Transport of Blood Gases Blood pressure and velocity

Blood Pressure Resistance is caused by the friction between the blood and the vessels walls. Resistance is caused by the friction between the blood and the vessels walls. Force exerted by the blood on the inside walls of the blood vessels Force exerted by the blood on the inside walls of the blood vessels

Factors affecting Blood Pressure Health factor/atherosclerosis/diet/ stress/drugs/hereditary Health factor/atherosclerosis/diet/ stress/drugs/hereditary

Factors affecting Blood Pressure Age/level of fitness/intensity of exercise; Age/level of fitness/intensity of exercise;

Factors affecting Blood Pressure Contraction of the heart/stroke volume/ejection fraction/heart rate Contraction of the heart/stroke volume/ejection fraction/heart rate Pressure depends on whether the blood is forced through the vessel or if blood flow is reduced. Pressure depends on whether the blood is forced through the vessel or if blood flow is reduced. Blood pressure varies depending on whether the heart is contracting or relaxing Blood pressure varies depending on whether the heart is contracting or relaxing Barorecpetors detect change and send message to increase or decrease cardiac output Barorecpetors detect change and send message to increase or decrease cardiac output

Ejection of the blood by the ventricles contracting creates a high pressure pulse of blood- Systolic pressure Ejection of the blood by the ventricles contracting creates a high pressure pulse of blood- Systolic pressure The lower pressure as the ventricles relax is the Diastolic pressure The lower pressure as the ventricles relax is the Diastolic pressure

Factors affecting Blood Pressure Resistance/ Friction/ Elasticity of walls Resistance/ Friction/ Elasticity of walls Blood vessel length/distance from the heart Blood vessel length/distance from the heart Blood vessel diameter/size/ vasoconstriction/vasodilation/cross sectional area/lumen size Blood vessel diameter/size/ vasoconstriction/vasodilation/cross sectional area/lumen size

Factors affecting Blood Pressure. Blood viscosity/sweating/loss of fluid. Blood viscosity/sweating/loss of fluid

Lets take your Blood Pressure! Blood pressure is measured at the brachial artery in the upper arm using a sphygmomanometer Blood pressure is measured at the brachial artery in the upper arm using a sphygmomanometer120__________80 Blood pressure is different in the various blood vessels and is dependent on the distance of the blood vessel from the heart. Blood pressure is different in the various blood vessels and is dependent on the distance of the blood vessel from the heart.

Effects of Exercise on BP During Aerobic exercise systolic pressure increases due to an increase in cardiac output, diastolic remains constant. During Aerobic exercise systolic pressure increases due to an increase in cardiac output, diastolic remains constant. Isometric work- diastolic also increases due to an increased resistance on the blood vessels caused by constant compression on the blood vessels creating an additional resistance to blood flow. Isometric work- diastolic also increases due to an increased resistance on the blood vessels caused by constant compression on the blood vessels creating an additional resistance to blood flow.

Exam Question During a game, the blood pressure of a player increases. During a game, the blood pressure of a player increases. What factors determine the ‘blood pressure’ in arteries? (3) What factors determine the ‘blood pressure’ in arteries? (3)

Answers A. Contraction of the heart/stroke volume/ejection fraction/heart rate; A. Contraction of the heart/stroke volume/ejection fraction/heart rate; B. Increased blood flow/cardiac output/Q; B. Increased blood flow/cardiac output/Q; C. (Peripheral) resistance/friction/ elasticity of walls; C. (Peripheral) resistance/friction/ elasticity of walls; D. Blood viscosity/sweating/loss of fluid; D. Blood viscosity/sweating/loss of fluid; E. Blood vessel length/distance from the heart; E. Blood vessel length/distance from the heart; F. Blood vessel diameter/size/ vasoconstriction/vasodilation/cross sectional area/lumen size; F. Blood vessel diameter/size/ vasoconstriction/vasodilation/cross sectional area/lumen size; G. Health factor/atherosclerosis/diet/ stress/drugs/hereditary; G. Health factor/atherosclerosis/diet/ stress/drugs/hereditary; H. Age/level of fitness/intensity of exercise; H. Age/level of fitness/intensity of exercise;

