Circulatory System

Question 1

what is pulmonary circulation?

Answer 1

transports blood to (deoxygenated) and from the lungs (oxygenated).

Question 2

what is systemic circulation? how big is this system?

Answer 2

transports blood to and from the rest of the body. This system is larger because blood must reach all organs of the body. Oxygenated blood is pumped from the heart to organs which gives up its oxygen and then returns to the heart.

Question 3

what are the components of the circulatory system?

Answer 3

The heart.
Veins and arteries.
blood.

Question 4

where is the heart located? what is it made of? describe the chambers. Why does blood flow in one direction? Which chambers pump first?

Answer 4

In the centre of the chest between the lungs.
Made of cardiac tissue, connective tissue (for valves) and nerve tissue (controls heart rate).
Four chambers.
Top top chambers, atria, are thinner walled receiving chambers.
Below are the thicker walled pumping chambers, ventricles.
The blood flows in one direction because of the four valves (between atria and ventricles and the ventricles and out going arteries).
First the atria contract and then the ventricles.

Question 5

what are the 10 steps involved in a circuit of blood around the body?

Answer 5

1. Deoxygenated blood enters through the venue cavae.
2. Flows into the right atrium.
3. Through a valve into the right ventricle.
4. The right atrium contracts, further filling the right ventricle.
5. Then the right ventricle contracts and the pressure causes the valve between the atrium and ventricle to close (atrioventricular valve) and opens the semilunar valve (between ventricle and pulmonary artery).
6. The blood moves to the lungs to be oxygenated.
7. By diffusion, oxygen enters the blood and carbon dioxide leaves in the capillaries in the lungs.
8. The oxygenated blood enters the left atrium through pulmonary veins.
9. It is pumped by the left ventricle to the rest of the body via the aorta.
10. A circuit takes 45 seconds.

Question 6

the heart is an active organ. how does it get what it needs?

Answer 6

It needs oxygen and nutrients.
The cells in the heart get their supply from the coronary circulation.
It includes arteries, arterioles, capillaries, venues and veins.

Question 7

what is the structure of arteries?

Answer 7

Consist of an epithelial layer of cells, an elastic layer, muscle wall and connective tissue.
Same structures as veins but thicker muscular walls.
More elastic than veins.

Question 8

what are the structure of veins?

Answer 8

Consist of an epithelial layer of cells, an elastic layer, muscle wall and connective tissue.
Same structures as arteries but thinner muscular walls.

Question 9

what are the structures of capillaries?

Answer 9

“Consist of a single layer of flattened epithelial cells.

Very thin walls.”

Question 10

what is the function of an artery?

Answer 10

Transport blood away from the heart.

Question 11

what is the function of a vein?

Answer 11

Transport blood towards the heart.

Question 12

what is the function of a capillary?

Answer 12

“Connect arteries and veins.

Deliver nutrients and other substances to extracellular fluids and receive wastes. “

Question 13

what are other features of arteries?

Answer 13

Higher blood pressure than veins.

Question 14

what are other features of veins?

Answer 14

“Contain many one-way valves.

Lower blood pressure than arteries. “

Question 15

what are other features of capillaries?

Answer 15

“Very numerous.

Form a network within tissues to be near most cells. “

Question 16

why do capillaries leak? what can this result in? what happens to the fluid?

Answer 16

The pressure results in some protein leakage, when pressure is higher, leakage is higher and can cause fluid loss to tissue, causing swelling.
Reabsorption accounts for about 85% but 15% enters the lymphatic system.

Question 17

what is plasma?

Answer 17

The fluid part is plasma.

Which is a pale yellow liquid that has dissolved gases, proteins, hormones, nutrients and wastes in it.

Question 18

how much of blood is RBC? what are they like when mature? what do they contain and what does this allow them to do?

Answer 18

40% of blood.
Mature red blood cells are concave and flexible.
They don’t have a nucleus.
They contain the red pigment, haemoglobin.
Haemoglobin binds to oxygen.

Question 19

what are WBC? what do they do? what are two types? how many?

Answer 19

Slightly larger than red blood cells.
Less than red blood cells.
Held on reserve in organs such as spleen, kidney, thymus and thyroid gland.
Involved in defence against microorganisms.
Phagocytes: remove debris and fight infection. Attracted to the sit of infection and engulf harm and damaged cells.
Lymphocytes: responsible for the production of antibodies and the development of immune responses.

Question 20

what are platelets? how big are they? what is their role?

Answer 20

Fragments of cells.
Much smaller than the others.
contain substances important in blood loss and promoting blood clotting.

Question 21

how do you get Marfan syndrome? what does it do? why? where is it very bad? what can it cause? (2)

Answer 21

An inherited disorder that affects connective tissue (supports and holds together other tissue).
A defective glycoprotein causes the connective tissue to be weakened.
This is very bad in the aorta where blood is pumped under high pressure. It can cause:
it can stretch and bulge (an aneurysm). This causes pain and blood flow may be slowed. This can cause blood clots which can break off and travel to the brain and cause a stroke or to the lungs and cause a pulmonary embolism. It can lead to death if the aneurysm ruptures.
The aorta may begin to tear so that blood leaks between the aorta tissues. This can cause pain, lack of blood flow to tissue and if untreated, death.

Question 22

what is arteriosclerosis and atherosclerosis? what can they lead to?

