6 | Transport in Humans Flashcards
Role of blood?
- Transport substances
- Defence
Components of blood?
RBCs
white blood cells
Plasma
Platelets (thrombocytes)
Structural adaptation of RBCs?
- Circular and biconcave shape to increase SA2VR for faster diffusion of oxygen
- Contains haemoglobin for oxygen to bind reversibly to oxygen
- Has no nucleus to store more haemoglobin to transport more oxygen
The function of RBCs?
Transport oxygen from the lungs to the rest of the body
What are the different white blood cells?
See drawing in notes
Phagocytes
Lymphocytes
Structural adaptations of phagocytes?
- Lobed nucleus to allow the cell to move towards the bacteria and change shape to engulf it
- Granular cytoplasm
Function of phagocytes?
Engulf and ingest foreign particles (e.g. bacteria) through phagocytosis
Function of lymphocytes?
Produce antibodies to protect the body from pathogens / agglutinate pathogens from phagocytes to engulf and ingest, and neutralise toxins
Structural adaptations of lymphocytes?
- Large, rounded nucleus to produce antibodies
- Small amount of non-granular cytoplasm
Function of plasma?
Transport dissolved substances to the rest of the body
Structural adaptations of plasma?
- A pale yellowish liquid made up of 90% water, which is the solvent for various substances, and various dissolved substances
- Contains: other flashcard
What does plasma contain?
5
(examples)
- Soluble proteins (antibodies, fibrinogen, prothrombin)
- Mineral salts (sodium + potassium)
- Nutrients (glucose, A.A, vitamins)
- Excretory / waste products (urea & CO2)
- Hormones (insulin, glucagon)
Function of platelets (thrombocytes)?
Aid in blood clotting
Structural adaptations of platelets (thrombocytes)?
- Not true cells
- Nucleus is absent
Process of blood clotting?
5
- When blood vessels are damaged, damaged tissues and blood platelets release an enzyme, thrombokinase
- Thrombokinase converts the protein prothrombin in the blood plasma into thrombin in the presence of calcium ions
- Thrombin catalyses the conversion of soluble fibrinogen to insoluble fibrin threads in the presence of vitamin K
- Fibrin threads forms a mesh across the damaged surface and traps RBCs, forming a clot
- The clot prevents further blood loss, and also restricts the entry of pathogens into the blood
Advantages of blood clotting
- Prevent excessive blood loss
- Prevent entry of microorganisms
Disadvantages of blood clotting?
- Sign of tissue rejection
- Heart attack (coronary thrombosis)
What is blood type determined by?
- Type of antigens on the cell surface membranes of RBCs
- Type of antibodies in the blood plasma
What causes agglutination or clumping of RBCs
An immune response will occur where antibodies in the blood plasma of the recipient would react with the antigens of RBCs of donor, causing agglutination or clumping of RBCs.
- Clumps may block up small blood vessels and prevent the flow of blood, which is very dangerous.
Which blood group is the universal donor?
Blood group O
Which blood group is the universal acceptor?
Blood group AB
Why is blood group O the universal donor?
There are no antigens on the donor’s RBCs and thus will not react with the recipient’s antibodies thus no agglutination will occur
Why is blood group AB the universal acceptor?
There are no antibodies in the plasma of the recipient, thus will not react with the donor’s RBC antigens thus no agglutination will occur.
Summary of blood groups
Notes
What are the different types of blood vessels?
Artery
Vein
Capillary
Function of artery?
- Transports blood away from the heart
- Carries oxygenated blood (except pulmonary arteries)
Structure and adaptation of artery
- Thick muscular walls to withstand high blood pressure
- Elastic walls to stretch and recoil to maintain the high blood pressure
Function of the vein?
- Transports blood towards the heart
- Carries deoxygenated blood (except pulmonary veins)
Structure and adaptation of vein?
- Thinner, less muscular, less elastic walls as blood pressure is much lower in veins. Blood flows smoothly and slowly
- Presence of valves to prevent backflow of blood
- Skeletal action (pinching of veins by skeletal muscles helps blood flow)
Function of capillaries?
Site of exchange of substances (glucose, oxygen, AA, CO2, urea) between blood and the tissue cells
Structure and adaptation of capillary?
- Wall is one cell thick made up of single layer of flattened cells (endothelial cells) to decrease the distance for diffusion and increases the rate of diffusion of substances
- Partially permeable to allow only some substances to pass through
- Extensive branching to form capillary network
– To increase SA2VR
– To increase rate of diffusion of substances - Slower rate of blood flow to provide time for exchange of substances
What occurs in the capillaries?
notes
What remains in the blood plasma in capillaries?
Plasma proteins, RBCs, platelets
What diffuses out into the tissue fluid from the blood capillary?
Only small molecules like glucose, oxygen, A.A., urea, CO2, water, hormones and white blood cells can diffuse out into the tissue fluid from the blood capillary
Blood flow?
Blood flows from the arterial end to the venous end due to higher blood pressure at the arterial end
How does oxygen diffuse into tissue cells?
Oxygen diffuses down a concentration gradient from the RBC, into the plasma, across the one cell thick capillary walls, into tissue fluid and then into tissue cells
Structure of heart
notes
Function of vena cava?
Transport blood rich in CO2 (deoxygenated) from tissue cells in te body back to the heart
Function of right atrium?
- Collects blood from the vena cava during r
relaxation - Pushes blood into the right ventricle during contraction
Function of tricuspid valve?
- Allows blood to flow only in one direction (right atrium –> right ventricle)
- Snaps shut when muscles of the ventricle contract
