Blood and Circulation

Question 1

What is blood?

Answer 1

A liquid tissue that transports substances around the body.

Question 2

What are the main functions of blood?

Answer 2

Blood has three main functions: to carry heat and energy, to transport materials, e.g. oxygen and glucose, around the body, and to protect the body against disease and infection.

Question 3

What are the main components of blood?

Answer 3

There are four: red blood cells, white blood cells, platelets and plasma.

Question 4

What is a red blood cell? Describe some functions and features of it.

Answer 4

A red blood cell is a cell found in blood that transports oxygen around the body. It does this through a substance called hæmoglobin, which binds to oxygen (or CO, which is why it is so dangerous) in order to transport it. They have no nuclei and are biconcave discs to maximise oxygen absorption. RBCs are small and flexible in order to squeeze through blood vessels. They are produced in bone marrow and die after circa 100 days.

Question 5

What is a white blood cell? Describe some functions and features and list the main kinds.

Answer 5

A white blood cell is the blood’s defence system against infection. They are larger than RBCs and have a nucleus. There are fewer in the bloodstream. The two main kinds are lymphocytes and phagocytes. Lymphocytes produce antibodies that bind to specific microbes in order to immobilise them and to alert phagocytes to their presence, whereas phagocytes engulf and digest said microbes. Most lymphocytes are either B- or T-.

Question 6

What is plasma? Describe some functions and features of it.

Answer 6

Plasma is a yellow fluid that forms the liquid component of blood. It is mainly water, and contains many dissolved substances that are then transported around the body: CO2, waste (e.g. urea), soluble food (e.g. glucose, vitamins, minerals, etc.), hormones, salt and antibodies.

Question 7

What are platelets? Describe some functions and features of them.

Answer 7

Platelets are fragments of cells, much smaller than R/WBCs. Their job is to cause RBCs to clot.

Question 8

How does a scab form?

Answer 8

Platelets collect at a cut to seal the hole and slow bleeding. The plug is then rapidly replaced by a stronger RBC clot, which stops bleeding entirely. An infected clot will have trapped bacteria underneath, which will multiply, causing more WBCs to be produced; they quickly move to the surrounding area and squeeze out through the blood vessels’ walls. The phagocytes attack and kill the bacteria, causing the scab to swell as it contains pus with dead bacteria/denatured WBCs. The last bacteria will be destroyed, the pus will drain, new skin will grow and the scab will heal.

Question 9

What is the circulatory system?

Answer 9

The circulatory system is the organ system responsible for the transportation of blood.

Question 10

What are the main components of the circulatory system?

Answer 10

The heart, lungs, arteries, capillaries, veins and kidneys are all important organs of the system.

Question 11

Who was William Harvey?

Answer 11

William Harvey was an English doctor who, in the 16th and 17th centuries, studied the heart and blood vessels. He was one of the first to use the scientific method in mediæval England. He discovered valves and the fact that blood was constantly circulated around the body, returning to the heart. He could not see capillaries, but predicted their existence.

Question 12

What are the three main blood vessels?

Answer 12

Arteries, veins and capillaries.

Question 13

Describe the features of an artery.

Answer 13

Arteries carry blood from the heart. They, with the exception of the pulmonary artery, carry oxygenated blood, with no valves as the pressure is great enough regardless, because of the action of the heart. They have a thick elastic wall but a small lumen.

Question 14

What is the lumen?

Answer 14

The part of the blood vessel that contains blood. It is surrounded by the endothelium.

Question 15

Describe the features of a vein.

Answer 15

Veins carry blood to the heart. They, with the exception of the pulmonary vein, carry deoxygenated blood. They contain valves to prevent back-flow because of the low pressure. They have a thin elastic wall but a large lumen.

Question 16

Describe the features of a capillary.

Answer 16

Capillaries connect arteries and veins, but are much smaller — one cell thick — and have a small lumen. They carry both de- and oxygenated blood, and have no valves, despite having a low pressure and slow transport speed to allow for the exchange of materials, which is their function.

Question 17

Why do arteries have thicker walls and veins and capillaries have thinner ones?

Answer 17

Arteries have thicker walls to prevent bursting, as they pump at a constant high pressure. Veins and capillaries, however, have a low pressure, meaning that thick walls are unnecessary.

Question 18

What are valves?

Answer 18

Valves are present in the heart and veins to prevent backflow. Valves mean that the circulatory system is one-way. They are unnecessary in arteries as the high pressure suffices to keep the blood flowing one way.

Question 19

How do the structures of the three blood vessels relate to their functions?

Answer 19

Arteries transport oxygenated blood at a high pressure — thick elastic walls and a small lumen get the job done by preventing bursting and maximising efficiency. Capillaries have a thin one-cell-thick wall to allow for exchange of materials. Veins transport deoxygenated blood at low pressure — the opposite of arteries — and this necessitates valves.

Question 20

What are some features of the heart?

Answer 20

• Strongest muscle in the body,
• A double pump,
• Muscular walls,
• Two sides (left and right),
• Four chambers (two chambers per side),
• 50-70 BPM (on average),
• Blood flows through heart in a certain direction.

Question 21

Which side of the heart pumps blood around the body?

Answer 21

The left side, which connects to the aorta.

