Types of circulatory systems

Open system

• Mostly invertebrates

• Low pressure

• Haemocoel

• Suitable for small organisms

Closed system

• Vertebrates

• High pressure

• Blood remains in blood vessels

• Separate tissue fluid

Closed circulatory system

• Vertebrates

• High pressure

• Blood remains in blood vessels

• Separate tissue fluid

• Heart – arteries – arterioles – capillaries – venules – veins – heart

• Exchange occurs between capillaries and body tissues

Component Structure function

Heart Muscular organ Acts as a pump that keeps the blood flowing

through the body in one direction

Blood vessels Network of tubular

structures

Contains the blood as it circulates throughout the

body

Blood Type of connective

tissue, consisting of red

blood cells, white blood

cells and platelets in a

matrix of blood plasma

Transports:

• O2 and CO2 to and from the lungs

• Absorbed nutrients from small intestine to liver

• Hormones from the endocrine glands to the

target organs

• Waste products like urea from liver to kidney

• Heat from the liver and muscles to the rest of

the body

Lymphatic vessels Network of tubular

structures

• Contains the lymph as it circulates throughout

the body

• Acts as an additional drainage system that

transports lymph to the immune organs and

into the bloodstream

Lymph Colourless fluid derived

from tissue fluid

• Contains white blood cells to fight infections

• Transports products of fat digestion from small

intestines into the blood stream

Double circulatory system

Advantages:

• Pumped to lungs

constantly to

be oxygenated

• Creates a high

pressure –

oxygen supplied

and wastes

removed

• Protection of the heart

External view of the heart

pulmonary artery

pulmonary vein

coronaryartery

left ventricle

right ventricle

inferior vena cava

right atrium

pulmonary vein

aorta

superiorvena cava

Internal structure of the heart

superior

vena cava

(transports blood

from the head)

inferior

vena cava

(transports blood

from rest of body)

The vena cava carries

deoxygenated blood from the body

to the right atrium

The right atrium collects deoxygenated

blood and pumps it to the right

ventricle

right atrium

The right ventricle pumps

deoxygenated blood to the lungs

right ventricle

The pulmonary artery carries

deoxygenated blood from the right

ventricle to the lungs

Pulmonary artery

The septum separates the left and

right sides of the heart

septum

The pulmonary veins carry

oxygenated blood from the lungs to

the left atrium

Pulmonary veins

The left atrium collects the

oxygenated blood and pumps it to the

left ventricle

Left atrium

The left ventricle pumps oxygenated

blood to the body via the aorta

Left ventricle

The aorta carries the oxygenated from

the left ventricle to the rest of the body

Aorta

Aortic arch

Atrio-ventricular valves prevent

backflow of blood into the atria when

ventricles contract

Bicuspid valve

(mitral valve)

Tricuspid valves

Tendonous cords

The semi-lunar valves prevent

backflow of blood from the arteries into

the ventricles

Aortic semi-lunar valve

Pulmonarysemi-lunar valve

FUNCTION OF THE HEART

To pump blood around the body so that all living cells

can receive oxygen and other nutrients and release

excretory products to be transported away

Transport systems in Humans

• Circulatory system

• Lymphatic system

Functions of the

transport system of humans

Human body cells

•Require food and oxygen to

release energy

•Waste products get produced

Lungs

Digestive

system

Kidneys

Sweat

Oxygen

Carbon

dioxide

food

Urine

Sweat

HOW IS THE HEART RATE

CONTROLLED?

How does the heart beat

1 Sinoatrial node (Pacemaker) – SA node

2 Atrioventricular node

3 Atrioventricular Bundle (Bundle of His)

4 Left & Right Bundle branches

5 Bundle Branches / Purkinje fibres

The SA node (patch of specialised cells) gives the

heart the signal to start beating

The AV node and Purkinje fibres (septum) form a

conduction system which keep the heart beating

regularly

• Electrical signal starts from SA node and spreads through the walls

of the atria

• Signal spreads to the AV node

• Once the atria relax the signal travels down the Purkinje fibres

• This causes the ventricles to contract from the bottom up, squeezing

the blood up into the arteries

The Cardiac Cycle

Systole - contraction Diastole - relaxation

• The sino-atrial node (SA node)sends electrical impulses to the muscle fibres of both the left and right atria.

• The two atria contract at the same time.

• The tricuspid and bicuspid valves open.

• The blood flows into the two ventricles which are relaxed.

• The SA node acts as a pacemaker causing the heart to beat at a slower or faster rate depending on the body’s needs.

• The two ventricles contract at same

time.

• The blood is forced into the aorta and

pulmonary artery.

• The tricuspid and bicuspid valves close.

• This prevents blood from flowing back

into the atria.

• Both the atria and ventricles relax.

• The semi-lunar valves at the base of

the aorta and pulmonary artery close,

preventing blood from flowing back into

the ventricles from the aorta or

pulmonary artery.

• Blood enters the atria through the

superior and inferior vena cavae and

pulmonary veins.

