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Physiology 1
Physiology
145
Veterinary Medicine
Graduate
01/29/2011

Additional Veterinary Medicine Flashcards

 


 

Cards

Term
The pulmonary circulation normally contains what percentage of the total blood volume?
Definition

Pulmonary arteries, capillaries and veins  contain approximately 9% of total blood volume.

 

 

   The heart in diastole normally contains about 7% of total blood volume.

Term
Pulmonary plus systemic capillaries of the body normally carry what percentage of the total blood volume at any one point?
Definition

8%

At any one point approximately 68% of blood vol is in the venous system (pulmonary + systemic veins), 7% is in the heart 17the arterial system (aorta and arteries and arterioles) in hand 8% in the capillaries.

Term

The total cross-sectional area of the pulmonary capillary bed is normally equal to that of the systemic capillary bed.

 

True or False?

Definition

True

 

The total cross sectional area for passive blood gas diffusion inthe systemic capillary beds is normally matched by the area available in the lungs in order to assure optimal pulmonay oxygenation of blood to match tissue needs, and to prevent the deadly possibility of CO2 accumulation in body fluids.

Term

Capillaries are generally more permeable on the venous end than on the arterial.

 

True or False?

 

Definition

True

 

There are a greater number of pores on the venous end of the capillary, so it is generally more permeable.

Term
What is the resting-state red blood cell transit time from the arteriolar to the venular end of an average-sized capillary bed (70 kg mammal).
Definition

1 - 2 seconds

blood moves through a capillary at the rate of about 0.07 cm/sec in the resting state.

 

Term

What equation best describes the relationship between blood flow and total cross-sectional area of blood vessels in the determination of linear velocity of blood flow?

 

a. v = QA

b. v = Q + A

c. v = Q/A

d. v = Q - A

e. v = A/Q2

Definition

C

 

Area (A) is in cm2

Velocity refers to rate of displacement with respect to time (cm/sec).

While blood flow is the volume per unit time. (Q cm3/sec or ml/sec)

so...

 

cm3/sec x 1/cm2

 

Term

Which is true?

a. When a blood vessel is narrowed, the velocity of blood flow through it increases, as does lateral distending pressure on the vessel walls.

b. In the narrowed portion of a blood vessel, kinetic energy of blood flow is decreased, while the velocity and potential energy are increased

c. When a blood vessel dilates, velocity of blood flow through it increases, as does lateral distending pressure

d. When a blood vessel is narrowed, velocity of blood flow through it increases while lateral distending pressure on the vessel walls decreases.

e. In a closed tube, such as the blood vessel, when kinetic energy of flow is increased as velocity increases, potential energy also increases.

Definition

D

Bernouilli principle states that in a closed tube total energy must remain constant, Thus kinetic energy of flow plus pressure must remain constant.  Therefore if kinetic energy increases as velocity increases, potential energy must be reduced (i.e. the distending pressure on the wall of the blood vessel.)

Term

Select False Statement:

a. Flow (Q) of blood through capillaries varies inversely with the viscosity (n) of blood contained therein (i.e. Q=1/n)

b. Measurements of Poiseuille revealed that the flow of fluid (Q) through a closed tube, like a blood vessel, varies directly with the fourth power of the tube radius (Q = r4)

c. Flow of blood (Q) through any given blood vessel is inversely proportional to the difference btwn the inflow (Pi) and outflow (Po) pressures. (Q=1/(Pi-Po))

d. Blood flow (Q) through a vessel is thought to vary inversely with the length (l) of that vessel (Q=1/l)

e. The viscosity of water at 20 degrees celcius is 1 centipose.


Definition

Q = (Pi-Po)r2/8nl

 

 

C is false.

 

 

Term

Which rearrangement of Pouseuilles law gives us the most accurate definition of resistance (R) to blood flow?

a. R = (Pi - Po) / Q = 8nl / ∏r4

b. R = ∏(Pi - Po) / 8nl / r4

c. R = 8nl∏(Pi - Po)r4

d. R = 8nl / ∏(Pi - Po)r4

e. R = ∏r4 / 8nl = Q / (Pi - Po)

Definition

Resistance to blood  flow is dependent on ratio of pressure drop to flow AND dependent on the dimensions of the blood vessel and the blood therein: (so A is correct)
a. R = (Pi - Po) / Q = 8nl / ∏r4


n = viscosity

Q = flow

l = length

∏/8 = constant of proportionality

(Pi - Po) = outflow - inflow pressures

r4 = fourth power of the radius


Term

 

Which of the following is the primary determinate of resistance to blood flow in the vascular system?

 

a. Viscosity of blood

b. Inflow pressure into capillary beds

c. Outflow pressure from the capillary beds

d. Plasma osmolarity

e. The radius of blood flow

 

Definition

The answer is e

 

Resistance to flow is greatest in capillaries, and resistance diminishes as blood moves into venules and veins

Also changes in vascular resistance occure as a result of changes in radius (i.e. the contraction and relaxation of blood vessels)

Term

Select False statement below:

a. Red blood cells travel faster then plasma through blood vessels

b. Hematocrit ratios of the blood contained in various tissues are lower that those in blood samples withdrawn from large arteries or veins in the same animal.

c. Greater pressure is required to force fluid through blood vessel when the flow is turbulent than when it's laminar.

d. The flexibility of erythrocytes is enhanced as the concentration of fibrinogen in plasma increases.

e. Where laminar flow exists within the cardiovascular system, a murmer is usually detected.

