Topic 5: Homeostasis Synapse Pathway (words)
Required Practical 7 Nerve impulses arrive at synapse
Required Practical 8 Neurotransmitter (chemical messenger) is
released into the synapse
Homeostasis: Neurotransmitter diffuses across the synapse
Maintenance of a constant internal Neurotransmitter binds with the receptor of
environment the membrane of the post-synaptic neuron
Keep out body at optimum conditions despite Binding of neurotransmitters to receptor
internal & external conditions for enzyme stimulates impulse in the post-synaptic neuron
control & cell functions
Factors affecting reaction time
Features of a nerve cell/neuron Age
Dendrites to contact other nerves at synapses Drugs
using neurotransmitters Alcohol
Long axon to transport electrical impulses to Neurological Disease
other nerve cells Tiredness
Large surface area Caffeine
Myelin sheath to insulate nerve impulses Stimulus
Mitochondria provides energy to make Distractions
neurotransmitters
The Brain
The nervous system Made up of neurons
2 parts: Part of the CNS w/ spinal cord
o Peripheral nervous system Cerebral cortex – consciousness, intelligence,
o Central nervous system – Brain & Spinal memory & language – top & front
Chord Cerebellum – controls muscle movement –
A response starts with a stimulus and a bottom & back
receptor Medulla – control unconscious actions e.g.
Stimulus: Detectable change in the breathing, digestions, heartbeat, in the
environment bottom stem
Pituitary Gland – hormones, little sticking out
Types of Neurons: at front of brain
3 types: Hypothalamus – temperature control, top of
o Sensory neuron: pituitary gland tube
E.g. the auditory or optic nerve Difficult to examine/study/treat brain:
o Interneuron (relay neuron): o Complex
Co-ordinates o Delicate/easily damaged
o Motor neuron: o Drugs can’t reach brain because of
Moving membrane around it
o Don’t know what part of the brain does
Reflexes VS Reactions: what
Reflexes are automatic responses to a Map out the brain by:
stimulus that protect us from harm. They are o Study patients with brain damage –
very fast and we don’t think about them. E.g. damage to a certain area of brain
fight or flight corresponds to damage elsewhere so
Reactions are thinking responses. you know what that part of the brain
does
Nervous Pathway: o Electrically stimulating parts of the brain
Stimulus Receptor Sensory Neuron (synapse) – pushing an electrode into the brain.
Interneuron (synapse) Motor Neuron Stimulation will cause a mental/physical
Effector Response change – to get info on the role of this
part
Synapses Pathway
o MRI Scanning – magnetic resonance
Electrical impulse Release of neurotransmitters
imaging scanner creates a map of the
Diffuse into the other neuron fits into the other
brain to show which part of the brain is
receptor (Specific & complimentary) electrical
active/affected by a tumour
impulse continues to post synaptic neuron
, o EEG Electroencephalogram – visual o Long-sightedness
record of electronic activity by neurons – o Focal point is too far
amplifies & detects electrical signals o Lens is too thin/eyeball is too
from the brain short/cornea is less curved
o Convex lenses - Move the focal point
The Eye forwards
Sensitive to light o Corrects hyperopia
Retina – layer of light sensitive cells found at Treatment:
the back of the eye o Generally these defects are treated with
Fovea – focal point – light should hit here spectacle lenses which refract the light
Optic nerve – sends signals to the brain from rays so that they do focus on the retina
eye o New technologies now include hard and
Sclera – Strong white outer layer that soft contact lenses, laser surgery to
supports the structure of the eye & prevents change the shape of the cornea and a
damage replacement lens in the eye.
