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Honors A level revision > Biology topic 9 > Flashcards

Biology topic 9 Flashcards

1
Q

Cerebellum function

A

Folded cortex
Coordination and motor activity

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2
Q

Medulla Oblongata

A

Base of the brain
Breathing and heart rate

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3
Q

Hypothalamus

A

Beneath middle part of the brain
Maintains constant internal environment, produces hormones
E.g controls pituitary gland

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4
Q

Homeostasis definition

A

Maintaining a constant internal environment despite external changes

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5
Q

Endocrine

A

Glands found around the body
No ducts
Hormones secreted directly into bloodstream
E.g adrenal gland

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6
Q

Exocrine

A

Release chemical substances to outside the body or onto another surface within the body
Ducts (small tubes) that release chemicals
E.g tear glands, sweat glands

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7
Q

Effect of hormones on the body

A

Hormone directly enters cell- steroid hormones e.g progesterone and testosterone
OR
Release of second messenger- non-lipid soluble hormones cannot travel across membrane, bind to receptor in membrane which triggers rxn to room second chemical messenger e.g adrenaline, FSH

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8
Q

Central nervous system

A

brain and spinal cord

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9
Q

Peripheral nervous system

A

neurones that connect CNS to the rest of the body

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10
Q

function of spinal cord

A

relay action potentials from receptor organs to effectors via brain or reflex actions

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11
Q

Relay reaction process

A

Involuntary action done to protect the body
1. Receptors detect stimulus
2. Sends message along sensory neurone to spinal cord
3. Connect with relay neurone in spinal cord
4. Connects to motor neurone which connects to effector and trigger response

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12
Q

Mylein Sheath

A

Insulates neurone which helps impulse travel faster
Made up of Schwann cells- wrap around nerve fibre to form mylein sheath

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13
Q

Speed of impulse depends on

A

Presence/absense of mylein sheath
Diameter of nerve fibre- thicker will travel faster

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14
Q

What is a leak channel

A

Channel proteins
Remain open all the time to maintain RP

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15
Q

What are voltage-gated ion channel proteins

A

Open or close to allow movement- AP generated
Charge depends on whether gates open or closed

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16
Q

Sodium-potassium pump

A

ATP used to pump 3Na+ out and 2K+ in
Outside more +ve results in -ve RP inside neurone

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17
Q

Value of resting potential

A

-70mV on average

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18
Q

Potential diff

A

Diff between outside and inside

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19
Q

Threshold potential

A

Around -55mV
Stimulus needs to reach TP for impulse to occur
More Na+ channels open
All or nothing principle

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20
Q

Ion gates for depolarisation, repolarisation and hyperpolarisation

A

Depolarisation- Na+ open K+ closed
Repolarisation- Na+ closed, K+ open
Hyperpolarisation- Na+/K+ pump open

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21
Q

Refractory period

A

Time taken for area of axon membrane to recover- repolarise and restore RP
FIbre cannot be restimulated during this time
Depends on Na/K pump and permeability of membrane to K+ ions

22
Q

Saltatory conduction

A

AP only occurs at Nodes of Ranvier so they appear to jump from one to the next
Speeds up transmission of impulse as less AP along axon

23
Q

Structure of motor neurone

A

Many fine dendrites
Brings impulse towards cell body
Single long axon –> impulses away

24
Q

Structure of relay neurone

A

Numerous short fibres

25
Q

Sensory neurone

A

Single long dendron
Impulses towards cell body
single axon –> impulses away

26
Q

Nodes of Ranvier

A

Small gaps in mylein sheath surrounding axon

27
Q

Generator potential

A

In receptor cells
Stim –> Na+ moves across membrane

28
Q

2 photo receptors in the receptor

A

Cones and rods

29
Q

Cones

A

Detect bright light and colour
Each cone has its own sensory neurone

30
Q

Rods

A

Detect grey scale
Low intensities of light e.g nighttime
Spread evenly on retina
Several rods synapse with same sensory neurone, generate AP

31
Q

How do rods work

A

Contain pigment- rhodopsin (opsin + lipoprotein retinal)
Cis/trans retinal
Photon hits rhodopsin, cis-retinal changes to trans-retinal
This changes shape of retinal and causes bonds to break + rhodopsin breaks down into opsin and retinal
Process called BLEACHING

32
Q

Bleaching

A

Causes Na+ channels to close in rods
Not permeable to Na+ but Na/K pump still works
Causes inside more -ve —-> generator potential
More bleaching —> greater GP

33
Q

Resynthesis of rods

A

Rhodopsin resynthesised –> ATP needed (mito)
trans —> cis retinal
cis retinal bonds with opsin to form rhodopsin

34
Q

How do cones work

A

Same process as rods but different pigment- idopsin
More light energy needed to break down idopsin, cnanot see colour in dim light

35
Q

Metabolism

A

Heat energy wasted, help keep warm

36
Q

Endotherms

A

Relies on its own metabolic processes to maintain body temp
Body temp higher than surroundings
Can live in most environments
High metabolic rate, food intake considerable
(warm-blooded animals)

37
Q

Ectotherms

A

Relies on external environment to control body temp
Low metabolic rate –> less food needed
Cold-blooded animals

38
Q

Too hot?

A

Vasodialation- blood moves to surface so heat lost
Sphincter muscles relaxes + open
Hair muscles relax/flat- no hair trapping heat

39
Q

Too cold?

A

Shivering- muscles contract, heat to warm up
Contraction of hair muscles- cause hair to stand up
Vasoconstriction- sphincter muscles contract, less blood on surface

40
Q

Cardiac output

A

Increase HR and stroke vol
cardiac output = cardiac vol x HR

41
Q

Baroreceptors

A

Detect blood pressure

42
Q

Chemoreceptors

A

Detect pH in blood (CO2 levels)

43
Q

Ultrafiltration

A

Efferent narrower than afferent to maintain high pressure
Water + smaller components of blood (urea, ions glucose) forced out into lumen of nephron forming glomerular filtrate—-> Bowmans capsule
Large proteins + blood cells stay in arteriole
3 layered filtration process
ions - K+ , Na+ , Cl-

44
Q

Function of endothelium

A

Capillary wall with large pores to allow plasma to pass through

45
Q

Basement membrane function

A

Extracellular protein only allow very small proteins to pass through

46
Q

Podocyte cells function

A

Wrapped around glomerulus, help with filteration and glomerulus support

47
Q

What occurs after ultrafiltration?

A

Blood reabsorbs some filterate back from tubule

48
Q

Features of proximal convoluted tube

A

Contain mitochondria
Microvili- SA for reabsorption
Movement of water by osmosis
AT of glucose + AA’s across membrane
Some reabsorption of urea- passive
Movement of proteins- pinocytosis (type of endocytosis)

49
Q

Loop of Henle

A
  1. filtrate from PCT down descending limb, loses water (osmosis)–> higher conc
  2. Conc of ions increase down descending limb, maintains osmotic gradient + H2O drawn out tubule
  3. Water reabsorbed back into blood of Vasa Recta, back to body
  4. Bottom of loop, filtrate + tissue fluid at eq, no osmosis
  5. Ascending limb, high permeability to ions. Thin ascending limb. Ions move out by facilitated diff, conc gradient maintained
50
Q

Too little water in blood

A

Receptors detect –> pituitary releases ADH –> increases permeability of collecting duct, increase reabsorption –> bladder decreases vol, increases conc of urine

51
Q

Too much water in blood

A

Receptors detect–> pituitary inhibit ADH –> decreases permeability + reabsorption –> bladder increase vol and decrease conc of urine

Honors A level revision (16 decks)

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