Definition
E is false.
Term

The amount of lymph formed per day in the body is roughly equivalent to the:

a. Extracellular fluid volume

b. Interstitial fluid volume

c. Intracellular fluid volume

d. Blood volume

e. Plasma volume

Definition

The answer is E

 

About 4% of the body weight moves through the lymphatic system every day (2-3 liters in a large dog or about 100 ml/hour)

 

Normal plasma volume is roughly 4% of body weight, whole blood 7%

interstitial fluid vol 16%

extracellular fluid vol 20%

intracellular fluid vol 30 - 40%

Term

Over one-half of lymph formed in body normally comes from the

a. liver and intestinal tract

b. lungs and kidney

c. skeletal muscle and intestinal tract

d. liver and kidneys

e. brain and lungs

Definition

The answer is a

 

Lymphatics are a major route for absorption of nutrients in intestinal tract. it is largely responsible for absorption of fat.

Term

All the following are known to increase lymph flow and potentially cause edema, EXCEPT:

a. Increased venous pressure

b. Increased arterial pressure

c. Decreased plasma colloid osmotic pressure

d. Increased capillary permeability

e. Increased interstitial fluid protein

Definition

 

B is correct

 

Arterial pressure does not change the overall sum of Starling's Forces in the cap bed is not the cause of edema

Term
What percentage of circulating blood volume is normally in capillaries at any one time?
Definition

The answer is a. 5%

 

60% is in veins

 

 

 

Term
How do you calculate the net effective filtration pressure (NEFP) on the arteriolar end of the capillary bed, as well as the net reabsorption pressure (NRP) at the venular end?a
Definition

NEFP = (Pca - Pif) - (¶p - ¶if)

NRP = (Pcv - Pif) - (¶p - ¶if)

 

Pc = capillary hydrostatic pressure

Pif = interstitial hydrostatic pressure

¶p = plasma colloid osmotic (oncotic) pressure

¶if = interstitial colloid osmotic (oncotic) pressure

 

 

Term

An estimated 16 ml/min (or 23 L/day) of fluid filters accros the arteriolar ends of all capillaries in the body .

T or F

Definition
True
Term

Fluid filtration across all cap beds of the body accounts for only 0.3% of the cardiac output at any one time

 

T of F?

Definition
True
Term

Unregulated fluid movement across cap membranes totals approximately 120 liters.min.

 

T or F

Definition
True
Term

The percent of plasma filtered by a particular capillary bed depends on the tissue type, filtration is low across capillaries on the brain, yet high across capillaries in the intestine and lungs, as well as sinusoids of the liver.

 

T or F

Definition
True
Term

The filtration and reabsorption of solutes and solvent across peripheral capillary membranes due to Starling's forces is normally far greater than the passive diffusion of these substances.

 

T or F

 

Definition
FALSE
Term
The normal 24-hour lymph flow in a 70 kg mammal is approximately...
Definition
2 - 4 liters
Term

Lymph flow is facilitated by all the following EXCEPT:

a. Movement of the skeletam muscle

b. Rhythmic contractions of capillary beds

c. Suction effect of high velocity flow of blood in the veins where lymphatics terminate

d. Rhythmic contractions of the walls of large lymph ducts (i.e. lymph pump)

e. The negative intrathoracic pressure created during inspiration

Definition
The answer is B
Term
What is the amount of protein returned to the circulation  each day through the lymphatics as a proportion of total circulating plasma protein?
Definition

25 - 50 %

 

The protein returned to circulation per day is equal to 25% - 50% of the total circulating plasma protein

Term

Which of the following factors would be least likely to cause edema?

a. Increased capillary pressure

b. Decreased plasma colloid osmotic pressure

c. Increased interstitial fluid oncotic pressure

d. Increased capillary permeabilty

e. Hypertension

Definition
e. Hypertension
Term

Agents that promote the production of lymph are called:

 

a. Cholagogues

b. Lymphagogues

c. Diuretics

d. Hydrocholeretics

e. Lymphocytes

Definition

The answer is b. Lymphagogues

 

fyi - Cholagogues = compounds that stimulate evacuation of the gallbladder

Term
The first heart sound of the cardiac cycle heard with a stethoscope:
Definition

is caused by oscillation of blood in the ventricular chambers and vibration of the chamber walls.

 

 

 

detected during the onset of ventricular systole and is consistant with the QRS-complex of the EKG, not the T-wave

It is normally the loudest and longest of the heart sounds.

 

Term
The second heart sound of the cardiac cycle 
Definition

occures with the closure of the semilunar valves

 

 

conditions that bring a more rapid closure to the semilunar valves  like increases in pulmonary or aortic bp increase the intensity of the sound

Term

The third sound of the cardiac cycle...

a. is normal in older animals

b. is particularly evident in the resting state

c. is associated with rapid inflow of blood into the ventricles.

d. normally occurs during the P-Q interval of the ECG

e. occurs due to closure of the mitral valve

 

 

Definition

The answer is C - Is associated with rapid inflow of blood into the ventricles.