Exam Question What are the effects of Exercise on BP? What are the effects of Exercise on BP?(2)

Answers During Aerobic exercise systolic pressure increases due to an increase in cardiac output, diastolic remains constant. During Aerobic exercise systolic pressure increases due to an increase in cardiac output, diastolic remains constant. Isometric work- diastolic also increases due to an increased resistance on the blood vessels caused by constant compression on the blood vessels creating an additional resistance to blood flow. Isometric work- diastolic also increases due to an increased resistance on the blood vessels caused by constant compression on the blood vessels creating an additional resistance to blood flow.

Blood Velocity As blood leaves the heart though the main arteries it has a high systolic pressure & Velocity. As blood leaves the heart though the main arteries it has a high systolic pressure & Velocity. What do you think happens to the blood velocity as it moves further away from the heart? What do you think happens to the blood velocity as it moves further away from the heart? Can you tell me why? Can you tell me why?

???? Decreases! Decreases! Due to; Due to; 1) Increase in cross sectional area of blood vessels that gets bigger the further away from the heart you travel. 2) Vessels get smaller and so larger total surface area Friction reduces, longer the vessel longer the blood is contact with it and the more friction affects it

Velocity of blood is related to the cross sectional area of the vessels it is passing through. Velocity of blood is related to the cross sectional area of the vessels it is passing through. Smaller the cross sectional area, the faster the flow Smaller the cross sectional area, the faster the flow Although the capillaries are the smallest vessel, there are some many of them, their cross sectional area is much greater than that of the arteries. Although the capillaries are the smallest vessel, there are some many of them, their cross sectional area is much greater than that of the arteries. Flow of blood is slower and more efficient for gas exchange Flow of blood is slower and more efficient for gas exchange

Lets draw it… Using graph paper ….. Using graph paper ….. X Axis- Arteries, Arterioles, capillaries, venules, veins, vena cava. X Axis- Arteries, Arterioles, capillaries, venules, veins, vena cava. Y Axis- Low, Medium, high Y Axis- Low, Medium, high Draw a line to represent: Draw a line to represent: Blood Pressure Blood Pressure Cross sectional Area Cross sectional Area Blood Velocity Blood Velocity

Velocity of blood reduces as it reaches the capillaries Velocity of blood reduces as it reaches the capillaries However; blood flow does speed up as it enters the Veins and Venules However; blood flow does speed up as it enters the Veins and Venules Can you think why? Can you think why?

Total cross sectional area decreases, causing and increase in velocity. Total cross sectional area decreases, causing and increase in velocity.

Blood doesn't flow at constant speeds around the body Blood doesn't flow at constant speeds around the body Fastest in arteries, and slows down as it reaches the capillaries Fastest in arteries, and slows down as it reaches the capillaries Speed of the blood is related to cross sectional area of blood vessels Speed of the blood is related to cross sectional area of blood vessels

Answer Venous return mechanism Venous return mechanism Veins have one way values/ prevent backflow Veins have one way values/ prevent backflow Muscle contractions compress veins and push blood towards the heart- skeletal muscle pump Muscle contractions compress veins and push blood towards the heart- skeletal muscle pump Breathing movements alter pressure in thorax assist flow back to the heart- Respiratory Pump Breathing movements alter pressure in thorax assist flow back to the heart- Respiratory Pump

Exam Question A 400 metre hurdler’s blood flows around his body, its pressure and velocity changes, as shown in Table 1. A 400 metre hurdler’s blood flows around his body, its pressure and velocity changes, as shown in Table 1. Which of the blood vessels in Table 2, A, B or C, represents veins? PressureVelocity Blood vessels AHigh Blood vessels BLow Blood vessels CLowMedium

How do we get the blood back to the heart? 1. Read the section called ‘Venous Return’ with your partner. 2. Read again and make notes 3. Groups of 4- can you now come up with an ‘A grade’ answer the exam question?

Exam Question Describe the mechanism that assists the return of blood to the heart Describe the mechanism that assists the return of blood to the heart (3 marks)