1
Q
stimulus
A
change in environment detected by an environment
2
Q
receptor
A
organ or specialised cell that can detect the change which is causing the stimulus
3
Q
response
A
as a result of the stimulus that is detected by a receptor
4
Q
taxis
A
response that involves movement in a specific direction
5
Q
positive taxis
A
move towards stimulus
6
Q
negative taxis
A
move away from the stimulus
7
Q
what is the role of a kinesis response
A
increase the chance that the organism will enter different conditions more rapidly
8
Q
kinesis
A
response involves movement but in random directions
9
Q
what is plant growth controlled by
A
IAA (specific auxin produced in tips and shoots)
10
Q
what happens to the auxins when the shoot is elongated from all sides
A
auxins are evenly distributed and move down shoot tip causing elongation of cells
11
Q
what happens to the auxins when the shoot is elongated from one side
A
auxins move towards shaded part of shoot, causing elongation in shaded part and bending towards light
12
Q
what is gravitropism
A
growth in response to gravity
shoots are negatively gravitropic, roots are positively gravitropic
13
Q
what is a reflex response
A
involuntary response to a stimuli which may protect the organism from harm
14
Q
what is the order of a reflex path
A
stimulus
receptor
sensory neuron
relay neuron
motor neuron
effector
response
15
Q
sensory neuron role
A
carries nerve impulses from receptor to spinal cord
16
Q
relay neuron
A
located in spinal cord
takes nerve impulses from sensory neuron to motor neuron
17
Q
motor neuron
A
carries nerve impulse from spinal cord to effector which could be a muscle or a gland
18
Q
what is phototropism
A
growth in direction of light
shoots are positively phototropic, roots are negatively phototropic
19
Q
why do the auxins on cells allow them to respond to stimuli such as light.
A
auxin reduces pH to keep cell walls flexible and allow cells to grow
20
Q
what are photoreceptors
A
light receptors in the eye, located in the retina
21
Q
how is light detected by photoreceptors in the eye
A
-light enters via pupil
-light entering is controlled by circular and radial muscles in the iris
-lens focuses light on the retina, where photoreceptors are, specifically fovea
-nerve impulses detected by photoreceptors are sent to brain via optic nerves
22
Q
what do the eye muscles do in bright light
A
circular muscles contract to make pupil smaller
23
Q
what do eye muscles do in dim light
A
radial muscles contract to make pupil larger, allowing more light in
24
Q
what are the two types of photoreceptors
A
cone cells
rod cells
25
what are cone cells responsible for
colour vision and sharp detail in bright light
26
what are rod cells responsible for
detect low light, enabling night vision and peripheral vision
27
what are pacinian capsules
type of receptors found deep in the skin, mostly on fingers, soles of feet or genitals. They are also found in joints, tendons and ligaments
28
pacinian corpuscles have a single sensory neuron, located in the center of...
connective tissue called lamellae, which forms layers separated by a gel. It also contains stretch mediated sodium channels in the cell membrane.
29
what happens to the sodium channels when under no pressure in the pacinian corpuscles
channels are closed
30
what happens to the sodium channels when under pressure in the pacinian corpuscles
-channels become deformed, opening them to a massive influx of sodium ions.
-The positive charge on sodium ions changes the membrane potential, so it becomes depolarised.
-generator potential is created leading on to create action potential in axon.
31
myogenic meaning
hearts ability to initiate its own contractions
32
where is the sinoatrial node and what is it
right atrium wall
pacemaker of the heart
33
what are the steps to the myogenic control of heart beat
-the sinoatrial node initiates a wave of electrical stimulation which causes the atria to contract at the same time
-ventricles do not contract once atrias have finished due to tissue
-electrical wave reaches atrioventricular nodes which pass to ventricles, down the bundle of his to the apex of the heart.
-The bundle of His branches and Purkyne fibres which carry the wave upwards. This causes the ventricles to contract, thus emptying them.
