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biology > control systems > Flashcards

control systems Flashcards

1
Q

how are resting potentials maintained

A
  • with a sodium potassium pump
  • sodium moves out, potassium in
  • gated sodium channels close to prevent moving in
  • outside more positive than inside
  • is polarised
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2
Q

role of rhodopsin in light

A
  • bleaches into retinal and opsin
  • opsin blocks gated na + channels
  • rod cell hyperpolarises
  • no IPSP released
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3
Q

negative feedback description

A
  • change occurs and is detected
  • leads to the activation of a mechanism that reverses the change
  • conditions return to ideal and mechanism switches off
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4
Q

positive feedback description

A
  • change is detected, communication system informs effector system causing a reaction
  • cycle repeats e.g blood clotting
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5
Q

what are endocrine glands and give example

A
  • ductless that release hormones into blood
  • adreneline - heart pumps faster, lungs increase breathing rate, blood vessels constrict, liver breaks down more glycogen, more muscle contraction
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6
Q

features of steroid hormones

A
  • lipid soluble/cross membrane
  • bind in cytoplasm forming TFs
  • move to nucleus and binds to promotor region
  • RNA polymerase transcribes
  • takes longer to effect
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7
Q

features and action of peptide/amide hormones

A
  • polar
  • binds to receptors on cell membrane
  • cAMP releases inside cell and triggers protein activation cascade
  • existing inactive proteins can activate others to bring change
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8
Q

role of auxins

A

elongates cells in meristem due to larger turgor pressure and increases cell plasticity
therefore bend towards light, exist on shaded
produced in apex

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9
Q

role of cytokinins

A

stimulate meiosis and lateral bud growth - attaches to receptors on membrane to form transcription factors
forms shoots

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10
Q

apical dominance

A
  • apex grows to access light
  • lateral buds inhibited as apex dominates - auxin produced to grow stem
  • cytokinins produced at auxillary buds for lateral stems
  • auxin transported down to prevent gene activation of cytokinins
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11
Q

role of giberellic acid

A
  • controls internode length and seed development
  • reinforces auxins and stem growth
  • end dormancy, grows in embryo
  • DELLA proteins bind to TFs to keep seeds dormant
  • when GA increases, amylase increaes, GA bind to DELLA which stops the inhibition of TFs
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12
Q

ending seed dormancy

A
  • uptake of water causes GA formation and diffuses into food stores
  • binds to DELLA - no inhibition
  • transcription of genes
  • food stores hydrolysed and transported to embryo
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13
Q

what are phytochromes

A

photoreceptor pigment that are blue/green and a conjugated protein

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14
Q

types of phytochromes

A

Pr - absrobs red (shorter) light
Pfr - far red (longer) light
changes r to fr in sunlight, slower change fr to r in darkness

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15
Q

long day and short day plants

A

long - Pfr is active, promotes the flowering gene - ft mRNA
short - PFR inhibits formation of ft mRNA

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16
Q

how impulses travel through central nervous system

A

stimuli
receptors
sensory neuron
motor neuron
effector muscle/gland
response

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17
Q

role of spinal cord

A

relay action potentials between receptors and effectors

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18
Q

role of cerebrum

A

voluntary responses, initiates movement and higher activity

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19
Q

role of medulla

A

controls heart rate vessel diameter and breathing

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20
Q

role of cerebellum

A

involuntary movement and fine motor

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21
Q

role of hypothalamus ad pituitary

A

links endocrine and nervous
in osmo and thermoregulation

22
Q

differences between motor and sensory neurons

A

motor have shorter dendrons (before cell body) and longer axons (after)
sensory have cell body in midde, motor have at the end

23
Q

the process of action potentials

A
  • stimulus causes gated na + channels to open, and they diffuse though conc gradient into cell
  • -55mv triggers depolarisation as na + flood in and inside becomes more positive and potential difference reaches +40mv
  • repolarisation - na channels close and k+ open to let it exit the cell so inside is less positive
  • hyperpolarisation when too many leave - k+ close
24
Q

transmission of action potentials

A
  • at nodes of ranviar where myelin is exposed
  • saltatory conduction where na+ jumps across myelin
  • after aps na+ diffuses high to low along to next node
  • negative ions move back to AP (+ attracted to -)
  • potential difference occurs when na+ arrives and cl- leaves
  • causing gates to open and causes local current
25
Q

what increases transmission speed of APs

A
  • myelinated
  • temperature
  • axon diameter/amount of membrane
26
Q

transmission at synapses

A
  • AP at pre-synaptic knob
  • ca2+ channels open and move in
  • vesicles move to pre synaptic membrane and release transmitter via exocytosis
  • NT diffuses across cleft, binds with receptors on ion channels (open) in post membrane
  • na rush in post synaptic neuron and depolarise
27
Q

deactivation at synapses with enzymes

A
  • cholinesterate hydrolyses ADH to create choline and ethanoic acid
  • ion channels of post membrane closes to restore resting
  • products enter pre-synaptic and recombine with ATP
28
Q

role and example excitatory neurotransmitter (EPSPs)

