Date post: | 10-Apr-2015 |
Category: |
Documents |
Upload: | api-3728508 |
View: | 3,632 times |
Download: | 2 times |
Chapter 8: Transport in Mammals
Syllabus Objectives:
(a) Identify the main blood vessels to and from the heart, lungs, liver and kidney
(b) State the functions of blood
• red blood cells - haemoglobin and oxygen transport
• white blood cells - phagocytosis, antibody formation and tissue
rejection
• platelets - fibrinogen to fibrin, causing clotting
• plasma - transport of blood cells, ions, soluble food substances, hormones, carbon dioxide, urea, vitamins, plasma proteins
(c) List the different ABO blood groups and all possible combinations for the donor and recipient in blood transfusions
(d) Relate the structure of arteries, veins and capillaries to their functions
(e) Describe the transfer of materials between capillaries and tissue fluid
(f) Describe the structure and function of the heart in terms of muscular contraction and the working of valves
(g) Outline the cardiac cycle in terms of what happens during systole and diastole (Histology of the heart muscle, names of nerves and transmitter substances are not required)
(h) Describe coronary heart disease in terms of the occlusion of coronary arteries and list the possible causes, such as diet, stress and smoking, stating the possible preventative measures
8.1 Transport in living organisms
How do useful materials reach all body cells / waste from the cells are removed rapidly?
8.1.1Features of a circulatory system
1
Simple Organisms - Simple Diffusion
Body cells are close to their surroundings.
Complex Organisms – Diffusion is NOT effective as cells are far away from body surfaceNeed a transport system Circulatory system in mammals, for example
A circulating fluid to carry materials
A pumping device to drive fluid around body
A system of branched tubes/ vessels connected to the heart through which fluid can circulate and reach all body cells
Made up of
Either by
8.2 Blood
Definition: A fluid tissue Average human adult has about 5.5 litres of blood Composition of blood:
8.2.1 Transport of oxygen (RBC)
Haemoglobin + Oxygen Oxyhaemoglobin
8.2.2 Protective functions of blood (WBC+platelets+some plasma proteins)
2
Blood Heart
Plasma Blood cells Platelets
Made up of
Blood
White Blood Cells (WBC)
Red Blood Cells (RBC)
Pale yellow liquid
90% water Carry
dissolved substances Biconcave,
flattened discs No nucleus Contain
haemoglobin Life-span: 3-
4 months Formed in
bone marrow Destroyed in
spleen and liver
Colourless Contains a
nucleus Can move
about and change its shape
Lives for only a few days
Lymphocytes Phagocytes Produced in
lymph glands and lymph nodes
Produced in bone marrow
Cell fragments Formed in
bone marrow
Function: Transport of
dissolved substances
Function: Transport of
Oxygen
Function: Protective Clotting of
blood
Protective Functions Air sac in lung
Body cells(Purplish red) (Bright red)
Phagocytosis Antibody production Clotting of blood
Protective functions
Phagocytes engulf and digest foreign particles (eg. Bacteria that enter blood)
Lymphocytes produce antibodies (proteins)
Platelets + damaged cells
8.2.3 Blood Groups
Surfaces of RBC contains antigens, which are the same in all your RBCs Natural antibodies do not react with the antigens on your RBC
o However, it could react with antigens from another persono When this happens, the antibodies will cause the RBC to clump
together (agglutination) – See Sect 8.2.2 above.o Clumping of RBC leads to the blockage or small blood vessels
prevent smooth flow of blood death Your blood group is based on the types of antigens and antibodies
present in your blood
Blood Group Antigen on RBC Antibody in plasmaA Antigen A Antibody bB Antigen B Antibody a
AB Antigens A and B No antibodiesO No Antigen Antibodies a and b
Note: Whenever Antibody a reacts with antigen A clumping occurs Antibody b reacts with antigen B clumping occurs No antibody reacting with antigen, or vice versa no clumping occurs
Recipient blood group
Antibody in
recipient’s plasma
Donor’s blood groupA (antigen A) B (antigen B) AB
(antigens A & B)
O (no antigens: universal
donor)A b - + + -B a + - + -
AB (universal acceptor)
No antibodie
s
- - - -
O a and b + + + -
3
Antibodies cause bacteria
to clump together
(agglutination)
Antibodies kill bacteriaBacteria
clumps undergo
Antitoxins neutralize
toxins produced by
bacteria
Ca2+ + Vit. K + thrombin
Fibrinogen fibrin threads network(Soluble in plasma)
(Insoluble)
+ trapped RBC
Forms blood clot
