Cardiovascular System

Structure

The Cardiovascular system has 3 main elements

1. The heart (Cardiac muscle)

2. Blood

3. Blood Vessels (Arteries, veins and capillaries)

Types of blood vessels

Arteries

Carries oxygenated blood away from the heart.

The blood is under high pressure.

Thick muscular walls.

veins

Carries deoxygenated blood back to the heart.

Blood under lower pressure.

Thinner walls than arteries.

capillaries

Tiny, thin walled structures.

Allow for diffusion of gas.

Functions of the cardiovascular system

THERMO REGULATION

In the heat, blood vessels close to the surface of the skin enlarge. This process is called vasodilation. This allows more heat to be lost from the blood.

In the cold, blood vessels at the skin’s surface close. This process is called vasoconstriction and takes blood away from the surface of the skin to help prevent it from losing heat.

TRANSPORTATION OF NUTRIENTS

The blood carries nutrients such as glucose and amino acids around the body. These are diffused via the capillaries.

TRANSPORTATION OF OXYGEN

Red blood cells transport oxygen to the working muscles. Without this our muscles would not be able to function.

REMOVAL OF WASTE PRODUCTS

Waste products such as carbon dioxide and lactic acid are transported out of the body in the blood.

the pulmonary and systemic circuits

The pulmonary circuit takes deoxygenated blood from the the heart to the lungs.
Blood is oxygenated in the lungs and transported back to the heart.
The blood is pumped from the heart to the body via the systemic circuit.
Here the oxygen in the blood is used by the working muscles and transported back to the heart.
The process then begins again.

key terms

HEART RATE

The number of times the heart beats in a minute.

STROKE VOLUME

The amount of blood ejected per beat of the heart.

blood pressure

The strength exerted by the blood on the vessel walls as a result of the heart beating.

cardiac output

The amount of blood ejected from the heart per minute.

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