CONTROL OF BLOOD
SUPPLY
•CIRCULATORY
•O2 AND CO2 TRANSPORT
•WARM UP AND COOL DOWN – EFFECTS
ON VASCULAR SYSTEM
VENOUS RETURN
VR IS THE DEOXYGENATED BLOOD RETURNING TO THE HEART
FIVE MECHANISMS HELP MAINTAIN VR DURING EXERCISE:
1.
2.
3.
4.
5.
POCKET VALVES
SKELETAL MUSCLE PUMP
RESPIRATORY PUMP
SMOOTH MUSCLE
GRAVITY
BLOOD POOLING
• INSUFFICIENT PRESSURE TO PUSH BLOOD BACK
TOWARDS THE HEART CAUSES BLOOD POOLING
(BLOOD SITS IN POCKET VALVES OF VEINS)
• ACTIVE COOL DOWN PREVENTS POOLING AFTER
EXERCISE BY MAINTAINING THE MUSCLE AND
RESPIRATORY PUMPS.
STARLING’S LAW OF THE HEART
• SV / Q IS DEPENDENT ON VR
• IF VR INCREASES, SV / Q INCREASES
• IF VR DECREASES, SV / Q
DECREASES
REDISTRIBUTION OF Q
•
AT REST
1. 15 – 20% OF RESTING Q GOES TO
MUSCLES
2. 80-85% SUPPLIES BODY’S ORGANS
(KIDNEYS, LIVER, STOMACH,
INTESTINES)
REDISTRIBUTION OF Q
•
EXERCISE
1.
2.
3.
4.
80-85% Q SUPPIED TO WORKING MUSCLES
DECREASED % TO ORGANS
BLOOD SUPPLY TO BRAIN MAINTAINED
INCREASED BLOOD TO SKIN DURING LOW INTENSITY X –
REDUCE BODY TEMP.
REDISTRIBUTION OF Q – VASCULAR SHUNT
SKELETAL MUSCLE ARTERIOLES AND PRE-CAPILLARY
SPHINCTERS VASODILATE, INCREASE BLOOD TO WORKING
MUSCLES
ORGAN’S ARTERIOLES AND PRE-CAPILLARY SPHINTERS
VASOCONSTRICT, DECREASING BLOOD FLOW TO ORGANS
5.
6.
7.
VASOMOTOR CONTROL CENTRE
• VASOMOTOR CONTROL CENTRE (VCC) LOCATED IN
MEDULLA OBLONGATA
• CHEMO AND BARORECEPTORS STIMULTATE VCC
• VCC STIMULATES SYMPATHETIC NS, WHICH
CONTROLS BLOOD VESSEL LUMEN DIAMETER OF
ORGANS AND MUSCLES
02 TRANSPORTATION
• 97% WITHIN PROTEIN HAEMOGLOBIN,
PACKED WITH RBC’S, AS
OXYHAEMOGLOBIN (Hb02)
• 3% WITHIN BLOOD PLASMA
C02 TRANSPORTATION
• 70% DISSOLVED IN WATER A
CARBONIC ACID
• 23% CARBOAMINOHAEMOGLOBIN
(HbCO2)
• 7% DISSOLVED IN PLASMA
WARM UP - VASCULAR
•
1.
2.
•
1.
2.
•
GRADUAL INCREASE IN BLOOD FLOW / Q DUE TO
VASCULAR SHUNT:
VASOCONTRICTION OF ARTERIOLES / PRE-CAPILLARY
SPHINCTERS TO ORGANS
VASODILATION OF MUSCLE ARTERIOLES / PRE-CAPILLARY
SPHINCTERS INCREASING BLOOD FLOW TO MUSCLES
INCREASED BODY TEMP / MUSCLE TEMP:
INCREASING ENZYME ACTIVITY REQUIRED FOR MUSCLE
CONTRACTIONS
DECREASES BLOOD VISCOSITY, IMPROVING BLOOD FLOW
TO MUSCLES, INCREASING DISSOCIATION OF O2 FROM
HAEMOGLOBIN
DECREASED ONSET BLOOD LACTATE ACCUMULATION
(OBLA)
COOL DOWN - VASCULAR
•
•
KEEPS METABOLIC ACTIVITY ELEVATED, WHICH
GRADUALLY DECREASES HR AND RESPIRATION
MAINTAINS RESPIRATORY / MUSCLE PUMP WHICH:
1.
2.
3.
4.
PREVENTS BLOOD POOLING
MAINTAINS VR
MAINTAINS BLOOD FLOW (SV / Q) - SUPPLYING O2
MAINTAINS BLOOD PRESSURE
•
KEEPS CAPILLARIES DILATED TO FLUSH MUSCLES WITH
OXYGENATED BLOOD WHICH:
INCREASES THE REMOVAL OF BLOOD, MUSCLE LACTIC
ACID AND CO2.
1.
KEY WORDS
SMOOTH MUSCLE
VASODILATE
VASOCONSTRICT
VENODILATE
VENOCONSTRICT
PULMONARY
SYSTEMIC
POCKET VALVES
VASCULAR SHUNT