 

not b bc it is more evident after exercise, when blood flow is rapid.

not a bc a faint third heart sound may be audible in young animals, but is rarely heard in adults

not e bc it is a result of a rapid inflow of blood into the ventricles

Term

Resting external myocardial work efficiency is approximately:

a. 1% - 2%

b. 10% - 20%

c. 20% - 30%

d. 30% - 40%

e. 40% - 50%

 

Definition
the answer is b - 10% - 20%
Term

Normal end-ventricular systolic volume (i.e. residual volume):

a. at rest is equal to that ejected during systole

b does not normally change following the onset of exercise

c. at rest is nearly zero

d. during exercise is about equal to that ejected during systole

e. at rest about equal to the end-ventricular diastolic volume

Definition

Answer is a

 

Ejection efficiency at rest is roughly 50%

It can go up to 85%-90% with exercise

Term

Atrial Systole:

a. plays a minor role in filling the ventricles of patients exhibiting AV valvular stenosis

b. is not essential for normal ventricular filling at rest

c. normally occurs immediately following the QRS- complex of the ECG

d. normally precedes ventricular filling

e. normally occurs simultaneously with ventricular systole

 

Definition

Answer is b. is not essential for normal ventricular filling at rest

 

most of ventricular filling is complete before atrial systole - usually it is only responsible for around 10% of ventricular volume - atrial kick

Term
Describe the Bainbridge reflex
Definition

Bainbridge

the venoatrial junctions of the heart (aka cardiopulmonary receptors) are mechano receptors that sense and increase in venous return to the atria (preload). They can increase heart rate and contractility via SNS output to the SA node

Term
Describe the Cushing Reflex
Definition
A chemo receptor in the brain senses an increase in [H+] due to an increase in intracranial pressure. The pressure causes a sympathetic-mediated response which is accompanied by a secondary baroreceptor-mediated parasympathetic bradycardia
Term
Describe Bezold-Jarisch reflex
Definition
Chemoreceptors in the heart and coronary vessels that sense chemical ischemia (restriction in blood supply) and illicit a parasympathetic induced bradycardia and hypotension.
Term
Explain the Diving Reflex
Definition

Thermoreceptors in the face sense immersion in water and induces:

a vagal (parasympathetic) response - HR slows and systemic blood flow is reduced

AND

a sympathetic (SNS) mediated vasoconstriction

 

This reduces O2 consumption while preserving coronary and cerebral blood flow.

Term

Match the electrode to the limb

 

a. left forelimb        negative / positive / or both

b. right forelimb      negative / positive / or both

c. left hind limb       negative / positive / or both

Definition

a. left forelimb        negative and positive i.e. both

b. right forelimb      positive / positive

c. left hind limb       negative / negative

Term

Describe the two baroreceptors aka "Buffer Nerves"

 


Definition

When stimulated,

Aortic Arch sends information via the vagus n (CN X)

Carotid sinus sends information via CN IX

Info is integrated in the nucleus tractus solitarius (NTS)

which direct changes in 3 different medullary CV centers

1) Cardiac Decelerator (parasympathetic) slows the SA node  -- this baroreceptor is active when Pmean increases and inactive when it decreases

2) Cardiac Accelerator center are part of the SNS and increase firing of SA node

3) Cardiac decelerator center (part of PNS) - senses decrease in Pmean It reduces TPR (total peripheral resistance)

Term

Erythrocytes generally travel slower through blood vessels than plasma.

 

T or F?

Definition

False

RBCs tend to travel faster through blood vessels than plasma

Term

An increase in contractility in the myocardium will increase

a. the width of the pressure volume loop

b. end-ventricular systolic volume EVSV

c. end-ventricular diastolic volume EVDV

d. All of the above

e. none of the above

Definition
the answer is a the width of the pressure loop.
Term

If cardiac output (CO) is 4,500 ml/min, mean artierial is 94 mmHg and right atrial pressure is 4 mmHg, systemic vascular resistance (in peripheral resistance units) is:

a. .02

b. 20

c. 50

d. 4.05 x 10 to the 6th powera

 

Definition
The answer is a.
Term

Match:

 

1 Arterioles

2 Capillaries

3 Veins

 

Exchange Vessels

Resistance Vessels

Capacitance Vessels

Definition

1 Arterioles  -  Resistance Vessels

2 Capillaries  -  Exchange Vessels

3 Veins   -  Capacitance Vessels

 

 

 

 

Term
Under sustained sympathetic stimulation (at rest) what would happen to the mean arterial Blood Pressure (Pmean)?
Definition
Pmean would go up.
Term

How much fluid is actually filtered out of plasma in a systemic capillary be?

 

How much is normally reabsorbed on the venous end of the capillar?

 

How much of the filtered fluid enters lymphatic circulation?

