Circulatory System

The 3 main parts of the circulatory system

1.The Heart

2.The blood vessels

3.Blood

Two Pathways

• Pulmonary Circulation– Carries blood to lungs and back

• Systemic Circulation– Carries blood to body and back

Capillaries of head and arms

Capillaries of abdominal organs and legs

Inferior vena cava

Pulmonary vein

Capillaries of right lung

Superior vena cavaAorta Pulmonary artery

Capillaries of left lung

The 3 main parts of the circulatory system

1.The Heart

2.The blood vessels

3.Blood

Circulatory System

HEART

Chambers of the Heart

The Heart

The heart is actually two separate pumps.

The left side pumps blood to the body (systemic circulation)

The right side pumps blood to the lungs (pulmonary circulation)

Right Ventricle

Right Atrium

Left Atrium

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 Ventricle

Septum

The Structures of the Heart

Types of blood vesselsArteries- Carry blood away from the heart- The Aorta is the largest artery

Veins- Carry blood away from the heart- veins contain valves- the vena cava is the largest veins

Capillaries- Known as the ‘Distribution Pipes”

Arteries have a thick, elastic layer to allow stretching and absorb pressure. The wall stretches and recoils in response to pumping, thus peaks in pressure are absorbed.

The arteries maintain pressure in the circulatory system much like a balloon maintains pressure on the air within it. The arteries therefore act as pressure reservoirs by maintaining (storing) pressure.

The elastic layer is surrounded by circular muscle to control the diameter and thus the rate of blood flow. An outer layer of connective tissue provides strength.

Arteries

Arteries:carries blood Away from heart

– Large– Thick-walled, Muscular– Elastic– Oxygenated blood

• Exception Pulmonary Artery– Carried under great pressure– Steady pulsatingArterioles: smaller vessels, enter tissue

Artery vs. Vein

The diameter of veins is greater than that of arteries.The blood pressure in the veins is low so valves in veins help prevent backflow. 

The contraction of skeletal muscle squeezes the veins and assists with moving blood back to the heart.

The vena cava returns blood to the right atrium of the heart from the body. In the right atrium, the blood pressure is close to 0.

Varicose veins develop when the valves weaken.Veins act as blood reservoirs because they contain 50% to 60% of the blood volume.

Smooth muscle in the walls of veins can expand or contract to adjust the flow volume returning to the heart and make more blood available when needed.

Veins

Veins:Carries blood to 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

Capillaries

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

Blood consists of three types of cells: oxygen-bearing red blood cells, disease-fighting white blood cells, and blood-clotting platelets, all of which are carried through blood vessels in a liquid called -----------.

Plasma is yellowish and consists of water, salts, proteins, vitamins, minerals, hormones, dissolved gases, and fats.

_________ have thicker walls than veins to withstand the pressure of blood being pumped from the heart.

Blood in the veins is at a lower pressure, so veins have one-way valves to prevent blood from flowing backwards away from the heart.

___________ the smallest of blood vessels, are only visible by microscope—ten capillaries lying side by side are barely as thick as a human hair. If all the arteries, veins, and capillaries in the human body were placed end to end, the total length would equal more than 100,000 km (more than 60,000 mi)—they could stretch around the earth nearly two and a half times.

Three types of blood vessels form a complex network of tubes throughout the body. __________ carry blood away from the heart, and _________carry it toward the heart. ____________are the tiny links between the arteries and the veins where oxygen and nutrients diffuse to body tissues.

The inner layer of blood vessels is lined with endothelial cells that create a smooth passage for the transit of blood.

This inner layer is surrounded by connective tissue and smooth muscle that enable the blood vessel to expand or contract.

Blood vessels expand during exercise to meet the increased demand for blood and to cool the body. Blood vessels contract after an injury to reduce bleeding and also to conserve body heat.

