Heart rate

Question 1

what is heart rate

Answer 1

the number of heart beats per minute

Question 2

electrical impulses are _____ generated by the ___ node - the _____ of the heart, leading to regular rhythmical contractions of the heart. This is called normal _____ rhythm

Answer 2

spontaneously
SA
pacemaker
sinus

Question 3

what is the resting heart rate for a normal adult on average?

Answer 3

70-72 beats per minute

Question 4

what are the most important influences on heart rate?

Answer 4

sympathetic and parasympathetic nervous stimuli

Question 5

effect of sympathetic stimulation on HR? This is called a ____ ____ effect

Answer 5

increases heart rate - positive chronotropic

Question 6

effect of parasympathetic stimulation on HR? This is called a ____ ____ effect. It brings about this effect via ____ nerves

Answer 6

decreases heart rate - negative chronotropic

vagus

Question 7

what effect does stretching of the SA node have and why might this come about

Answer 7

stretching of the SAN by an increase venous return to the heart directly increases the rhythmicity of the SAN, thereby increasing the HR

Question 8

where is the SAN located?

Answer 8

right atrial wall

Question 9

right atrial wall stretch (_____ reflex)

Answer 9

brainbridge

Question 10

right atrial wall stretch triggers _____ impulses via the ____ nerves to the ___ centre of the brain and the ____ impulses are carried back to the heart via the _____ nerves, to increase the HR, and possibly strength of______.

Answer 10

afferent
vagus
vasomotor
efferent
sympathetic
contraction

Question 11

name the hormones which increase the heart rate by stimulating the B1 receptors of the heart

Answer 11

catecholamines

Question 12

what effect do thyroid hormones have on B-adrenergic receptors in the heart?

Answer 12

they increase the number and their sensitivity to catecholamines

Question 13

what effect is a rise in body temperature (e.g. fever, excercise) thought to have on SA nodal cells?

Answer 13

through to increase the permeability of SA nodal cells to ions, acceerating self excitation of the SAN

Question 14

name 3 other factors that can increase HR

Answer 14

emotions - excitement and anger
pain
hypoxaemia

Question 15

name 2 other factors that can increase HR

Answer 15

vasovagal syncope (fainting)
raised intracranial pressure

Question 16

CO changes over time in order to maintain ______

Answer 16

homeostasis

Question 17

preload at rest is at _____ conditions

Answer 17

basal

Question 18

tonic ______ and tonic _____ activities and reciprocal changes in basal activities determine HR.

Answer 18

sympathetic

parasympathetic

Question 19

what is resting HR in a normal adult male?

Answer 19

approx 72 beats/min

Question 20

arteriolar and venous tone control resting systemic resistance and ____ ____ to the heart affecting ___ ___ filling volume and, therefore, ___ ___

Answer 20

venous return
ventricular diastolic
stroke volume

Question 21

what effect does exercise have on SV and HR

Answer 21

increases them both

Question 22

during exercise:
metabolites in exercising skeletal muscle _____ arterioles causing a ____ in total systemic resistance and, therefore, ______. This ______ muscle blood flow and, subsequently, ____ ____ to the heart.

Answer 22

dilate
drop
afterload
increases
venous return

Question 23

what is homeostasis

Answer 23

a tendency to stability in the normal body states with a relative constancy in the internal environment of the body

Question 24

what is homeostasis

Answer 24

a tendency to stability in the normal body states with a relative constancy in the internal environment of the body