Transport in Humans (B9)

IGCSE biology

What does the circulatory system do?

Supply oxygen and nutrients to the body and remove waste materials and carbon dioxide

What does the circulatory system consist of?

A pump (the heart) to keep blood moving, blood vessles to carry blood, and valves to make sure blood flows in a single direction

Define a single circulatory system

A closed circulatory system where blood passes through the heart only once during each complete circuit of the body

Describe the pathway of blood in fish (single circulatory system)

Description: Blood flows from the heart to the gills for oxygenation, and from the gills to the rest of the body (heart-->gills-->rest of the body-->heart)

Define a double circulatory system

A system where blood passes through the heart twice for each complete circuit of the body

Which two circuits does blood follow in the double circulation?

The pulmonary circuit (heart to lungs and back): A shorter circuit where blood flows from the heart to the lungs for oxygenation and then back to the heart

Systemic circuit (heart to body and back): The second shorter circuit where blood flows from the heart to the rest of the body and back to the heart

What are some advantages of double circulation?

Blood is pressurized twice before going to the lungs and the body, which allows efficient gas exchange and faster oxygen and nutrient delivery.

Oxygen and glucose are supplied rapidly from the cells for respiration, and carbon dioxide, waste, and water are removed quickly from them

Blood can be supplied to distant parts of large animals

Allows sufficient flow of warm blood around the body

What do the walls of the heart consist of, and what is each half divided into?

Muscle is divided into two halves separated by the septum. Each half is divided into an upper chamber called an atruim (atria in plural), and a lower chamber called a ventricle

Where are the one-way valves?

There is one where blood leaves the atrium and enters the ventricle. Also, there's one where blood leaves a ventricle towards the lungs or the body.

In which direction is blood pumped?

Away from the heart in the arteries, and then it returns to the heart.

Describe the pathway of blood across the body

1. Body-->right atrium (deoxygenated blood enters through vena cava)

2. Right atrium-->right ventricle (through tricuspid valve)

3. Right ventricle-->lungs (via pulmonary artery, blood picks up oxygen)

4. Lungs-->left atrium (oxygenated blood returns via pulmonary veins)

5. Left atrium-->left ventricle ( through bicuspid/mitral valve)

6. Left ventricle--> body (via aorta, blood delivers oxygen)

How can heart activity be monitored?

By using an electrocardiogram (ECG), listening to the closing valves, or by determining the pulse rate

How can you record ECG?

By fastening small electrodes over the heart and other areas of the body and recording the electrical activity of the heart.

What is the sound patter on the hear like?

Like a 'Lub-dup, lub-dup, lun-dup'

What do the 'lub' and 'dup' sound mean?

The 'dup' sound is when blood flow closes the valves between the atria and the arteries from the heart.

The 'dup' sound is when the blood flow closes the valves between the atria and the arteries leading from the heart

What is a pulse?

A feeling near the surface of the skin

What is a pulse caused by?

The expansion and recoil of an eatery due to the pressure of blood pumped from the heart

What are the stages of the heartbeat?

1. Blood flows from the veins to the atrium

2. The atria contract, pushing blood into the ventricles. The fall in pressure in the atria causes the valves between the ventricles and the atria to close. This prevents blood from flowing back from the ventricles into the atria.

3. The ventricles contract, pushing blood into the arteries and ventricles to close. This prevents blood from fllowing back from the arteries into the ventricles

What do the coronary arteries do?

Although the heart is full of blood, its muscles are too thick and active, so the coronary arteries divide into branches that surround the heart, and they must supply the heart with blood, nutrients, and oxygen, which makes them play a very important role in the functioning of the heart.

When does CHD occur?

When the coronary arteries can't deliver enough oxygen-rich blood to the heart muscles because of blockages that prevent the cardiac muscle from producing enough energy for contraction, it can lead to heart disease. Blockages reduce the diameters of the coronary arteries, making it hard for blood to flow. This all may result in damage and possibly death due to the lack of blood.

What are some risk facotrs of CHD?

Age, diet, genetic predisposition, gender, smoking, stress

How can you prevent CHD?

Balanced diet: consuming all necessaty nutrients in correct amounts

What are protective and high-risk foods for CHD?

Protective: Plant oils, Fish oils

High-risk: Animal fat, cholesterol-rich, and high salt foods

What are protective and high-risk lifestyles for CHD?

Protective: Maintaining suitable body mass, regular exercise

High-risk: Overweight, lack of exercise, stress

What is a blood vessel?

An extensive and interconected netweok of hollow tube-like structures through which blood flows

What are the three types of blood vessels?

Arteries: A thick-walled blood vessel that carries blood away from the heart

Capillaries: Smallest type of vessel, thin walls allow substances to be easily exchanged with the surrounding tissue

Veins: Type of thin-walled blood vessel that carries blood to the heart

Describe the structure of the arteries

Arteries have thick walls and a narrow lumen to withstand high pressure from the heart. Veins have thinner walls, a wider lumen, and contain valves to prevent backflow of blood.

Describe the structure of the veins

Walls are thinner than arteries.

Lumen is wider to allow easier blood flow at lower pressure.

Contain valves to prevent backflow of blood.

Describe the structure of the capillaries

Walls are very thin (one cell thick) to allow exchange of substances.

Lumen is very narrow, just wide enough for red blood cells to pass through single file.

Do not contain valves.

What are the components of blood?

Plasma: watery fluid that transports blood cells, ions, soluble nutrients, hormones, and carbon dioxide in the blood

Platelets: fragments of cells that are involved in clotting

Red blood cells: carry oxygen

White blood cells: fight pathogens

What shape do red blood cells have, and what is its purpose?

They have a biconcave shape (thin in the center and thick in the edges): the shape provides a large SA, which increases the rate at which oxygen diffuses in and out of the cell. It has thin cells because oxygen has to diffuse a very short distance to reach the center of the cell. The shape also helps it bend and squeeze through the smallest capillaries.

What is hemoglobin?

Protein that gives red blood cells (and blood) their colour

What do mature red blood cells lack?

A nucelus whihc creates more space for hemoglobin

When does hemoglobin bind oxygen?

When oxygen levels are high in the lungs

When does hemoglobin release oxygen?

When oxygen levels are low in respiring cells

What does the adaptation of hemoglobin (binding and releasing oxygen) ensures?

Efficient oxygen transportation from the lungs to the body cells

What are white blood cells?

Large, lobed, colourless nucles that are part of the immune system

Which are the two main types of white blood cells?

Phagocytes: the cells involved in phagocytosis

Lymphocytes: the cells involved in antibody production

What does a platelet plug (clot) stop?

A wound that causes bleeding

What does skin protect?

Against pathogens

What do injuries create an opening for?

Pathogens

What does blood clotting do?

Seal openings caused by injuries that create openings for pathogens, restoring the barriers

What are the main roles of clotting?

Prevent blood loss and pathogen entry