3.1.1.2 Cardiovascular system part 2

Question 1

cardiac conduction system definition

Answer 1

describes the electrical impulses/nervous control of heart beat

Question 2

cardiac cycle

Answer 2

• describes the flow of blood through the heart
• contracting and relaxing of the muscles

cardiac system: controlled by electrical impulses sent around heart

Question 3

cardiac conduction system description

Answer 3

• human heart and its muscles are myogenic
• beating of heart is NOT dependant upon nervous connections to heart
• nerve fibres can regulate heart beat but dont trigger the beat
• network of specialised cardiac muscles cells that stimulate the heart contraction is known as the conduction system
• need this system as heart is myogenic

Question 4

myogenic

Answer 4

human heart and its muscles are
the electrical stimulation necessary for contraction of its muscles originates from within heart itself
-the capacity of the heart to generate its own impulses

Question 5

electrocardiogram

Answer 5

-bigger changes = pumping out of ventricles = pump further places (body and lungs)

Question 6

summary of cardiac conduction system

Answer 6

1. spontaneous cardiac impulse generated by SA node
2. impulse spreads through wall of both atria = contract
   delay to allow blood to ventricles
3. impulse reaches AV node
4. impulse is transmitted down Bundle of His
5. impulse continues along right & left bundle branches
6. impulse spreads through ventricle walls = contract and along the purkinjie fibres

Question 7

blood pressure

Answer 7

force exerted by the blood against the blood vessel wall
measure amount of strain your arteries feel as your heart moves blood around
units are mm or mmhg

healthy = 120 over 80
-measure at brachial artery

Question 8

blood pressure equation

Answer 8

blood flow x resistance

weight training both systolic and diastolic increase due to more resistance
-width of blood vessels affect - dilate arterials = less resistance

Question 9

components of blood pressure

Answer 9

systolic pressure = heart contracts (increase when exercise) – peak pressure produced by contracting ventricles
diastolic pressure = heart relaxed –pressure at arteries when ventricles relaxed

Question 10

prolonged high bp

Answer 10

damage arterial walls and mess with circulation, endanger heart lungs, brain kidneys (nearly all of you)

Question 11

changes detected by the body as a sign heart rate needs to increase?

Answer 11

1. increase in CO2
2. increase in blood pressure
3. increase in muscle movement

increase in temp
-those unfitter have a higher resting rate to cope with the lower stroke volume

Question 12

parts of the body involved in regulation of heart rate

Answer 12

1. chemoreceptors
2. baroreceptors
3. proprioceptors
4. SA node
5. medulla (cardiac control centre) (brain)
6. central nervous system (CNS) – sympathetic (cardiac accelerator) and parasympathetic

Question 13

pathway of nerves

Answer 13

chemoreceptors, baroreceptor, proprioceptor all send sensory nerves to medulla

medulla sends sympathetic accelerator nerve (increase in HR) to SA node
medulla also sends parasympathetic vagus nerve (decrease in HR) to heart

Question 14

medulla

Answer 14

makes sense of info from receptors which affect impulses travelling down sympathetic and parasympathetic nerves

medulla oblongata= most important part of brain regulates processes that keeps us alive, breathing and HR

Question 15

sympathetic (s) and parasympathetic/vagus nerve (p) stimulation of the heart

Answer 15

s= increase HR and force of contraction
s= nerves transmit impulses from CCC to SA and AV nodes and to ventricular muscles
s activity increases, emission of cardiac impulses from SA node increase and HR rises
increased s activity stimulates ventricles = heart beats more forcefully

p=innervates SA node
p activity increases = emission of cardiac impulses from SA node decreases and HR falls

both division of CNS (s and p) = active always, heart simultaneously receives impulse from both divisions
s and p nerves have opposing effects on heart

sympathetic – SA, AV nodes and left ventricle

parasympathetic – SA node

Question 16

heart activity is controlled by

Answer 16

inhibitory effects of the parasympathetic nerves stimulating effects of sympathetic nerves

balance between sympathetic & parasympathetic nerve activity

Question 17

SA node and AV node definition

Answer 17

SA node: small mass of cardiac muscle in wall of R atrium generate heart beat

AV node: relays impulse between upper and lower section of heart

Question 18

bundle of his and purkinjie fibres definition

Answer 18

bundle of his: collection of heart muscle cells = transmit electrical impulses from AV node via bundle branches to ventricles

Purkinjie fibres: muscle fibres that conduct impulses in ventricle walls

Question 19

chemoreceptors

Answer 19

• tiny structure in carotid arteries and aortic arch, detect changes in blood acidity caused by increase or decrease in concentration of CO2
• or lactic acid

Question 20

baroreceptors

Answer 20

• special sensors in tissues in aortic arch, cation sinus heart and pulmonary vessels that respond to changes in BP to either increase or decrease in HR
• decrease in BP also as a start of exercise = vasodilation = less resistance = decrease BP

Question 21

proprioceptors

Answer 21

sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement

Question 22

neural control mechanism

Answer 22

controls rate cardiac impulses are fired

3 main mechanisms:

1. sympathetic nervous system
2. parasympathetic system
3. medulla oblongata

1 and 2 are part of autonomic system

Question 23

cardiac control centre

Answer 23

CCC is in the medulla oblongata of brain

• CCC receives sensory input from chemoreceptors, baro and propio receptors
• these receptors transmit nerve impulses along sensory nerves to CCC
• nerve impulses are transmitted from the CCC to heart along motor neurones of sympathetic and parasympathetic nerves