PulseThe pulse is the

regular expansion and

contraction of an

artery

BLOOD PRESSURE

12080

SYSTOLIC BLOOD PRESSURE – as the left ventricle

contracts, blood is pushed into the aorta, stretching the

elastic walls. The maximum pressure reached in the aorta

when the ventricles contract is the called systolic pressure

DIASTOLIC BLOOD PRESSURE - during diastole the

walls of the aorta recoil. This keeps up the pressure on

the reduced blood volume forcing blood into smaller

vessels. This lower pressure in the aorta when the

ventricles relax is called diastolic pressure

baumanometer

BLOOD VESSELS

ARTERIES

Pump blood from

the heart to all the

cells of the body

Pump oxygenated

blood

High pressure

Pressure reservoirs

Control the

distribution of blood

VEINS

Pump blood from

the cells to the heart

Low pressure

Have valves to

prevent backflow

Pump deoxygenated

blood

Capillaries

Easy diffusion of

substances between

blood and cells

Allow phagocytes

(white blood cell) to

move in and out

Artery Vein Capillary

Blood is under a high

pressure

Blood is not under a high

pressure

Blood is not under a high pressure

Does not have valves Does have semi-lunar valves Does not have valves

Has thick muscular walls Has thin muscular walls Has a single layer of cells in the

walls for easy diffusion

Has a smaller lumen then

veins

Has a large lumen Has a very narrow lumen

Carries blood away from the

heart

Carries blood to the heart Produces tissue fluid at the capillary

beds

Oxygenated blood except

pulmonary arteries

Deoxygenated blood except

pulmonary veins

Exchanges O2 & CO2 between

plasma & tissue fluid

Leads to capillaries Leads from capillaries Branches of arteries and join up to

form veins

Varicose veins

Thrombosis

Effect of exercise on heart rate

• When you exercise, cellular respiration increases so more

CO2 is produced

• This lowers the pH of the blood

• Impulse is sent via sensory neurons to the medulla

oblongata

• Responds by telling the SA node to beat quicker.

• Why?

THE LYMPHATIC SYSTEM

The lymphatic system is a circulatory system that transports lymph

throughout the body. Unlike the blood circulatory system, the

lymphatic system has no pump. It is a drainage system.

Lymph Is the body fluid containing white blood cells, chief

lymphocytes, that is drained from the tissue spaces by the

lymphatic vessels

• Blood plasma and white blood cells leak out of the capillaries and return to the

blood circulation system

• In between body tissues are blood capillaries and lymphatic capillaries

• Blood plasma that leaks out of the capillaries and surrounds body tissues it is called

tissue fluid

• Tissue fluid that drains into the lymph vessels is called lymph.

• Lymph capillaries join to form lymph vessels

• Lymph vessels flow through lymph nodes

• Lymph nodes contain many white blood cells – immunity

• Lymph nodes: neck, armpits, groin

• Lymph is returned to the circulatory system via a vein in the neck

• Flow is uni-directional because of valves

Constituents of lymph

• Water

• Solutes – proteins, salts, glucose,

urea

• Fat

• White blood cells – lymphocytes and

macrophages

• Lymphocytes – B and T

• B – produce antibodies that enter

blood to fight germs

• T – variety of functions

• Macrophages – trap and digest

foreign matter and harmful

bacteria by phagocytosis

Functions Of The Lymph System

• Helps maintain the fluid

balance

• Helps defend the body

against infection

• Transports absorbed fat –

lacteals in villi absorb fat

CIRCULATORY DISEASES

Diseases and disorders

Diseases of the cardiovascular system can be serious and are a major cause of death, seeing as blood is the manner in which all your cells in the body receive useful substances and get rid of waste products.

Sometimes causes are genetic, but lifestyle is also a major contribution to diseases and disorders. These are smoking, drinking, lack of exercise, obesity etc.

Examples of diseases and disorders

• Anaemia

When a person has too few red blood cells due to a lack of iron. The person appears pale with no energy.

• Leukaemia

A type of blood cancer that causes uncontrolled division of the leucocytes (white blood cells).

• Blood pressure

Hypertension is high blood pressure and hypotension is low blood pressure. In high blood pressure, the heart has to work harder, which can lead to stroke, heart attack or kidney disease. In low blood pressure, a person feels dizzy and has fainting spells.

• Angina, arteriosclerosis

Angina is chest pain associated with too little oxygen being delivered to the heart muscles. This can be associated with arteriosclerosis which is a narrowing of the arteries due to arteriosclerotic plaque.

• Heart attack and strokes

In a heart attack, the coronary arteries, supplying oxygen to the heart, become blocked or they spasm. The heart no longer has enough oxygen to work and stops pumping.

In a stroke, a clot may form and block one of the arteries to the brain, starving it of oxygen, or a blood vessel may burst as a result of a blockage or hypertension and weakening of the artery walls.

Coronary artery disease

• Heart attack – coronary artery is

blocked or cut off – heart is starved of

oxygen and the tissue dies

• High risk factors:

– High blood pressure, smoker, obesity,

high blood cholesterol, diabetes, stress,

sedentary lifestyle, diet high in sugar

and fat and low in fruit and vegetables

– Sex- male, middle-age, high achiever

personality, genetic predisposition

Atherosclerosis

• Hardening of the

arteries, also called

atherosclerosis, is a

common disorder. It

occurs when fat,

cholesterol, and other substances build up

in the walls of arteries

and form hard

structures called

plaques.

Treatment • Coronary artery bypass graft

• Coronary angioplasty

• Atherslerosis treated with:

– Balloon angioplasty (with or without stent)

– Laser angioplasty (breaks up thrombus)

– Coronary by-pass

– Heart transplant

• Irregular heartbeat treated with:

– Pacemaker (regulates heartbeat if too slow or too fast)

• Valve replacements (repair or replace valves)

• Heart transplant (receive heart from recently

deceased person – commonly brain dead)

• Thrombosis in a brain artery – brain

cells get cut off form oxygenated

blood

• Symptoms

– paralysis on one side of the body

– Difficulties speaking/swallowing

– Problem seeing properly

– Unconsciousness

Stroke

• Sudden rupture of blood vessel in the

brain – sudden death, same

symptoms as above

• Rupture of blood vessel inside skull

but outside brain – pressure – severe

headache – brain cells could die