Circulatory system

Premedical

Endothermic way of life require 10x more energy (exothermic).

Cells of body require nutrients, oxygen and exclude carbon

dioxide and wastes.

Cardiovascular system:

•Blood - blood cells and plasma

•Vessels – arteries, veins, capillaries, arterioles, venules,

capillary bed

•Heart – atria and ventricles

Blood pressure

Double circulation : independent body and lung circulatory system supported by 4 chambered heart of mammals

Lungs

Body cells

double circulatory systemlymphatic system

the right side of the

system

deals with

deoxygenated

blood.

the left side of the

system

deals with

oxygenated

blood.

The Heart

These are arteries. They carry blood away from the heart.

This is a vein. It brings blood from the body, except the lungs.

Coronary arteries supply the heart with blood

first branches

The heart has four chambers

2 atria

2 ventricles

The Heart

left ventricle

left atriumright atrium

right ventricle

valve

vein from lungs

artery to head and bodyartery to lungs

vein from head and body

valve

How does the heart work?

blood from the body

blood from the lungs

The heart beat begins when the

heart muscles relax and blood

flows into the atria.

Heartbeat: STEP ONE

The atria then contract and

the valves open to allow blood

into the ventricles.

How does the heart work?

STEP TWO

How does the heart work?

The valves close to stop blood

flowing backwards.

The ventricles contract forcing

the blood to leave the heart.

At the same time, the atria are

relaxing and once again filling with

blood.

The heartbeat – the cycle repeats itself.

STEP THREE

Systole is a phase where the myocardium is contracting in

a coordinated manner in response to an endogenous

electrical stimulus

Diastole is the period of time when the heart fills with

blood after systole.

Cardiac output is the volume of blood being pumped by

the heart, in the time interval of one minute

Puls - frequency of contractions, normal 70 - 75 / minute

Heartbeat - valves close, impact of blood to valves

Heart murmur – defect of valve

Four valves prevent a backward blood flowing.

The AV valve on the right side of the heart is called the

tricuspid valve because it has three leaflets (cusps).

The AV valve on the left side of the heart is called the

bicuspid valve (or mitral valve) because it has two leaflets.

Semiluminar: the pulmonary valve

the aortic valve

Mechanism of heartbeat continuity:

Special cardiomyocytes cells with the ability to

generate the electrical impulses. They have internal

rhythm of contractions.

Pacemaker – Sinoatrial node – right atrium

Atrioventricular bundle - right side

EKG

Blood pressure – hydrostatic pressure

is a force exerted by circulating blood on the walls of blood

vessels. During each heartbeat, BP varies between a

maximum (systolic) and a minimum (diastolic) pressure.

Thoracic cavity

between the lungs and is contained in the

pericardial sac

• Epicardium – outer layer of heart wall

• Endocardium – inner layer that consists of

endothelial cells, which line the heart, covers the

heart valves, and lines the blood vessels.

• Myocardium – middle layer composed of cardiac

muscle.

There are 3 types of blood vessels

a. ARTERY

b. VEIN

c. CAPILLARY

The ARTERY

thick muscle with

elastic fibres

elastic fibres allow the

artery to maintain a

blood pressure

the thick muscle can

contract to push the

blood along.

The VEIN

thin muscle and elastic fibres

Veins have valves, which prevent a backward blood flow

Body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessels.

The CAPILLARY

the wall of a capillaryis only one cell thick

Basement membrane and endothel

The exchange of materials between the blood and the body can only occur through capillaries.

artery vein

capillariesbody cell

The CAPILLARYA collection of capillaries is known as a capillary bed.

The semi-permeable membrane (basement

membrane) of capillary walls allows

nutrients, oxygen, and water

to diffuse from the blood to the tissues.

Waste products, like

carbon dioxide, diffuse from the tissues

into the blood.

Subclavian vein

Superior vena cava

Pulmonary artery

Inferior vena cava

Renal vein

Iliac vein

Femoral vein

Carotid arteries

Subclavian artery

Pulmonary vein

Aorta

Renal artery

Iliac artery

Femoral artery

The aorta is

the largest

artery in the

body

This portion of the systemic circulation is known as

the hepatic portal system.

The gastric vein (stomach), splenic vein (spleen),

pancreatic vein (pancreas), and mesenteric veins

(small intestines) empty into the portal vein that

carries the blood to the liver.

The hepatic vein carries blood to the inferior (caudal)

vena cava.

The lymphatic system is part of the immune system and acts as a

secondary (accessory) circulatory system.

•return water and proteins to blood

• remove excess fluids from body tissues,

• absorb fatty acid and transport fat to circulatory

system, and

• produce immune cells (lymphocytes, monocytes,

and plasma cells).

Flow of Blood & Lymph Within Tissue

As the collecting lymph vessel accumulates lymph from

more and more lymph capillaries in its course, it becomes

larger and is called the afferent lymph vessel as

it enters a lymph node. Here the lymph percolates through

the lymph node tissue and is removed by the efferent

lymph vessel. An efferent lymph vessel may directly

drain into one of the (right or thoracic) lymph ducts

Both

the lymph ducts

return the lymph to the

blood stream by

emptying into the

subclavian veins

Lymph nodes filter foreign substances, such as

bacteria and cancer cells, before it is re-entered into

the blood system through the larger veins.

Lymph nodes act as the body’s first defense against

infection.

Lymph node

Photo from U. S. Federal Government courtesy of Wikipedia.

Lymph node has a fibrous outer covering (capsule), a cortex, and a medulla

Lymphoid tissue:

spleen, thymus,

bone marrow and the

lymphoid tissue

associated with the

digestive system.

www.worldofteaching.com

Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson, Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings Publishing Company, 1996 –2010. chapter 42

Thank you for your attention