1. Regulation of Blood Flow
Biology 20 – Unit D: Human Systems
Section 10.3 (pg )

2. Cardiac Output
Cardiac Output: The amount of blood that flows (is pumped) from the heart each minute
Amount of blood pumped from right side = amount of blood pumped from left side

3. Stroke Volume
Stroke Volume: The quantity of blood pumped with each beat of the heart = ~70 mL/beat (resting)
Cardiac Output = Stroke Volume x Heart Rate
Cardiac Output = 70 mL/beat x 70 beats/min
Cardiac Output = 4900 mL/min

4. Cardiac Output Calculation
What’s your weight in kg? (lbs x 0.45)
What’s your heart rate?
Come up and tell me

5. Question 1 What is Cardiac Output?
(a) volume of blood that is pumped with each heart beat
(b) volume of blood that is pumped by the heart each minute
(c) The number of times the heart contracts per minute
(d) The number of times the sinoatrial node stimulates the heart

6. Blood Pressure The force of the blood on the walls of the arteries
Measured by a sphygmomanometer
Gauge measures the pressure exerted by the blood during ventricular contraction
Bladder increases until a low-pitched sound can be detected – systolic blood pressure
Bladder is deflated even more until sound disappears – ventricular relaxation – diastolic blood pressure

7. Blood Pressure Measured in mmHg (mm of Mercury)
Systolic pressure/Diastolic pressure
= Pressure in Arteries/pressure in Veins
Normal = 90/60 – 140/90; Average = 120/80
Example of High Blood pressure = 160/100
Hypertensive
Example of Low Blood pressure = 80/50
Hypotensive

8. Blood Pressure BP = Systolic/Diastolic BP = 120/80 (Normal)
Systolic = pressure in arteries
Diastolic = pressure in veins
BP = Systolic/Diastolic
BP = 120/80 (Normal)

9. Question 2
True or False. Pressure increases as blood flows away from the heart.

10. Blood Pressure Depends on:
Cardiac output (as cardiac output increases, blood pressure increases and vice versa)
Arteriolar resistance (diameter of arteriole is regulated by smooth muscle)
Constriction closes the opening - reduces blood flow through the arteriole and increases blood pressure = vasoconstriction
Arteriole dilation increases blood flow and decreases blood pressure = vasodilation
Responds to neural and hormonal controls

11. Blood Vessel Regulation
Diameter of arterioles adjusts in response to metabolic products such as
Glucose by-products (in the break down of glucose)
Carbon dioxide
Lactic acid
Causes relaxation of arterioles  dilation  blood flow (increase of oxygen) increases
How the body maintains equilibrium

12. Hypertension High blood pressure Increased resistance to blood flow
Could cause vessels to weaken and rupture
Body increases the amount of connective tissue – leading to hardened/less elastic arteries.
Diet is mainly responsible
E.g. too much salt  higher blood pressure
Heart Attack/Stroke!

13. Hypotension Low blood pressure
Reduces your capacity to transport blood  and oxygen
Adjusted by the sympathetic nerves

14. Blood Vessel Regulation
Vasoconstriction: the narrowing of blood vessels/arterioles (less blood to tissues)
Increases blood pressure
Caused by a nerve impulse that contracts smooth muscle
Less O2 to tissues
Vasodilation: the widening of blood vessel/arterioles (more blood to tissues)
Decreases blood pressure
Relaxation of smooth muscle
Helps you release excess heat

15. Blood Pressure Regulation
Autonomic nervous system (controls motor nerves that regulates the diameter of arterioles; unconscious/involuntary) – medulla oblongata in the brain
Parasympathetic – decelerates heart beat
Sympathetic – accelerates heart beat

16. Question 3
A blood pressure regulator in the brain is called the _____________ ______________.
(don’t worry about spelling)

17. Blood Pressure Regulation
Blood pressure receptors are called baroreceptors are located in the aorta and the carotid artery
Nerve transmits signals to medulla oblongata
Vagus nerve transmits inhibitory signal to sinoatrial node
Heart rate decreases
Baroreceptors sense increased blood pressure

18. What happens when blood pressure drops…?
Nervous System
Parasympathetic Sympathetic
Blood Vessels/Arterioles
Dilate (widen) constrict (narrow)
Blood Pressure
Decreases Increases
Cardiac Output
Increases Decreases

19. Question 4
When a someone becomes hypertensive, the body tries to regulate itself by
Stimulating the ________________ nervous system
Causing arterioles to ________________
Which ______________ blood pressure
And _____________ their cardiac output.

