National 5 Biology | Unit 2 | Key Area 6: Animal Transport Systems

Name the four components of blood:

Red blood cells, white blood cells, platelets, and plasma.

What is the function of red blood cells?

To transport oxygen around the body. Red blood cells “collect” oxygen at the lungs and “deliver” it to body cells.

Red blood cells contain the protein haemoglobin. What does haemoglobin do?

Haemoglobin binds loosely and reversibly with gases, especially oxygen to form oxyhaemoglobin. Haemoglobin is red, which gives the red blood cell its colour.

What is the equation for haemoglobin and oxygen?

haemoglobin + oxygen ⇋ oxyhaemoglobin

Where does haemoglobin bind to oxygen?

At the lungs

Where is oxyhaemoglobin broken down?

At body cells

Why is the exchange of oxygen from lungs to red blood cells possible?

Concentration gradients in different organs. Air in the lungs has a higher concentration of oxygen than the blood, so oxygen diffuses across the walls of the alveolus into the blood capillaries, where it enters the red blood cells.

How is the concentration of oxygen in respiring tissues in comparison to the concentration of oxygen in the blood?

Respiring tissues have a lower concentration of oxygen than in the blood.

Describe some special features of red blood cells that maximise the uptake of oxygen.

- They contain no nucleus

- They have a biconcave disc shape

What role do white blood cells play in the body?

White blood cells are an important part of the body’s immune system.

Name the two main types of white blood cell.

Lymphocytes and phagocytes

Pathogen

Pathogens are disease-causing microorganisms (bacteria, viruses and fungi).

How do phagocytes function?

Phagocytes engulf pathogens in the process of phagocytosis.

How do lymphocytes function?

Lymphocytes produce antibodies (a protein) that destroy pathogens. Each pathogen requires a specific antibodies to destroy it.

What role does plasma play in the body?

- Carries digested food materials to all body cells

- Carries waste, eg. CO2 and urea from body cells to the lungs/kidneys, etc.

- Hormones to receptor organs

What role do platelets play in the body?

Platelets are tiny cell fragments involved in blood clotting.

What role does the heart play in the body?

The heart is responsible for moving blood around the body. Muscle cells in the walls of the heart contract, squeezing the chambers and forcing blood out of them.

Describe the structure of the heart.

The heart is made of special muscle cells (ie. cardiac muscle cells). It is divided into four chambers. The left side of the heart is completely separate from the right side of the heart by a thick wall.

Coronary artery

Coronary arteries are blood vessels which carry oxygenated blood to heart muscle cells. If the heart cells are deprived of oxygen, the heart can go into cardiac arrest.

Which side of the heart carries oxygenated blood?

Left side

Which side of the heart carries deoxygenated blood?

Right side

Where does deoxygenated blood enter the heart?

The vena cava (vein) into the right atrium.

Where does deoxygenated blood leave the heart?

The pulmonary artery to the lungs.

Where does oxygenated blood enter the heart?

The pulmonary vein into the left atrium

Where does oxygenated blood leave the heart?

The aorta (artery) to the rest of the body.

What role do valves play in the heart?

Valves separate the chambers of the heart. They ensure the flow of blood through the heart travels in one direction, preventing back flow.

How does blood travel around the body?

Blood travels around the body in one direction. Arteries carry blood away from the heart. Veins carry blood into the heart.

What connects arteries to veins?

Capillaries, the smallest blood vessels

Describe features of the artery that make it different from the vein.

- Arteries have thick, elastic muscular walls and a small lumen (opening) as blood is under high pressure in an artery. The muscular walls and the force of the heart squeeze blood along.

- Arteries carry blood away from the heart to the rest of the body.

- Arteries carry oxygenated blood (exception being pulmonary artery which carries deoxygenated blood from the heart to the lungs).

Describe features of the vein that make it different from the artery.

- Veins have thin, smooth, muscular walls and a large lumen (opening) as blood is under low pressure in a vein.

- The backflow of blood is prevented by semi-lunar valves.

- Veins carry blood into the heart from the rest of the body.

- Veins carry deoxygenated blood (exception being pulmonary vein which carries oxygenated blood from the lungs to the heart.)

Describe features of the capillary.

Capillaries are the smallest blood vessels. Each body cell has a local capillary, and are in direct contact with it.

What is the capillary’s purpose, and how does it achieve this and maximise efficiency?

Capillaries form networks at tissues and organs. Capillaries allow body cells (living tissue) to exchange materials with blood (and vice-versa). Capillaries have one cell thick walls to allow for efficient and rapid diffusion of materials.