34
what are the steps in autonomic regulation of heart rate
-the sinoatrial node is connected to 2 nerves from medulla oblongata in brain
-the accelerator nerve (SNS) delivers high frequency of impulses to SAN to increase heart rate
-the vagus nerve (PNS) delivers slow impulses to decrease heart rate
35
how does pH increase heart rate
changes in pH caused by high Co2 concentration, detected by chemoreceptors which send impulses to medulla more frequently via sympathetic pathway
more frequent impulses sent to SAN so increased heart rate
36
how do changes in blood pressure increase heart rate
detected by baroreceptors
increased frequency of impulses sent from medulla via parasympathetic pathway to SAN, causing increase in heart rate
37
what is the structure of a neuron
cell body containing the organelles
extensions called dendrites giving impulses to body
axon giving impulses the opposite way usually towards another neuron
polarisation of membrane- outside of membrane is positively charged, whereas inside is negatively charged (enables neurons to carry impulses called action potentials)
38
when is a neuron polarised
resting state
39
why is the resting potential polarised
imbalance between sodium and potassium ions
40
what maintains the resting potential
sodium potassium pump
41
direction of sodium ion movements at rest
pumped out the axon via sodium potassium pump
42
direction of potassium ion at rest
pumped into the axon via sodium potassium pump
43
why cant sodium ions move back into the axon at resting potential but potassium ones can
sodium channels are closed whereas potassium ones are open
44
what does the high concentration of sodium ions outside of the axon cause inside at resting potential
an electrochemical gradient as the potassium ions are permeable but sodium ions are not
45
what is the type of transport used for the sodium potassium pump and what does it need at resting potential
- active transport
-atp
46
myelin sheath
fatty substance that surrounds axon, becoming an electrically insulating layer
47
schwann cell
specialised cell found on axon
produces myelin sheath
48
node of ranvier
a gap of exposed membrane between myelin sheath
49
what is the resting potential
the difference in electrical charge across the membrane while the neuron is at rest
50
action potential
a rapid, temporary reversal of the electrical charge across a cell membrane (depolarization), allowing neurons and muscle cells to transmit signals
51
what are the steps in creating an action potential
-at resting potential k+ channels open by Na+ channels close
-stimulus energy causes na+ channels to open so they diffuse in
-more na+ channels open so more can diffuse in
-once action potential is at 40 mv, na+ channels close and k+ channels open so they can diffuse out (repolarization of axon)
-outward diffusion of k+ causes inside of axon to be more negatively charged than usual (hyperpolarization)
-K+ gates close and sodium potassium pumps cause na+ to go out and k+ in.
-resting potential of 65mv is re established and axon is depolarized
52
when does summation happen
if a stimulus is weak and only a small amount of neurotransmitters will be released.
-this might not be enough to excite the postsynaptic membrane to threshold level and stimulate an action potential
53
spatial summation
2+ presynaptic neurons release their neurotransmitters at the same time onto a shared postsynaptic neuron.
this will be enough to reach the threshold to trigger an action potential
54
temporal summation
2+ nerve impulses arrive at cleft in quick succession to the same presynaptic neuron
makes action potential more likely as more neurotransmitters are released into synaptic knob.
they have to follow each other quickly, otherwise it'll be removed from cleft before it reached a high enough level to trigger action potential
55
myelinated axon
axon covered in myelin sheath
56
where will depolarisation occur in a myelinated axon vs an unmyelinated axon
myelinated axon- nodes of ranvier
unmyelinated axon- across the whole axon
57
what is saltatory conduction (happens in a myelinated axon)
the rapid, "jumping" propagation of action potentials along myelinated axons, where the signal skips between gaps in the myelin sheath called nodes of Ranvier
58
what factors affect nerve impulse transmission speed
myelinated axon diameter- wider is faster, narrower is slower
temperature- warmer is faster, colder is slower
59
what is the refractory period of generating an action potential
when axon cannot be depolarised to initiate new action potential as sodium channels enter recovery stage
ensures action potential only travels one way
60
roles of synapses
transmits signals between neurons
prevent action potentials going in wrong direction as neurotransmitters are only in pre and receptors are only on post
61
what is an inhibitory neurotransmitter and excitatory one
a chemical messenger that decreases a neuron's likelihood of firing an electrical signal (action potential), effectively slowing down or blocking nerve impulses
vice versa
62
how do nerve impulses move across the synapse
-nerve impulses arrive, presynaptic membrane depolarises causing calcium ion channels to open so ca+ enters.