Cornea – Curved transparent at the front of Endocrine System:
the eye to refract light Pituitary Gland – master gland that secretes
Iris – Muscles that control the size of the pupil hormones
Ciliary muscles & Suspensory ligaments – hold Pancreas – secretes insulin and glucagon to
the lens in place & controls its shape control blood glucose
(antagonistic muscles – muscles with opposite Thyroid – secretes thyroxine to control
effect) metabolic, heart rate & temperature
Pupil Reflex: (Thyroxine from the thyroid gland stimulates
o Too much light the basal metabolic rate. It plays an important
Damage to light sensitive cells role in growth and development)
Circular muscles contract Adrenal Gland – secretes adrenaline for fight
Radial muscles relax or flight (Adrenaline is produced by the
Pupil constrict adrenal glands in times of fear or stress. It
o Too less light increases the heart rate and boosts the
Not enough stimulus to cells delivery of oxygen and glucose to the brain
Circular muscles relax and muscles, preparing the body for ‘flight or
Radial muscles contract fight’)
Pupil dilate Oestrogen – secretes oestrogen for the
Accommodation – The process of the eye menstrual cycle & for secondary sex
changing shape to focus on a near of distant characteristics
object Testes – secretes testosterone for the sperm
o Near Object & for secondary sex characteristics
Ciliary muscles contract Works slower than nervous system but acts
Suspensory ligaments loosen longer
Lens is thicker + more curved = Blood transports hormone to target
refract light rays strongly organ/tissue
o Far Object Endocrine – secrets chemicals inside body
Ciliary muscles loosen Exocrine – secretes chemicals outside body
Suspensory ligaments tighten Control of Body Temperature:
Lens is thinner = refract light rays 37°C – optimum temperature
weakly Too hot – enzymes denature
Myopia: Too cold – enzymes work too slowly
o Short-sightedness Monitored & controlled by the
o Focal point is too short thermoregulatory centre in the brain
o Lens is too curved/eyeball is Blood goes through the thermoregulatory
too wide/cornea is too centre in the brain (hypothalamus) and it
curved monitors the body temp by sensing the blood
o Concave lenses - Moves the temp
focal point backwards External surface temperature is monitored by
o Corrects myopia receptors in the skin that send impulses to the
thermoregulatory centre
Hyperopia:
Required Practical 7 Nerve impulses arrive at synapse
Required Practical 8 Neurotransmitter (chemical messenger) is
released into the synapse
Homeostasis: Neurotransmitter diffuses across the synapse
Maintenance of a constant internal Neurotransmitter binds with the receptor of
environment the membrane of the post-synaptic neuron
Keep out body at optimum conditions despite Binding of neurotransmitters to receptor
internal & external conditions for enzyme stimulates impulse in the post-synaptic neuron
control & cell functions
Factors affecting reaction time
Features of a nerve cell/neuron Age
Dendrites to contact other nerves at synapses Drugs
using neurotransmitters Alcohol
Long axon to transport electrical impulses to Neurological Disease
other nerve cells Tiredness
Large surface area Caffeine
Myelin sheath to insulate nerve impulses Stimulus
Mitochondria provides energy to make Distractions
neurotransmitters
The Brain
The nervous system Made up of neurons
2 parts: Part of the CNS w/ spinal cord
o Peripheral nervous system Cerebral cortex – consciousness, intelligence,
o Central nervous system – Brain & Spinal memory & language – top & front
Chord Cerebellum – controls muscle movement –
A response starts with a stimulus and a bottom & back
receptor Medulla – control unconscious actions e.g.
Stimulus: Detectable change in the breathing, digestions, heartbeat, in the
environment bottom stem
Pituitary Gland – hormones, little sticking out
Types of Neurons: at front of brain
3 types: Hypothalamus – temperature control, top of
o Sensory neuron: pituitary gland tube
E.g. the auditory or optic nerve Difficult to examine/study/treat brain:
o Interneuron (relay neuron): o Complex
Co-ordinates o Delicate/easily damaged
o Motor neuron: o Drugs can’t reach brain because of
Moving membrane around it
o Don’t know what part of the brain does
Reflexes VS Reactions: what
Reflexes are automatic responses to a Map out the brain by:
stimulus that protect us from harm. They are o Study patients with brain damage –
very fast and we don’t think about them. E.g. damage to a certain area of brain
fight or flight corresponds to damage elsewhere so
Reactions are thinking responses. you know what that part of the brain
does
Nervous Pathway: o Electrically stimulating parts of the brain
Stimulus Receptor Sensory Neuron (synapse) – pushing an electrode into the brain.
