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A2 Biology > Unit 6 - Organisms respond to changes in their environments > Flashcards

Unit 6 - Organisms respond to changes in their environments Flashcards

1
Q

Nodes of ranvier

A

Between the Schwann cells.

Used in action potential and speed up the impulse.

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2
Q

Saltatory conduction

A

The propagation of actions potentials along a myelinated neurone from one node of ranvier to the next.

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3
Q

Factors that affect impulse speed

A
  • Myelination increases the speed of impulse transmission due to saltatory conduction.
  • The wider the axon the greater the speed of conduction.
  • The higher the temperature the greater the transmission speed due to faster diffusion of ions.
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4
Q

Dendrons

A

Extensions of cells body which divide into dendrites.

Carry nerve impulses towards cell body.

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5
Q

Axon

A

Long single fibre that carries nerve impulses away from cell body.

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6
Q

Schwann cells

A

Surround axon, protect and insulate it. Carry out phagocytosis and form the myelin sheath.

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7
Q

Repolarisation

A

Membrane becomes polarised again and a resting potential is reestablished.
Means an action potential can be generated again

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8
Q

Action potential

A

Sodium ion channels open

Sodium ions enter cell and cause depolarisation

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9
Q

Sensory neutrons carry

A

Nerve impulses from receptors towards CNS

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10
Q

Motor neurones carry

A

Nerve impulses away from the CNS to effectors

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11
Q

Sympathetic nervous system

A

Stimulates effectors and speeds up any activity.

Controls effectors during strenuous exercise or powerful emotions helping us cope with stressful situations.

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12
Q

Parasympathetic nervous system

A

Inhibits effectors and slows down any activity.
Controls activity under normal resting conditions.
Conserves energy and replenishes body’s reserves.

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13
Q

Taxes

A

Simple, directional response

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14
Q

Kinesis

A

Response which is not directional but instead affects the speed to try and find a new environment

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15
Q

Tropism

A

Direction of growth in plants affected by different stimuli

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16
Q

IAA

A

A plant growth factor which inhibits growth in the root and promotes growth in the stem tip

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17
Q

Central nervous system

A

Made up of brain and spine

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18
Q

Peripheral nervous system

A

Made up of the nerves that originate in brain if spine and is split into sensory and motor neurones

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19
Q

Rhodopsin

A

Pigment used in rod cells

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20
Q

Iodopsin

A

Pigment used in cone cells

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21
Q

Sympathetic nervous system

A

Stimulates effectors and speeds up an activity

22
Q

Parasympathetic nervous system

A

Inhibits efforts and slows down an activity

23
Q

Sinoatrial node

A

Group of cells found above the right atrium which stimulates heart contraction

24
Q

Medulla oblongata

A

Region of the brain which controls heart rate

25
Nervous system
Uses nerve cells to pass electrical impulses | Responses are rapid and temporary
26
Hormonal system
Uses bloodstream to transport hormones to cells | Response is slower and often long-lasting
27
Neurone
Specialised cell for transporting impulses | Consists of cell body, dendrons, an axon and Schwann cells
28
Myelin sheath
Portions of lipid-rich membrane that wrap around nerve cells to insulate them and allow faster impulse transmission
29
Depolarisation
Sodium ions flood into the axon flipping the charges and causing an action potential
30
Hyper polarisation
As potassiums ions flood out of the axon carrying an unusually high negative charge within the axon
31
Refractory period
Sodium voltage gates close and it is impossible for another impulse to be passed on Allows differentiation between impulses
32
Sarcomere
Portion of myofibril between Z lines and containing the A band and the H zone
33
Slow-twitch fibres
Contract more slowly and with less force but over a longer period Large store of myoglobin
34
Fast twitch fibres
Contract quicker and with more force but over a shorter period of time Large store of phosphocreatine
35
Sliding filament mechanism
Theory that actin and myosin fibres slide past each other during contraction
36
Phosphocreatine
chemical used to rapidly regenerate ATP. Stored in the muscle and is reserve store of phosphate
37
Homeostasis
Maintenance of an internal environment within strict limits in organisms
38
Insulin
Hormone produced by beta cells in the islets of the langerhans that convert glucose into glycogen
39
Glucagon
Hormone produced by alpha cells in the islets of langerhans that convert glycogen into glucose
40
Negative feedback
Process by which the body responds to a bodily condition staying away from the ideal level. It brings back to a normal level
41
Glycogenesis
Conversion of glucose to glycogen
42
Glycogenolysis
Breakdown of glycogen into glucose
43
ADH
Hormone produced in the hypothalamus and secreted by the pituitary gland. It affects the permeability of the distal convoluted tubule
44
Loop of Henley
Section of the nephron that begins in the cortex, drops into the medulla and returns into the cortex. It primarily deals with the reabsorption of water from the filtrate
45
Glomerulus
Ball do intertwined capillaries that are situated in the bowmans capsule The filtrate is forced out here
46
Podocytes
Cells surrounding the glomerular capillaries. | They allow the movement of necessary molecules
47
Glycogenesis
The conversion of glucose to glycogen in response to high blood glucose concentrations. The liver removes glucose from the blood and converts it to glycogen.
48
Glycogenolysis
Breakdown of glycogen to glucose in response to low blood glucose concentrations. The liver can convert stored glycogen into glucose which diffuses into the blood.
49
Gluconeogenesis
Production of glucose from sources other than carbohydrate. When the glycogen supply is exhausted, the liver can produce glucose from non-carbohydrate sources such as glycerol and amino acids
50
Afferent arteriole
Group of blood vessels that supply the nephrons. Diverge into capillaries of glomerulus

A2 Biology (14 decks)

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