The composition of blood1. The plasma (Fluid) – makes up 55% of the blood volume

2. The solids (cells) – makes up 45% of the blood volume

Blood Plasma (fluid)- 97% water- other 3% (antibodies and protein & nutrients and wastes)

Blood Solid (cells)- Red Blood Cells – Carry O2 and contain hemoglobin- White Blood Cells – Attack bacteria & other invaders- Platelets – Control the blood clothing process

Liquid Portion Carries • Blood cells

– Erythrocytes (RBC - red blood cells)– Leucocytes (WBC - white blood cells)

• Platelets (non cellular particles)• Proteins

– Enzymes – Hormones – Endocrine System

• Nutrients - Digestive System• Gases - Respiratory System• Inorganic salts

Blood is made up of a number of types of cells:

Plasma: Plasma is a straw-coloured fluid in which blood cells are suspended. It is made up of approximately 90% water as well as electrolytes such as sodium and potassium and proteins. Red Blood Cells (Erythrocytes): The main function of red blood cells is to carry oxygen. RBC's contain a protein called Haemoglobin. This combines with oxygen to form Oxyhaemoglobin. Each RBC has a lifespan of approximately 120 days before it gets broken down by the spleen. New RBC's are manufactured in the bone marrow of most bones. There are approximately 4.5-5 million RBC's per micro-litre of blood. White Blood Cells (Leucocytes): There a number of types of white blood cells, although the function of all of them is to help fight disease and infection. They typically have a lifespan of a few days and there are only 5-10 thousand WBC's per micro-litre of blood. Platelets (Thrombocytes): Platelets are disc shaped cell fragments which are involved in clotting the blood to prevent the excess loss of body fluids.

Red Blood cells

Erythrocytes (RBC)• Transporters of

– Oxygen– Carbon Dioxide

• RBC– Lack a nucleus– Contain hemoglobin– Disk-shaped

• RBC are produced in red bone marrow of – ribs, – humerus, – femur, – sternum, and other long bones

• Lives for 120 days• Old RBC are destroyed in liver and

spleen

Leukocytes (WBC)

• WBC fight infection– Attack foreign

substances• Less abundant• Large cells• Some live for months

– Most just a few days• Several types• ALL contain nuclei

Platelets

• PLATELETS are for CLOTTING blood• Cell fragments• Produced in bone marrow• Short life span (1 week)• Fibrin (sticky network of protein fibers)

– Form a web trapping blood cells

The Blood

• Body contains 4-6 L• Consists of

– Water– Red Blood Cells– Plasma– White blood cells and

platelets

Whole Blood Sample

Red blood cells

White blood cells

Platelets

Plasma

Sample Placed in Centrifuge Blood Sample That Has Been Centrifuged

Whole Blood Sample

Red blood cells

White blood cells

Platelets

Plasma

Sample Placed in Centrifuge Blood Sample That Has Been Centrifuged

Whole Blood Sample

Red blood cells

White blood cells

Platelets

Plasma

Sample Placed in Centrifuge Blood Sample That Has Been Centrifuged

Parts of the Blood

Blood Clotting

Break in Capillary Wall

Blood vessels injured.

Clumping of Platelets

Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin..

Clot Forms

Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

1. Transportation: The blood carries other substances around the body inside arteries, veins and capillaries. These include gasses (Oxygen and Carbon Dioxide), waste products (water, urea), hormones, enzymes and nutrients (glucose, amino acids, vitamins and minerals). The blood flows through the circulatory system.

2. Maintaining Homeostasis: Altering the blood flow to the skin can help to reduce body temperature. Transportation of enzymes which are used to maintain our internal environments.

3. Immunity and defense: White blood cells fight infection and platelets help repair damage and clot the blood

What is the function of blood??

- transports food, hormones, metabolic wastes, and gases (oxygen, carbon dioxide) to and from cells.

What is the circulatory system?