Question 22

Which side of the heart has a thicker muscle?

Answer 22

The left side, as it pumps blood around the body. Specifically, the left ventricle has more muscle than the right.

Question 23

How does blood get out of the heart and back into the body’s bloodstream?

Answer 23

It is pumped out through the aorta. The atria must squeeze and contract to push the blood to the ventricles, which squeeze and contract to push the blood out.

Question 24

What is the definition of double circulation?

Answer 24

In one complete circuit of the body, blood goes through the heart twice.

The heart is a double pump — it pumps blood to the lungs first before pumping it around the body.

Question 25

What is the route that blood takes through the right side of the heart?

Answer 25

Blood enters through the superior (upper body) and inferior (lower body) venæ cavæ into the left atrium, which squeezes and contracts to push the blood through the tricuspid valve into the right ventricle. The blood travels through the right ventricle, where it is pushed up through the pulmonary artery.

Question 26

What is the route that blood takes through the left side of the heart?

Answer 26

The blood comes back from the lungs after being oxygenated; it enters the right atrium from the pulmonary vein. The blood is pushed through the mitral valve to the right ventricle, where it is then pushed through the aortic valve to the aorta to be pumped around the body.

Question 27

What is special about the pulmonary artery and vein?

Answer 27

The pulmonary artery is the only artery in the body to carry deoxygenated blood, and the pulmonary vein is the one vein in the body to carry oxygenated blood.

Question 28

Label the heart.

Answer 28

Refer to physical flashcard.

Question 29

What is the purpose of tendons in the circulatory system?

Answer 29

Tendons hold veins’ valves in place and prevent them from turning inside out.

Question 30

What is heart disease?

Answer 30

Coronary heart disease (CHD) is the death of coronary cells. This often occurs because the arteries carrying blood to said cells get blocked up by cholesterol. Cholesterol is a waxy, fatty substance produced in small quantities of the liver and also found in saturated fat. A build up will cause narrowing of the arteries — arteriosclerosis. CHD can also occur due to smoking. CO is found in tobacco — it will bind to hæmoglobin instead of oxygen. The cells will not get enough oxygen to make energy and thus will die.

Question 31

How can heart disease be treated?

Answer 31

``` Lifestyle changes Medication Coronary stents (expanding mesh tubes) Heart surgery Pacemaker/ICD (implantable cardioverter-defibrillator) ```

Question 32

How can heart disease be prevented?

Answer 32

``` Stop smoking or do not start. Lower or cut out alcohol intake. Remove stress-causers. Avoid air pollution (where possible). Avoid risk factors for hypertension. Avoid risk factors for diabetes. Have a healthy, balanced diet. Avoid risk factors for obesity. Get/remain physically active. ```

Question 33

How does a heart attack occur?

Answer 33

Cholesterol builds up in arteries. It causes a blockage, which reduces amount of blood flowing and forces heart to pump more quickly in order to fulfil energy requirements for cells. Oxygen and glucose struggle to reach cells for energy. Respiration cannot occur, energy cannot be produced and heart cells die. Cells release troponin, a protein, which can be tested for using Biuret’s reagent. Other heart cells must work harder in order to have the same output as before, but the dead cells cause irregular contractions, and too much strain occurs. A heart attack happens. OR RBCs may carry too much CO instead of O2 (usually due to smoking). Respiration cannot occur, energy cannot be produced and heart cells die. Cells release troponin, a protein, which can be tested for using Biuret’s reagent. Other heart cells must work harder in order to have the same output as before, but the dead cells cause irregular contractions, and too much strain occurs. A heart attack happens.

Question 34

What is a pulse?

Answer 34

The rhythmical throbbing of arteries as blood is pumped through them. Heart rate can be found through feeling the pulse.

Question 35

What is pulse rate measured in?

Answer 35

Beats per minute (bpm/BPM).

Question 36

How can you find your pulse? how can it be measured w/o any specialist equipment?

Answer 36

Find an artery that can be compressed — most common ones are wrist and neck — and feel it with two fingers. You should feel a steady throbbing. Time 15s while feeling your pulse. Count the beats. Multiply this number by four to get an approximate amount of BPM.

Question 37

What is recovery rate?

Answer 37

The time taken by the heart to return to its resting heart rate after exercise. The quicker the recovery rate, the fitter you are. It measures the efficiency of lungs and heart — the more efficient they are, the more they can cope with the extra oxygen and glucose demands during exercise.

Question 38

What will exercise do to the pulse?

Answer 38

Exercise raises the pulse as the heart needs to pump oxygen and glucose in a shorter period of time to cope with demand.

Question 39

What links pulse rate and fitness?

Answer 39

The lower the pulse rate, the fitter the person. Generally, a fitter heart will not have to work as hard in order to pump blood around the body.

Question 40

What are some risk factors for heart disease?

Answer 40

``` Reversible: Smoking Alcohol Poor diet: Sugar, salt and saturated fat intake; lack of fruit and vegetables, etc. Hypertension Diabetes Obesity Stress Air pollution Physical inactivity Raised blood cholesterol ``` ``` Irreversible: Family history Being male Being old Being an ethnic minority ```

Question 41

What is a normal resting heart rate?

Answer 41

Anywhere from 50 to 80 BPM.