Human Transport Flashcards
Describe the composition of the blood
RBCs, WBCs, platelets, plasma
What is the role of plasma?
It is a straw yellow liquid and carries everything in the blood.
It transports heat energy, hormones, urea, CO2 and digested food.
What are the adaptions of the red blood cells for carrying haemoglobin?
- Small
- No nucleus, more room for haemoglobin
- Bi-concave shape, large surface area
- Haemoglobin forms oxyhemoglobin
What is the role of haemoglobin?
- Transports oxygen to cells for respiration
- In the lungs, it reacts with oxygen to form oxyhaemoglobin
- The reverse reaction occurs in the body cells and releases oxygen
How do phagocytes respond to disease?
Phagocytes detect pathogens, engulf them and digest them. They are non-specific.
How do lymphocytes respond to disease?
- each pathogen has antigens on the surface
- when lymphocytes come across antigens they produces proteins called antibodies which lock onto the pathogen and mark it for other white blood cells. These antibodies are specific to that pathogen
- antibodies are produced rapidly and flow around the body to mark all similar pathogens
- memory cells are produced that remember a specific antigen and can reproduce antibodies very fast if the pathogen is ever detected again
Describe the structure of arteries
- strong and elastic walls - blood at high pressure
- elastic fibres allow arteries to expand
- thick walls compared to lumen, contain thick layers of muscle
Describe the structure of the capillaries
- permeable walls so substances can diffuse
- cell walls only one cell thick for diffusion
- very small lumen
Describe the structure of veins
- walls aren’t as thick as arteries - blood not as high pressure
- bigger lumen for blood to flow despite lower pressure
- valves to keep blood flowing in the right direction
Why is the wall of the left ventricle thicker?
- needs more muscle to pump blood around the whole body (oxygenated), right ventricle only has to pump to lungs
- blood under higher pressure
How does exercise increase heart rate?
- muscles need more energy, so you respire more
- need more oxygen to cells and remove more carbon dioxide, blood has to flow faster, heart rate has to increase
- exercise increases amount of CO2 in blood
- detected by receptors
- send signal to brain
- brain sends signals to heart - contracts more quickly more force
How does the hormonal system control heart rate?
- when an organism feels threatened adrenal glands release adrenaline
- binds to receptors in the heart, contracts more forcefully and heart rate increases
- increased oxygen supply to tissues, gets body ready for action
What factors increase the risk of CHD?
- coronary arteries blocked by layers of fatty material build up
- cause arteries to narrow, blood flow restricted and lack of oxygen to heart muscle, can lead to a heart attack
- risks include diet high in saturated fat - fatty deposits in the arteries, leading to CHD
- smoking increases blood pressure - damage to coronary arteries (chemicals also cause damage), making build ups more likely
- being inactive can lead to high blood pressure and damage the lining of arteries making it more likely that fatty deposits will form
How do platelets help blood to clot?
- When a blood vessel is damaged platelets clump together the plug the damaged area
- This is known as blood clotting, this stops you from losing too much blood and prevents microorganisms from entering the wound
- In a clot, platelets are held together by a mesh of fibrin protein
How does vaccination prevent future infections?
- Vaccination involves injecting dead or inactive pathogens into the body. These carry antigens, so though harmless, an immune response is triggered, and antibodies are produced (lymphocytes)
- Memory cells will also be produced and will remain in the blood, so if live pathogens ever enter, the antibodies will be produced much faster and in greater numbers