Definition

0.5% of plasma entering the capillary bed = 16 ml/min

16ml/min x 60 min = 100 ml/hr x 24 hrs = 24 L/day

 

90% of the above fluid is reabsorbed = 14.4 ml/min

 

10% of the filtered fluid goes to the lymphatic system

1.6ml/min x 60 min = 100 ml/hr x 24 hrs = 2.4 L/day

Term
Amount of lymph formed per day in a 70 Kg animal
Definition

1.6 ml/min x 60 min = 100 ml

 

100 ml/hr x 24 hrs = 2.4 L/day

 

 

Roughly equivalent to the plasma volume

Major contributors:
Liver

Small Intestine

Lungs

Term
Peripheral lymph flow (and ultimately the negative interstitial fluid pressure (Pif)) is largely due to:
Definition

Movements of skeletal muscles

Suction effect of high velocity blood flow in the veins in which the lymphatics terminate

Rhythmic contractions of the walls of large lymphatic ducts (i.e. lymph pump)

 

Term

Explain the relationship between

Blood Flow (ml/sec of cm3/sec)

Velocity of blood flow (cm/sec)

Arterial blood pressure (BP; distending pressure; mmHg)

Definition

V = Q / A

 

Contraction of an arteriole will not affect flow, but will increase flow velocity and decrease distending pressure / capillary hydrostatic pressure / and blood pressure.

 

Bernoulli's principle states that for a fluid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure - i.e. distending pressure or Blood Pressure.

Term

What happens to filtration and/or reabsorption pressure in the capillary bed following arteriolar constriction (vasoconstriction)?

 

Could this play a role in hypertension, and/or the physiologic response to hemorrhage (i.e. hypovolemic shock)?

Definition
Net reabsorption pressure would overcome filtration pressure and would bring more fluid into the vascular system from interstitial and intracellular fluid sites i.e. "capillary fluid shift"
Term

Starlings Forces

 and how to use them

 

Definition

 

Pc (plasma capillary hydrostatic pressure)

p (plasma colloid osmotic (oncotic) pressure)

Pif (interstitial fluid hydrostatic pressure)

if (interstitial fluid colloid osmotic (oncotic) pressure)

 

(Pc - Pif) - (Pp - Pif)


alveolar end (25 - (-6)) - (28 - 5) = 8.3 mmHg

venular end (10 - (-6)) - (28 - 5) = -6.7 mmHg

Term

Presence of protein in interstitial fluid is due to :

 

Definition

Cell turnover

Capillary protein leakage (e.g. albumin (liver) lungs)

Lipoprotein exocytosis (CM (intensive) VLDL (liver))

Slow removal by the lymphatics

Term
Interstitial Fluid Pressure
Definition

Negative in most tissue beds (holds tissues together)

Lymph pump (helps to establish & maintain this negativity

 

Positive in the liver, kidney and brain

 

Term

General Causes of Edema

 

Definition

↑Pc

↓¶p

↑Pif

↓ Capillary Permeability

Lymphatic Obstruction

 

first four increase lymph flow

 

hypertension does NOT cause edema

Term

Explain Ohm's Law

 

Definition

Ohm's law help us to understand how blood flow (Q) changes when resistance (R) is altered

Q = ΔP/R where ΔP = P1 - P2

 

rearranged

ΔP = QR

↑ Arterial BP = CO x ↑TPR

 

Term

Pouseuille's equation

 

Definition

Helps us to understand how blood viscosity (n), length (l), and radius (r) of a blood vessel affects resistance (R) or (TPR) to blood flow?

R = 8nl/∏r4

radius much more influential than viscosity

Q = (P1 - P2)∏r4/8nl

(Q = ΔP/R is Ohms Law)

 

increased hemcrit (Hct) or an increase in plasma protein

(↑R due to ↑n)

↑n = ↓Q

Term

Equation for Reynolds Number

 

 

 

 

Definition

NR = pdv / n

 

NR < 2000 = laminar flow

NR < 2000 = turbulent flow

P = blood density

d = vessel diameter

v = blood flow velocity

n = viscosity

anemia → ↓Hct → ↓n → ↑CO or Q → ↑CO → ↓NR

Thrombi → ↓d → ↑v → NR

Term

Name the 7 phases of the Wiggers diagram

 

Definition

Phase A = Atrial Systole

Phase B = Isovolumetric Contraction

Phase C = Rapid Vetricular Ejection

Phase D = Reduced Ventricular Ejection

Phase E =Isovolumetric Ventricular Relaxation

Phase F = Rapid Ventricular Filling

Phase G = Reduced Ventricular Filling (Diastasis)

 

Term

Describe events during

Phase A = Atrial Systole

 

Definition

Atria contract

Final phase of ventricular filling

Period of Atrial Kick = 10 - 40 % of ttl Ventricular vol

 

ECG = second half of P wave

and

PR interval

 

4th heart sound

Term

Describe events in

Phase B = Isovolumetric Contraction

include relevent ECG information

 

Definition

Ventricles contract and Ventricular pressure increases

NO CHANGE in ventricular volume BUT ventricular chamber geometry changes

All valves are closed  (AV closes at begining and semilunar opens at the end)

corresponds to QRS-complex (no wave for repolarization of atria)

First heart sound heard - due to oscillation of blood against ventricular walls

 

 

