Cardiac L 14

Question 1

cardiac muscle is regulated by the

Answer 1

autonomic nervous system

Question 2

is cardiac muscle striated or non striated

Answer 2

striated

Question 3

Myosin and actin filaments form

Answer 3

sarcomeres

Question 4

Contraction occurs by means of sliding

Answer 4

thin filaments

Question 5

cardiac muscle is connected via

Answer 5

via gap
junctions called intercalated discs (electrical
synapses that permit impulses to be
conducted cell to cell).

Question 6

is cardiac muscle multinucleated?

Answer 6

NO

Question 7

define myocardium

Answer 7

a mass of cardiac muscle cells connected to
each other via gap junctions.

Question 8

do action potentials have to occur at all cells in myocardium to simulate ALL the cells in myocardium?

Answer 8

no, Action potentials that occur at any cell in a myocardium can
stimulate all the cells in the myocardium
-behaves as single functional unit

Question 9

what is pacemaker potential?

Answer 9

Cardiac muscle producing action potentials automatically
(without innervation)

Question 10

what is heart rate influenced by?

Answer 10

autonomic innervation and
hormones.

Question 11

are voltage-gated calcium
channels directly connected to calcium
channels in the SR?

Answer 11

NO,
instead:calcium acts as a second messenger to open
SR channels: called calcium induced calcium release

Question 12

what is cardiac output?

Answer 12

Cardiac output – the volume of blood
pumped each minute by each ventricle:
cardiac output = stroke volume X heart rate
(ml/minute) (ml/beat) (beats/min)
a. Average heart rate = 70 bpm
b. Average stroke volume = 70 to 80 ml/beat
c. Average cardiac output = 5,000-5,500 ml/minute

Question 13

how is cardiac rate regulated?

Answer 13

Spontaneous depolarization occurs at SA node
when HCN channels open, allowing Na+ in.

a. Open due to hyperpolarization at the end of the
preceding action potential

b. Sympathetic norepinephrine and adrenal
epinephrine keep HCN channels open, increasing
heart rate.

c. Parasympathetic acetylcholine opens K+ channels,
slowing heart rate.

d. Controlled by cardiac center of medulla oblongata
that is affected by higher brain centers

Question 14

what antagonistic influence increases cardiac rate?

Answer 14

Positive chronotropic effect
Tachycardia >100 bpm

Question 15

what antagonistic influence decreases cardiac rate?

Answer 15

Negative chronotropic effect
Bradycardia < 60 bpm

Question 16

what are the sympathetic and parasympathetic effects of the SA node?

Answer 16

sympathetic:Increased rate of diastolic
depolarization; increased
cardiac rate

parasym:Decreased rate of diastolic
depolarization; decreased
cardiac rate

Question 17

what are the sympathetic and parasympathetic effects of the AV node?

Answer 17

sym:Increased conduction rate
para:Decreased conduction
rate

Question 18

what are the sympathetic and parasympathetic effects of the atrial muscle?

Answer 18

sym: Increased strength of
contraction

para:No significant effect

Question 19

what are the sympathetic and parasympathetic effects of the ventricular muscle?

Answer 19

sym: Increased strength of
contraction

para: No significant effect

Question 20

what 3 variables is stroke volume regulated by?

Answer 20

1. End diastolic volume (EDV): volume of blood in the
   ventricles at the end of diastole
   a) Sometimes called preload
   b) SV increases with increased EDV.
2. Total peripheral resistance: Frictional resistance in
   the arteries
   a) Called afterload
   b) Inversely related to SV
3. Contractility: strength of ventricular contraction
   a) SV increases with increased contractility.

Question 21

normally, about how much % of the end diastolic volume (EDV) is ejected?

Answer 21

60%,
aka the ejection fraction: amount of blood pumped out of the ventricle/total amount of blood in ventricle

Question 22

what is the frank starling law?

Answer 22

increased end diastolic volume (EDV) results in increased contractility and thus increased stroke volume

Question 23

what is Intrinsic Control of Contraction Strength due to?

Answer 23

1) Due to myocardial stretch

a) Increased EDV stretches the myocardium,
which increases contraction strength.
b) Due to increased myosin and actin overlap and
increased sensitivity to Ca2+ in cardiac muscle
cells

Question 24

what is the Adjustment for rise in peripheral resistance?(Intrinsic Control of Contraction Strength.)

