UNIT 14 Coordination and response Flashcards
electrical impulses travel along
neurones (nerve cells)
electrical impulses- sent through nerves to quickly send signals around our body
used for
rapidly coordinating or regulating the body’s functions
immediate short term change: nerves
delayed, long term change: hormones used
automatic nervous system examples:
WHILE, sympathetic division: WHAT IS IMPORTANT FOR THIS, immediate changes
pupils constrict, salivation, heat rate slows, stomach digests
;; pupils dilate, bladder relaxes, kidneys release adrenaline
what is a nerve
a bundle of neurons
mammalian nervous system
made of
1) the central nervous system (CNS) consisting
of the brain and the spinal cord
2) the peripheral nervous system (PNS) consisting of the nerves outside of the brain
and spinal cord
role of the nervous system
coordination and regulation of body functions
Neuron Structure
Dendrites
Dendrites RECEIVE SIGNALS from surrounding neurons
- are branched to allow connections with many neurons
Axon
Axon is a long structure off the cell body that electrical signals can be rapidly sent through
- its long length allows for signals to be sent rapidly
axon terminal
where the signal is passed to the next neuron over the synapse (the gap between these nerves)
branched so can make connections with other nerves
nerve signals
nerve signals are ALWAYS sent one-way
down towards the nerve ending
Identify in diagrams and images sensory, relay
and motor neurones
sensory: have their cell body half way down the axon
relay: have a short axon (as they are not sending signals long distances)
motor: have the cell body at the end with the dendrites
a reflex action
a means of
automatically and rapidly integrating and
coordinating stimuli with the responses of
effectors (muscles and glands)
never signals are sent
through reflex responses
explain: A STIMULUS (e.g. pain, smell, taste, visual, chemical) is received by a receptor
Sensory neurons…
Sensory neurons pass these signals/impulses [from the receptor] back to RELAY neurons in the CNS
The relay neuron
The relay neuron sends this signal on to the motor neuron
The motor neuron
The motor neuron sends the signal to an effector organ
(usually a muscle or gland)
which is then stimulated to respond
reflexes
reflexes allow us to respond to stimuli extremely fast without conscious thought (i.e. the signal does not need to be interpreted by the brain)
so
sensory -> relay -> motor
SRM
synapse
a junction between two
neurones
synapses ensure that impulses travel in one direction only
Describe the structure of a synapse
the presence of vesicles containing neurotransmitter molecules:
the synaptic gap:
receptor proteins:
Describe the events at a synapse
(a) an impulse [travelling along first axon] stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap
(b) the neurotransmitter molecules diffuse across the gap
(c) neurotransmitter molecules bind with receptor proteins on the next neurone
(d) an impulse is then stimulated in the next neurone
📍 neurotransmitters are then recycled or destroyed once an impulse is sent [[to prevent continued stimulation of the second neurone which would cause repeated impulses to be sent]]
As this is the only part of the nervous system where messages are chemical as opposed to electrical, it is the only place where …
only place where drugs can act to affect the nervous system
effector organ desponds to stimulus
in this case by contracting the bicep and relaxing the tricep, moving hand away from hot pot
3 examples of effector organ
- any muscle or gland
- bicep
- tricep
- quadricep
structure to follow on effect [5 marks]
📍 Pain receptors on Mr Baker’s skin were activated due to the stimulus of the [hot pot/pin, etc]
📍 Signal transmitted from receptor to the sensory neuron. The sensory neuron passes the signal from the receptor back to the relay neurons in the CNS
📍 The relay neurons passes the signal on to motor neurons
📍 The motor neurons send the electrical signal on to an effector organ (e.g., bicep, tricep, calf muscles, etc.)
