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224 CSN > ch 20 the heart > Flashcards

ch 20 the heart Flashcards

1
Q

right side of the heart is called ……….. left side of the heart is called …………….

A

pulmonary circulation systemic circulation

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2
Q

the 4 main functions of the heart

A

generates blood pressure, routes blood, insures one-way blood flow, regulates blood flow

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3
Q

what are the 4 layers of the pericardium (superficial to deep)

A
  1. fibrous pericardium 2. serous pericardium aka parietal pericardium 3. pericardial cavity (contains pericardial fluid) 4. visceral pericardium (also the epicardium if referring to the heart wall).
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4
Q

why is L ventricle more muscular than R

A

needs to pump blood through longer vessels and narrower capillaries

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5
Q

from where do the R & L coronary arteries branch off from?

A

the aorta

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6
Q

coronary blood flows only when the heart is …………

A

relaxed

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7
Q

R AV valve is known as the …………… L AV valve is known as the …………….

A

Tricuspid Bicuspid or mitral

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8
Q

Semilunar Valves are known as ……………….. and …………….. . How many cusps do the have?

A

Pulmonary valve and Aortic valve. 3 cusps.

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9
Q

what causes valves to close?

A

blood flow. blood pressure causes blood flow.

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10
Q

What is the heart skeleton made of? Whats its function?

A

fibrous connective tissue. It surrounds and supports the valves to keep shape and insulates the heart from its own electrical activity.

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11
Q

How does cardiac muscle differ from skeletal muscle?

A
  1. smaller, branched cells with 1 nucleus. 2. more mitochondria 3. less extensive sarcoplasmic reticulum and broader T-tubules. 4. gets some calcium from across sarcolemma 5. attached to adjacent cells by desmosomes (for strength) and gap junctions (for fast communication).
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12
Q

…………………. cardiac cells control and coordinate heartbeat. …………………. cardiac cells produce the force. Which ones are larger in size?

A

conducting contractile Contractile are bigger than conducting.

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13
Q

what causes action potentials in the heart?

A

the hearts conducting pacemaker cells (not neurons).

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14
Q

What is the pathway of the hearts action potentials?

A

SA node - AV node (delay here) - AV bundle (aka bundle of HIS) - R&L bundle branches - Purkinje fibers

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15
Q

Why does the AV node delay the action potential from the SA node?

A

To give time to the atria to contract and send blood into the ventricles.

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16
Q

Where does ventricular contraction start from?

A

The apex of the heart

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17
Q

What is the heart’s size, shape, and location?

A

Size: 250-300 grams like a closed fist. Cone shaped with apex and base, located in mediastinum, pointed slightly left 2/3 are located to left of sternum from 2nd to 5th intercostal space

18
Q

reasons why its important to know heart’s location:

A

positioning of stethescope, electrodes for ECG, and to do CPR

19
Q

What is Calcium Induced Calcium Release (CICR)?

A

calcium ions that enter the cardiac muscle cell during an action potential cause the release of more calcium ions from the cell’s sarcoplasmic reticulum. This feature is unique to cardiac muscle and is necessary for the contraction of cardiac muscle (unlike skeletal muscle that gets all its calcium from the sarcoplasmic reticulum).

20
Q

why does cardiac muscle have a long refractory period?

A

To avoid tetany and ensure rhythmic contractions

21
Q

Action potential in contractile cardiac muscle cells: 1. What causes depolarization? 2. What causes early repolarization? 3. What causes plateau? 4. What causes full repolarization?

A
  1. Na+ channels open and Na+ floods into the cell. K+ are closed and Ca+2 slowly open contributing to depolarization. 2. Na+ close , so no more Na+ influx. Some Ca+2 close. K+ begin to open so K+ slowly leaves cell. 3. Slow influx of Ca+2 from remaining open Ca+2 channels. 4. All Ca+2 close, Na+ stays closed, K+ open, so K+ leaves cell returning to resting potential.
22
Q

What is a pacemaker potential?

A

a spontaneously developing action potential in conducting cardiac muscle fibers that causes an action potential in the SA node.

23
Q

Action potential in conducting cardiac muscle cells: 1. What causes the pacemaker potential? 2. What causes full depolarization? 3. What causes repolarization?

A
  1. small number of Na+ channels open, bringing in some Na+. Small number of Ca+2 opens too. 2. Ca+2 opens even more, bringing in more Ca+2 3. Ca+2 close and K+ open. Ca+2 stops coming in and K+leaves the cell returning to resting potential.
24
Q

what is the primer pump? what is the power pump?