Answer 24

a) Increased peripheral resistance will
decrease stroke volume

b) More blood remains in the ventricles, so
EDV increases

c) Ventricles are stretched more, so they
contract more strongly

Question 25

Extrinsic Control of Contractility

Answer 25

1) Contractility – strength of contraction at any given fiber length 2) Sympathetic norepinephrine and adrenal epinephrine (positive inotropic effect) can increase contractility by making more Ca2+ available to sarcomeres. Also increases heart rate. 3) Parasympathetic acetylcholine (negative chronotropic effect) will decrease heart rate which will increase EDV →increases contraction strength →increases stroke volume, but not enough to compensate for slower rate, so cardiac output decreases

Question 26

regulation of cardiac output equation

Answer 26

cardiac output=cardiac rate x stroke volume(total peripheral resistance and mean arterial pressure)

Question 27

what is the distribution of blood at rest? -small veins and venules, systemic veins, large veins - capillaries -systemic arteries -heart -lungs`

Answer 27

- 60-70% - 4-5% -10-12% -8-11% -10-12%

Question 28

what are the 3 factors in venous return?

Answer 28

1. blood volume (uring volume, tissue filled fluid) 2. negative intrathoracic pressure(breathing) 3. venous pressure(skeletal muscle pump, sympathetic nerve stimulation-->venoconstriction)

Question 29

VENOUS RETURN -what factors is end diastolic volume controlled by?

Answer 29

-factors that affect venous return: 1. total blood volume 2. venous pressure difference between arteries and veins(driving force for blood return)

Question 30

which stretches more: veins or arteries?

Answer 30

veins (have higher compliance and thinner walls)

Question 31

where is most blood volume stored?

Answer 31

veins

Question 32

where is the pressure difference in the venous system(which has highest which has lowest)

Answer 32

highest pressure in venules versus lowest pressure in venae cavae into the right atrium (0mm Hg)

Question 33

The rate of blood flow is inversely proportional to

Answer 33

the frictional resistance to blood flow within the vessels.

Question 34

what are the 2 most important factors in blood flow?

Answer 34

1. mean arterial pressure 2. vessel radius

Question 35

vasoconstriction of __________________ provides the greatest resistance to blood flow and can redirect flow to/from particular organs

Answer 35

arterioles

Question 36

______________ ____________ ____________ is The sum of all vascular resistance in systemic circulation

Answer 36

total peripheral resistance

Question 37

Vasodilation in a large organ may : **increase OR decrease** total peripheral resistance and mean arterial pressure.

Answer 37

decrease

Question 38

Increase in cardiac output and increase total peripheral resistance through release of ____________ onto smooth muscles of arterioles in the viscera and skin to stimulate vasoconstriction (alpha-adrenergic).

Answer 38

norepi

Question 39

____________ is released onto skeletal muscles, resulting in increased vasodilation to these tissues (cholinergic)

Answer 39

acetylcholine (cholinergenic)

Question 40

____________ __________ stimulates beta-adrenergic receptors for vasodilation

Answer 40

Adrenal epinephrine

Question 41

what neurotransmitter stimulates vasodilation -located in

Answer 41

Acetylcholine digestive tract, external genitalia, and salivary glands

Question 42

what is reactive hypermia vs active hypermia

Answer 42

Reactive hyperemia – constriction causes build-up of metabolic wastes which will then cause vasodilation (reddish skin) 5. Active hyperemia – increased blood flow during increased metabolism (reddish skin

Question 43

local vasodilation is controlled by changes in:(4)

Answer 43

1) Decreased oxygen concentrations due to increased metabolism 2) Increased carbon dioxide concentrations 3) Decreased tissue pH (due to CO2, lactic acid, etc.) 4) Release of K+ and paracrine signals (nitric oxide etc.)

Question 44

blood flow is restricted during what part of the cardiac cycle?