20. Regulating Body Temperature
Thermoregulation: maintenance of body temperature within a range that enables cells to function efficiently
Consider the exchange of heat between the body and the environment
What is normal body
temperature?

22. Question 5
Which of the following regulates a body that has become too hot?
Blood vessels dilate and shivering
Blood vessels constrict and shivering
Blood vessels dilate and sweating
Blood vessels constrict and sweating

23. Thermoregulation
Hypothalamus: a region of the brain that is responsible for coordinating many nerve and hormone functions
Stimulus
Physiological Response
Result
Decreased Environmental Temperature
Constriction of blood vessels in skin
Body hairs become erect (goosebumps)
Hypothalamus initiates shivering
Heat is conserved
More head is generated by increased metabolism (skeletal muscle movement)
Increased Environmental Temperature
Dilation of blood vessels
Sweating
Heat is dissipated

24. Capillary Fluid Exchange
Every tissue is within 0.1mm of a capillary
Capillaries provide cells with oxygen, glucose, and amino acids
Fluid exchange between the blood and the surrounding extracellular fluid
Water passes through spaces between the capillary cells
Fluid & Osmotic pressure influence water movement
Water moves from an area of higher pressure to an area of lower pressure

26. Precapillary Sphincters

28. Capillary Fluid Exchange

30. Question 6
When fluid pressure outside of a capillary is greater than the fluid pressure inside a capillary, the water moves (a) into the capillary (b) out of the capillary (c) along side the capillary (d) nowhere

31. The Lymphatic System
Lymph: the fluid found in lymph vessels that contains some proteins that have leaked through capillary walls
Leaked proteins drain from the extracellular fluid (ECF) and return to the circulatory system by way of the lymphatic system

32. Lymph is transported in open-ended lymph vessels (similar to veins)
Low pressure return system uses muscle contractions
Lymph is returned to the venous system

34. Lymphoid Organs Lymph Nodes
Are enlargements that house white blood cells that filter out any bacteria
Filter damaged cells and debris from the lymph and store lymphocytes
Red bone marrow is where all types of blood cells are produced
White blood cells
Spleen – has many blood sinuses (each hold ~150mL blood) – reservoir
Lymphoid Organs

35. Question 7 Which of the following does the lymphatic system NOT do?
Return leaked protein to the circulatory system
Houses white blood cells
Transports lymph into open-ended lymph vessels
Transports oxygen and carbon dioxide

36. Edema (a.k.a. Swelling)
Results when small blood vessels become leaky and release fluid into tissues. The fluid accumulates causing tissues to swell.

37. Response of the Circulatory System to Exercise
Go for a run!
Oh no! Lactic acid buildup in your calf!
Sympathetic nerves stimulate the adrenal glands which release epinephrine/adrenaline
Epinephrine travels through the blood and stimulates the release of red blood cells from the spleen
Increased numbers of red blood cells aid in oxygen delivery
Epinephrine and stimulation from sympathetic nerves increases heart and breathing rates  higher levels of blood and faster oxygen transport & wastes are removed!

38. Summary
Cardiac output is the amount of blood the heart can pump each minute
Blood pressure is the force of blood on the walls of the arteries. It is measured as systolic and diastolic blood pressure in millimetres of mercury (mmHg)
Blood pressure is higher in vessels closer to the heart
Increased cardiac output increases blood pressure. If arteries are constricted, blood flow is slower and blood pressure is higher

39. Summary
Capillaries are associated with fluid exchange between blood and extracellular fluid
The movement of water between blood and the ECF is regulated by fluid pressure and by osmotic pressure
Water moves from an area of high fluid pressure, the capillary, to an area of low fluid pressure, the ECF
Proteins and dissolved minerals in the blood cause fluid from the ECF to move into the blood by osmosis

40. Summary
Proteins in the ECF are returned to the circulatory system by the lymphatic system
Lymph nodes house white blood cells that filter bacteria
Red bone marrow is where all types of blood cells are produced
The spleen stores and purifies blood. The spleen releases red blood cells in response to low blood pressure or low oxygen levels in blood.