A

artia ventricles

25
Q

what are the 5 steps of a cardiac cycle and what is happening in each? How long does one cardiac cycle last?

A
  1. Atrial Systole: active ventricular filling. AV valves open. 2. Ventricular Systole: period of isovolumetric contraction. All valves closed. Atria fill w/ blood and ventricles start to contract. 3. Ventricular Systole: period of ejection. Ventricles fully contract and push blood thru semilunar valves. 4. Ventricular Diastole: isovolumetric relaxation. Semilunar valves close and ventricles begin to relax. 5. Ventricular Diastole: passive ventricular filling. Av valves open (accounts for most of ventricular filling).

.7-.8 seconds depending on HR

26
Q

name all the structures

A

name the structures

27
Q

The lubb sound is caused by?

The Dupp sound is caused by?

Where do you position the stethescope?

A
  1. Closing of AV valves as ventricles contract.
  2. Closing of semi-lunar valves as ventricles relax.
  3. 5th intercostal space 3” left of mid-line
28
Q

p wave=

QRS complex=

T wave=

A
  1. Atrial depolarization. Atrial systole. Active ventricular filling
  2. Ventricular depolarization. Ventricular systole. AV valves close, first heart sound. Isovolumetric contraction then ejection.
  3. Ventricular repolarization. Ventricular diastole. SL valves close. Dicrotic notch. Second heart sound. Isovolumetric relaxation then passive ventricular filling begins until next P wave.

*atrial repolarization and atrial diastole occurs during QRS, but is masked by QRS complex*

29
Q

systole

diastole

A

contraction

relaxation

30
Q

What is cardic output (CO)?

What is peripheral resistance (PR)?

What is MAP?

A

volume of blood pumped by the heart in one minute

total resistance against which the blood must be pumped

Mean Arterial Pressure (MAP)= COxPR

*increasing CO or PR will increase MAP*

31
Q

What is Heart Rate (HR)?

What is Stroke Volume (SV)?

How do these relate to CO?

A

the number of time the heart beats (contracts) per min.

the volume of blood pumped per heartbeat (cardiac cycle)

*SV= EDV-ESV end diastolic volume-end systolic volume*

CO=HRxSV

32
Q

What is a typical end-diastolic volume and end-systolic volume?

How do these give us stroke volume SV?

A

typical edv= 125

typical eds=55

edv-esv=SV

typical stroke volume = 70mL

33
Q

What is MAP?

What is Peripheral Resistance (PR)?

A

Mean Arterial Pressure. It is the average pressure in the great vessels over time. It is proportional to COxPR

PR is the resistance of the peripheral vessels to blood flow.

*increase in CO or PR will increase MAP*

34
Q

Increasing HR or EDV or decreasing ESV will…….

A

Increase CO cardiac output

35
Q

What is intrinsic regulation?

A

The regulation of CO by the heart itself. For example, during exercise there is greater venous return. The heart muscle must stretch more to allow for more filling (greater preload) this will increase the force of contraction.

36
Q

What is the Starling Law?

A

increased preload causes the cardiac muscle cells to contract with a greater force and produce a greater stroke volume.

37
Q

What is Extrinsic Regulation?

A

The regulation of CO by neural and hormonal factors.

38
Q

Describe neural control of the heart

Describe Hormonal control of the heart

A

Exerted by ANS

Sympathetic: increases CO by cardiac nerves by releasing NE on adrenergic receptors which help release Ca+2

Parasympathetic: reduces CO by ACh being released and increasing K+ hyperpolarizing SA node

Hormonal: triggered by sympathetic division. Releases NE from adrenal medula. Slower to react yet longer lasting than NE released from sympathetic synapses

39
Q

What do baroreceptors do?

A

Regulate blood pressure.

If too low, message is sent to cardioregulatory center in medulla and sypathetic response is stimulated to increase BP.

If BP is too high, sypathetic response is inhibited and parasympathetic response is stimulated to decrease BP.

40
Q

What do chemoreceptors do?

A

regulate heart’s response to blood pH, CO2, and O2 levels.

If pH drops, CO2 rises. HR needs to increase to get more blood to the lungs to be oxygenated. The opposite happens if pH rises and CO2 drops

If O2 levels drop HR is increased and widespread vasoconstriction occurs.

41
Q

What happens if there is too much K+ in blood?

What happens when extracellular K+ decreases?

Elevated Ca+2 levels do what?

Reduced Ca+2 do what?

A

HR and SV decreases

HR is lowered because it takes longer for cell to depolarize.

Increase force of contraction and reduces HR.

Increase HR

224 CSN (13 decks)

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