Term

Describe events in

Phase C = Rapid Vetricular Ejection

mention ECG events too

Definition

Starts with Semilunar Valves opening

Ventricles are contracting

increase in ventricular pressure reaches max

decrease in ventricular volume

increase in aortic pressure - reaches max

 

corresponds to ST segment of ECG

Term

Descibe events in

Phase D = Reduced Ventricular Ejection

include info on ECG

Definition

Ventricles eject at a slower rate

decrease in ventricular volume - reaches min

decrease in aortic pressure

 

corresponds to t wave = ventricular repolarization

Term

Describe events during

Phase E =Isovolumetric Ventricular Relaxation

 

Definition

begins when semilunar valves close (this creates a dicrotic notch aka incisura)

 

ventricles relaxed

decrease in ventricular pressure

NO CHANGE in vetricular volume

 

2nd heart sound heard here - due to oscillations of blood and tensed vessel walls caused by recoil of closed semilunar valves

 

Term

Describe events during

Phase F = Rapid Ventricular Filling


 

Definition

Begins when AV valve opens

ventricle relaxed

ventricle fill passively

increased ventricular volume

ventricular pressure low

 

3rd heart sound heard here

Term

Describe events during

Phase G = Reduced Ventricular Filling

Definition

AKA (Diastasis)

av valves open; aortic and pulmonic valves closed

ventricles relaxed

final phase of PASSIVE ventricular filling

end of overall cardiac diastole

Term

What is

NR = pdv/n

Definition

Reynold's number determines turbulent flow (and possiblity of murmer or bruit)


p is blood density

d is vessel diameter

v = blood velocity

and

n = blood viscosity


NR < 2000 = Laminar Flow

NR > 2000 = Turbulent Flow

Term

Which contributes more to Reynolds number:

velocity of blood or vessel diameter?

Definition

NR = pdv/n

 

since v = Q/∏r2

v increases as radius decreases - raised to the second power

thus

v contributes more to NR than d (aka 2r)

Term
What is C = V/P
Definition

Equation for Blood Vessel Compliance/Capacitance (C)

 

the volume (V) of blood a vessel can hold at a given pressure (P)

 

C is highest in veins

C is lowest in aging arteries

Term
What is the equation for Pmean?
Definition

Pmean = Pdia + 1/3 PP

 

PP = Psys - Pdia

 

Why?

Because greater fraction of cardiac cycle is spent in diastole

Term
Describe the time for the AP to spread through the heart (at rest)
Definition

SA node = 0 msec

AV node = 60 msec DELAY here

Bundle of His = 160 msec

Apex of heart = 200 msec

End of AP = 220 msec

 

Term
Why do APs of SA and AV nodes look different?
Definition

SA and AV nodes have prepotentials caused by T-gated Ca++ channels

 

Only has Phases 0, 4, and 3

no phase 1 nor 2

 

 

Term
Describe the phases of the SA and AV node APs
Definition

Phase 4 = depolarization (prepotential)=Ca++ influx from fast T-channels creates a Ca++ current (ICaT)

(Note: Na+ influx gNa creates a "funny" current (If) which contributes very little to prepotential)

Phase 0 = rapid depolarization = Ca++ conductance (gCa) through slow Ca++ L-channels. It's the ICaL that creates the impulse

Phase 3 = Repolarization by potassium current (IK) due to K+ conductance (gK)

As the IK decays the prepotential (aka pacemaker potential) bring another AP

Term
What other cells have pacemaker potential and why is the SA node the pacemaker?
Definition

AV node and His-Purkinje system are "latent paecmakers" that are usually in "overdrive suppression"

 

SA node has the fastest rate of Phase 4 depolarization (i.e. prepotential) and the shortest refractory period

 

Term
How is the slope of the prepotential controlled?
Definition

SNS stim increases the slope, brining AP to threshold faster

 

PNS stim decreases the slope by hyperpolarizing the RMP and slowing the entrance of Ca++ into the cell

Term
What is the ionic basis for the rise in the prepotential slope?
Definition

NE acts on ß1 receptors in the SA node and:

increase AC activity

increase cAMP formation

increase Ca++ conductance (gCa) through both T&L Ca++ channels

 

Depolarizes prepotential and increases rapidity of firing AP

Term
What does Acetylcholine (ACh) do to the pacemaker cells
Definition

decreases slope of prepotential

ACh acts on Muscarinic (M2) receptors to:

1) increase K+ conductance (gK)

this hyperpolarizes the cell

 

AND

2) decrease cAMP which delays opening of Ca++ T-channels

 

Both methods htperpolarize prepotential

Term
Explain the phases of the cardiac myocytes (not the AV and SA nodes)
Definition

Phase 0 = Rapid depolaization due to opening of Na+activation gates Na+ enters following chem and conc gradients

Phase 1 = Rapid Repolarization

Na+ inactivation gates close due to depolarization (keeping membrane from reachin ENa

K+ gates open permitting ITO K+ leaves following chem and conc gradients

Phase 2 = Plateau inward ICa through L-channels almost equal to outward IK

Phase 3 = Repolarization: ↓ICaL(until stops) and ↑IK

Phase 4 = near EK an inward retifying K+ current maintains gK (net K+ out)

Term
What is Verapimil and what does it do?
Definition

Ca++ channel blocker

affects L-channels of smooth and cardiac mm and the SA node

 

used to treat high BP

relaxes vascular sm mm = vasodilation and ↓TPR (little effect on venous beds)

↓chronotropy = ↓phase 0 of SA and AV nodes

↓dromotropy & ↓inotropy=less Ca++ influx during phase 2

 

Term
What are Cardiac Glycosides and what do they do?
Definition

Na++/K+ ATpase (gate) inhibitors

(e.g. foxglove, Digitalis)

Na++ can't leave cell, lowers gNa and the Na/Ca exchange decreases.  Meaning more Ca++ in cell and extended muscle contraction.

