Cardiac Output

Question 1

Cardiac Output Def.

Answer 1

Volume ejected from ventricle per min (L/m). Volume ejected per beat (stroke volume) X no. of beats per min (Heart rate). Average ~ 5 L/min

Question 2

What system regulates cardiac output

Answer 2

Autonomic Nervous System

Question 3

RMP of Cardiac Cell

Answer 3

~ -55 mV

Question 4

Action Potential Activation

Answer 4

~ -40mV

Question 5

Parasympathetic effect on heart rate

Answer 5

Choline activates cholinergic receptors. This decreases cAMP and decreases heart rate

Question 6

Sympathetic effect on heart rate

Answer 6

Androgenic receptors increase cAMP, increasing heart rate

Question 7

What antagonist decreases heart rate

Answer 7

Beta Blockers

Question 8

What antagonist increases heart rate

Answer 8

Atropine

Question 9

Tachycardia Def.

Answer 9

Increase in heart rate, sympathetic nervous system effect

Question 10

Adrenegeric Action Def.

Answer 10

Beta-adrenoreceptor (g-protein couple) stimulate cAMP which activates PKA. Increases Ca^2+ entry (depolarisation). Ca^2+ binds to troponoin to activate cross bridging

Question 11

Sympathetic Agonists

Answer 11

Positive (promoting) chronotropes (faster acting) and inotropes (increase output force)

Question 12

Para synthetic Chronotypes

Answer 12

Negative chronotropes ( slow down rate). No ionotropic effects

Question 13

Beta-blockers (atenolol and propranol) Outline

Answer 13

Negative chronotropes and ionotropes

Question 14

Relationship between cardiac output and blood re-entering heart

Answer 14

Blood volume exiting heart = blood volume entering heart

Question 15

Intrinsic Regulation of Heart Outline

Answer 15

Heart can adapt to changes in blood volume without reference to nerves or hormones

Question 16

Frank Sterling Law of Heart Outline

Answer 16

Greater stretch of cardiac muscle = greater force of contraction. Thus increasing preload (volume of blood stretching muscle) = increasing stroke volume (force pushing blood out of heart)

Question 17

What happens when cardiac muscle is understretched

Answer 17

Myosin and actin in muscle are imperfectly aligned. Cross bridges aren’t as efficient. The more the myocardium is stretched = more efficent cross bridge overlap (greater force generated)

Question 18

Relationship between stretching and stroke volume

Answer 18

Closely positively associated until heart muscle is stretched past a ceratin stage where cross bridges can no longer overlap and force that generates stroke volume decreases

Question 19

Preload Outline

Answer 19

Ventricular filling during diastole. Affected by atria and venous pressure, gravity and circulation blood pressure

Question 20

Blood Volume + Venous Tone

Answer 20

Great veins tore blood at any time, increased blood volume = increased central venous pressure. Increased central venous pressure = increased preload

Question 21

Gravity Realtionship to pressure

Answer 21

Increased gravity force = decreased blood pressure. Low blood pressure at head (when standing). Hypotension occasionally occurs when standing up

Question 22

How blood flows against gravity

Answer 22

Vein’s valves (preventing backflow) and skeletal muscle blocks (compress against veins, only active by movement). These push blood towards heart

Question 23

Inspiration Thoracic Pump Outline

Answer 23

Inspiration raises abdominal (stomach) pressure and
lowers thoracic (chest) pressure. Blood in abdomen moves to thorax, blood in legs remains there

Question 24

Expiration Thoracic Pump Outline

Answer 24

Lowers abdominal pressure and decreases thoracic pressure. Blood moves from legs to abdomen

Question 25

Starling and Contractility

Answer 25

Stroke volume increases by changing orientation. Inotropes increase Ca, increasing contractility

Question 26

Consequences of Too Low Blood Pressure

Answer 26

Low tissue perfusion. Organ failure (noticeably brain and kidney filtration)

Question 27

Consequences of Too High Blood Pressure

Answer 27

High perfusion. Damage to cells causing damage to cells

Question 28

Mean Arterial equation Factors

Answer 28

Mean Arterial Output = Net Peripheral Ressistance x Cardiac Output

Question 29

Distribution of Water

Answer 29

67% intracellular and 33% extracellular. 1/9 is vascular and 2/9 = interstitial

Question 30

Renin-Angionestic System Def

Answer 30

Potent vasoconstricting (increase ressistance). Stimulates adelsterone increased absorption from kidney = increased blood volume

Question 31

Arginine Vasopressin

Answer 31

ADH released due to high osmolality and low blood volume. Increase reabsorption

Question 32

Atrial Natriuretic Peptide

Answer 32

Inhibits absorption from kidneys. Lowers blood volume

Question 33

Baroreceptor Reflex Outline

Answer 33

Short term blood pressure regulation via negative reflex. Mechanoreceptors (sense pressure changes), central relays (brain stem and medulla oblongata) and effector efferent (innervates heart and vessels). Signals nucleus tractus soliteras in medulla

Question 34

Baroreceptor Nerve Fibres

Answer 34

Increase aterial pressure = increase firing rate. Rate = dynamic, magnitude = static senitivity. Regulate sympathetic and parasympathetic

Question 35

Blood Pressure Dropping

Answer 35

decreased pressure = less vessel stretching = decreased baroreceptor firing to NTS = decreased PNS and increased SNS = increased heart rate

Question 36

Heart Failure Outline

Answer 36

Inability to maintain cardiac output. Decreasing output = decreasing pressure = increased SNS via baroreceptors = increase renin-angiotenion