📍 Effector organ (& muscles) responds to the stimulus (e.g. by contracting bicep, relaxing tricep, moving hand away from hot pot/move away from and off the pin), taking weight off leg
fovea
- tiny pit in retina
- highest concentration of cone cells - no rods, only cones
- provides CLEAREST vision of all;;;
most in focus of vision (light perfectly lines up; most light accesses these cells at this time) - eye lens will focus light on to the fovea
Sense organs -
- Optic nerve
Sends nerve signals from the rod and cone cells in the retina to the brain
Retina
Is where light is focused in the eye. It contains light sensitive rox and cone repector cells
Iris
Is the coloured part of the eye which affects the size of the pupil
Lens
Is able to change shape to focus light onto the retina
Pupil
Is the opening in the eye which allows light to enter.
cornea
Is the curved part of the eye which refracts light as it enters.
suspensory ligaments
Attaches the lens to the ciliary muscles
ciliary muscles
They contract or relax to make the suspensory ligaments go slack or tight respectively,
therefore changing the shape of the lens
Describe sense organs as…
groups of receptor cells
responding to specific stimuli: light, sound, touch,
temperature and chemicals
Identify in diagrams and images the structures of
the eye, limited to: cornea, iris, pupil, lens, retina,
optic nerve and blind spot
Describe the function of each part of the eye
a)
a) cornea - refracts light
b) iris –
iris: controls how much light enters the
pupil
(c) lens –
lens: focuses light on to the retina
[changes shape to alter direction of light rays passing through eye]
retina –
retina: contains light receptors, some
sensitive to light of different colours
part of eye where light rays form an image
e) optic nerve
carries impulses to the brain
Steps: How an impulse is passed on at a synapse
1.
an impulse arrives at the end of the presynaptic neurone
2.
vesicles move towards and fuse with the presynaptic membrane. this releases neurotransmitters into the synaptic cleft
3.
the neurotransmitters diffuse across the synaptic cleft (down a concentration gradient)
4.
neurotransmitters attach to receptors on the postsynaptic membrane
5.
this triggers an impulse which travels along the postsynaptic neurone
6.
the neurotransmitters are recycled or destroyed once an impulse is sent
Controlling light - IRIS REFLEX [RESPONSE]
Radial muscles do what in low light?
in LOW light, RADIAL muscles contract so pupil appears larger;
dilates
circular muscles do WHAT in bright light?
CIRCULAR muscles contract in BRIGHT light so pupil appears smaller;
constricts
e.g.s of reflex response
iris response, touching something hot/pain response
miosis - constriction [becomes shorter]
circular muscle constricts when our pupil constricts and becomes smaller
in bright light
mydriasis - dilation
radial muscle constricts when pupil dilates
in dimness
RMCPDD
(radial muscle constricts pupil dilates dimness)
bright light
walking into brightly lit room, my iris would work to REDUCE the amount of light able to enter my eye
would happen as the CIRCULAR muscles in the iris CONSTRICT, pupil SMALLER, so LESS light would enter the eye
means light sensitive cells of the retina would have an appropriate amount of light to be able to send impulses to the brain along the optic nerve to form the image seen
rod cells
- detect differences in light intensity
- do not detect colour
- used extensively in dim light
cone cells
C FOR COLOUR
- detect differences in colour
- different cones detect red/blue/green
info is carried by
info is carried by sensory neurons to the occipital lobe, is processed
red, green and blue cones work together to allow us to perceive a range of colours
refraction [light bent from original direction depending on wl]
reflection [light appears to bounce off surface; all wl’s affected equally]
HORMONES - define
a chemical substance, produced by a gland and carried by the blood,
which alters the activity of one or more specific target organs
glucagon is secreted by the pancreas
AND
(pancreas produces insulin + hormones to regulate blood glucose levels + digestive enzymes e.g. amylase & lipase)
pancreas: glucagon AND insulin
glucagon
- secreted from pancreas
- causes liver to break down glycogen into glucose and release it into bloodstream
- this hormone is used when our blood sugar levels are low but we are not in a fight or flight situation
insulin
- secreted from pancreas
- causes liver to absorb glucose FROM bloodstream & convert it to glycogen for later use
- used when our blood sugar levels are high
endocrine vs exocrine glands
endocrine-
endocrine glands secrete substances into your bloodstream (e.g. pituitary gland: master gland situated at BASE OF BRAIN)
exocrine glands
secrete substances on to the surface of your body (e.g. sweat or salivary glands)
pituitary gland
releases ADH
adrenal glands - next to kidneys
produce
produce adrenaline
adrenaline
- secreted from adrenal gland
- causes liver to break down glycogen & release glucose into bloodstream
testes
produce testosterone (male sex hormone)
ovaries
produce oestrogen (female sex hormone)
adrenaline has evolved for
so adrenaline is…
fight or flight situations
the hormone secreted in
‘fight or flight’ situations
effects of adrenaline
(a) increased breathing rate
(b) increased heart rate
(c) increased pupil diameter
the role of adrenaline in the control of
metabolic activity
“replace products for respiration”
(a) increasing the blood glucose concentration ;; glucose released from liver
(b) increasing heart rate
Nerves
electrical
Sends signals fast through neurons
effect is short-term (muscle contractions/gland secretions)
Hormones
chemical
Send signals slowly through bloodstream
With reference to the pancreas and liver, describe the role of insulin in controlling blood glucose levels [4]
ref. to blood sugar level being high ;
(insulin) secreted by pancreas ;
passes in blood stream + to liver ;
stimulates liver to absorb glucose ;
converts glucose to glycogen ;
Explain what would happen to the insulin in the stomach if it was swallowed as a tablet.
