Vascular System
Structure
veins
Functions
carry blood through the body
deliver oxygen and nutrients to the body tissues
remove waste products
(with heart & lungs) ensure there is adequate supply of oxygen during exercise
capillaries
arteries
smaller lumen
thick smooth muscle layer
elastic outer layer
smooth inner layer
less elastic outer layer
wider lumen
thin smooth muscle walls
valves
thin
dense network
semi-permeable membrane
one cell thick
pre-capillary sphincters
venous return
return of blood to right side of the heart via the vena cava
mechanisms
pocket valves
gravity
skeletal muscle pump
smooth muscles
respiratory pump
suction pump of heart (diastole)
- pressure changes in thoracic cavity
- muscles contract and relax when breathing
- muscles contract
- veins between muscles are compressed
- blood squeezed back to heart
- changes in pressure compress veins
- assisting blood return
- prevent backflow of blood
transportation and storage of blood gases
oxygen
carbon dioxide
attaches to haemoglobin
oxyhaemoglobin
dissolves in blood plasma
dissolves in blood plasma
form bicarbonate ions
attaches to haemoglobin
carbominahaemoglobin
attaches to myoglobin in muscle
myoglobin has higher affinity for oxygen than haemoglobin
stores oxygen and transports to mitochondria
A-VO2 Diff (Arterio-Venous Oxygen difference)
difference in oxygen concentration in arteries to veins
vascular shunt (redistribution of blood)
vasodilation
pre-capillary sphincters
vasoconstriction
vascular shunt
contraction of vessels that narrows lumen
relaxation of vessels that widens lumen
ring of muscle wrapped around outside of start of capillaries
squeezing/directing blood flow to where it is needed
control of blood flow (vascular shunt)
- impulse sent to vasomotor control centre
- receptors (chemoreceptors, baroreceptors, proprioceptors)
sympathetic nervous system
sympathetic nervous system
- increase impulse firing
- decrease impulse firing
- vasodilation of arterioles
- relax and open pre-capillary sphincters
- vasoconstriction of arterioles
- contract and close pre-capillary sphincters
Oxy-haemoglobin dissociation curve
dissociate
'to leave'
when oxygen leaves haemoglobin, enters muscle (myoglobin)
blue line
when PPO2 is high, Hb will be fully saturated
when PPO2 is low, Hb will be less saturated
green line
during exercise
BOHR SHIFT
line shifts to the right
causes:
increase concentration of CO2
increase in blood acidity, more hydrogen ions
increase in temperature