Unit 1, Module 1 Glossary

Question 0

Stimulus

Answer 0

Any change in the environment that causes a response

Question 1

Cell Signalling

Answer 1

The process by which cells communicate with each other. This is a process in which one cell will release a chemical that is detected by another cell. The second cell will respond to the signal by the first cell.

Question 2

Response

Answer 2

A change in behaviour or physiology as a result of a change in the environment.

Question 3

Homeostasis

Answer 3

The maintenance of the internal environment in a constant state despite external changes.

Question 4

Negative Feedback

Answer 4

A process in which any change un a parameter brings about the reversal of that change so the parameter is kept fairly constant.

Question 5

Positive Feedback

Answer 5

A process in which any change in a parameter brings about an increase in that change.

Question 6

Oxytocin

Answer 6

A hormone released by posterior pituitary gland to facilitate birth and breast feeding.

Question 7

Ectotherm

Answer 7

An organism that relies on external sources of heat to regulate its body temperature

Question 8

Endotherm

Answer 8

An organism that can use internal sources of heat, such as heat generated from metabolism in the liver, to maintain its body temperature.

Question 9

Polarised

Answer 9

A membrane that has a potential difference across it. This is the resting potential

Question 10

Depolarisation

Answer 10

The loss of polarisation across the membrane. It refers to the period when sodium ions are entering the cell making the inside less negative with respect to the outside.

Question 11

Generator potential

Answer 11

A small depolarisation caused by sodium ions entering the cell.

Question 12

Action potential

Answer 12

A brief reversal of the resting potential across the cell surface membrane of a neurones all action potential have a value of +40mV

Question 13

Resting potential

Answer 13

The potential difference. Or voltage across the neurone cell membrane while the neurone is at rest.

Question 14

Voltage-gated channels

Answer 14

Channels in plasma membranes that allow the passage of ions, they respond to changes in potential difference across a membrane and as a result open or close.

Question 15

Threshold potential

Answer 15

A potential difference (usually -50mV) across the membranes if the Depolarisation of the membrane does not reach the threshold potential then no action potential is created. If the depolarisation reaches the threshold potential then more sodium ion channels open and an action potential is created.

Question 16

Hyper polarised

Answer 16

The condition of a membrane that is mor highly polarised than the usual resting state,my resting potential is lower than usual.

Question 17

Polarised

Answer 17

Membrane with a potential difference across it.

Question 18

Depolarisation

Answer 18

The loss of polarisation across a membrane - when a membrane loses its resting potential

Question 19

Refractory period

Answer 19

The short period of time after firing during which it is more difficult to stimulate a neurone.

Question 20

Local currents

Answer 20

The movements of ions along the neurone. The flow of ions is caused un an increase in concentration at one point, which causes diffusion away from the region of high concentration.

Question 21

Saltatory

Answer 21

Refers to the way. That the action potential appears to jump form one more of Ranvier to the next.

Question 22

Neurotransmitter

Answer 22

A chemical that diffuses across the cleft of the sun apse to transmit a signal to the postsynaptic neurone.

Question 23

Cholinergic synapses

Answer 23

Those that use acetylcholine as their transmitter substance.

Question 24

Synaptic knob

Answer 24

A swelling at the end of the presynaptic neurone.

Question 25

Acetylcholinesterase

Answer 25

An enzyme in the synaptic cleft. It breaks down the transmitter substance acetylcholine.

Question 26

All or nothing

Answer 26

Refers to the fact that a neurone either conducts an. Action potential or does not. All action potential are of the same magnitude +40mV.

Question 27

Summation

Answer 27

A term that refers to the way that several small potential changes can combine to produce one larger change in potential difference across the membrane.

Question 28

Hormones

Answer 28

Molecules that are released by endocrine glands directly into the blood. They act as messengers, carrying a signal from the endocrine gland to a specific target organ or tissue.

Question 29

Endocrine gland

Answer 29

A gland that secretes hormones directly into the blood. Endocrine glands have no ducts.

Question 30

Exocrine gland

Answer 30

A gland that secretes molecules into a duct that carries the molecules to where they are used.

Question 31

Target cells

Answer 31

Those that possess a specific receptor in their plasma membrane. The shape of the shape is complementary to the shape of the hormone molecule, many similar cells together form a tissue.

Question 32

Adenyl cyclase

Answer 32

An enzyme associated with the reception for many hormones, including adrenaline. It is found on the inside of the cell surface membrane.

Question 33

First messenger

Answer 33

A hormone that acts as a message in the blood.

Question 34

Second messenger

Answer 34

A chemical inside the cell released in response to a hormone binding to the cell surface membrane, e.g. cAMP.

Question 35

Pancreas

Answer 35

A small organ in the abdomen that secretes digestive fluids and hormones.

Question 36

Pancreatic duct

Answer 36

A duct leading from the pancreas to carry digestive juices to the small intestine.

Question 37

Islets of Langerhans

Answer 37

Small patches of tissue in the pancreas that have an endocrine function.

Question 38

Alpha cells

Answer 38

Cells in the islets of Langerhans hat release glucagon in response to low blood glucose levels.

Question 39

Beta cells

Answer 39

Cells in the islets of Langerhans that release insulin in response to high blood glucose levels.

Question 40

Insulin

Answer 40

The hormone, released from the pancreas, that cause blood glucose levels to go down.

Question 41

Glucagon

Answer 41

The hormone that cause blood glucose levels to rise.

Question 42

Hepatocytes

Answer 42

Liver cells. They are specialised to perform metabolic functions.

Question 43

Diabetes mellitus

Answer 43

A disease in which blood glucose concentrations cannot be controlled effectively.

Question 44

Hyperglycaemia

Answer 44

The state in which the blood glucose concentration is too high.

Question 45

Hypoglycaemia

Answer 45

The state in which blood glucose concentration is too low.

Question 46

Genetically engineered

Answer 46

Bacteria whose DNA has been altered. In this case a gene coding for human insulin has been inserted into the DNA of the bacteria.

Question 47

Stem cells

Answer 47

Unspecialised cells that have the potential to develop into any type of cell.

Question 48

Cell metabolism

Answer 48

The result of all the chemical reactions taking place in the cytoplasm

Question 49

Myogenic

Answer 49

Theses muscle tissues can initiate its own contractions

Question 50

Pacemaker

Answer 50

The region of tissue in the right atrium wall that can generate an impulse and initiates the contraction of the chambers

Question 51

Medulla oblongata

Answer 51

It is found at the base of the brain. It is the region of the brain that coordinates the unconscious functions of the body such as the breathing rate and heart rate.

Question 52

Cardiovascular centre

Answer 52

A specific region of the medulla oblongata that receives sensory inputs about levels of physical activity, blood carbon dioxide concentration and blood pressure. It sends nerve impulses to the SAN in the heart to alter the frequency of excitation waves.