Circulatory System

Question 1

What is a circulatory system?

Answer 1

• Transport systems
• Link between cells in body and external environment
• Blood transports substances between cells of all body systems
• Important in maintaining constant internal environment

Question 2

What is the function of blood?

Answer 2

1. Transport oxygen and nutrients to cells
2. Transport carbon dioxide and other waste products away from cells.
3. Transport hormones to cells
4. Maintain pH of body fluids
5. Distribute heat and maintain body temp
6. Maintain water content and ion concentration of body fluids
7. Protect against disease-causing micro-organisms
8. Clotting when vessels are damaged, preventing blood loss

Question 3

Components of blood #1

Answer 3

• Plasma:
  - Mixture of water with dissolved substances such as sugar and salts
  - Function: transport components of blood – cells, nutrients, wastes, hormones, proteins and antibodies throughout body

Question 4

Components of blood #2

Answer 4

• Red blood cells (Erythrocytes):
  - Biconcave disks (flattened in the middle on both sides)
  - No nucleus (increases flexibility and SA)
  - Contains haemoglobin which carries oxygen
  - Produced in bone marrow, destroyed in liver and spleen
  - Function: transport oxygen and carbon dioxide

Question 5

Components of blood #3

Answer 5

• White blood cells (Leucocytes):
  - There are different types of white blood cells that fight diseases in different ways, these are:
  - Neutrophils: engulf and digest pathogen
  - Monocytes: engulf pathogens and aged/damaged cells by phagocytosis
  - Basophils: responsible for allergic reactions, defend against parasites and bacteria
  - Eosinophils: inflammatory response, respond to large parasites and worms

Question 6

Components of blood #4

Answer 6

• Platelets (Thrombocytes):
  - Very small, no nucleus
  - Formed in bone marrow, very short life span
  - Function: adhere to blood vessel lining when injured to form scaffold for coagulation of blood to form clot

Question 7

The heart

Answer 7

• Made of cardiac muscle
• Pericardium membrane surrounds heart
  - Holds in place while still allowing to beat
  - Prevents overstretching
• Left and right separated by septum- allows for separation of oxygenated and deoxygenated blood (allows for maintenance of concentration gradient)
• Right – collects blood from body and pumps to lungs
• Left – received blood from lungs and pumps to rest of body

Question 8

The heart chambers

Answer 8

• 4 chambers – 2 atria, 2 ventricles
• Atria thinner walls than ventricles
• Left ventricle thicker walls than right ventricle

Question 9

The heart valves

Answer 9

• Function: Ensures blood flows in 1 direction
• Atrioventricular valves: separate atrium and ventricle, preventing backflow.
  - Flaps of thin tissue that attach to heart
  - Prevented from turning inside out by fibrous cords
• Semilunar valves: separate ventricles and arteries
  - Right = pulmonary artery
  - Left = aorta
  - Cusps press flat against artery when blood flows through
  - When blood tries to flow back cusps fill and seal off artery