Chapter 8: Transport in animals

Function of circulatory system

To transport materials around the body

• take glucose and oxygen to cells for respiration

• Taking carbon dioxide and water away from cells because of respiration

Circulatory system consists of

• heart (the pump) to keep the blood moving

• Blood vessels: arteries (away from the heart), veins (to the heart) and capillaries

• Valves to ensure blood flows in one direction

• Blood (transport medium)

Types of circulation

• single circulation: heart pumps once to get around the whole system

• Double circulation: heart pumps twice (one to lungs and once to the body) to get around the whole system

Advantages of single circulatory system

• Less risky for things to go wrong within the system

• Less complex as it takes less nutrients and oxygen

Advantages of double circulatory system

• pumps with more pressure so blood moves faster around the body

• More oxygen for more aerobic respiration will be transported

• More energy can be released

Single circulatory system pathway

Heart → gills (to oxygenate) → body → heart

Double circulatory system pathway

Heart → lungs (to oxygenate) → heart (to pump again) → body

Heart diagram

• left ventricle has thickest wall because it pumps blood the furthest distance so more force must be generated

• September: separates oxygenated and deoxygenated blood

How to measure heartbeat

1. Pulse: caused by expansion and recoil of artery due to pressure of blood pumped from the heart

2. Listening: “lub dup” sound

3. Electrocardiogram (ECG): small electrodes are fastened to record the electrical activity of the heart.

Detailed stages in heartbeat

1. Blood flows from the veins to the atrium

2. Atrium contracts

3. Blood pumped into the ventricles

4. Decreases in pressure causes the atrial ventricular valves to close

5. This prevents back flow of the blood

6. Ventricles contract

7. Blood is pumped into the arteries

8. This causes the pressure in the ventricles to decrease

9. This makes the semilunar valves close

Detailed journey of the blood from the heart

1. From the right atrium, the blood flows past the atrial ventricular valves to the right ventricle.

2. From the right ventricle, the blood flows past the semi lunar valves into the pulmonary arteries.

3. The blood goes to the lungs, get oxygenized by gas exchange then flows back to the left atrium through the pulmonary vein

4. The blood from the left atrium flows past the atrial ventricular valves to the left ventricle

5. Blood from the left ventricle travels to the aorta, passing the semilunar valves, around the body

6. After traveling around the body, blood flows through the vena cava and into the right atrium

Blood vessels types and definition

Arteries: carry blood away from the heart

Veins: carry blood towards the heart

Capillaries carry blood between the cells

Characteristics of arteries

• small lumen: to maintain high pressure

• Thick layers of muscle and elastic fibers to waist and the high pressure

• Smooth lining to decrease friction

• No valves

• Blood is at high pressure

Characteristics of veins

• large lumen: to help blood flow

• Thin walls

• Blood is at low pressure

• Valves: to prevent backflow of blood

Characteristics of capillaries

• Tiny vessels with narrow lumen to fit between cells

• Walls are thin: one cell thick to reduce diffusion pathway

• Blood is at low pressure

• No valves

How arteries maintain high pressure

• small lumen to help wrist and high pressure

• Elastic recoil of the artery wall as this pressure pushes out

How enough pressure is maintained by veins

• being compressed by skeletal muscles

• Valves

Blood vessels that go/come to/from…

• lungs: pulmonary

• Liver: hepatic

• Kidney: renal

Coronary arteries

Supplies blood to the heart itself with nutrients and oxygen

Coronary heart disease

This is when coronary arteries are unable to supply oxygen and nutrient rich blood to the heart muscles because of the blockages in them.

Effect of blockages in coronary arteries

• cardiac muscles dependent on it cannot produce enough energy for contraction → leading to death of heart muscles

• Blood cells cannot move through the artery because blockages reduces the diameter of the coronary arteries, making it ore difficult for blood to flow through.

Risks for CHDs

• age

• Diet

• Smoking

• Stress

Foods that increase chances of CHDs

• red meat

• Buttered popcorn

• Chocolate

Foods that don’t increase chances of CHDs

• salads

• Fruits

• Oily fish

• Olive oil

Components of blood

• red blood cell: carry oxygen from lungs and deliver it throughout the body

• Plasma: transports blood cells, soluble nutrients, hormones and carbon dioxide in the it

• Platelet: prevents/stops bleeding and travel to injured areas

• Lymphocyte: produces antibodies to defend against pathogens

• Phagocyte: does phagocytosis to destroy pathogens

Blood clotting

1. Fibrinogen, a soluble protein, is activated by the substances released by activated platelets at the injury

2. This converts fibrinogen to fibrin

3. Red blood cells, white blood cells, fibrin and platelets come together at the injury site

4. Fibrin produces a mesh, trapping red blood cells and platelets, forming a blood clot

5. When blood clot dries, a scab forms. Under the scab, healing takes place