Module 5 - Keywords

Question 1

Generator potential

Answer 1

Small depolarisation caused by sodium ions entering the cell

Question 2

Resting potential

Answer 2

When neurone is at rest (no stimulus), -70mV. Sodium/potassium ion pumps [3 out/2 in], K+ leakage

Question 3

Depolarisation

Answer 3

Loss of polarisation due to entry of Na+ entering the cell. Potential difference across membrane becomes less negative

Question 4

Threshold potential

Answer 4

Creates an action potential. There is a big enough stimulus for enough Na+ to enter the cell for the potential difference to exceed -50mV

Question 5

Action potential

Answer 5

Membrane is depolarised to +50mV. All or nothing response. Transmitted along axon membrane

Question 6

Repolarisation

Answer 6

Membrane becomes polarised again due to loss of K+ through v-g channels. Potential difference across membrane becomes more negative

Question 7

Hyperpolarisation

Answer 7

Too many K+ diffuse out - potential difference under -70mV

Question 8

Refractory Period

Answer 8

Following an action potential, there is a need to redistribute sodium and potassium ions and restore resting potential. During this time another impulse cannot be generated. Ensured impulses are separated, determines maximum frequency of impulse transmission, ensure impulse passes in one direction only along axon

Question 9

Local Currents

Answer 9

Movements of ions along the neurone

Question 10

Saltatory conduction

Answer 10

How the action potential ‘jumps’ from one Node of Ranvier to the next

Question 11

Excretion

Answer 11

Removal of unwanted/toxic/waste products of metabolism

Question 12

Deamination

Answer 12

Removes the amine group from amino acid, produces keto acid (can be respired) + also produces ammonia (soluble + highly toxic). Occurs in the liver

Question 13

Ornithine cycle

Answer 13

Ammonia is converted into urea

Question 14

Ultrafiltration

Answer 14

Filtration at molecular level in glomerulus by the basement membrane; smaller molecules (urea, water, glucose, amino acids, ions) are filtered out of the blood into the lumen of the Bowman’s capsule

Question 15

Selective Reabsorption

Answer 15

Useful substances are reabsorbed from the nephron (most happens in the PCT) into the blood e.g. glucose. Excretory substances remain in the nephron e.g. urea

Question 16

Hairpin countercurrent multiplier

Answer 16

Arrangement of a tubule in a sharp U shape so one part passes close to another with the fluid in opposite directions. Allows exchange between the contents + can be used to create a high concentration of solutes

Question 17

Osmoregulation

Answer 17

Control and regulation of water potential of the blood and bodily fluids. Controlled by the kidney (particularly the collecting duct)

Question 18

Osmoreceptors

Answer 18

Monitor changes in water potential of the blood. Found in the hypothalamus

Question 19

Neurosecretory cells

Answer 19

Make ADH in the hypothalamus in response to low water potential in the blood. This collect in the terminal bulb found in the posterior pituitary gland where ADH is released

Question 20

ADH

Answer 20

Anti diuretic hormone. Increases reabsorption of water

Question 21

Dialysis

Answer 21

Use of a partially permeable membrane to filter the blood

Question 22

Endocrine glands

Answer 22

Produce and secrete hormones directly into the blood - they have no ducts

Question 23

Exocrine glands

Answer 23

Do not produce hormones - they secrete molecules into a duct which carries them to where they are needed

Question 24

Hormones

Answer 24

Molecules released by endocrine lands into the blood and act as messengers carrying a signal from the endocrine gland to the target tissue

Question 25

Target cells/tissue

Answer 25

Possess specific receptors on their cell surface membrane which is complementary in shape to a hormone molecule

Question 26

Hepatocytes

Answer 26

Liver cells

Question 27

Diabetes mellitus

Answer 27

A disease in which you can’t control your blood glucose concentrations effectively

Question 28

Hyperglycemia

Answer 28

Blood glucose levels are too high

Question 29

Hypoglycemia

Answer 29

Blood glucose levels are too low

Question 30

Glycogenolysis

Answer 30

Glycogen being converted into glucose. Occurs in the liver.

Question 31

Gluconeogenesis

Answer 31

Fatty acids/amino acids –> glucose. Occurs in the liver

Question 32

Glycogenesis

Answer 32

Glucose being converted into glycogen. Occurs in the liver

Question 33

Myogenic

Answer 33

Muscle can initiate its own contractions