Circulatory System - Human Systems - Lecture Slides, Slides of Human Biology

Download Circulatory System - Human Systems - Lecture Slides and more Slides Human Biology in PDF only on Docsity!

Circulatory System

Circulatory System Intro

The Circulatory or cardiovascular system consists of:

• The Heart
• The Blood
• Blood Vessels

Together with the lymphatic system, the circulatory system:

• Delivers oxygen and nutrients to cells
• Removes waste from cells
• Maintains the balance of water in the body

Blood

• A Specialised type of connective tissue
• It is a thick liquid with a metallic taste
• Blood accounts for about 8% of our total body weight
• Blood volume in a healthy adult:

Male = 5-6L Female = 4-5L

Functions of Blood

Blood performs a number of specialised functions:

• Transports nutrients, oxygen, carbon dioxide, waste products and hormones to cells and organs around the body.
• Protects us from bleeding to death, via clotting, and from disease, by destroying invasive microorganisms and toxic substances.
• Acts as a regulator of temperature (vessels constrict to conserve or dilate to release heat to the surface for cooling), the water content in cells and body pH.

Red Blood Cells

• Bi-concave discs
• Contains an oxygen-carrying pigment called Haemoglobin (Hb). This gives blood its red colour.
• Oxygen (O 2 ) is carried by Hb and transported from the lungs to all cells. This reaction forms oxyhaemoglobin (aided by iron molecules).
• Carbon Dioxide(CO 2 ) is also transported this way. Formation is called carbaminohaemoglobin.

Red Blood Cells

• Red Blood Cell shape
• Red Blood Cell cut in half
• Red Blood Cells as they appear in a blood clot

Platelets

• Small colour-less bodies that usually appear as irregular spindles or discs that are much smaller than RBC & WBC.
• Produced in red

bone marrow.

• Life cycle is approximately 5 to 9 days.
• Platelets are involved in the process of clotting and they help to repair slightly damaged blood vessels.

White Blood Cells

• Slightly larger than red blood cells.
• Classified according to the presence of absence of granules in their cytoplasm.
• Life cycle is from a few hours to a few days.
• Produced in bone marrow and lymph tissue.
• They move to areas of infection or disease to engulf invading bodies (puss is the accumulation of WBC).

Phagocytosis

See overhead or handout for diagram

Blood Vessels

Heart > Arteries > Arterioles > Capillaries > Venules > Veins > Heart

Arteries

• Carry blood away from the heart to tissues
• Thick elastic walls as blood is pumped through them at high pressure in surges.

Veins

• Carry blood from tissues to the heart
• Thinner walls and less elastic as pressures decreases the blood gets closer to the heart.
• The contraction and relaxation of the muscles assists the blood to stream back steadily to the heart.
• Gravity affects blood flow – blood above the heart flows easily.

Veins

• Valves prevent the blood from flowing back the wrong way against the force of gravity. After standing for a long time, legs can feel heavy and swollen. Blood pools in the lower legs because of gravity and lack of movement. Once moving, the mucsles squeeze the blood up through the veins towards the heart.

Capillaries

Arterioles branch off arteries and venules branch off veins. They meet in the middle to form capillaries.

• Semipermeable membrane where O2, CO2 and nutrients are exchanged between the blood and cells of the body.
• Feeds muscles, joints, tissues and organs in clusters.

Blood Vessels