Components of the circulatory system include:

BLOOD: consisting of liquid plasma and cells

BLOOD VESSELS (vascular system): the "channels" (arteries, veins, capillaries) which carry blood to/from all tissues. Arteries carry blood away from the heart. Veins return blood to the heart. Capillaries are thin-walled blood vessels in which gas/ nutrient/ waste exchange occurs.

HEART : a muscular pump to move the blood

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.

The Heart and blood vessels together make up the Circulatory System.

What is the circulatory system?

No Circulatory Systems

• In simple organisms in moist environments

Circulation• Movement of fluid through an organism• Circulatory system

– Transport system– Uses fluid to move substances

Respiratory system via Circulatory system The arteries, veins, and capillaries are divided into two systems of circulation: systemic and pulmonary.

The systemic circulation carries oxygenated blood from the heart to all the tissues in the body except the lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to the heart.

The pulmonary circulation carries this spent blood from the heart to the lungs.

In the lungs, the blood releases its carbon dioxide and absorbs oxygen. The oxygenated blood then returns to the heart before transferring to the systemic circulation.

Physical Activity With exercise, metabolism speeds up and because of this the muscles require more oxygen So the heart beats faster to supply the muscles with more oxygen-rich blood In turn the speed of blood flow increases.

Blood PressureBlood pressure is defined as the force exerted by the blood against the vessel wall. Blood pressure is highest in arteries and gradually decreases as it passes through arterioles, capillaries, venules and finally, veins.Blood pressure is also variable and can increase due to exercise where the cardiac output increases thus forcing more blood through the arteries or by altering the peripheral resistance. This occurs by vasoconstriction, increases in blood viscosity (thickness) and changes in shape or size of the vessels. The regulation of blood pressure is the responsibility of the sympathetic and parasympathetic nervous systems.

Blood Pressure

• Blood against the blood vessel’s walls– The systolic pressure refers to

• the pressure recorded while the ventricles pump the blood.

– The diastolic pressure refers to • the pressure recorded as the ventricles fill with blood.

• A normal blood pressure is 120/80

Digestive system via Circulatory system

The circulatory system also transports nutrients derived from digested food to the body.

Nutrients enter the bloodstream by passing through the walls of the intestine - absorbed through a network of capillaries and veins that drain the intestines, called the hepatic portal circulation.

The hepatic portal circulation carries the nutrients to the liver for further metabolic processing.

The liver also cleans the blood by removing waste products and toxins.

The circulatory system plays an important role in regulating body temperature. During exercise, working muscles generate heat. The blood supplying the muscles with oxygen and nutrients absorbs much of this heat and carries it away to other parts of the body. If the body gets too warm, blood vessels near the skin enlarge to disperse excess heat outward through the skin. In cold environments, these blood vessels constrict to retain heat.

Blood vessels expand during exercise to meet the increased demand for blood and to cool the body. Blood vessels contract after an injury to reduce bleeding and also to conserve body heat.

Functions of the circulatory system:

Distribute nutrients,

Transport and exchange oxygen and carbon dioxide,

Remove waste materials,

Distribute secretions of endocrine glands,

Prevent excessive bleeding,

Prevent infection, and

Regulate body temperature.

What happens when you mix blood types?

• Plasma contains proteins that correspond to the shape of the different antigens

• If you mix one type with the wrong one, you get CLUMPING

• Type O is the universal donor • Type AB is the universal acceptor

What Makes Our Blood Type?

Blood Type of Donor

A

B

AB

O

Blood Type of Recipient

A B AB O

Unsuccessful transfusion Successful transfusion

Blood Transfusions

Rh Factor

• Rhesus factor (Rh), also inherited– Rh+ (have antigen)– Rh- (NO antigen)

• Can cause complications in pregnancies– mother Rh- 1st baby Rh+ : blood mixes with

mother; mother’s body makes anti-Rh+ antibodies– 2nd Rh + body attacks baby– Now have medicine to prevent antibody

formation

How about the circulatory system in animal? Fish? Amphibians?

Reptilians? Insects?

Humans cannot survive for more than a few minutes without O2. Why?