Cardiovascular Phys

Question 1

What are the two endocrine hormones in the heart and what do they respond to

Answer 1

ANP- In response to increased atrial pressure

BNP- in response to overstreached ventricles

Question 2

what is the unique feature of cardiac musculature and how does contraction spread

Answer 2

-individual fibres are connected by intercalated discs with gap junctions

-the gap junctions allow for passage of ions between the myocytes
-the intercalated discs allow the heart to contraction in synchrony as one unit

Question 3

What are the 5 phases of cardiac mm contraction

Answer 3

Phase 0- NA influx- rapid depolarization

Phase 1- inactivation of fast NA with K efflux (small lil repolarization)

Phase 2- Ca influx they L type (plateu phase)

Phase 3- inactivation of Ca channels with K efflux (full repolarization)

Phase 4- remove of excess Na and Ca

Question 4

What is the absolute and relative refractory periods of the cardiac cycle

Answer 4

absolute- no action potential can be initiated regardless of stim strength because NA channels closed (phase 1/2)

Relative- stronger contraction needed (half way thru phase 3-4)

Question 5

what does digoxin do

Answer 5

increases influx of calcium thus increasing force of contraction

Question 6

what is the frank starling law

Answer 6

cardiac output is directly proportional to the venous return

-force of contraction of a myocardial fibre is proportional to the length
–the greater amount of blood entering=the greater stretch

Question 7

what is the 1st and 2nd heart sounds

Answer 7

1st- closure of tricuspid and mitral valves

2nd- closure of pulmonary and aortic

Question 8

What is the 3rd and 4th heart sounds

Answer 8

3rd- congestive heart failure

4th- just before 1st heart sound- hypertrophic ventricles

Question 9

what is the normal pace for the SA node and AV node and then when they superimposed normally

Answer 9

SA- 80-100

AV- 40-60

Together- 70

Question 10

where is conduction velocity the fastest and slowest in the heart

Answer 10

slowest- AV node

Fastest- purkinje fibres

Question 11

what does the P, QRS and T wave represent

Answer 11

P- atrial depolarization

QRS- ventricular depolarization

T- ventricular repolarization

(atrial not seen as its under QRS complex)

Question 12

What would the U wave be

Answer 12

repolarization of the purkinje fibres

Question 13

Sympathetic inn of the heart is from what

Answer 13

T1-5 (the middle and inf cerv ganglia)

Question 14

How is the heart rate, conduction velocity and force of contraction increased in heart

Answer 14

HR (chronotropism) increas rate of Phase 4

Conduction (dromotropism)- decrease PR interval (from p to q)

Force (inotopism)- increasing Ca influx in phase 2

Question 15

What is parasympathetic inn of heart

Answer 15

vagus vis its cardiac branches

Question 16

What is blood pressure calculated by

Answer 16

CO x Peripheral resistance

Question 17

What are the 2 main mechanisms of controlling BP

Answer 17

Baroreceptors (fast due to NT)

Renin-angiotensin- aldosterone mechanism (slow due to hormones)

Question 18

How does the baroreceptor system work

Answer 18

located on carotid sinus and in aortic arch (afferent carried by CNIX, X)

Question 19

what is poiseuilles law

Answer 19

Peripheral resistance is directly proportional to the viscosity of blood and length of the vessel and inversely proportional to radius to 4th power

Question 20

what % of blood is found in each part of the body (venous system, arteries, pulmonary, capillary systems)

Answer 20

Venous- 60%
arterial- 20
pulmonary 15
cap- 5