cardiovascular systems

Question 1

components of cv systems

Answer 1

heart
arteries and arterioles
veins and venules
capillaries

Question 2

purpose of cv system

Answer 2

control blood transport around body
- transport o2 and nutrients to tissues
- removal CO2 from tissues
- transport hormones
regulation body temperature
support immune function

Question 3

cardiac cycle

Answer 3

diastole
- relaxation phase: pressure in ventricles low
- filling with blood from atria
-> atria pressure > ventricular pressure
-> AV valves open
- 75% blood enters in relaxation
systole
- pressure in ventricles rises
- blood ejected in pulmonary and systemic circulation
-> ventricular pressure > aortic pressure
-> SL valves open
heart sounds
- ‘lub’ = closing of AV valves
- ‘dub’ = closing of SL valves
P wave
- firing of SA node
-stimulates depolarization of atria
QRS complex
- ventricular depolarisation
- hides atrial repolarisation
T wave
- ventricular repolarisation

Question 4

measure electrical activity of heart

Answer 4

electrocardigogram
- composite record of electrical events

Question 5

heart rate

Answer 5

frequency of heart beat per min (bpm)
resting values
- ~70 bpm (untrained)
-~ 50 bpm (trained)
-> with 1 beat send more blood to muscles
bradycardia (slow heart rate)
- resting < 60 bpm
tachycardia
- resting > 100 bpm

Question 6

stroke volume (sv)

Answer 6

amount of blood pumped per heart beat (ml)
stroke volume = end diastolic volume (before contraction) - end systolic volume (after contraction)
resting untrained values
- female = 50 ml
-male = 70 ml
resting trained values
- female = 80ml
- male = 110 ml

Question 7

cardiac muscle and neural control

Answer 7

cardiac control centre
- cardioaccelerator centre (CAC) at SNS
- cardioinhibitory centre (CIC) at PNS

Question 8

ejection fraction (EF)

Answer 8

proportion of blood pumped out of the left ventricle with each beat (%)
average 60% at rest
EF(%) =(stroke volume/ end diastolic volume) x 100

Question 9

cardiac output (Q)

Answer 9

total volume of blood flow from the heart per minute (L/min)
untrained
- female = 3.5 L/min
- male = 4.9 L/min
trained
-female = 4.0 L/min
- males = 5.5 L/min
Q= heart rate x stroke volume

Question 10

blood pressure

Answer 10

force exerted by blood against the arterial walls during cardiac cycle (mmHg)
systolic blood pressure
- force exerted during ventricular systole
- highest pressure within the vascular system
- changes the most during the day
diastolic blood pressure
- force exerted during ventricular diastole
- lowest pressure within the vascular system
during exercise
- systolic increases
-> beat harder and faster as need to pump more blood to the muscles
-diastolic decreases
blood pressure expressed as ration SBP/DBP

Question 11

vessel resistance

Answer 11

vessel length x viscosity /(vessel radius)^4

Question 12

vessel flow

Answer 12

pressure gradient/ vessel resistance

Question 13

blood flow

Answer 13

pressure gradient x (vessel radius)^4 / vessel length x viscosity
vessel radius had greatest impact
vessel length is constant
slight variation in viscosity
doubling the diameter
- 16 x flow rate increase
halving the diameter
- 16 x flow rate decrease

Question 14

blood pressure determinants

Answer 14

blood volume
stroke volume
peripheral resistance
blood viscosity
heart rate

Question 15

vasoconstriction

Answer 15

radius decrease
resistance to flow increases

Question 16

vasodilation

Answer 16

radius increase
resistance to flow decreases

Question 17

cardiac muscle

Answer 17

intrinsic heart rate
- internal rhythm set ~ 100 bpm
- resting HR about 70 bpm
- decrease with age
-> neural influence controlled by medulla oblongata can override rhythm
neural control
- cardioaccelerator centre at SNS
-> part of sympathetic nervous system
-> connected with sinus node and AV node
-> cardio inhibitory centre at PNS

Question 18

parasympathetic nervous: vasodilation

Answer 18

activation of vagus nerves (CN10)
neurons release acetylcholine
inhibits SA and AV discharge delaying the rate of sinus discharge
decrease HR

Question 19

sympathetic nervous system: vasoconstriction

Answer 19

activate sympathetic cardiac accelerator
nerves release epinephrine (adrenaline) and norepinephrine (noradrenaline) from adrenergic fibres
positive chronotropic and inotropic effects through beta-adrenergic reactions
increase HR
increase ventricular contractility

Question 20

cardiovascular control centre receptors

Answer 20

baroreceptors: located in the carotid sinus and in the aortic arch. they sense pressure changes by responding to change in the tension of the arterial wall
peripheral chemoreceptors: regulate respiratory activity and chemical environment of arterial blood (PO2, PCO2 and pH) within appropriate physiological ranges
mechanoreceptors/proprioreceptors: respond to changes in muscle length or tension
metaboreceptors: found in skeletal muscle respond to increased metabolic products and stimulate an increase in blood circulation in response to exercise

Question 21

regulation of stroke volume

Answer 21

1. end diastolic volume
   - volume of blood in ventricles at end of diastole
   -> alters the ventricular preload
   - Frank Starling mechanism
   -> normal, excessive fatigue, improved adaptation
   -> greater EDV results in more forceful contraction
2. average aortic blood pressure
   - pressure the heart must pump against to eject blood
   -> alters ventricular afterload
   - vasodilation
   -> radius of vessel increases
   -> resistance decreases
   -> blood flow increases
3. strength of ventricular contraction
   - alters the contraction
   - increased SNS activity

Question 22

end diastolic volume and venous return

Answer 22

venoconstriction vis SNS
skeletal muscle pump
-rhythmic skeletal muscle contraction force blood in extremities to heart
- prevention of back flow with veins
-> respiratory pump
-changes in thoracic pressures compress veins