Redistribution of Blood

Redistribution of BloodRedistribution of Blood

We only have 4-5 litres of blood in our bodyWe only have 4-5 litres of blood in our body Huge capillary networkHuge capillary network More space for blood than there is blood!More space for blood than there is blood! Competition for blood between regions of Competition for blood between regions of

the bodythe body Especially during exerciseEspecially during exercise

In Pairs………In Pairs………

Discuss the redistribution of blood during Discuss the redistribution of blood during exercise to the: skeletal muscles, coronary exercise to the: skeletal muscles, coronary vessels, brain, kidney and liver.vessels, brain, kidney and liver.

Which body parts need more oxygen?Which body parts need more oxygen?Which parts still need the same?Which parts still need the same?

Which parts can have a reduced flow?Which parts can have a reduced flow?

IncreasedIncreased blood flow to blood flow to

skeletal musclesskeletal muscles IncreasedIncreased blood flow to blood flow to

the skinthe skin IncreasedIncreased blood flow to blood flow to

coronary vesselscoronary vessels SameSame blood flow to the brain blood flow to the brain ReducedReduced flow to kidneys flow to kidneys ReducedReduced flow to liver flow to liver

Shunting of BloodShunting of Blood

Achieved by Achieved by vasodilatationvasodilatation (opening) and (opening) and vasoconstrictionvasoconstriction (closing) of the arterioles (closing) of the arterioles that supply the blood entering the capillary that supply the blood entering the capillary beds.beds.

Within the arterioles – rings of circular Within the arterioles – rings of circular muscle act as muscle act as sphincterssphincters

Ring of muscle contracts and the size of the Ring of muscle contracts and the size of the opening decreases reducing the blood flowopening decreases reducing the blood flow

VasoconstrictionVasoconstriction

Controlled by the Controlled by the sympathetic nervous sympathetic nervous systemsystem

Stimulation by impulses from nerves Stimulation by impulses from nerves causes the smooth muscle in arteries causes the smooth muscle in arteries and pre capillary sphincters to contractand pre capillary sphincters to contract

VasoconstrictionVasoconstriction Reduced blood flowReduced blood flow

Vasodilatation Vasodilatation

The same sympathetic nerves act as The same sympathetic nerves act as vasodilatatersvasodilataters which increase the diameter which increase the diameter of the vessel and so the blood flow.of the vessel and so the blood flow.

Other local factors that cause this;Other local factors that cause this; Drop in O2 and increase in CO2= Increase Drop in O2 and increase in CO2= Increase

in acidityin acidity Movement in the joints and tendons- instant Movement in the joints and tendons- instant

vasodilatation as result of muscle activity vasodilatation as result of muscle activity

Explain how redistribution of Explain how redistribution of blood occurs during exercise. blood occurs during exercise.

A. Increase in CO2 levels/acidity/ decrease in O2 levels/pH/ A. Increase in CO2 levels/acidity/ decrease in O2 levels/pH/ chemoreceptors chemoreceptors

B. Movement of joints/tendons/ mechanoreceptors/proprioceptors B. Movement of joints/tendons/ mechanoreceptors/proprioceptors C. Vasomotor centre/medulla C. Vasomotor centre/medulla D. Autonomic/sympathetic nervous system/(nor)adrenaline D. Autonomic/sympathetic nervous system/(nor)adrenaline E. Pre-capillary sphincters/rings of circular/smooth muscle E. Pre-capillary sphincters/rings of circular/smooth muscle F. Vasodilation to areas needing blood/muscles F. Vasodilation to areas needing blood/muscles G. Vasoconstriction of areas not needing so much blood/kidneys/liver/ G. Vasoconstriction of areas not needing so much blood/kidneys/liver/

gut gut

TaskTask

Blood FlowBlood Flow

Skeletal Muscles;Skeletal Muscles;

To supply the muscles with oxygen To supply the muscles with oxygen and nutrients, remove waste and nutrients, remove waste productsproducts

Coronary arteriesCoronary arteries; ;

Blood supply is increased here to the Blood supply is increased here to the heart so it can beat stronger and heart so it can beat stronger and fasterfaster

Blood FlowBlood FlowSkin;Skin; Increased flow here as heat is Increased flow here as heat is

generated by the working muscles generated by the working muscles and we need to maintain a constant and we need to maintain a constant temp.temp.

Need to lose heat- Need to lose heat- radiation and radiation and evaporationevaporation

RadiationRadiation- body hotter than its’ - body hotter than its’ environment. Vasodilatation of environment. Vasodilatation of capillaries near skin warms the skin capillaries near skin warms the skin so allowing heat to be lostso allowing heat to be lost

Blood FlowBlood Flow

Evaporation;Evaporation; sweating sweating Sweat forms a layer of water on the skins’ Sweat forms a layer of water on the skins’

surface. When the water evaporates it surface. When the water evaporates it loses heat and so cools the skinloses heat and so cools the skin

Exercise= sweat and skin reddens due to Exercise= sweat and skin reddens due to increase blood flowincrease blood flow..

Where does the blood come Where does the blood come from?from?

Brain- stays the same as it can’t switch Brain- stays the same as it can’t switch off!off!

Brain function maintained during exercise Brain function maintained during exercise Oxygen/nutrients required Oxygen/nutrients required

Reduced flow to abdominal organs- Reduced flow to abdominal organs- liver, kidney and digestive organsliver, kidney and digestive organs

VasoconstrictionVasoconstriction This is why you should not eat before This is why you should not eat before

exercise- Puky!!exercise- Puky!!

Explain why performers should not eat Explain why performers should not eat

immediately before exerciseimmediately before exercise. .

During exercise, less blood goes to the gutDuring exercise, less blood goes to the gut But, blood/oxygen needed in gut for But, blood/oxygen needed in gut for

digestion of food digestion of food Less blood/oxygen available to muscles Less blood/oxygen available to muscles

Lets Recap…..Lets Recap…..

Begin to exercise…Begin to exercise… Increase in demand for O2 and increase in need to Increase in demand for O2 and increase in need to

get rid of waste products- CO2 and Lactic.get rid of waste products- CO2 and Lactic. Increases in blood acidity detected by Increases in blood acidity detected by

chemoreceptorschemoreceptors Stimulates sympathetic nervous systemStimulates sympathetic nervous system Pre capillary sphincters in non-essential areas Pre capillary sphincters in non-essential areas

contract and cause vasoconstrictioncontract and cause vasoconstriction Pre capillary sphincter in skeletal muscle relax and Pre capillary sphincter in skeletal muscle relax and

cause vasodilation. cause vasodilation.