1. PLEASE PRINT YOUR NAME and YOUR TA'S NAME ON EVERY PAGE.

ONLY pages with names on them will be graded.

2. Read the questions carefully.

3. Most questions require only a brief and concise answer. Length of expected answer is positively correlated with number of points the question is worth --

---DO NOT write on the back of exam-answers on back of exam are NOT graded.

4. At the end of the exam, check to see that you have answered EVERY question.

5. If you have a question during the test, raise your hand and we will come to you.

Helpful facts

 

log 10 100 = 2

log 10 10 = 1

log 10 1 = 0

log 10 0.1 = -1

1. The Na/K pump is found on the membrane of all cells. Discuss how it contributes to the function (make sure to indicate the function) of each of the following cells.

(5)neuron:

(2)_Na/K pump set up an ion gradient across the cell membrane

(3)_Cell uses this ion gradient to generate

RMP (when leaky channels are open)

AP (when voltage gated channels are activated)

(5) cell in ascending limb of Loop of Henle

(1)_ Na/K pump set up an ion gradient across the cell membrane

(2)_now the Na/Cl/K cotransporter uses this gradient (secondary active transport) to move these ions from the filtrate to the inside of the cell

(2) movement of Na into the interstitial space generates an osmotic gradient used to concentrate urine.

cardiac muscle

(1)_ Na/K pump set up an ion gradient across the cell membrane

this ion gradient is used to

(2)-generate and AP when voltage sensitive channels are activated

(2)-Na/Ca exchanger (secondary active transport) uses this Na gradient to move Ca out of the cell which is required for the relaxation phase of contraction.

2. Write out the Nernst Equation for sodium in a typical mammalian cell and give a word definition of the the Nernst equation .

formula: 4 points

E Na (mV) = 60 log [Na out]

Z [Na in]

word definition:

(5) indicates the size of the electrical gradient that will balance (equilibrate) a given chemical gradient of sodium when sodium is allowed to freely pass across the barrier.

(It sets the membrane potential--it helps you figure out at what point equilibrium is reached-- it does not tell you the RMP-- the RMP is a specific situation where leaky K are open- indicating RMP only earned partial credit)

(2) Area Vasculosa

b) Compare the chick respiratory organ to the respiratory organ of the rat. (list 3 physical characteristics critical to respiration that they share)

(2 pts @)

1. Large surface area

2. very thin membrane

3.moist

or good capillary supply or interface with the environment or both use hemoglobin to transport oxygen

c) Contrast the respiratory system of the chick embryo with the respiratory system of the rat. (give 1 major difference)

(2)The Rat respiratory system is ventilated by contraction of the diaphragm which generates a low pressure in the lung and draws air in by BULK FLOW.

However in the chick area vasculosa oxygen simply diffuses through the shell--NO BULK FLOW.

a) What part(s) of the neuron were you physically stimulating with the electrode?

(2) axons

c) In which direction(s) did the action potential travel? ____BOTH DIRECTIONS_____

d) defend your answer.

(4) the electrode caused depolarization at the point of contact, this opened all V-channels in the region--so AP would spread in ALL directions because V-Na channels in ALL directions where in the ready position (none had not been INACTIVATED by a prior AP).

(1) loss of REGULATION of contraction by calcium

(3) muscle would be in a constant state of contraction because Tm blocks the myosin binding sites on actin

b) Which protein(s) in a skeletal muslce actually generate force (do work)

(3) MYOSIN (ATP is not a protein-- it is a source of energy)

(2)Atmospheric or Barometric pressure gradient between alveoli and outside

if you only answered pressure gradient, no adjective specifying which pressure you got half the credit)

b) How is this driving force generated?

(4) Diaphragm contracts--increases chest vol.--decreases pressure in alveoli--air flows in

diaphragm relaxes--- chest vol decreases--- pressure in alveoli increases--air flows out

c)What is the driving force for release of oxygen from hemogolobin? (be specific)

READ the question-- answer= the partial pressure of oxygen (PO2) in the plasma!

d) What determines (establishes) this driving force (in part C).?

This driving force is the force that causes the release of oxygen from Hb! To get full credit you must address THIS force.

(2) The PO2 in the cell determines the PO2 in the plasma of the capillaries.

(2)The PO2 in the cell is determined by the metabolic rate of the cell.

a) What is happening to the PCO2 levels in your blood? INCREASE/decrease/stay the same----WHY?

(2) Decreased ventilation--decreased removal of CO2 from alveoli so alveolar PCO2 goes up

(2)which means less CO2 can leave blood so blood PCO2 goes up.

blood PCO2 is determined by how much CO2 is added by the cell (this has not changed) and the rate of removal at the alveoli (this has changed, it has decreased)

b) Why do you have a strong urge to breath at this time (45 sec)?

(3) As blood PCO2 increases-- more CO2 moves into the CSF and is changed into H ions--- increased CSF [H] stimulates neurons in respiratroy center to increase firing of AP to neurons (causing EPSP on these neurons) that innervate the diaphragm.

c) Explain how you can continue to hold your breath for another 15 seconds.

Your brain sends AP via neurons that will generate IPSPs on the neurons that innervate the diaphragm. These neurons are receiving two messages-- EPSP from respiratory center and IPSP from your brain.

This is the same graph that is in your lab manual and that was used in lecture. The solid line shows the rate of filtration and the dashed line show the rate of reabsorption of sodium at the PCT (this is the Tmax line)

A person's blood glucose is 500 mg/100ml,

how much glucose is filtered? _____approximately 600___________mg/min

Give one physiological factor that would decrease this rate.__decrease BP --because rate of filtration is determined by hydrostatic pressure (BP)_

Where in the kidney does filtration take place? __Bowman's Capsule___________

How much glucose would appear in the urine? _____about 250_______ mg/min

Hypothetically, what would you have to do to this person's kidney to decrease the amount of glucose appearing in the urine? ( be specific, indicate what cells to change and how)

(4) increase the number of glucose transporters and Na/K pumps on the PCT

(2 pts for glucose transporter, 2 pts for pump)

 Where is the most likely place for the tumor?_hypothalamus or Posterior pituitary__

--Compare this person's urine.(volume, color, osmolarity, amount of sodium) to a nromal person's urine. The urine of the person with the tumor is

 Volume:______much greater_- osmolarity:____much lower_____

 color:____clear________ mg of salt _______SAME________

 How would this condition impact the following apsects of their cardiovascular system?

 --The person's blood pressure would ____decrease__________

--Would this alter the heart rate? if so how and why?

 Yes--HR would increase. To try to raise the BP the body can either increase HR, increase SV or increase R (BP= CO x R)

 (5, 1 pt per step) Low blood volume AND/OR low blood [Na]----JGA----releaese Renin---Renin converts angiotensinogen into angiotensin.

 Where would you expect to find angiotensin receptors.

(name of cells/gland/organ) __adrenal cells_.

 IF angiotensin raised the intracellular free calcium levels in the cells of this organ, how did it do this? (draw out it out label all parts.)

 show diagram that was in the lab manual--8 pts. 1 /step

angiotensin--receptor(on membrane)-G protein---PLC gamma--IP3--IP3 regulated Ca channel on SER--release of Ca

It phosphorylates (1) other proteins and enzymes found in the cell (2)

How is it possible that the conus beats in the intact heart?

 (1) it must contain contractile tissue

(2) it must be connected to the rest of the heart via GAP JUNCTIONS

 Why doesn't the isolated conus beat?

 (3) conus must not contain any cells with pacemaker activity (spontaneously depolarize)