Blood and Circulation Flashcards
(46 cards)
1
Q
What is a circulatory system?
A
- A closed circuit made up of the heart and blood vessels, where blood is pumped round and round.
2
Q
In mammals what does blood transport?
A
- Oxygen fromt he lungs to all other parts of the body
- Carbon dioxide from all parts of the body to the lungs
- Nutrients from the gut to all parts of the body
- Urea from the liver to the kidneys
3
Q
How do one-celled organisms obtain oxygen?
A
- By diffusion throuh the surface membrane of the cell.
4
Q
What determines how much oxygen the organism can get (the supply rate)?
A
- The are of the cell’s surface
5
Q
How does a high surface area to volume ratio help single-celled organisms?
A
- Their cell surface membrane has a large enough are to supply all the oxygen that their volume demands.
6
Q
What is a single circulatory system?
A
- The blood is pumped from the heart to the gas exchange organ and then directly to the rest of the body
7
Q
What is a double circulatory system?
A
- The blood is pumped from the heart ot he gas exchange organ, back to the heart and then to the rest of the body
8
Q
Why is a double circulatory system is more efficient than a single circulatory system?
A
- The heart pumps the blood twice, so higher pressure can be maintained.
- The blood travels more quickly to organs.
9
Q
Label the heart
A
- Note: Diagrams of the heart are always drawn as if you were facing the person, so left and right sides are reversed.
10
Q
What is the cardiac cycle?
A
- The cardiac cycle refers to the sequence of events in the heart that make up one complete heart beat.
11
Q
What happens in one cardiac cycle?
A
- Blood enters the atria. Cannot pass into ventricles because bicuspid and tricuspid valves are close.
- Walls of the atria contract. This raises the pressure of the blood in the atria, whcih forces open bicuspid and tricuspid valves. Blood passes through these valves into the ventricles.
- When ventricles are full, they contract. This increases the pressure of blood in the ventricles whcih closes the bicuspid and tricuspid valves again. Blood cannot return to the atria.
- Ventricles continue to contract and pressure continues to increase. This forces open the semi-lunar valves at the base of the aorta and the pulmonary artery. Blood is ejected into these two arteries. The pulmonary artery carries blood to the lungs.
- As the ventricles empty, higher pressure in the aorta and poulmonary artery closes the valves i these blood vessels. The cycle begins again as the left atria start to fill wth blood on.
12
Q
What divides the left side and the right side?
A
- A septum
13
Q
Why is the wall of the left ventricle much thicker than that of the right ventricle?
A
- Because the right ventricle pumps blood only to the lungs while the left ventricle pumps blood to all other parts of the body.
14
Q
What is the purpose of the valves?
A
- To ensure a one-way flow of blood through the heart or through veins.
15
Q
How are the valves opened or shut?
A
- By the pressure and movement of blood
16
Q
What are the walls of the heart made out of?
A
- Cardiac muscle
17
Q
Where does the cardiac gets its blood supply from?
A
- It has its own blood supply - the coronary circulation.
- Blood reaches the muscles via coronary arteries.
18
Q
What factors make coronary heart disease more likely?
A
- Heredity
- High blood pressure
- Diet
- Smoking
- Stress
- Lack of exercise
19
Q
What is atherosclerosis?
A
- Depositon of chloresterol thickens and roughens the artery lining.
- A plaque forms at the site and becomes infiltrated with fibrous connective tissue and still more cholesterol. Such plaques narrow the artery
20
Q
What happens as atherosclerosis progresses?
A
- Arteries become narrower, and the threat of heart attack or stroke increases.
21
Q
What is a heart attack?
A
- The death of cardiac muscle tissue resulting from prolonged blockage of one or more coronary arteries, the vessels that supply oxygen–rich blood to the heart.
22
Q
What pressure of blood do arteries carry?
A
- High blood pressure
23
Q
Why do the arteries need to have a thick, elastic wall?
A
- So that they can stretch slightly as the heart contracts and the pressure rises, in order to avoid bursting.
24
Q
What pressure of blood do the veins carry?
A
- Low pressure
25
Why does the lumen in the veins have to be wider than that of the arteries?
* The blood flows much more slowly, so the lumen needs to be wider than for an artery with the same capacity.
