BLOOD & CIRCULATORY SYSTEM

Prepared by Mr.Yeung

CIRCULATORY SYSTEM

• Overview• Every cell in a living organism

must have direct access to its nutrient supply

• Single celled organisms • rely on simple diffusion to

move materials into the cell

• Multi-cellular organisms • require some type of

system

CIRCULATORY SYSTEM

• Functions• Carries nutrients and wastes to and

from cells• Carries chemical messages between

different cells• Distributes heat throughout the body• Maintains fluid levels in the body• Defends against invading organisms

CIRCULATORY SYSTEM – KEY PARTS

1. Blood

• 55% Plasma

• 45% Formed Elements

• Cells

• white blood cells

• red blood cells

• Platelets

• (<1%) cell fragments

• Humans have ~5L of blood

2. Vessels

• Arteries, veins and capillaries

3. Heart

4. Periphery Organs

• Kidneys

• Liver

• Intestines

• Lungs

BLOOD • Blood composition

BLOOD - PLASMA

• Fluid portion of the blood

• Contains 90% water

• Other 10% dissolved substances

• Contains dissolved materials

• gases, glucose, amino acids, ions and vitamins.

• wastes and hormones.

BLOOD – PLASMA CONT’D• Soluble proteins

• Immunoglobulins

• antibodies and carrier/transport proteins

• Fibrinogens

• aid in blood clotting

RED BLOOD CELLS STRUCTURE

• You are a water thief

• The way you steal water is to have the water absorb into your clothing.

• You must climb and squeeze through tiny windows

• What shape would you be to maximize the amount of water?

BLOOD – ERYTHROCYTESRED BLOOD CELLS

• Red blood cells (RBCs)

• 4-6 million per mm3 (ml) of whole blood

• Function to transport gas around the body

BLOOD - ERYTHROCYTES• Structure

• biconcave disks,

• increased surface area, Increases ability to exchange gas

• Have no nucleus at maturity

• Increased space for hemoglobin, increases ability to carry oxygen

• proteins in cell membranes determine blood type

BLOOD – ERYTHROCYTES CONT’D

• Continuously produced in bone marrow

• Mainly in large bones

• the skull, ribs, vertebrae, and ends of the long bones.

• Production of red blood cells is stimulated by erythropoietin

• From kidney

• In response to decreased oxygen in blood

BLOOD – ERYTHROCYTES CONT’D

• Contain hemoglobin

• Red iron containing pigment

• Heme portion of molecule forms an unstable, reversible bond with oxygen.

• Carries 20 ml oxygen per 100 ml of blood

• Oxygenated state = oxyhemoglobin

• Bright red

• Reduced state = deoxyhemoglobin

• purple-blue.

BLOOD – ERYTHROCYTES CONT’D

• Structure of Hemoglobin

BLOOD – ERYTHROCYTES CONT’D

• Lifespan- 120 days

• Destroyed in liver by fixed macrophages

• Hemoglobin is broken down

• Iron is recycled-taken to bone marrow

• Heme portion is degraded and excreted as bile pigments

BLOOD – ERYTHROCYTES CONT’D

Possible disorders

• Anemia- decreased red blood cells

• Most common type comes from iron deficiency

• Carbon monoxide poisoning

• Carbon monoxide binds at heme sites more strongly than oxygen

BLOOD – LEUKOCYTESWHITE BLOOD CELLS

• White blood cells (WBCs)

• General term for a variety of cells without hemoglobin

• Less numerous than RBC’s- 4000-11000 per mm3 of whole blood

• Larger cells, nucleated

BLOOD – LEUKOCYTES CONT’D

• Important part of the immune system.

• able to enter fluids surrounding tissues to fight infection

• Blood stream is only a means of transport to location of infection.

BLOOD – LEUKOCYTES CONT’D

Fighting Infections:

• Fight infection by destroying pathogens

• Other leukocytes will also clean up the mess!

• Pus is composed of dead invaders and leukocyte fragments

MACROPHAGE ENGULFING BACTERIA

• Fig. 12.12

BLOOD – LEUKOCYTES CONT’D

• Lifespan

• Different types live different lengths of time

• Some live only a few days-die combating invading pathogens

• Some live months or years

BLOOD – LEUKOCYTES CONT’D• Change in numbers may indicate disease

• Infectious mononucleosis

• Due to Epstein-Barr virus

• AIDS

• HIV – Human Immunodeficiency Virus

• Decreased number of T lymphocytes

• Leukemia

• Blood cancer

• Uncontrolled numbers of WBC’s

BLOOD - THROMBOCYTES

• Platelets

• fragmentation of large cells called megakaryocytes

• 150,000-300,000 per mm3 of whole blood

• Tiny cells that play important role in blood clotting.

BLOOD – THROMBOCYTES CONT’D• Blood clotting

• Platelets form a plug for immediate stoppage of bleeding

BLOOD CLOTTINGSteps:• Platelets contain the starter enzyme for blood

clotting to occur.• Platelets releases thromboplastin and converts

prothrombin to thrombin.• Thrombin joins with fibrinogen to form fibrin.• Fibrin traps red blood cells and clots.

Thromboplastin à Prothrombin à Thrombin + Fibrinogen èFibrinhttps://www.youtube.com/watch?v=--bZUeb83uU