Blood Vessels and Exercise Physiology

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Questions and Answers

What is the primary function of the right side of the heart?

Pumps deoxygenated blood to the lungs (correct)

Maintains blood pressure in systemic circulation

Pumps oxygenated blood to the body

Distributes hormones throughout the body

Which component of blood constitutes the majority of total blood volume?

Red blood cells

Plasma (correct)

Platelets

White blood cells

What role does the SA node play in the heart?

Contracts the ventricles to pump blood

Controls blood pressure in arteries

Serves as the main pacemaker of the heart (correct)

Filters deoxygenated blood

Which blood vessels primarily store blood in the circulatory system?

Veins Signup and view all the answers

What is a unique feature of the pulmonary artery?

Contains deoxygenated blood Signup and view all the answers

How does increased plasma volume affect blood dynamics?

It improves blood flow through the body Signup and view all the answers

What is the function of the valves in the heart?

Prevent backflow of blood Signup and view all the answers

What primarily determines the composition of the total blood volume in an individual?

Hydration levels Signup and view all the answers

What is the primary reason the aorta is thicker than other blood vessels?

It is under higher pressure and needs more muscle. Signup and view all the answers

Which function do arterioles perform during exercise?

They control blood flow to individual organs. Signup and view all the answers

When does vasodilation typically occur in arterioles?

When there is high CO2 and low O2 levels. Signup and view all the answers

How does exercise affect the amount of blood flow to the muscles?

The total amount of blood remains constant. Signup and view all the answers

What role do valves in the venous system play?

They prevent retrograde blood flow. Signup and view all the answers

What is the equation that defines cardiac output?

Q = heart rate x stroke volume. Signup and view all the answers

What mechanism helps prevent venous pooling when standing upright?

Muscle pump. Signup and view all the answers

What do we call the vessels that can control resistance to blood flow?

Arterioles. Signup and view all the answers

Study Notes

Blood Vessels

The aorta is the largest vessel in the body, with a diameter of 2.5cm. It has a thicker muscle wall than other vessels because it is under more pressure.
Vessel diameter and thickness decrease as they branch away from the aorta. Capillaries are very small and thin, increasing surface area for diffusion.
Arterioles control blood flow to individual organs, redistributing blood flow during exercise.
Arterioles can be controlled extrinsically by the brain or intrinsically by the vessel itself.
At rest, arterioles are vasoconstricted but vasodilate when more blood flow is needed to an organ.
Vasodilation occurs when there are high levels of carbon dioxide (CO2) and low levels of oxygen (O2).
Arterioles are known as resistance vessels because they can control the resistance to blood flow.

Blood Flow Redistribution During Exercise

Exercise increases blood flow dramatically.
Blood flow is redistributed from organs like the intestines to working muscles.
The percentage of blood going to the brain stays the same, even though the overall blood volume increases.
This redistribution ensures that working muscles receive adequate oxygen and nutrients, and waste products like CO2 are removed.

Venous System

Venous system has low pressure, compared to the arterial system, making it easy to distend (stretch) and hold blood.
Venous pooling occurs when blood accumulates in the lower limbs due to gravity, which is dangerous as it can lead to fainting due to reduced blood flow to the brain.

Muscle Pump

The muscle pump helps prevent venous pooling by moving blood against gravity.
Muscles squeeze the veins, forcing blood upwards.
Valves in the veins prevent blood from flowing back down.

Cardiac Output (Q)

Cardiac output (Q) is the total volume of blood pumped by each ventricle per minute.
Q = heart rate x stroke volume (SV).
Stroke volume (SV) is the volume of blood ejected by each ventricle with each beat.
SV = end diastolic volume (heart relaxed) - end systolic volume (heart contracted).

Functions of Cardiovascular System

Delivery: Oxygen and nutrients to muscles.
Removal: CO2 from tissues to lungs and other waste products.
Transport: Hormones.
Maintenance: Homeostasis and pH balance.
Protection:
- Hydration (blood plasma is mainly water)
- Fighting infection (white blood cells)

Components of the Cardiovascular System

Closed Loop System: All parts of the system are connected.
Fluid Medium: Blood.
Channels: Blood vessels.
Pump: Heart.

Structure of the Heart

Two Sections (Two Pumps): Right side (deoxygenated blood) and left side (oxygenated blood).
Right Side (Pulmonary):
- Receives deoxygenated blood from the body via the vena cava.
- Blood travels through the AV valve to the right ventricle.
- Blood is pumped to the lungs via the pulmonary artery (only artery carrying deoxygenated blood) for oxygenation.
Left Side (Systemic):
- Receives oxygenated blood from the lungs via the pulmonary vein (only vein carrying oxygenated blood).
- Blood travels through the AV valve to the left ventricle.
- Blood is pumped to the body via the aorta.
Other Features:
- Four valves prevent backflow of blood.
- A septum divides the heart into two sections. The left ventricle is thicker (more muscle) because it needs more force to pump blood throughout the body.

Electrical Activity of the Heart

SA Node: The pacemaker of the heart, generating electrical signals that control heart rate.
The electrical signal travels from the SA node to the AV node, then through the septum and out to the branches of the heart.

Composition of Total Blood Volume

Plasma: Mostly water (55%), with the proportion varying depending on individual hydration.
Formed Elements:
- Mostly red blood cells (over 99% of formed elements).
- White blood cells and platelets.
Plasma volume increases more than red blood cell volume during hydration, leading to a decrease in the red blood cell percentage in the blood.
This is beneficial because it increases blood volume overall, making it easier for blood to flow throughout the body.

Vascular System

Blood Storage:
- Venous system: 64% of blood volume.
- Arterial system: 10% of blood volume.

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Description

This quiz covers important concepts related to blood vessels, including the structure and function of the aorta, arterioles, and capillaries. It also explores how blood flow is redistributed during exercise, focusing on the mechanisms of vasodilation and vasoconstriction. Test your knowledge on these critical aspects of human physiology!