Interneuron (synapse) Motor Neuron Stimulation will cause a mental/physical
Effector Response change – to get info on the role of this
part
Synapses Pathway
o MRI Scanning – magnetic resonance
Electrical impulse Release of neurotransmitters
imaging scanner creates a map of the
Diffuse into the other neuron fits into the other
brain to show which part of the brain is
receptor (Specific & complimentary) electrical
active/affected by a tumour
impulse continues to post synaptic neuron
, o EEG Electroencephalogram – visual o Long-sightedness
record of electronic activity by neurons – o Focal point is too far
amplifies & detects electrical signals o Lens is too thin/eyeball is too
from the brain short/cornea is less curved
o Convex lenses - Move the focal point
The Eye forwards
Sensitive to light o Corrects hyperopia
Retina – layer of light sensitive cells found at Treatment:
the back of the eye o Generally these defects are treated with
Fovea – focal point – light should hit here spectacle lenses which refract the light
Optic nerve – sends signals to the brain from rays so that they do focus on the retina
eye o New technologies now include hard and
Sclera – Strong white outer layer that soft contact lenses, laser surgery to
supports the structure of the eye & prevents change the shape of the cornea and a
damage replacement lens in the eye.
Cornea – Curved transparent at the front of Endocrine System:
the eye to refract light Pituitary Gland – master gland that secretes
Iris – Muscles that control the size of the pupil hormones
Ciliary muscles & Suspensory ligaments – hold Pancreas – secretes insulin and glucagon to
the lens in place & controls its shape control blood glucose
(antagonistic muscles – muscles with opposite Thyroid – secretes thyroxine to control
effect) metabolic, heart rate & temperature
Pupil Reflex: (Thyroxine from the thyroid gland stimulates
o Too much light the basal metabolic rate. It plays an important
Damage to light sensitive cells role in growth and development)
Circular muscles contract Adrenal Gland – secretes adrenaline for fight
Radial muscles relax or flight (Adrenaline is produced by the
Pupil constrict adrenal glands in times of fear or stress. It
o Too less light increases the heart rate and boosts the
Not enough stimulus to cells delivery of oxygen and glucose to the brain
Circular muscles relax and muscles, preparing the body for ‘flight or
Radial muscles contract fight’)
Pupil dilate Oestrogen – secretes oestrogen for the
Accommodation – The process of the eye menstrual cycle & for secondary sex
changing shape to focus on a near of distant characteristics
object Testes – secretes testosterone for the sperm
o Near Object & for secondary sex characteristics
Ciliary muscles contract Works slower than nervous system but acts
Suspensory ligaments loosen longer
Lens is thicker + more curved = Blood transports hormone to target
refract light rays strongly organ/tissue
o Far Object Endocrine – secrets chemicals inside body
Ciliary muscles loosen Exocrine – secretes chemicals outside body
Suspensory ligaments tighten Control of Body Temperature:
Lens is thinner = refract light rays 37°C – optimum temperature
weakly Too hot – enzymes denature
Myopia: Too cold – enzymes work too slowly
o Short-sightedness Monitored & controlled by the
o Focal point is too short thermoregulatory centre in the brain
o Lens is too curved/eyeball is Blood goes through the thermoregulatory
too wide/cornea is too centre in the brain (hypothalamus) and it
curved monitors the body temp by sensing the blood
o Concave lenses - Moves the temp
focal point backwards External surface temperature is monitored by
o Corrects myopia receptors in the skin that send impulses to the
thermoregulatory centre
Hyperopia:
