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Physiology > Lecture 1 Cardio > Flashcards

Lecture 1 Cardio Flashcards

Cardio/GI (73 cards)

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1
Q

What produces the driving force/pressure for movement of blood throughout the body?

A

Pumping action of the heart

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2
Q

The movement of blood throughout the body is ___

A

unidirectional

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3
Q

most cells in the body are only a few cell diameters away from a ____

A

capillary

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4
Q

what type of movement is responsible for movement of nutrients and metabolic end products in/out of the interstitial fluid?

A

simple diffusion

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5
Q

what type of system is the circulatory system?

A

closed - consists of two major components

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6
Q

_____: Blood is pumped from the left ventricle of the heart to the peripheral tissues through the central aorta

A

systemic circulation

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7
Q

Another way to study it - in systemic circulation, the blood is pumped from the ____ of the heart to the _____ through the ____

A

Blood is pumped from the left ventricle of the heart to the peripheral tissues through the central aorta

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8
Q

The peripheral arterial system is formed by the continuous _____

A

branching of larger vessels into smaller ones as the blood moves toward the periphery of the system and then reunite into progressively larger vessels as the blood returns to the heart.

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9
Q

Arteries from large to small:

Veins from small to large:

A

arteries - arterioles - capillaries

venules - veins

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10
Q

In pulmonary circulation, blood is…

A

pumped from the right ventricle of the heart to the lungs. Blood leaves the right ventricle and enters the pulmonary trunk

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11
Q

Describe the division and reuniting of arteries/veins in pulmonary circulation

A

The pulmonary trunk immediately divides into two pulmonary arteries

Continuous branching of larger vessels into smaller ones results in: pulmonary capillaries

Reuniting of pulmonary capillaries results in the formation of pulmonary veins which ultimately empty blood into the left atrium.

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12
Q

Describe gas exchange in the pulmonary circulation system

and in the systemic circulation system

A

blood flowing through the lungs picks up O2 form the alveoli (air sacs) and CO2 leaves the blood and enters the alveoli

At the peripheral tissues, O2 leaves the blood and enters the interstitial space while CO2 leaves the interstitial space and enters the blood.

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13
Q

Nutrient exchange within the GI system

A

blood flowing through the GI system picks up nutrients and delivers them to the interstitial space. Metabolic waste products enter the blood from the interstitial space and are delivered by the blood to some of the organs for elimination

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14
Q

output of the left ventricle supplies blood to the systemic circulation (___L/min in a 70kg male) and this is called ____

A

5

cardiac output

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15
Q

While at rest, most blood flow goes to…

A

skeletal muscle, kidney, and abdominal organs

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16
Q

During exercise, most blood goes to…

A

skeletal muscle (73%)

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17
Q

blood flows with its..

A

pressure gradient - from high hydrostatic pressure to low

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18
Q

what increases the hydrostatic pressure?

this pressure is the ..

A

pumping actions of the left and right ventricles

driving force for blood flow to the peripheral vascular beds and lungs

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19
Q

What causes resistance to blood flow?

A

shear forces that exist between the blood and the vessel wall and the blood’s viscosity

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20
Q

How is blood flow and the pressure gradient measured?

A

vol/time and mmHg, respectively

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21
Q

How do we calculate resistance?

A

we multiply the viscosity by the length of the blood vessel and divide that figure by the inside radius of the vessel wall to the 4th power. We then multiply that number by (8/pi).

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22
Q

since viscosity and length of the blood vessel do not change much under normal physiological conditions, we can say…

A

resistance to blood flow is inversely proportional to the 4th power of the radius of the blood vessel.

this means that small changes in the radius produce large changes in the resistance. If the radius is decreased by a factor of 2, the resistance is increased by a factor of 16.

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23
Q

Flow equation

A

F=Delta(P)/R

Pressure gradient divided by resistance.

this equation indicates that blood flow is directly proportional to the pressure gradient and inversely proportional to the vascular resistance.