Answer 22

Arteries lose collagen and elastin filaments and harden.
This is called arteriosclerosis and puts pressure on the heart as it must pump harder to force blood through hard arteries.
Over time, fatty substances such as cholesterol build up causing the arteries to narrow. This is called atherosclerosis.
If plaque breaks off or blood clots form on it strokes and heart attacks occur.
If this happens to the coronary artery, the heart muscle can die.

Question 23

what does the respiratory system do for the body?

Answer 23

Organisms must exchange oxygen and carbon dioxide with their environment to maintain cellular respiration.
Oxygen is needed for aerobic respiration.
Carbon dioxide must be removed as it increases pH levels in water, causing acidity.

Question 24

where does gas exchange occur and how? how easily can oxygen and carbon dioxide diffuse?

Answer 24

Gas exchange takes place by diffusion across a moist plasma membrane.
Gases must dissolve before diffusion can occur.
Oxygen and carbon dioxide are small and uncharged so can diffuse easily along the gradient.

Question 25

what are the characteristics of an efficient gas exchange surface?

Answer 25

Large surface area. Barrier to be crossed should be thin and consist of material that allows gas to pass through easily. An adequate supply of gas should be transferred. If the system is not adequately ventilated, rate of exchange drops. There should be efficient removal of substance after transfer. Oxygen is carried away by blood. If this doesn’t happen, oxygen will build up and rate will slow. Usually energy is used to ventilate and circulate blood. The efficient supply and removal of oxygen maintains the gradient. Using energy is most economical when rates of ventilation and blood flow match. moist

Question 26

what order does air travel through the airways? what structures and features are present?

Answer 26

—from the pharynx air passes into the airways: the trachea, bronchi and brochioles. The trachea and bronchi are lined with cilia cells that secrete mucus that traps dust and bacteria and sweep them back up to the pharynx and swallowed. The larynx (contains vocal cords) is located at the upper end of the trachea.

Question 27

what are alveoli?

Answer 27

—air enters terminal sacs, called alveoli, where gas exchange takes place.

Question 28

what features do alveoli have that makes it an efficient gas exchange surface? how is it connected to the circulatory system?

Answer 28

Alveoli have high surface area (between 30 and 70 square metres). Each alveolus is lined with a thin layer of alveolar epithelium which are supplied with blood capillaries. Once oxygen enters the capillaries, it travels in the body. Animals must have a large, moist gas exchange surface and water evaporates causing great water loss.

Question 29

how are the lungs kept expanded?

Answer 29

the chest cavity is under negative pressure

Question 30

what is the floor of the chest cavity?

Answer 30

The floor of the chest cavity is called the muscular diaphragm.

Question 31

how does inhalation and exhalation occur?

Answer 31

The cavity is expanded by the contraction of the diaphragm downwards and the rising of the ribs. This draws air into the airways. Inhalation is an active process. Exhalation is normally the result of the elastic recoil of the thorax as it returns to its resting state. Forceful exhalation involves active compression of the rib cage.

Question 32

what is tidal volume? how does it vary?

Answer 32

Tidal volume is the amount of air moved in and out with each breathe. Tidal volume varies with the need for oxygen. Normal resting levels of inhalation and exhalation are much less then our vital capacity which is the maximum volume of air.

Question 33

what is residual volume?

Answer 33

At the end of exhaling there is some stale air in our lungs. The next inhalation draws this back in. It is impossible for lungs to fill entire with fresh air. The volume of air left is called residual volume.

Question 34

why is haemoglobin needed?

Answer 34

The amount of oxygen that dissolves in blood or water is small. Haemoglobin increases the oxygen carrying ability of blood. Haemoglobin combines reversibly with oxygen. Increasing the oxygen carrying capacity reduces the amount of energy needed in pumping blood.

Question 35

what does haemoglobin contain? how much oxygen can combine? what does it form?

Answer 35

Haemoglobin is a complex protein containing iron. Four oxygen molecules can combine with one haemoglobin. Haemoglobin combines with oxygen to form oxyhemoglobin. In areas of low oxygen, oxygen is released from oxyhemoglobin.

Question 36

what is anemia?

Answer 36

Insufficient red blood cells or haemoglobin is low. It is usually caused by a deficiency of iron. It results in pale skin, tiredness, muscle weakness, headaches and problems with concentration. Treatments include iron supplements, change in diet, surgery or oxygen therapy and blood transfusions.

Question 37

how is carbon dioxide transported?

Answer 37

About 7% is dissolved in plasma and about 23% is combines with haemoglobin molecules (carbamino-haemoglobin) but at a different site to where oxygen binds. It also can combine with oxygen. The rest passes into red blood cells where it is converted into hydrogen carbonate irons and is transported out by plasma. When the blood reaches the lungs, the hydrogen carbonate moves back into the RBC and is converted back into carbon dioxide to be released by breathing.

Question 38

what happens in asthma?

Answer 38

Cells lining the airways are sensitive to foreign particles and become swollen, filled with mucus and constricted. This causes a resistance in air flow. It is particularly difficult to breathe out. When the pressure on the lungs is increased to force air out, the narrowed airways are compressed.

Question 39

what is emphysema?

Answer 39

Caused by the breakdown of air sacs reducing the lung surface area available for gas exchange, sometimes to less that one quarter of what it should be. Occurs mostly in old age and is a consequence of smoking. Increased resistance to air flow making breathing difficult.

Question 40

what is pneumonia?

Answer 40

Caused by an infection that causes the lung to be inflamed and the air sacs to be filled with white blood cells and fluid. The fluid decreases the surface that can come into contact with air. The lung tissue is swollen so oxygen has to diffuse further.