ref. to being digested / broken down ;
by protease / pepsin
state the type of neurone that stimulates effectors
motor
state 2 stimuli that can be detected by receptors in the finger
pain
heat
using labels from fig, state SITE OF CELL BODY OF
- a sensory neuron
- a relay neuron
- sensory = GANGLION
- relay = GREY MATTER (of spinal cord)
light passes thru parts of eye to reach retina
complete => show correct order that light passes through them
cornea => aqueous humour => pupil => lens => vitreous humour => retina
retina contains rods and cones
distinguish btwn rods and cones
type of light detected? distribution in the retina?
rods: low light intensity/dim light. rod cells spread over retina
cones: differences in colour. cones are focused in the fovea.
before entering dark room pupil is normal sized
after entering dark room,
pupil dilates
explain how size of pupil was changed when Jasmine went into the dark room [2]
(pupil gets bigger)
radial muscles contract
circular muscles relax
explain why Jasmine could see shapes but not colours in the dark room [3]
role of rods is to detect black and white images
sensitivity even in low light intensities
role of cones in detecting colour
cones need high light intensity to trigger them
suggest & explain what the light conditions were when the photograph was taken
light conditions: bright
explanation: small pupils
explain importance of eyes reacting to light in this way
- less light enters the eyes
- retina protected from damage
why lion not see colour
no cones present
describe how eyes of lion adjust to focus on the zebras
- image of zebras on retina
- ciliary muscles relax
- suspensory ligaments becomes taut
- lens made thin
- less refraction of light
X is a circular muscle.
What effect does it have when it contracts?
circular contracts = reduces pull = curve inc!!!!
+ size of the pupil decreases
reduces the pull on the lens, increasing its curvature
part prevents the internal reflection of light in the eye?
Choroid
btwn sclera and retina on outer layer (2nd layer)
In what form are impulses transmitted in the nervous system?
electrical ;
State the structure, present in many mammalian neurones, which reduces leakage
of the impulse.
myelin
Ahmed was provided with several young plant shoots and a sample of auxin.
(ii) Describe an experiment he could carry out to show that auxin causes bending of a shoot. [4]
📍 paint auxin on one side of shoot ;
📍 place shoot in a dark place AW ;
📍 leave 1 to 3 days
📍 ref. to control without auxin ;
📍 ref. to repeats used ;
Explain the mechanism that results in a shoot bending towards light. [3]
auxin accumulates on shaded side of shoot;
difference in concentrations on shaded side and light side ;
cells with higher concentration of auxin absorb more water ;
causes unequal growth ;
Synthetic plant hormones behave in a similar way to auxins. Describe how synthetic
plant hormones are effective as weedkillers. [2]
plants stimulated to grow rapidly
root growth inhibited by high concentrations of auxin ;
so plants die
Suggest the path the spray would take from the mouth to enter the alveoli.
trachea / windpipe → bronchus → bronchiole
Suggest the process by which the insulin would pass from the alveoli into the
bloodstream.
diffusion
State three features of the alveoli that might help the insulin to pass into the blood
stream efficiently.
thin walls / walls one cell thick ;
large surface area ;
large numbers of alveoli
motor neuron, away from spinal cord
person looks at an object which is close to their eye
suspensory
ligaments slacken,
lens fattens
CLOSE. ..!!