 

↑ chronotropy

↑ inotropy

↑ dromotropy

 

Term
Compare ionic currents of Myocytes and nodes
Definition

Myocytes                                         SA/AV nodes

 

INa (Na+ fast, phase 0)                                ICaT (phase 4)

ITO (K+ phase1)                                          If (phase 4)

ICaL (phase 2)                                  ICaL (phase 0)

IK  (phases 2, 3, & 4)                        IK phase 3

Term
Name and describe the 4 Refractory Periods
Definition

ARP absolute refractory period = Na+ activation gated closed

ERP effective refractory period = some Na+ gates are opening

RRP relative refractory period = even more Na+ gates are opening

SNP supranormal refractory period =gates fully recoverd and membrane potential close to threshold - APs more likely

Term
Draw Einthovens triangle and label leads and electrodes
Definition
[image]
Term
P wave
Definition
[image]
Term

Draw ECG for early ventricular depolarization

 

Definition
[image]
Term
LATE VENTRICULAR DEPOLARIZATION
Definition
[image]
Term
Draw ventricular depolarization and explain ECG
Definition
[image]
Term
What causes the neg Q and neg S waves on ECG?
Definition
[image]
Term
PR interval
Definition
Atrial depolarization (p) and AV node conduction time (flat section)
Term
describe T wave
Definition
Ventricular repolarization
Term
Describe QT interval
Definition
Time from onset of ventricular depolarization to end of ventricular repolarization
Term
describe U wave
Definition
slow repolarization of papillary mm
Term
describe ST segment
Definition
Plateau of ventricular AP (Ca++ influx, phase 2)
Term
Define HR interms of ECG
Definition
number of R waves (or QRS complexes) per unit of time
Term
Explain Starling Law of the Heart
Definition

the vol of blood ejected in phase d and e depends on the vol present an the end of ventricular diastole

 

 

muscle stretchinf due to ↑ in preload increases:

- number of sites available for actin-myosin interaction

- Ca++ sensitivity of troponin

- Ca++ release from the SR

Term
How would hypercalcemia and hypocalcemia effect S-T segment?
Definition

Hypercalcemia would shorten S-T segment

 

Hypocalcemia would lengthen the S-T segment

 

cause is the effect of Ca++ on Phase 2

Term
How does cardiac output relate to stroke volume and heart rate?
Definition
CO = SV x HR
Term
[image]
Definition
[image]
Term
Explain the factors effecting Stroke Volume
Definition
[image]
Term
Diagram the pressure volume loop of increased preload
Definition
[image]
Term
Diagram the pressure volume loop of increased afterload
Definition
[image]
Term
Diagram the pressure volume loop of increased contractility
Definition
[image]
Term

diagram a pressure-volume loop

label axis and valve behavior

Definition
[image]
Term
Name the low pressure mechanoreceptors
Definition

atria

pulmonary circulation

 

these sense volume or fullness

aka effective circulating volume (ECV)

Term
Name high pressure receptors
Definition

carotid arteries

aortic arch

renal afferent arterioles (renin production)

 

sense pressure

Term
name the chemoreceptor and what they sense
Definition

carotid bodies

aortic bodies

 

sense Po2 Pco2 pH and BP

Term
Name the osmoreceptors in the brain and what they sense
Definition

Supraoptic and paraventricular nuclei of the hypothalmus

sense osmolarity

they are sensitive to a 1% change in [Na+] of plasma

Term
Describe the Baroreceptor Reflex Arch
Definition

carotid and aortic bodies sense BP

send input to Medulary CV center

↑BP (due to ↑aortic or carotid Pmean) → PNS activation

↓BP → SNS activation

Term

Describe the ADH and ANP Release Reflex

 

Definition

an increase in blood volume (BV) causes

↓antidiuretic hormone (ADH, vasopressin) from posterior pitutitary

↓ADH causes diuresis (urine production) and ↓BV

 

Also

Atria secrete ANP (atrial natriuretic peptide) that causes diuresis and inhibits ADH output

 

 

 

Term

Nocireceptors:

describe the different reflexes to severe fear or pain versus simple fear or pain

Definition

Severe fear or pain stim PNS and cause vasovagal syncope (fainting)

 

Simple fear or pain stimulate SNS and cause sweating, tachycardia, and hypertension - can lead to left ventrical hypertrophy

Term
Describe the primary and secondary reflex mechanism of cardiac response to peripheral chemoreceptor stimulation
Definition

chemoreceptors sense ↓PO2 ↑CO2 and ↓pH

 

the primary relfex effect on SA node is inhibitory (PNS) this lowered hr yet hypoxia (↓O2) also causes hyperpnea (↑breathing) hyperventilation causes both hypocapnia (↓CO2) and lung stretching both of which stimulate a SNS response that overrides the PNS response and the net effect is ↑HR

 

This is ONLY if the patient has working lungs

w/o the PNS would slow down heart and pos kill pt.

