What is the circulatory system?

• The circulatory system carries blood and dissolved substances to and from different places in the body.

• The Heart has the job of pumping these things around the body.

• The Heart pumps blood and substances around the body in tubes

called blood vessels.

Structure of the Circulatory System

Inferior Vena CavaVein that brings oxygen-poor blood from the lower part of the body to the right atrium

Tricuspid ValvePrevents blood from flowing back into the right atrium after it has entered the right ventricle

Pulmonary ValvePrevents blood from flowing back into the right ventricle after it has entered the pulmonary artery

Pulmonary VeinsBring oxygen-rich blood from each of the lungs to the left atrium

Superior Vena CavaLarge vein that brings oxygen-poor blood from the upper part of the body to the right atrium

AortaBrings oxygen-rich blood from the left ventricle to the rest of the body

Pulmonary ArteriesBring oxygen-poor blood to the lungs

Aortic ValvePrevents blood from flowing back into the left ventricle after it has entered the aorta

Mitral ValvePrevents blood from flowing back into the left atrium after it has entered the left ventricle

Left Atrium

Left Ventricle

Septum

Right Atrium

Right Ventricle

The Heart

Artery to Lungs Artery to Head and Body

Vein from Head and BodyVein from Lungs

Right Atrium Left Atrium

valve

Right Ventricle Left Ventricle

Function of the Circulatory SystemIn Respiration:• Delivers oxygen to the cells and removes carbon dioxide

In Nutrition:• Carries digested food substances to the cells of the body

Function of the Circulatory System

In Excretion:• Disposes waste products and poisons that would harm the body if gets

accumulated.

Function of the Circulatory System

Function of the Circulatory System

Other Functions

• Protects body from diseases

• WBCs ( White Blood Cells) engulf and destroys bacteria, viruses, and other harmful invaders

• Keeps the body temperature stable

• Helps carries hormones

3 Types of Blood Vessels

1. ARTERY- a blood vessel that carries blood from the heart to the body.

3 Types of Blood Vessels

2. VEIN- a blood vessel that carries blood from capillaries toward the heart.

- Carries blood that contains waste and CO2

– Exception pulmonary vein

– Blood not under much pressure

– Valves to prevent much gravity pull

– Venules: larger than capillaries

3 Types of Blood Vessels

3. CAPILLARY- a smaller blood vessel connecting arterioles with the ventricles or ventrioles

– Smallest vessel– Microscopic– Nutrients and gases diffuse here– Walls one cell thick

Composition of a Blood

red blood cellwhite blood cell

platelets plasma

Red Blood Cell

•A biconcave disc that is round and flat without a nucleus

• Contains hemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it.

•Can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.

White Blood Cell

• The two main ones are the lymphocytes and the macrophages.

• Macrophages ‘eat’ and digest micro-organisms .

• Lymphocytes fight disease by making antibodies to destroy invaders by dissolving them

Platelets

Platelets are bits of cell broken off larger cells

Overview of the Circulatory System