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24
Q

List the chambers of the heart

A

L Atrium, L Ventricle

R Atrium, R Ventricle

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25
what are the walls of the heart composed of, primarily?
cardiac muscle cells and this collection of cells is referred to as the myocardium.
26
The inner surfaces of the cardiac chambers are lined with..
endothelial cells
27
Which valve is between the L atrium and L ventricle? Describe it's function
mitral valve (bicuspid) It allows blood to flow only form L atrium to L ventricle. It opens passively when the blood pressure is greater in the atrium than in the ventricle. If blood tries to move back into the L atrium, this valve closes passively and the papillary muscle prevent the cusps from being pushed up into the L atrium
28
Which valve is located between the R atrium and the R ventricle? Describe its function
Tricuspid It only allows blood to flow from R atrium to ventricle. It opens passively when the blood pressure is higher in the R atrium than in the R ventricle. If blood tries to move back into the atrium, it closes passively and the papillary muscles prevent the cusps from being pushed up into the R atrium
29
What valve is between the Left ventricle and the central aorta? Function?
Aortic valve (3 cusps) Only allows blood to flow from L ventricle into the aorta. It opens passively when BP is higher in the L ventricle than in the central aorta. If blood tries to backflow, it passively closes
30
Which valve is between the R ventricle and the pulmonic trunk? Function?
Pulmonic valve (3 cusps) Only allows blood to flow from the R ventricle into the Pulmonic Trunk. Opens passively when the BP is greater in the R Ventricle than in the pulmonary trunk. If blood tries to backflow into the R ventricle, the valve cusps close passively.
31
When the valves are functioning properly, they present little ____ to blood flow and very small pressure differences across these valves..
little resistance are sufficient to produce large blood flows.
32
How do cardiac muscle fibers play a role in blood pressure?
they encircle the chambers of the heart and, when properly activated, they contract and squeeze the cardiac chamber which reduces its size thereby exerting pressure on the blood contained within that chamber.
33
Compare Cardiac and skeletal muscle
cardiac is striated like skeletal muscle but the individual cells are shorter and have several branching processes
34
What joins cardiac muscle cells end-to-end?
intercalated disks gap junctions are found adjacent to the IC disks.
35
Gap junctions?
gap junctions are found adjacent to the intercalated disks and provide a low resistance pathway that permits the cell-to-cell conduction of action potentials
36
The conducting system of the heart is comprised of cardiac muscle cells that have become...
specialized for conducting APs rather than producing contractile force.
37
What is the primary sympathetic neurotransmitter for the heart? And the associated receptors?
norepinephrine beta adrenergic
38
What is the primary parasympathetic neurotransmitter for the heart? and the associated receptor?
Acetylcholine muscarinic
39
The cardiac muscle fibers get their blood supply (coronary blood flow) from the ___
coronary arteries (the 1st two branches of the central aorta).
40
The majority of blood flow leaving the heart passes through a large vein called the _____
coronary sinus (empties into the atrium)
41
Each side of the heart consists of two pumps - the ___ and the ____
atrial pump and the ventricular pump - effectively making each side a dual pump
42
What has to happen for effective pumping action of the heart?
Both sides of the heart must be activated to beat in some sort of regular fashion on each side, the atrial pump must be activated before the ventricular pump is activated.
43
where is the heartbeat normally initiated?
small group of cells in the right atrium near the entrance of the SVC - sino-atrial node (SA node)
44
Cells in the SA node ___at a regular rate, producing cardiac action potentials and thus, establish the ___
depolarize heart rate
45
How are action potentials spread in the heart?
cell-to-cell conduction through gap junctions
46
What do action potentials in the SA node cause?
BOTH atria to depolarize and contract at the same time
47
What happens after the action potentials depolarize the Atria?
they enter a portion of the conduction system called the atrio-ventricular node (AV)
48
Where is the AV node?
base of the R atrium near the tricuspid valve
49
The AV node is the only...
electrical connection between the atria and the ventricles
50
Conduction of the action potential through the AV node is ___, allowing the ____ to be completed before ____ is initiated.
Conduction of the action potential through the AV node is SLOW, allowing the ATRIAL CONTRACTION to be completed before VENTRICULAR CONTRACTION is initiated.
51
Once through the AV node, the action potential enters the ____
bundle of His
52
The Bundle of His quickly divides into _____, which course down the _____ toward the apex of the ventricles.
The Bundle of His quickly divides into LEFT AND RIGHT BUNDLE BRANCHES, which course down the INTERVENTRICULAR SEPTUM toward the apex of the ventricles.
53
At the apex of the heart, the bundle branches (from Bundle of His) make contact with ____ that rapidly distribute the action potential throughout the ventricular muscle tissue
Purkinje Fibers
54
The cells of the cardia tissue are specialized for rapid conduction of APs and are NOT composed of ____
nerve tissue
55
Resting membrane potential of the cardiac muscle cells is about ____
-90 millivolts
56
The action potential consists of a period of ____ and a period of ____
rapid depolarization rapid repolarization
57
The distinctive feature of the cardiac action potentials is the ____
prolonged plateau phase that exists between depolarization and repolarization.
58
The plateau phase results in a total action potential duration of
300-400 milliseconds
59
What are the 5 phases of cardiac action potentials
Phase 0 - rapid depolarization Phase 1 - Initial repolarization Phase 2 - Plateau Phase 3 - Final repolarization Phase 4 - Resting membrane potential
60
What causes rapid depolarization?
opening of voltage-gates sodium channels - increases sodium permeability
61
At about the same time as the voltage-gated sodium ion channels open (during depolarization), the permeability of ____ decreases
potassium
62
What 2 actions cause the plateau phase?
The K channels remain closed (inhibits repolarization) and the voltage-gated calcium channels (L type) open at the end of depolarization (allows calcium to enter the cell)
63
What happens when the Ca2+ channels close and the K channels open?
repolarization
64
The cells of the SA node exhibit a special kind of electrical activity called ___
pacemaker activity
65
The cells of the SA node do not have a ____ but instead exhibit...
The cells of the SA node do not have a resting membrane potential but instead exhibit slow depolarization during the resting phase.
66
The slow depolarization in the SA node cells eventually cause them to reach their ___, at which point ___
The slow depolarization in the SA node cells eventually cause them to reach their THRESHOLD, at which point an action potential is initiated
67
The pacemaker cells have no ___ Pacemaker activity is intrinsic to the heart and does not require ___
plateau phase activity of nerves
68
The slow depolarization of the SA node cells is the result of 2 ionic permeability changes (different from normal AP generation)
voltage-gated Na channel that opens as a result of the previous repolarization (not the same Na channels as other AP) transient Ca2+ channel (T type) both carry positive charges into the cell and depolarize the membrane toward threshold.
69
In the SA node, once threshold is reached,_____ opens briefly and carries more positive change into the cell.
In the SA node, once threshold is reached, a voltage-gated Ca2+ channel (L type) opens briefly and carries more positive change into the cell.
70
SA node cell repolarization occurs when ...
SA node cell repolarization occurs when the L-type Ca2+ channel closes and the K+ permeability returns to normal.
71
The regular generation of action potentials is responsible for producing ____
regular contractions of the heart at the same rate.
72
The intrinsic rate of firing of the SA node pacemaker (with no ANS input) is ___
100/min
73
Since ___ predominates over ___, the resulting rate of generation of SA node action potentials is approximately ___
parasympathetic activity supplying the SA node sympathetic fibers 70/min

Physiology (8 decks)

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