Answer 44

systole

Question 45

Regulation of Coronary Blood Flow: ____________ from sympathetic nerve fibers (alpha-adrenergic) stimulates vasoconstriction, raising vascular resistance at rest. -_______________________________ (beta-adrenergic) stimulates vasodilation and thus decreases vascular resistance during exercise. -Vasodilation is enhanced by intrinsic metabolic control mechanisms – __________________-__

Answer 45

Norepinephrine -adrenal epi -increased CO2, K+, paracrine regulators

Question 46

what is an angiogram? -what is a coronary angioplasty

Answer 46

-An angiogram is an X-ray picture with a contrast dye. An angiogram of the coronary arteries might reveal narrowing caused by atherosclerotic plaques, a thrombus, or a spasm. A coronary angiogram is the standard method for assessing coronary artery disease -Coronary angioplasty is the technique of inserting a catheter with a balloon into the occluded site of a coronary artery and then inflating the balloon to push the artery open. Stents are often inserted to support the opened section of the coronary artery. 3. Coronary artery bypass grafting (CABG) surgery is the most common open-heart surgery, involving the grafting of a vessel taken from the patient onto the aorta so that it bypasses the narrowed coronary artery.

Question 47

Arterioles have high vascular resistance at rest due to:

Answer 47

alpha-adrenergic sympathetic stimulation -Even at rest, skeletal muscles receive 20 to 25% of the body’s blood supply

Question 48

Regulation of Blood Flow Through Skeletal Muscles(4 factors)

Answer 48

1. Arterioles have high vascular resistance at rest due to alpha-adrenergic sympathetic stimulation a. Even at rest, skeletal muscles receive 20 to 25% of the body’s blood supply. 2. Blood flow does decrease during contraction and can stop completely beyond 70% of maximum contraction. 3. Vasodilation is stimulated by both adrenal epinephrine 4. Intrinsic metabolic controls enhance vasodilation during exercise

Question 49

Blood Flow to the Brain and Skin (cerebral and cutaneous flow)

Answer 49

1. Cerebral flow is primarily controlled by intrinsic mechanisms and is relatively constant; the brain can not tolerate much variation in blood flow. 2. Cutaneous flow primarily controlled by extrinsic mechanisms and shows the most variation; can handle low rates of blood flow

Question 50

blood pressure is affected by:(4)

Answer 50

blood volume/stroke volume, total peripheral resistance, and cardiac rate a. Increase in any of these will increase blood pressure. b. Vasoconstriction of arterioles raises blood pressure upstream in the arteries. c. Arterial blood = cardiac X total peripheral pressure output resistance

Question 51

Blood Pressure Regulation a. Kidneys can control blood volume and thus _______ ________ b. The sympathoadrenal system stimulates vasoconstriction of arterioles (raising total peripheral resistance) and increased cardiac output.

Answer 51

stroke volume

Question 52

Hypertension can be classified as “essential” or “secondary.

Answer 52

1) Essential or primary hypertension is a result of complex and poorly understood processes 2) Secondary hypertension is a symptom of another disease, such as kidney disease.

Question 53

what are some causes of ESSENTIAL HYPERTENSION(4)

Answer 53

a. Increased salt intake coupled with decreased kidney filtering ability b. Increased sympathetic nerve activity, increasing heart rate c. Responses to paracrine regulators from the endothelium d. Increased total peripheral resistance

Question 54

baroreceptor reflex is: activated by: most sensitive to:

Answer 54

one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels Activated by changes in blood pressure detected by baroreceptors (stretch receptors) in the aortic arch and carotid sinuses 2. Increased blood pressure stretches these receptors, increasing action potentials to the vasomotor and cardiac control centers in the medulla. 3. Most sensitive to drops in blood pressure 4. The vasomotor center controls vasodilation and constriction. 5. The cardiac center controls heart rate. 6. Fall in blood pressure = Increased sympathetic and decreased parasympathetic activity, resulting in increased heart rate and total peripheral resistance 7. Rise in BP has the opposite effects. 8. Good for quick beat-by-beat regulation like going from lying down to standing

Question 55

difference between blood pressure at systole and at diastole is systole-diastole=PULSE PRESSURE

Answer 55

the pulse pressure If your blood pressure is 120/80, your pulse pressure is 40 mmHg. (120-80=40) 3. Pulse pressure is a reflection of stroke volume

Question 56

The average pressure in the arteries in one cardiac cycle is the

Answer 56

mean arterial pressure This is significant because it is the difference between mean arterial pressure and venous pressure that drives the blood into the capillaries. 3. Calculated as: diastolic pressure + 1/3 pulse pressure From previous slide: DBP = 80 + 0.33 PP (40) = 93.2 mmHG

Question 57

Occurs when there is inadequate blood flow to match oxygen usage in the tissues a. Symptoms result from inadequate blood flow and how our circulatory system changes to compensate. b. Sometimes shock leads to death.