Legend : + agglutination (clumping happens) (not compatible) - no agglutination (no clumping) (compatible)
8.3 Blood Circulation in humans
Mammals possess a double circulation In double circulation, blood passes through the heart twice before it
completes one circuit of the body
8.3.1 Pulmonary circulation/circuit Carries deoxygenated blood (low oxygen conc) from heart
to lungs at low pressure (flows slowly) Gives blood time to be well oxygenated
Blood then becomes oxygenated (high oxygen conc) Oxygenated blood then returns to the heart (to Left
Atrium)
8.3.2 Systemic circulation/circuit Distributes oxygenated blood from heart to all parts of the
body except the lungs Then returns the deoxygenated blood from these parts to
the heart again
4
Median septum
LegendA: AtriumV: Ventricle
Body parts other than lungs
Low-pressure circulation
High-pressure circulation
Blood leaves heart at high pressure so that it can reach all the body tissues at a faster rate, bringing oxygen to them rapidly
8.4 The Heart
A muscular organ Contracts and relaxes regularly throughout life Consists of 4 chambers
2 atria (upper chambers) (LA & RA) 2 ventricles (lower chambers) (LV and RV)
Median septum separates LA & LV from RA & RV Prevents mixing of oxygenated blood on left side of heart with
deoxygenated blood on right side Ensures
All oxygenated blood is sent to all parts of body All deoxygenated blood goes to the lungs
Structure of atria and ventricles Chamber Structure AdaptationAtria Walls are thin Only needs to force blood into ventriclesVentricles
Walls are thick Needs to push blood out of the heart
Walls of LV is thicker than RV enables it to pump blood more forcefully at high pressure to the rest of the body
Presence of valves to prevent backflow of blood ensure that blood flows in one direction only
5
Tricuspid valves
Bicuspid valvesSemi lunar valves
Ensures blood flows in one direction
8.4.1 Mode of action of the heart
Ventricle relaxing Ventricle contracting
1 heart-beat = 1 contraction (systole) + 1 relaxation (diastole) of atria & ventricles
As ventricles contract arteries dilate
6
Atria relax
Blood fills atria from veins Atria contracts
Tricuspid/Bicuspid valves open
Blood enters relaxed ventricle
Ventricle contracts
Semi lunar valves openBlood pumped into arteries
Tricuspid/Bicuspid valves close “lub” sound
Atria begin to relax
Ventricles relax
Semi lunar valves close “dub” sound
o Each dilation cause elastic walls of arteries to recoil force blood along as a series of waves/pulses
o This pulse rate is High after exertion Low during rest
8.5 Blood vessels
7
Arteries Capillaries Veins
Blood vessels
Carry blood away from heart
Take nutrients, oxygen and useful substances to the cells and remove
waste produced in cells
Carry blood towards heart
8.5.1 Comparison between blood vessels
Blood vessel Artery Capillary VeinWall and Lumen Wall is thick,
muscular and elastic
Wall is one-cell thick, lumen size of a RBC
Wall is thin, less muscular and elastic
Diagram of cross-section
Valves Absent Absent Semi-lunar
8
valves to prevent backflow of blood
Blood flow 1. Blood moves along by contraction of the muscles of its walls.
2. Blood flows under great pressure, fast, in spurts.
1. Blood flows smoothly
2. Pressure at arteriole end > pressure at venule end.
1. Blood flows smoothly and slowly
2. Blood moves along vein by contractions of the body muscles on the vein
Nature of blood Oxygenated (except for pulmonary artery)
Oxygenated at arteriole end, deoxygenated at venule end (except lungs!)
Deoxygenated (except for pulmonary vein)
8.5.2 Coronary arteries
2 Coronary arteries supply the heart muscles with nutrients and oxygen
Coronary heart disease (CHD)
9
Fat deposits (atherosclerosis)
Blood clots (thrombosis)
Partially block the lumen of coronary arteries
Obstruct blood flow to the heart muscles
Heart muscles do not get enough nutrients/oxygen
Heart muscles start to degenerate
Severe heart pain heart attack
Causes of CHD: High fat diet, smoking, being overweight, lack of exercise, stress
8.6 Transfer of materials between capillaries, tissue fluids and body cells
Body cells are bathed in tissue fluido Tissue fluid = dilute plasma without plasma proteins
Role of tissue fluid:o To allow nutrients and oxygen to diffuse out of the blood
in capillaries into the fluid, and then eventually to body cells
o Waste products formed by the cells diffuse out of the tissue fluid, and from there diffuse into the blood in the capillaries
10
Some enters tissue fluid