Human transport system

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  • Created by: Sophie
  • Created on: 15-05-14 19:14
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Why humans need a circulatory system
- Small surface area compared to volume large diffusion path diffusion alone=too slow
- More active than smaller organisms greater oxygen, etc., requirements
- Pump blood oxygen and glucose to cells cells respire
The double circulatory system
- When blood pumped around body, goes through heart twice
- Pulmonary circuit- carries deoxygenated blood to heart, oxygenated back
- Systemic- carries oxygenated blood around body, deoxygenated back to heart
- Necessary because:
- Keeps blood pressure high blood moves fast to supply cells quickly + remove waste
- NOTE: pulmonary artery carries deoxygenated blood- it is the ONLY artery which does
Heart dissection
- Left side firmer to touch, thicker (musclier) walls (must be able to pump blood around body at high
pressure), aorta (thicker than vena cava) leads there
- Heart made of cardiac tissue
- Hard white substance around heart = fat- insulates, protects, provides respiration fuel
- Ventricles firmer + larger than atria (left ventricle = thickest)
- Blood vessels on surface of ventricles: coronary arteries + veins, from aorta or vena cava
- Coronary vessels provide heart with fuel- if blocked, that part of heart unable to respire
would die heart attack
- Valves control direction of blood flow
Structure and function of blood
- Plasma: liquid part of blood (mainly water)- carries blood cells + distributes heat around body;
carries dissolved nutrients, hormones, CO2, urea; straw coloured
- RBCs contain red pigment: haemoglobin
- RBCs lose nucleus whilst developing in bone marrow

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Feature RBC WBC- lymphocytes WBC- phagocytes Platelets
Fragments of other
Biconcave, disc- Large nucleus Lobed nucleus
like (more SA)
Where is/are they Bone marrow Bone marrow
Nucleus? No Yes No
Function Transport oxygen Produce Engulf bacteria + Release chemicals
in form of antibodies to other microbes that to make blood clot
oxyhaemoglobin destroy microbes + have infected our when we cut
antitoxins to bodies ourselves (to
neutralise toxins prevent blood loss +
pathogen entry)
Blood vessel Structure Diagram Function
Artery - Thick…read more

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Blood clotting
1. Blood vessel damaged (smooth walls rough edges)
2. Damaged tissue releases chemicals + platelets bump into rough edges
3. Prothrombin (soluble) thrombin (enzyme)
4. Thrombin acts on fibrinogen (soluble) fibrin (insoluble)
5. Fibrin fibre mesh across wound
6. RBCs and platelets trapped in mesh, forming clot
1. Diastole (filling phase) (approx. 0.4s)
· Cardiac muscle relaxed, so atria fills with blood from vena cava (RHS) + aorta (LHS)
2. Atrial systole (atrial contraction) (0.…read more

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Blood needs to be pumped faster
- Heart rate and stroke volume must increase
- Carbon dioxide and lactic acid also removed from muscles as a result
Effects of smoking on heart
- Blockage or narrowing of arteries (incl.…read more

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