TOPIC 3: CIRCULATORY

SYSTEM: Part 2Learning outcomes:

1. Compare open and closed circulatory system

2. Identify different circulatory pathways in vertebrates

3. Explain the composition of human circulatory system and its functions

4. Describe capillary exchange in the tissues

5. Explain the human circulation system

6. Describe blood circulation in human heart

7. Describe the composition and functions of blood

8. Explain the function of lymphatic system

9. Explain the roles of immune system

Peer to Peer

1. Heart and Blood flow2. Blood and its elements3. Platelet and blood clotting4. Lymphatic systems5. Non specific defenses

The Human Heart

• The mammalian heart is a double pump.– The right side pumps

oxygen-depleted blood to the lungs.

– The left side pumps

oxygen-rich blood to the body.

• The two sides of the heart are separated by a wall of tissue called the septum.

• This septum prevents the oxygen-depleted and oxygen-rich blood from mixing.

• Each side of the heart has two chambers.– An upper atrium that receives

blood– A lower ventricle that pumps

blood out• There are valves that regulate the

flow of blood through the heart.– The atria and ventricles are

connected by the atrioventricular valves (tricuspid & bicuspid).

– The semilunar valves connect the ventricles to the attached blood vessels.

1. The right atria receives the blood returned to the heart via the vena cava.

2. The blood passes to the ventricle through the tricuspid valve.

3. The right ventricle pumps blood to the lungs through the pulmonary semilunar valve, the pulmonary trunk, and pulmonary arteries.

4. After gas exchange in the lungs, the pulmonary veins bring oxygen-rich blood back to the left atria of the heart.

5. The blood passes through the bicuspid valve to the left ventricle.

6. The left ventricle pumps the blood through the aortic semilunar valve to the aorta.

7. The aorta distributes the blood to the body.

Blood: A Transport Medium

• The blood serves several functions.1. Blood serves as a transport medium to

capillaries for fluid and solute exchange.2. The blood distributes components of the

immune system. 3. The blood helps regulate body temperature.4. The blood can form clots to prevent excessive

blood losses from wounds.

Blood Component

Whole blood

If we spin the tube at high speed, the blood will separate into two layers

Fluid part

Formed element part

Blood Component: A Closer Look

Plasma• Plasma consists of two main components.–Water (>90%)–Protein (<10%)

• The plasma also contains nutrients, wastes, and salts.

• The salts help buffer the blood pH and maintain the osmotic potential of the blood.

Formed Elements: RBC• There are three types of formed elements.

1. Red blood cells2. White blood cells3. Platelets

• The red blood cells are small cells that contain hemoglobin for oxygen transport.

• A decrease in the number of red blood cells in the body can lead to anemia.

Formed Elements: RBC

• Red blood cells are produced by the marrow of the skull, ribs, vertebrae, and long bones.

• The kidneys secrete erythropoietin, which stimulates red blood cell production.

• As red blood cells are released from the bones, they become specialized for oxygen transport.

• Red blood cells are eventually recycled to produce new red blood cells.

Formed Elements: RBC

Formed Elements: WBC

• The white blood cells that fight infection are also called leukocytes.

• White blood cells are found not only in the blood but in the lymphatic system.

• The life span of white blood cells varies from a few days to years.

Formed Elements: WBC

• White blood cells called monocytes are transformed into macrophages, another type of phagocytizing cells.

• Macrophages also release growth factors that increase the number of white blood cells called lymphocytes.

• Lymphocytes called T cells specialize in the destruction of virus-infected cells.

Formed Elements: WBC

• Lymphocytes called B cells produce antibodies.

• The unique antibody produced by each B cell is unique to a particular foreign protein or polysaccharide, called an antigen.

• When an antibody combines with an antigen, the complex is phagocytized by a macrophage.

Platelets and Blood Clotting

• Platelets, or thrombocytes, are fragments of bone marrow cells called megakaryocytes.

• The platelets are critical to blood clotting, also called coagulation.

• Also important to blood clotting are 12 chemicals called clotting factors.

Platelets and Blood Clotting

• Hemophilia, a blood clotting disorder, is due to the absence of one clotting factor.

• The liver produces two clotting factors.1. Prothrombin2. Fibrinogen

Platelets and Blood Clotting

1. The formation of a clot begins when platelets clump at the site of a puncture.

2. The platelets and injured tissues release prothrombin activator, which converts prothrombin to thrombin.

3. Thrombin is an enzyme that modifies fibrinogen to become fibrin.

4. The fibrin threads wind around the clumped platelets to form the framework of the clot.

5. During clot retraction, the clot gets smaller as the cells shrink and are replaced by a fluid called serum.

6. When the blood vessel is repaired, the enzyme plasmin destroys the fibrin.

The Lymphatic System• The lymphatic system has several functions in the

human body.1. This system returns excess fluid (lymph) from the

tissues to the heart.2. Fat is taken up from the digestive tract.3. The lymphatic system works with the immune

system. • The lymphatic vessels are an extensive network of

ducts and vessels throughout the body.

The Lymphatic System

Lymph Nodes• The lymph nodes produce lymphocytes

that help to protect the body against infections.

• The lymph nodes filter the lymphatic fluid to remove antigens and pathogens.

• Antigens and pathogens are removed by the phagocytic macrophages.

• Lymphocytes in the lymph nodes all contribute to the defense against antigens and pathogens in the lymphatic fluid.

Role of Blood and Lymphatic Components

in Immune System

Nonspecific Defenses

• The body has a variety of nonspecific defenses that help protect the body from infection.1. Barriers to entry2. The inflammatory response3. Natural killer cells

1) Barriers to Entry• There are two primary barriers that prevent entry of

pathogens into the body.1. The skin- outer layer of skin, harden die/dead cells

form, a protecting barrier against invasion by pathogen.

2. The mucous membranes- Nasal cavity & trachea secreted mucous to trap the dust article& spore

• In addition to mechanically blocking pathogen entry, the skin has oil glands secrete chemicals to counter pathogens.

2) The Inflammatory Response

• Any damage to the body’s tissues trigger events of the inflammatory response.– Reddening– An increase in temperature– Swelling– Pain

• The inflammatory response also involves three cell types.1. Mast cells2. Neutrophils3. Macrophages

• The body’s response to an infection begins with an inflammatory response.

1. The injured site swells and reddens.

2. The damaged tissues release kinins to increase blood flow through the capillaries.

3. The damaged tissues release histamines to increase capillary permeability

• White blood cells called neutrophils pass through the capillary walls and phagocytize foreign material.

The Mast cells release chemicals such as histamine to increase the blood flow through the capillaries.

This increased blood flow contributes to the redness, swelling, and warmth.

Because of the swelling, nerve receptors are triggered to create the sensation of pain.

• Neutrophils are phagocytic white blood cells that migrate to the site of injury.

• Macrophages have several roles.1. These cells are phagocytic. 2. These cells release

chemicals that trigger white blood cell production in the red marrow.

3: Natural Killer Cells

• Natural killer cells are non-specific lymphocytes that kill virus-infected and cancerous cells by cell to cell contact.

• Natural killer cells kills cells that lack surface proteins * identifying them as “self”.

* MHC 1 markers