Th e Circulatory System By Nitesh Sharma X – C [email protected] om

The circulatory system by Nitesh Sharma

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The circulatory system

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By Nitesh SharmaX – C

[email protected]

Circulatory System• The Circulatory System is responsible for

transporting materials throughout the entire body.

• It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce.

• It is an amazing highway that travels through your entire body connecting all your body cells.

Components• Heart• Blood• Vessels

– Arteries– Veins– Capillaries





Circulatory System

• Which gases are transported to and from the body’s cells by the blood flowing in the circulatory system?



Oxygen is the gas needed for respiration and is transported to the body’s cells.

Circulatory System

• The circulatory system carries two types of blood

• Arrangement of the circulatory system means that these two types of blood do not mix.

Oxygen-rich blood


De-Oxygen rich blood

Blood travelling to the body cellsHigh oxygen contentLow carbon dioxide content

Blood travelling away from the body cellsLow oxygen contentHigh carbon dioxide content

Circulatory System

• The heart is the organ at the centre of the circulatory system. It pumps blood around the body.

Circulatory System

• The inside of the heart is divided into two sections so that the two types of blood (oxygen-rich and oxygen-poor) are kept apart

Oxygen-poor blood

Right sideof the heart

Oxygen-rich blood

Left sideof the heart

Circulatory System

The Heart: Structures

• The right and left sides of the heart are separated by a septum, or wall.

• The septum prevents the mixing of oxygen rich and oxygen poor blood.

• On each side of the septum are two chambers.• The upper chamber (receives blood) is the atrium.• The lower chamber (pumps blood out of heart) is the ventricle.

The Heart: Structures

• Four chambers– Two Atria

• Upper chambers• Left and right• Separated by interatrial


– Two Ventricles• Lower chambers• Left and right• Separated by interventricular


Right Ventricle

Right Atrium

Left Ventricle

Left Atrium

The Heart: Structures

• The chambers of the heart have different functions:

blood tothe body

blood from the body

blood to the lungs

blood from the lungs

The Atria collect blood that enters the heart.

The ventricles pump blood out of the heart.

The Heart: Structures

• The valves between the atria and ventricles are connected to the inner walls of the heart by tough tendons.

valve open

The Heart: Structures

• The tendons allow the valves to close and hold the valve flaps in place. They prevent the valves from flipping up and turning inside out

valve open valve closed

The Heart: Structures

• A valve acts like a door that only opens in one direction.

• In the heart, the tendons holding the valve are like the arm holding the door.

• One end of each tendon is fixed to the wall of the heart and so the valve can only open in one direction.

The Heart: Structures

How does the heart pump blood?

• The heart can pump blood because it is made of muscle. Muscle tissue works by contracting (squeezing) and relaxing.

• All the parts of the heart on either side, work together in a repeated sequence.

• The two atria contract and relax; then the two ventricles contract and relax.

• This is how blood moves through the heart and is pumped to the lungs and the body.

• One complete sequence of contraction and relaxation is called a heartbeat.

How does the heart pump blood?

Blood Vessels• As blood moves through the

circulatory system it moves through 3 types of blood vessels:– Arteries: Carry blood away from

the heart .– Capillaries: Link arterioles to

veins.– Veins: Carry blood towards the


Arteries Large vessels• Carry blood from heart to tissues of body.• Carry oxygen rich blood, with the exception of pulmonary arteries.• Thick walls-need to withstand pressure produced when heart pushes

blood into them.

Smallest blood vessels Walls are only one cell thick and very narrow. Important for bringing nutrients and oxygen to tissues and

absorbing CO2 and other waste products.


Blood Vessels

Veins• Once blood has passed through the capillary systems it must

be returned to the heart. Done by veins• Walls contains connective tissue and smooth muscle.• Largest veins contain one way valves that keep blood flowing

toward heart.• Many found near skeletal muscles. When muscles contract,

blood is forced through veins.

Blood Pressure• The heart produces pressure

• The force of blood on the wall of the arteries is known as blood pressure.

• Blood pressure decreases as the heart relaxes, but the rest of the circulatory system is still under pressure.

• When blood pressure is taken, the cuff is wrapped around the upper portion of the arm and pumped with air until blood flow in the artery is blocked.

• As the pressure in the cuff is relaxed, 2 numbers are recorded.– Systolic pressure- the first number taken, is the force felt in the

arteries when the ventricles contract.

– Diastolic pressure- the second number taken, is the force of the blood on the arteries when the ventricles relax.

Blood Pressure

Blood• What percent of your body is blood? • How much blood do we contain?

– On average 4-6 liters– We contain about a pint of

blood for every 15 pounds of body weight

• Composition of Blood:– What percent of your blood is

cellular? – What percent of your blood is





Blood• Composed of plasma and blood cells• Types of Cells are:

– Red Blood Cells– White Blood Cells– Platelets

Plasma Straw colored 90% water 10% dissolved gases, salts, nutrients, enzymes,

hormones, wastes, and proteins.

Blood• Plasma proteins

– 3 Types: Albumins, globulins and fibrinogen.– Albumins and Globulins- transport substances such as fatty acids,

hormones and vitamins.– Fibrinogen- Responsible for blood’s ability to clot

Red Blood Cells Most numerous type Transport oxygen Get color from hemoglobin Disk shaped Made in red bone marrow Circulate for 120 days

• White Blood Cells– Guard against infection, fight parasites, and attack bacteria– Number of WBC’s increases when body is fighting– Lymphocytes produce antibodies which fight pathogens and

remember them


Platelets Aid the body in clotting Small fragments Stick to edges of broken blood cell and secrete clotting factor to

help form clot.

BloodBlood has 3 main

Functions– Transport– Protection– Temperature



Red Blood Cells


White Blood Cells

Nitesh [email protected]