein, a chloride ion is brought into the cell (in a one-to-one ratio). This is known as the chloride shift and it takes place in order to maintain electric neutrality so that there is no build up of charge. The same thing happens in our lungs just the process is reversed (i.e bicarbonate ions are brought into the red blood cell while the chloride ions are moved out of the cell).

Question 36

Identify the regions in the central nervous system that play important roles in the generation and control of cyclic breathing

Answer 36

Medulla- the basic control center
Pons- modification

Pre- Botzinger complex (sensitive to acidity)-> pacemaker
Dorsal respiratory group: unconscious
stimulation= inspiration
lack of stimulation= respiration
quiet breathing 

Ventral Respiratory Group: conscious
inspiratory and expiratory neurons
active inspiration/ expiration

Pontine centers- fine tune everything
antagonistic
pneumotaxic center: prevents the cessation of breathing
apneustic center: prevents inhibition of the DRG

Question 37

List the anatomical locations of chemoreceptors sensitive to changes in arterial PO2, PCO2, and pH that participate in the control of ventilation. Identify the relative importance of each in sensing alterations in blood gases

Answer 37

Location of peripheral receptors
The carotid bodies are located in the carotid sinus and the aortic bodies are located in the aortic arch
Peripheral chemoreceptors: H+ and PO2
Arterial PO2
PO2 is not the main regulator of respiration
Arterial PO2 is monitored by peripheral chemoreceptors known as the carotid and aortic bodies.
Stimulate respiration in response to a drop in arterial PO2 or an increase in arterial [H+]
Arterial PO2 must fall below 60 mm Hg before the peripheral chemoreceptors respond to stimulate ventilation
Pulmonary disease
low atmospheric oxygen

Central chemoreceptors: PCO2
PCO2 is the main regulator of ventilation
PCO2 central receptors are located in the medulla, next to the medullary respiratory center
Very sensitive to changes in ECF pH
Changes in arterial PCO2 alter ventilation by bringing about corresponding changes in the brain ECF H+ concentration
Elevated CO2 → increased in ECF [H+] → activates the central chemoreceptors → increase in ventilation

Question 38

If a substance is filtered but not reabsorbed or secreted, its GFR…

Answer 38

is equal to the plasma clearance

ex: inulin or creatinine

Question 39

plasma clearance is…

Answer 39

how much plasma is free of substance X not the other way around.

Question 40

If a substance is filtered and secreted but not reabsorbed, the plasma clearance…

Answer 40

is greater than the GFR because All the filtered plasma that is reabsorbed got cleared plus active secretion cleared more plasma
ex: hydrogen and PAH

Question 41

If a substance is filtered/ reabsorbed but not secreted… the plasma clearance…

Answer 41

will be less than the GFR because The reabsorbed plasma has some if not all of the substance it initially had
ex: glucose

Question 42

Equations to know

Answer 42

urine flow rate= 1 ml/min

filtered load: GFR (ml/min) x plasma concentration (g/mL)= FL (g/min)

plasma clearance: [xurine g/mL]x(UFR mL/ min)/ [plasma conc. g/mL]= PC (mL/min)

Question 43

Sodium reabsorption in the ascending loop is an

Answer 43

active process

Question 44

The DT and CD are impermeable to water without

Answer 44

vasopressin

Question 45

Filtrate that comes out of the loop of Henle is always

Answer 45

hypotonic

Question 46

What two substances inhibit ADH release

Answer 46

alcohol and caffeine

Question 47

What is the osmolarity of the filtrate as it enters the distal tubule?

Answer 47

100 mOsm

Question 48

The smooth muscle in the bladder is innervated by

Answer 48

parasympathetic fibers, when stimulated causes the bladder to contract.

internal- smooth muscle, involuntary
external- skeletal muscle

Question 49

Internal urethral sphincter

Answer 49

mechanically opens when the bladder contracts, voluntary override to cause relaxation of external urethral sphincter .
When both sphincters are opened, we urinate.

Question 50

microtubular highway

Answer 50

dinesin moves toward the cell, kinesin moves away from the cell.