A

glutamate and ach
- causes na+ gates to open to cause depolarisation and can easily diffuse across synapse

29
Q

role and example inhibitory neurotransmitter (IPSPs)

A

GABA
- attaches to receptor sites, cl- channels open and move in making it more -
- cant reach threshold

30
Q

action of lidocaine

A
  • local anaesthetic
  • blocks na+ channels
  • post synaptic neurone cannot depolarise and AP for pasin can’t travel to brain
31
Q

action of cobra venom

A
  • irreversible binding to ach receptors on post synaptc membrane
  • na+ gates stay open and cells can’t repolarise
32
Q

action of nicotine

A
  • binds with ach receptors
  • more ach produced - synapses excited - alert
  • dopamine also released
33
Q

rods vs cones

A

rods - even spread, low light, black and white mostly, convergence, rhodopsin
cones - less, more further back, high intensity light, colour, high acuity, idopsin

34
Q

rod cells in the dark

A
  • na+ actively pumped inner to outer segment through channels for a gradient
  • na+ flows into pre synaptic membrane and causes depolarisation
  • IPSP released to prevent depolarising
35
Q

rods in dim light

A
  • rhodopsin bleaches into retinal and opsin
  • opsin closes gated na+ channels so can only pump out
  • cell hyperpolarizes and no IPSP released
36
Q

cones in light

A

uses idopsin to bleach
opsin closes na channels and cell hyperpolarises

37
Q

how heart rate is controlled

A

sympathetic nerve is connected to SAN from accelorator region, releases noradreneline that binds to receptors
vagus nerve connects to SAN from inhibitory region and releases ach

38
Q

increasing heart rate

A
  • increased cos and lactate in blood lowers ph
  • detected by chemoreceptors in arteries and send an AP to stimulate accelerator region
  • travels down SAN
39
Q

reducing heart rate

A
  • baroreceptors in carotid artery, aorta and atrium detect high blood pressure
  • AP stimulates inhibitory region, Ap travels to vagus and SAN, releasing ach to lower hr
40
Q

what is ADH

A

a peptide hormone that binds to receptors on the collecting duct, the 2nd messenger triggers insertion of aquaporins- an integral protein to increases permeability

41
Q

osmoregulation loop

A
  • change is detected by the hyperthalamus
  • too much water= pituitary gland secretes less ADH, less permeable, unconcentrated urine
  • too little water = p gland secretes more adh, duct more permeable and has concentrated urine
42
Q

thermoregulation in ectotherms and reptiles

A
  • physiological and behavioural adaptations
  • use less food in respiration, more energy for growth
  • more vulnerable
43
Q

thermoregulation in endotherms and mammals

A
  • hypothalamus has thermo regulatory centre
  • in low temp the heat gain centre inhibits less centre, sent via sympathetic nerve
  • vasocontriction: vessels close to skin constrict so less flow to surface
  • hair traps heat
  • high temp: loss inhibits gain and sent via parasympathetic
  • sweat takes away heat in evaporation
44
Q

fate of amino acids in the liver

A
  • glucogenesis in the liver - urea is a product
  • deamination - breaking down excess amino acids by removing the amino group to produce urea
45
Q

structure of a nephron

A

afferent and efferent arteriole
bowmans capsule and glomerulus
proximal convulated tubule
loop of henle
distal convulated tubule
collecting duct
medulla

46
Q

ultrafiltration

A
  • in endothelium of bowmans capsule capillary
  • amino acids, mineral ions, glucose, urea and water is filtrate
  • high hydrostatic pressure pushing blood into bowmans and low pushing back
  • oncotic pressure into glomerulus
47
Q

selective reabsorption

A
  • proximal tubule
  • moves glucose, aa, and water from lumen of pct cells to peritubular capillary but NOT urea
  • sodium potassium pump from pct to capillary (3:2 na out k in)
  • binds sodium with a specific molecule to travel across - gradient
48
Q

water reabsorption

A
  • loop of henle
  • low water potential in medulla, filtate in henle
  • surrounded by lots of blood vessels called vasa recta to reabsorb water and exchange 02 c02
  • descending limb is permeable, water leaves by osmosis and is reabsorbed into blood
  • ascending limb permeable to ions - actively pumped out and reenter descending
49
Q

blood ph and ion rebsorption

A

distal convulated tubule
- h+ oh- and hco3 ions adjusted - ph is 7.35-.45
- selective reabsorption of useful ions using cotransporter proteins
- eg calcium and chloride

50
Q

collecting ducts

A

collecting ducts
- permeability directed by adh

biology (12 decks)

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