26
Why do the veins have a valve system?
* To prevent the backflow of blood
27
What is the function of the capillaries?
* They cary blood through organs, bringing the blood close to every cell in the organ.
28
How are the capillaries adapted to their function?
* They are one cell thick
* They are located near cells to make the distance of diffusion smaller.
29
What are the four functions of the blood?
* Transport – delivering oxygen and nutrients (e.g. amino acids, glucose) to cells around the body.
* Defence – white blood cells form the major part of the immune system.
* Hormone transport – hormones are transported around the body in the blood stream where they can influence particular target cells (e.g. insulin affecting glucose stores in the liver).
* Waste disposal – waste products such as urea and carbon dioxide are transported in the blood to excretory organs (the kidney for urea, the lungs for carbon dioxide).
30
Whaat is the function of plasma?
* Carries the blood ells around the body
* Carries dissolved nutrients, ormones, carbon dioxide and urea
* Distributes heat around the body
31
What is the function of the red blood cells?
* Transport of oxygen
32
What is the function of lumphocytes in the white blood cells?
* Produce antibodies to destroy microorganisms
33
What is the function of phagocytes in the white blood cells?
* Engulf bacteria and other microoorganisms that have infected bodies.
34
Where are red blood cells made?
* Made in the bone marrow
35
How do haemoglobin transport oxygen?
* Combines with oxygen to form oxyhaemoglobin when there is a high concentration of oxygen in the surroundings.
* When the concentration of oxygen is low, oxyghaemoglobin turns back into the haemoglobin and the red blood cell unloads its oxygen.
36
How are the red blood cells adapted to their function?
* Do not contain a nucleus, means mroe haemoglobin can be packed into each red blood cell so more oxygen can be transported.
* Biconcave shape allows efficient exchange of oxygen in and out of the cell.
* Has a hgih surface area to volume ratio, giving a large area for diffusion.
* Thinness of the cell gives short diffusion distance to the centre of the cell.
* Have very thin cell surface membranes which allow oxugen to diffuse through easily.
37
How do the white blood cells protects the body against the invasion of pathogens?
* Phagocytosis
* Antibody production
38
How do phagocytosis work?
1. The phagocytes change their shape to form a pseudopodia. This engulfs the pathogens into the cell.
2. The whole pathogen is engulfed within a vacuole.
3. Lysomes bind to the vacuole, they release digestive enzymes to break down the pathogen.
4. The broken down pathogens are released out of the cell by exocytosis
39
What are antigens?
* Telltale chemical markes ont he surface of pathogens that the antibodies recognise.
40
What do the antibodies od when they have recognised a antigen?
* Stick to the surface antigens and destory the pathogen.
41
How do the antibodies destroy the pathogens?
* Cause the bacteria to stick together, so that phagocytes can ingest them more easily.
* Act as a label, so that it is more easily recognised by a phagocyte.
* Cause pathogens to burst open
* Neutralising toxins produced by the pathogens.
42
What do some lymphocytes develop into?
* Memory cells
43
What are the function of memory cells?
* They remain int eh blood for many years. If the miroorganism re-infect, the memory lymphocytes start to prodce the antibody specfiic to that antigen, so that the pathogen can be quickly dealt with.
44
Why is the secondary immune response much faster and more effective than the first response?
* As the number of antibodies in the blood quickly rises to a high level, killing the mcirooroganism before they have time to multiply to a point where tjeu would cause disease
45
How does a vaccination work?
* Person is injected with an agent that carries the same antigens as a specific diseae-causing pathogen.
* Lymphocytes recognise the antigen and multiply exactly as if that microorganism had entered the blood stream.
* Produce memory cells and make the peron immune to the disease.
46
How does blood clotting work?
* Damage to the blood vessel exposes collagen fibres, this activates platelets by chemical signals
* Platelet itself swells and becomes sticky, releasing chemicals that activates other platelets and causing the vessel to contract
* Platelets plug at the damage site to preven bood loss and prevent entry of pathogens
* Chemcias released transform prothrombin into its active state thrombin
* Thrombin cleaves molecules of fribonogen (solube plasma protein) into insolube threads of fibrin.
* Fibrin forms a meshwork over the platelet plug, holds everthing in plase, whislt a scab forms and heals itself.
