OCR Biology Module 3 exchange and transport

active transport

Process by which plants take in minerals from the soil.

adhesion

When water molecules form hydrogen bonds with carbohydrates in the walls of xylem vessels, resulting in capillary action.

alveoli

Air sacs in the lungs.

aorta

Large artery carrying blood from the heart to the body.

apoplast

Pathway of water through cell walls and intercellular spaces in the root.

arrhythmia

Irregular heart rhythm.

arteries

Carry blood away from the heart.

arterioles

Smaller blood vessels connecting arteries to capillaries.

assimilates

Products of photosynthesis transported in the phloem.

atrial fibrillation

Type of arrhythmia where the atria contract very fast.

atrioventricular node

Stimulates the ventricles to contract after a slight delay.

atrium

Top chamber of the heart.

bicuspid valve

Prevents backflow of blood from the left atrium to the left ventricle.

Bohr effect

Effect of carbon dioxide concentration on the uptake of oxygen by haemoglobin.

bradycardia

Slow heart rate below 60 bpm.

breathing rate

Speed at which the lungs inflate and deflate.

bronchioles

Small tubes leading off the bronchi and terminating in alveoli.

bronchus

The trachea divides into two of these.

buccal cavity

Area inside the mouth of a bony fish.

bundle of His

Bundle of conducting tissue made up of Purkyne fibres.

capillaries

Tiny blood vessels with permeable walls due to gaps (fenestrations) between cells.

carbaminohaemoglobin

Formed when carbon dioxide combines with haemoglobin.

carbonic acid

Formed when carbon dioxide combines with water.

carbonic anhydrase

Enzyme involved in the reaction between carbon dioxide and water in red blood cells.

cartilage

Rings of this hold the trachea open.

Casparian strip

A band of waxy material called suberin forming a waterproof layer in the roots of plants.

chitin

Spirals of this hold the tracheae open in insects.

chloride shift

When chloride ions move into red blood cells to replace hydrogen carbonate ions which move out into the plasma.

ciliated epithelium

Specialised tissues lining the tubes of the respiratory system. Involved in removal of bacteria and dirt particules.

circulatory system

Body system made up of the heart and blood vessels.

closed circulatory system

Type of circulatory system in which blood is enclosed in vessels.

cohesion

When water molecules form hydrogen bonds with each other, leading to capillary action in xylem vessels.

cohesion-tension theory

Model of water movement from the soil in a continuous stream up the xylem.

collagen

Strong protein that withstands the stretch in blood vessels.

companion cells

Cells linked to sieve tube elements by plasmodesmata.

coronary artery

The blood vessel that supplies heart muscle cells with oxygen and glucose for respiration, and can lead to a heart attack if blocked.

countercurrent flow

The flow of blood in the opposite direction to water in fish gills to maintain the concentration gradient.

cuticle

Waxy cuticle on the leaves of plants that prevents water loss.

deoxygenated

Blood without oxygen

diaphragm

Sheet of muscle beneath the thorax involved in breathing.

diastole

Relaxation of the heart muscle, lowering the pressure in the chambers.

dicotyledon

Type of plant with two leaves on the germinating shoot.

diffusion gradient

A difference in concentration between two areas.

double circulatory system

Type of circulatory system in which blood passes through the heart twice for each complete circulation of the body.

ectopic heartbeat

An extra heart beat that doesn't fit with the normal rhythm.

elastic fibres

Found in the walls of the alveoli. Composed of elastin. Also found in blood vessels.

elastic recoil

Process which helps to squeeze air out of the alveoli and prevents them from bursting.

electrocardiogram

Records the electrical activity of the heart by monitoring electrical differences in the skin above it.

erythrocyte

Red blood cell.

exchange surface

A specialised surface through which substances can diffuse (e.g. oxygen from lungs to blood)

exoskeleton

Tough outer surface of insects which means they require a different method of gas exchange.

expiration

Breathing out.

expiratory reserve volume

Volume of air remaining in the lungs after a normal breath, but which can be exhaled by deeper breathing.

Fetal haemoglobin

Has an oxygen dissociation curve to the left of adult haemoglobin, due to a higher affinity for oxygen.

gaseous exchange system

A specialised system for obtaining and getting rid of gases required for metabolic reactions.

gill filaments

Large stacks of structures in the gills which need a flow of water to keep them apart.

gill lamellae

Increase the surface area of the gill filaments.

gills

Specialised gas exchange surfaces in bony fish.

goblet cells

Specialised cells found in tubes of the respiratory system that produce mucus.

guard cells

Cells surrounding the stomata that control opening and closing.

haemoglobin

Protein in red blood cells involved in oxygen transport.

haemoglobinic acid

Formed when hydrogen ions bind to haemoglobin, providing a buffering effect in red blood cells and preventing changes in pH.

haemolymph

Transport liquid in insects.

hydrogencarbonate ions

Formed along with H+ when carbonic acid dissociates in red blood cells.

hydrophytes

Plants with adaptations to survive living in water or very wet habitats.

hydrostatic pressure

Pressure from the surge of blood during ventricular contraction.

inferior vena cava

Blood vessel that carries blood from the lower half of the body back to the heart.

inspiration

Breathing in.

inspiratory reserve volume

Maximum amount of air that can be breathed in over and above normal inhalation.

intercostal muscles

Muscles which move the ribs during breathing.

interstitial fluid

Alternative name for tissue fluid - the liquid that bathes cells.

lignified

Describes walls of xylem vessel with a strengthening polymer laid down.

lignin

A strengthening polymer which is laid down in the walls of xylem vessels.

lung surfactant

Substance found in the lungs which allows the alveoli to remain inflated.

lymph

Similar to plasma and tissue fluid, but with fewer nutrients. It drains away from cells in separate vessels.

lymph node

Areas along lymph vessels where Lymphocytes (white blood cells) build up.

lymphocytes

Type of white blood cells which produce antibodies and are found in the lymphatic system.

mass transport

When substances are transported in a mass of fluid with a means of moving it around.

metabolism

The sum of all the chemical reactions in the body.

myogenic

Describes how cardiac muscle has its own intrinsic rhythm.

oncotic pressure

The tendency of water to move into the blood by osmosis.

open circulatory system

Type of circulatory system in which blood is not enclosed in vessels and is pumped straight from the heart into the body cavity.

operculum

A flap covering the gill opening in fish.

osmosis

How water moves into or out of the blood or cells.

oxygen dissociation curve

Graph showing the affinity of haemoglobin for oxygen in different situations.

oxygenated

Blood carrying oxygen.

oxyhaemoglobin

The complex formed when oxygen binds to the protein found in red blood cells.

parenchyma

Packing and supporting tissues in plant stems.

peak flow meter

A device used to measure the rate at which air can be expelled from the lungs.

phloem

Living tissue that transports organic solutes around the plant.

phloem loading

When soluble products of photosynthesis are moved into the phloem by active transport.

plasma

The liquid part of blood made up of water and dissolved substances.

plasmodesmata

Gaps in plant cell walls allowing cytoplasm to flow between cells.

pleural membrane

Thin membrane surrounding the lungs.

potometer

Device that measures water uptake by plants.

pulmonary artery

Blood vessel that carries deoxygenated blood from the heart to the lungs.

pulmonary vein

Blood vessel that carries oxygenated blood from the lungs to the heart.

Purkyne fibres

Tissue that conduct wave of excitation to the apex of the heart so that the ventricles can contract.

residual volume

The volume of air left in the lungs after the deepest possible breath out.

rib cage

Set of bones surrounding the lungs.