-calcium ions allows vesicles to fuse with presynaptic membrane
-neurotransmitter released into cleft
-diffuses across cleft to postsynaptic and binds to receptors opening sodium ion channels so they can diffuse in
-new action potential created and the neurotransmitter is hydrolysed and sent back
63
tendons
non elastic tissue which connects muscle to bone
64
ligaments
elastic tissue that joins bones and determines how much movement
65
joints
the area where two bones attach, to allow movement
made of fibrous connective tissue and cartilage
66
antagonistic muscle pairs
pairs of muscles that pull in opposite directions, as one contracts the other relaxes
67
skeletal muscles
attached to bones via ligaments and filaments
they are grouped together to make a large strong structure that can contract efficiently
68
myofibrils
made from thick and thin ligaments which overlap to give banded
69
what is the thick ligaments made from in myosin
myosin
they have heads to attach to binding sites on actin when muscle is being contracted
70
what is the thin ligaments made from in myosin
actin
twisted together to make the filament
71
what is required for muscle contraction and how is it used
a lot of ATP
molecule of ATP is hydrolysed every time a myosin head moves and everytime a calcium ion is pumped back into the RER (high conc of Ca+ anyway)
72
where is ATP produced for muscle contraction
-aerobic respiration
-uses myoglobin to keep good oxygen supply
73
what molecule is used to provide phosphate for ADP phosphorylation so that atp can continue being made
phosphocreatine
74
what are muscles with slow twitch fibres
specialised for slow contractions and specialised to long periods of exercise
75
how are muscles with slow twitch fibres adapted to their function
large store of myoglobin
rich supply of blood vessels
lots of mitochondria
76
what are muscles with fast twitch fibres
adapted for rapid release of energy during intense exercise
77
how are muscles with fast twitch fibres adapted to their function
-thick and numerous myosin filaments
-high conc of glycogen
-high conc of enzymes for anaerobic respiration
-a store of phosphocreatine- ATP can be rapidly generated
78
what are the 7 steps in muscle contraction
1. Ca+ is released from sarcoplasmic reticulum
2.Ca+ in sacroplasm binds tropinin and exposes myosin binding sites on actin filament
3.myosin heads bind to actin, ADP produced
4.myosin heads change formation and filaments slide
5.ATP binds to myosin, releasing actin
6.ATP is hydrolysed, myosin back to normal position
8.if calcium is returned to sarcoplasmic reticulum muscles relax and cycle can repeat
79
what are the 3 processes the liver carries out in regulation of blood glucose
-glycogenesis
-glycogenolysis
-gluconeogenesis
80
what happens during glycogenesis in liver when regulating blood glucose
making glycogen from glucose released in blood
81
what happens during glycogenolysis in liver when regulating blood glucose
breaks down stored glycogen into glucose to release into blood
82
what happens during gluconeogenesis in liver when regulating blood glucose
synthesis from other molecules such as amino acids
83
what is the process if blood glucose conc is too high
1. detected by beta cells in pancreas (islets of langerhans)
2.insulin secreted by beta cells, inhibiting action of alpha cells
3.insulin travels to target cells
4.insulin binds to receptors on plasma membrane, causing vesicles with glucose transport proteins to fuse with membrane
5.increases permeability of cells to glucose, increasing uptake of glucose
6. converted to glycogen
84
what is the process when blood glucose concentration is too low
1. alpha cells in islets of langerhans in pancreas detect change and release glucagon
2.inhibits beta cells
3.glucagon stimulates hepatocytes to convert glycogen into glucose
4.glucose diffuses out of hepatocytes into blood
5.cells use fatty acids and amino acids for respiration instead
85
how is glycogen broken into glucose using secondary messenger adrenaline
1. adrenaline fuses to receptor of liver cell and causes it to change shape on the inside
2. activates enzyme adenylyl cyclase which converts ATP to cyclic AMP
3.the cAMP then changes shape and activates protein kinase enzyme which catalyses conversion of glycogen into glucose
86
type 1 diabetes
-occurs early in life and results in loss of insulin
-have to control their own glucose by self injecting
87
type 2 diabetes
-later in life
-decreased insulin production or glycoprotein receptors become unresponsive to insulin
-can be manipulated by diet and exercise
88
what does the outer fibrous capsule do in the structure of the kidney
protects the kidney
89
what does the renal pelvis do in the kidney
collects urine into ureter
90
what does the cortex layer include in structure of kidney
bowman's capsule
convoluted tubules
blood vessels
91
what is the medulla made from in structure of the kidney
-loops of henle
-collecting ducts
-blood vessels
92
ultrafiltration in kidney (step 1)
-blood enters kidney via renal artery
-divides into afferent arteriole and then capillaries called glomerulus
-water and soluble molecules forced out while larger ones cannot fit
-
93
selective reabsorption in kidney (step 2
-glucose reabsorbed by co transport from capillaries to blood
-actively transport sodium ions from epithelial cells to blood creating low conc in epithelial cell
-facilitated diffusion brings in glucose
-glucose diffuses into blood capillaries
-
94
loops of henle in kidney (step 3)
-sodium ions actively transported out of ascending limb by ATP
-low water potential between two limbs
-water moves from descending limb by osmosis into low water potential
-enter blood capillaries
95
Distal Convoluted Tubule and the Collecting Duct in kidneys (step 4)
-water naturally moves out of it by osmosis
-parallel to loops of henle so as you move down medulla ion conc increases
biology
flashcards
Decks in class (8)
# Cards
-
topic 2- cells111
-
topic 1- Biological Molecules130
-
topic 4- DNA, Genes And Chromosomes103
-
topic 3- gas exchange, digestion, mass transport93
-
topic 5- energy transfer in and between organisms60
-
Topic 6- organisms responses to changes internal and external enviroments by95
-
topic 7- genetics, populations, evolution and ecosystems61
-
topic 8- control of gene expression92
