Chapter 6: Transport in Humans Flashcards
1
Q
Components of human transport system
A
- a series of blood vessels
- blood
- heart
2
Q
Main components of blood
A
- plasma
- red blood cells
- white blood cells
- platelets
3
Q
Plasma
A
- yellowish-liquid in blood
- contains mainly water & substances such as glucose, salts, proteins, amino acids, fats, vitamins, hormones & excretory products such as urea
- also contains red & white blood cells
- transport blood cells, nutrients, excretory products and hormones
4
Q
Red blood cells
A
- main function is to transport oxygen from lungs to other parts of the body
- contains haemoglobin that combine reversibly with oxygen. In lungs, O2 concentration is high, haemoglobin binds to O2 to form oxyhemoglobin. In tissues, O2 concentration is low, oxyhemoglobin releases oxygen to cells
- they have biconcave shape to increase surface area-to-volume ratio which increases rate of absorption and release of oxygen
- they are flexible ๐ can change into bell-shaped structures so that they can flow easily through narrow blood capillaries
- no nucleus ๐ more space for haemoglobin to be stored
5
Q
White blood cells
A
- Phagocytes
- Lymphocytes
- they are irregular in shape and have a nucleus
6
Q
Phagocytes
A
- performs phagocytosis
- process whereby white blood cell engulfs and destroys foreign particles such as bacterial
7
Q
Lymphocytes
A
- recognise foreign particles
- destroy disease-causing organisms such as bacteria and viruses
- causes bacteria to clump together for easy ingestion by phagocytes
- neutralise toxins produced by bacteria
8
Q
Platelets
A
- fragments of cytoplasm
- contains enzymes that catalyses the conversion of fibrinogen to fibrin threads
- these threads form a network that entangles red blood cells to form a clot
- the clot prevents excessive blood loss and entry of harmful organisms into the bloodstream
9
Q
How does blood clot
A
- when tissues are damaged at the site of the cut, platelets release thrombokinase
- thrombokinase catalyses the conversion of blood protein prothrombin into thrombin in the presence of calcium ions
- thrombin catalyses conversion of soluble fibrinogen threads into insoluble threads of fibrin
- fibrin threads entangle blood cells and the whole mass forms a clot/scab
- the clot seals the wound, preventing entry of microorganisms and excessive blood loss
10
Q
Organ transplant and tissue rejection
A
- happens when a personโs tissue/organ is damaged or diseased and it is replaced by a healthy tissue or organ from the donor
- this new organ may be treated as a foreign body and when the white blood cell recognise the tissue/organ as foreign, they produce antibodies to destroy the foreign tissue. This is known as tissue rejection
- hence, tissue of both donor and recipient must be as genetically similar as possible
- another way to reduce risk of tissue rejection is the use of drugs which inhibits the responses of the recipientโs immune system
11
Q
Blood types
A
- special proteins on surface of red blood cells is antigens
- antibodies are produced by white blood cells and float in your blood
- your antigens and antibodies will not react with each other, but may react with antigens and antibodies of another personโs blood ๐ causes clumping of red blood cell (agglutinate)
12
Q
4 blood groups
A
A: antigen A, antibody b
B: antigen B, antibody a
AB: antigen A & B but no antibody
O: no antigen but have antibody a & b
13
Q
What is the Heart
A
- pumps blood to ensure blood constantly circulates throughout body
- when heart relaxes, it fills up with blood
- when heart contracts, blood is squeezed out with great force
- blood then circulates through the blood vessels, which directs blood flow around the body
14
Q
What is the Arteries
A
- blood vessels that carry blood away from the heart
- large artery that leaves left side of the heart is the aorta
- aorta branches out into smaller arterioles
15
Q
what is the Arterioles
A
- arteries branch out to form arterioles
- arterioles branch out to form capillaries
16
Q
what is the Blood capillaries
A
- microscopic blood vessels that are found between the cells of almost all tissues
- walls made out of a single layer of flattened cells (short diffusion distance)
- capillary walls are partially permeable, enabling certain substances to diffuse through it
- small arteries branch out to form capillaries
- numerous branches provide larger surface area for the exchange of substances between blood and tissue cells
- the total cross-sectional area of the blood vessels also increases, lowering blood pressure, hence flow of blood slows down, giving more time for exchange of substances
17
Q
what is the Venules
A
- before capillaries leave an organ, they will unite to form small vessels called venules
18
Q
what is the Veins
A
- venules join to form bigger veins, with carry blood back to the heart
19
Q
Arteries
A
- receives blood directly from the heart
- blood that flows in arteries are fast moving ๐ walls are thick, muscular and elastic
- elastic layer is much thicker in the arteries closest to the heart
- thick elastic walls help withstand high blood pressure
- elasticity enables wall to stretch and spring back ๐ pushes blood in spurts along artery, giving rise to the pulse
- when muscles in wall contract, artery constrict, lumen narrows and less blood flows through it
- when muscles in wall relax, artery dilates, lumen widens and more blood flows through it
- carries oxygenated blood (except pulmonary artery)