Term
Describe ANS control of heart
Definition

PNS presominates thus producing "vagal tone"

 

PNS stim: ACh binds to M2 receptors and decreases chronotropy, inotropy, and dromotropy, also has tendency to dilate coronary vasculature

ACh on M2 on blood vessels vasodilate, but there aren't many M2 on blood vessels

 

SNS stim: NE binds to ß1 receptors on heart and increase chronotropy, inotropy, and dromotropy

NE binds to α1 and α2 receptors on blood vessels and vasoconstrict

 

 

 

Term
what are the roles of prejunctional β2 and α2 receptors
Definition

prejunctional β2 receptors facilitate NE release

 

prejunctional α2 receptors inhibit NE release

Term
describe significance of SNS constriction of capacitance vessels
Definition
facilitate venous return to the heart.  esp imp during hemmorhage
Term

describe

active and reactive hyperemia

 

 

Definition

active hyperemia occurs when blood flow to an organ changes in direct proportion to its metabolic activity

 

reactive hyperemia occurs when there is an increase of blood flow in response to a prior period of decreased blood flow.  The loger the occlusion, the greater the debt.

Term
describe Histimine's role in local blood flow
Definition

histimine is released by mast cells in tissue in response to injury. It causes:

arteriolar vasodilation

venous constriction

and increased capillary permeabililty

Term
describe coronary blood flow
Definition

decreases in systole

increases in diastole

 

as HR increases perfusion decreases

 

Autoregulatory vasodilation restores bf following exercise

adenosine most imp

NO next most imp

 

 

Term

Desribe PNS stimulation on coronary blood flow

 

Definition

ACh direstly causes coronary vasodilation

BUT

PNS causes ↓HR, which ↓O2 demand, which indirectly causes vasoconstriction due to lack of vasodilator metabolites.

So PNS generally decreases coronary blood flow

Term
what is pulmonary wedge pressure?
Definition
Pulmonary venous and left atrial pressure
Term
list 3 factors that determine fluid flux out of capillaries and explain how 2 of these can cause pulmonary edema
Definition

hydrostatic pressure, oncotic pressure and permeability

 

Cardiogenic pumonary edema: increase in left arterial pressure causes ↑hydrostatic pressure and net outward fluid flux.

Pulmonary capillary wedge pressure is above normal

 

ARDS (adult respiratory distress syndrome): increased capillary permeability causes pulmonary edema, can be caused  by epithelial injury due to toxins or infection. Difficult to treat because protenatious fluid is hard to remove.

 

 

 

 

 

Term
how is pressure measured in the pulmonary arteries?
Definition

A pressure transducer ina catheter is introduced via the systemic venous circulation and measures pressures in the

right atrium

right ventricle

and

pulmonary arteries

Term
how does pulmonary arterial and systemic arterial circulation differ with respect to pressure, vessel compliance and local hypoxia?
Definition

Pulmonary arteries have large diameter and less smooth muscle. They do not regulate supply of blood to different organs and are not concerned with directing flow. High Flow, Low Resistance, Low Pressure.

The mean pulmonary arterial pressures are much lower (avg = 17mmHG)

pressure difference from inlet to outlet is only 15mmHG (17 - 2mmHg) while systemic is (100 - 2mmHg)

Pulmonary arteries are more compliant/distensible

pulmonary arteries vasoconstrict inresponse to hypoxia except for bronchial vessels, which, like systemic arteries, dilate.



Term

Define subdivisions of total lung capacity

Which can be directly measured?

Which change with exercise?

Definition
  • Tidal Volume (VT) volume of single expired breath
    - increases with exercise
  • Vital Capacity (VC) maximal volume expired after max inhalation
  • Residual Volume (RV) vol remaining in lungs after max exhalation
    - measured using gas dilution techniques
  • Functional Residual Capacity (FRC) vol in lungs at end of tidal exhale
    - measured using gas dilution techniques


Term
Equation to find partial pressure of oxygen in inspired gas
Definition

PIO2 = (Ptotal-PH2O) x FIO2

 

= (760-48) x 0.21

 

= 150mmHG

Term
Alveolar gas equation
Definition

PAO2 = PIO2 - PaCO2/0.8

150mmHg - 40/0.8 = 100mmHg

 

the partial pressure of O2 in alveolar gas is found by taking partial pressure of CO2 in arterial blood, dividing it by respiratory exchange ratio (VCO2/VO2)which is 0.8

subtract this sum from pressure of inspired gas which is normally 150mmHg

 

Term

How do you calculate the partial pressure of a gas?

 

 

Definition

Dalton's Law

P02 = FO2 x Ptotal

 

the partial pressure of oxygen equals the fraction of oxygen in the ambient air times the barometric pressure for ambient air

 

changes for inspired air because of water vapor

PIO2 = (Ptotal - PH2O) x FIO2

(760-47) x 0.21 = 150mmHg

Term
how do you find partial pressure of inspired oxygen?
Definition

Ususally, the partial pressure of oxygen equals the fraction of oxygen in the ambient air times the barometric pressure for ambient air

 

With inspired air one must subtract out water vapor

PIO2 = (Ptotal - PH2O) x FIO2

(760-47) x 0.21 = 150mmHg

Term
If alveolar ventilation doubles and CO2 production remains constant, what happens to arterial CO2?
Definition
Term
Draw a compliance curve (label axes) for a normal lung, a fibrotic lung, and a emphasematous lung.
Definition
[image]
Term

list two functions of surficant

how does it help maintain stable alveoli of unequal diameter?