Answer 57

circulatory shock

Question 58

what is it? a. Due to low blood volume from an injury, dehydration, or burns b. Characterized by decreased cardiac output and blood pressure c. Blood is diverted to the heart and brain at the expense of other organs. d. Compensation includes baroreceptor reflex, which lowers blood pressure, raises heart rate, raises peripheral resistance, and produces cold, clammy skin and low urine output.

Answer 58

hypovolemic shock

Question 59

what is it? a. Dangerously low blood pressure (hypotension) due to an infection (sepsis) b. Bacterial toxins (endotoxins) induce NO production, causing widespread vasodilation. c. Mortality rate is high (50 to 70%).

Answer 59

septic shock

Question 60

what are other other causes of circulatory shock?(3)

Answer 60

a. **Severe allergic reactions** can cause anaphylactic shock due to production of histamine and resulting vasodilation. b. **Spinal cord injury** or anesthesis can cause neurogenic shock due to loss of sympathetic stimulation. c. **Cardiac failure** can cause cardiogenic shock due to significant myocardial loss

Question 61

what is this?] 1. Occurs when cardiac output is not sufficient to maintain blood flow required by the body a. Caused by myocardial infarction, congenital defects, hypertension, aortic valve stenosis, or disturbances in electrolyte levels (K+ and Ca2+) b. Similar to hypovolemic shock in symptoms and response a. Left-side failure – raises left atrial pressure and produces pulmonary congestion and edema causing shortness of breath b. Right-side failure – raises right atrial pressure and produces systemic congestion and edema

Answer 61

congestive heart failure

Question 62

what are the 2 types of congestive heart failure?

Answer 62

a. Left-side failure – raises left atrial pressure and produces pulmonary congestion and edema causing shortness of breath b. Right-side failure – raises right atrial pressure and produces systemic congestion and edema

Question 63

what are 5 circulatory changes during dynamic exercise?

Answer 63

1. Vascular resistance through skeletal and cardiac muscles decreases due to: a. Increased cardiac output b. Metabolic vasodilation c. Diversion of blood away from viscera and skin 2. Blood flow to brain increases a small amount with moderate exercise and decreases a small amount during intense exercise 3. Cardiac output can increase 5X due to increased cardiac rate. 4. Stroke volume can increase some due to increased venous return from skeletal muscle pumps and respiratory movements 5. Ejection fraction increases due to increased contractility

Question 64

what circulatory changes does endurance training result in?

Answer 64

a. Lower resting cardiac rate due to greater inhibition of the SA node b. Increase in stroke volume because of the increase in blood volume c. Improved O2 delivery

Question 65

paracrine regulation of blood flow:

Answer 65

1. Used by some organs (brain and kidneys) to promote constant blood flow when there is fluctuation of blood pressure; also called autoregulation. 2. Myogenic control mechanisms: Vascular smooth muscle responds to changes in arterial blood pressure. Paracrine Regulation of Blood Flow 1. Molecules produced by one tissue control another tissue within the same organ. a. Example: The tunica interna produces signals to influence smooth muscle activity in the tunica media. 2. Smooth muscle relaxation influenced by bradykinin, nitric oxide, and prostaglandin I2 to produce vasodilation 3. Endothelin-1 stimulates smooth muscle contraction to produce vasoconstriction and raise total peripheral resistance.

Question 66

what are 3 aerobic requirements of the heart for exercise training?

Answer 66

a. Increased density of coronary arterioles and capillaries b. Increased production of NO to promote vasodilation c. Decreased compression of coronary arteries during systole due to lower cardiac rate

Question 67

vasoconstriction

Answer 67

norepi

Question 68

vasodilation

Answer 68

epi