Biology · OCR Paper 1
Exchange and Transport in Animals
Why large organisms need exchange surfaces and transport systems, and how the human circulatory system, the heart, the blood vessels, the lungs and the blood are adapted to their jobs. Matches OCR GCSE Biology A (Gateway Science) B2.2a to B2.2e (the challenges of size). Every lesson is for both Combined Science and separate Biology, at Foundation and Higher.
Lessons
Ticks are remembered on this device only.
-
1
Surface Area to Volume Ratio and Exchange Surfaces
A big organism cannot get everything it needs by diffusion through its skin. This lesson shows how to calculate surface area to volume ratio and why…
9 terms -
2
The Heart and Double Circulation
The heart is a muscular pump that sends blood to the lungs and then round the body. This lesson names the chambers and blood vessels of the heart, follows the…
9 terms -
3
Blood Vessels
Blood travels round the body in three kinds of vessel. This lesson explains how the structure of arteries, veins and capillaries fits their jobs, and how to…
8 terms -
4
The Lungs and Gas Exchange
The lungs bring oxygen into the blood and take carbon dioxide out. This lesson follows air from the trachea to the alveoli and explains how the lungs are…
8 terms -
5
Blood
Blood is a tissue made of a liquid and three kinds of cell fragment. This lesson names each part of the blood, explains what it does and shows how to recognise…
8 terms
Key terms in this chapter
All 42, gathered from every lesson.
- Surface area to volume ratio
- The surface area of an object divided by its volume. It gets smaller as the object gets bigger.
- Surface area
- The total area of the outside of an object.
- Volume
- The amount of space inside an object.
- Exchange surface
- A surface specialised for swapping substances with the surroundings, such as the lungs or the small intestine.
- Diffusion path
- The distance particles have to travel to cross an exchange surface. A thin surface gives a short path.
- Villi
- Tiny finger-like folds in the lining of the small intestine that increase its surface area.
- Alveoli
- The tiny air sacs of the lungs, where oxygen and carbon dioxide are exchanged with the blood.
- Gill
- The gas exchange organ of a fish, made of many thin filaments.
- Ventilation
- Moving air or water over an exchange surface, so that the concentration gradient stays steep.
- Double circulatory system
- A circulation in which blood passes through the heart twice on each trip round the body, once to the lungs and once to the body.
- Atrium
- An upper chamber of the heart that receives blood.
- Ventricle
- A lower chamber of the heart that pumps blood out.
- Vena cava
- The vein that brings deoxygenated blood from the body to the right atrium.
- Aorta
- The artery that carries oxygenated blood from the left ventricle to the body.
- Pulmonary artery
- The artery that carries deoxygenated blood from the right ventricle to the lungs.
- Pulmonary vein
- The vein that brings oxygenated blood from the lungs to the left atrium.
- Coronary artery
- An artery that supplies the heart muscle with oxygenated blood.
- Pacemaker
- A group of cells in the right atrium that controls the resting heart rate.
- Artery
- A blood vessel that carries blood away from the heart at high pressure.
- Vein
- A blood vessel that carries blood to the heart at low pressure.
- Capillary
- A tiny blood vessel with a wall one cell thick, where substances are exchanged with the cells.
- Lumen
- The space inside a blood vessel through which the blood flows.
- Valve
- A flap inside a vein that stops blood flowing backwards.
- Elastic fibres
- Stretchy fibres in the walls of arteries that let them stretch and recoil.
- Rate of blood flow
- The volume of blood that passes a point in a given time.
- Pulse
- The surge felt in an artery each time the heart pumps blood into it.
- Trachea
- The windpipe, the tube that carries air from the mouth and nose towards the lungs.
- Bronchus
- One of the two tubes that branch from the trachea, one into each lung.
- Bronchiole
- A smaller tube that branches from a bronchus and ends in alveoli.
- Alveolus
- A tiny air sac in the lungs where gas exchange takes place.
- Gas exchange
- The swapping of oxygen and carbon dioxide between the air and the blood.
- Ventilation
- Breathing, which moves fresh air into the lungs and stale air out.
- Concentration gradient
- A difference in the concentration of a substance between two places.
- Capillary network
- The net of tiny blood vessels that surrounds each alveolus.
- Plasma
- The pale yellow liquid part of the blood that transports dissolved substances.
- Red blood cell
- A cell with no nucleus that carries oxygen around the body.
- Haemoglobin
- The red pigment in red blood cells that joins with oxygen.
- White blood cell
- A blood cell with a nucleus that helps to defend the body against pathogens.
- Platelet
- A small fragment of a cell that helps blood to clot.
- Biconcave
- Shaped like a disc that is dimpled on both sides.
- Phagocyte
- A white blood cell that engulfs and digests pathogens.
- Blood clot
- A mass of platelets and fibres that seals a wound.