Definition

surfactant reduces surface tension - reducing pressure needed to keep alveoli open

 

Surfactant allows surface tension to vary directly with radius, so smaller alveoli have smaller surface tension

 

thus pressures to keep alveoli open are equalized and both small and large alveoli can exist

Term
contrast compliance of chest wall and lungs at high and low lung volumes
Definition

at high lung volumes, the relaxed chest wall is compliant , but at low volumes it is stiff and thus resist lung collapse, and retains residual volume


at residual volume = chest wall has strong outward recoil and inward recoil of lung is small

at functional capacity = elastic recoils of lung and chest wall are equal, but opposite

at larger lung volume= elastic recoil of chest is smaller and recoil of lung increases

At TLC = elastic recoil of both lung and chest wall direct inward

Term
What is minute ventilation and how is it measured?
Definition
measured using Spirometry
Term

Draw the relationship between ventilation and perfusion and height in the chest of a human

 

how is a dog and a horse different?

Definition
[image]
Term
Diagram alveolar capillary relationship for normal exchange, for a dead space unit, and for a physiological shunt
Definition
[image]
Term
what pathologic conditions cause high or low V/Q ratios?
Definition

Causes for high V/Q ratio:
emphysema
canine heartworm disease
hemorhage
positive pressure ventillation
Causes for low V/Q ratio:
shunt
obstruction
extreme bronchitis

pulmonary fibrosis\

prolonged anesthesia

Term
Why does V/Q mismatch have more effect on PaO2 than on PaCO2?
Definition

increase in PCO2 causes hyperventillation to already over-ventilated alveoli.

 

There is no limit to how low CO2 can go (i.e the blood-CO2 dissociation curve is nearly linear)

BUT

not much more oxygen can be dissolved into the plasma to make up for total oxygen content of the blood

Term

How does PaCO2 influence ventilation?

How does hypoxia affect this response?

Definition

↑ in PaCo2 allows more to diffuse across BBB into CSF

this ↑[H+]

Central and peripheral Chemoreceptors stim ↑ ventillation

 

Hypoxia accentuates the stimulation of ↑↑↑ ventillation

Term
list mechanoreceptors stimulated by maximum ispiration
Definition

stretch receptors in lung parenchyma and airway sm mm - terminate inspiration

 

irritant receptors in airway epithelial cells - promote rapid shallow breathing in response to noxious agents


J-receptors (juxta-capillary) in lung interstitium near capillaries - respond to interstitial edema


chest wall mechanoreceptors - increase inspirator mm activity to maintain tidal volume

Term
define tachpnea and dyspnea
Definition

tachnea - increases respiratory rate

 

Dyspnea - subjective sensation of breathlessness

Term

define

Cheyne Stokes Respiration

Definition
waxing and waning tidal volume usually caused by severe CNS disorder
Term
define Kussmaul breathing
Definition

regular rapid rate with large tidal volume

usually caused by metabolic acidosis

Term
list the mediators inactivated or metabolized by pulmonary endothelial cells
Definition

Bradykinin

Serotonin

PGE, PGF2a

NE

Histamine?

Adenine nucleotides

Acetocholine (ACh)

Term
How does inadequate ventilation affect plasma pH?
Definition

Poor ventilation causes a buildup of CO2 and an increase in [H+] causing respiratory acidosis

 

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3

 

 

Term
how does gas exchange differ between an amphibian and a mammal?
Definition

Amphibians

can use their skin for gas exchange

metomophisize from gills to "lungs"

have no necks so less dead air

their lungs are sac-like - no alveoli

their hearts have 2atria and one ventrical so deoxygenated and oxygenated blood mix.


Both mammals and amphibians have internal lungs where gas exchange takes place from pool of air to constantly flowing blood in capillaries

Term

what are the anatomical differences between the avian and  mammalian respiratory system

 

Definition

Birds

lack a diaphram

ventilation is separate from gas exchange

pneumatization of bone

-Parabronchii - cross-current gas exchange

Air sacs

 

very efficient

Term

draw the Hb-O2 dissociation curve

for a mouse and an elephant on same graph

Definition
[image]
Term
define then list one positive and one negative result of collateral ventillation systems
Definition

Pores of Kohn allow alternate routes for air to travel in lungs

 

positive:

allow alternate routes for air to travel in lungs around an obstruction for example

 

negative:

allows infection to spread throughout lung

 

Term

Explain the difference between FRC and VRX.  Which is the higher volume in a kitten? In a horse?

 

Definition

FRC - functional residual capacity

VRX - relaxation volume = the volume at which the outward chest wall recoil is balanced by the lung's inward recoil

 

In small animals and newborns VRX < FRC

i.e. the end of a tidal breath may not go as low as VRX

 

In horses the VRX > FRC

i.e. the last part of the expiration may require energy

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