Nervous System & Homeostasis The effector(s) = body systems or body
functions
1. Define homeostasis & other body 1. Function: actions will change the variable in
components that regulate organ responses question
2. Describe structural divisions of the nervous (e.g., blood flow in skin is an effector à may
system. increase or decrease to control temperature)
3. Describe the structure & function of CNS
including structural divisions of the brain & Receptors
spinal cord.
4. Describe the major nerves in PNS and where Homeostasis is monitored by
they originate receptors: detect the levels in the
body. (e.g., blood pressure, sensors –
Homeostasis 1 outside heart and @ carotid)
Homeostasis: body’s ability to maintain Feedback loops: detection, processing
relatively stable/constant internal all sensory information, producing
environment with relation to outside response on about where things
environment. need to be changes (feedback loop)
Changes in external OR internal conditions Sensors: detect what’s going on in body (can
challenge homeostasis. be specialised to an area)
Homeostatic range exists, rather than a specific Integration centre: receives & produces
set point (e.g., core temp btwn. 36.5 and 37.8 °C) signals to maintain homeostasis
and this range can shift. Effectors: carry out change
A dynamic state of equilibrium or balance exists. These don’t always work together, sometimes
(i.e., the value will ↓ ↑ within this range), ranges only the sensors and effectors may work together
can be set or shiftable etc.
Communication within the body Sometimes these parts are all in one organ.
Positive & negative feedback
Nervous system: (electrical impulses)
Endocrine system: (chemical messengers : Negative Feedback 🙋IMPORTANT
hormones) Negative feedback loop: opposes detected
change by adjusting, and ceasing when set point
① Control mechanisms – maintaining is reached.
homeostasis.
💡 Bathtub doesn’t have 50mL of water, Eyes
Variable: is the factor or event being sense this. Brain integrates decides you need to
regulated. plug hole and put more water. Muscles are
Receptor = the sensor effector. Continue sensing – once reached desired
1. Monitors environment level you will turn the taps off!
2. Responds to changes (stimuli) Positive Feedback
3. Sends information to control centre
Positive feedback loop: Reinforces change to
Control centre = an integration point (e.g., a continue or accelerate an effect.
region of the brain) 💡 Blood clotting, at site of injury blood will
1. Analyses input from the receptor(s) simply continue clotting until hole is completely
(sensor(s)) sealed.
2. Sends signals to the effectors
REVISION – RECEPTORS IN SKIN
, Mechanoreceptors: detect sensation in the pancreas & & intestines
skin. intestines
Thermoreceptors: detect temperature Saliva flow ↓inhibits saliva ↑stimulates saliva
flow flow
Receptor adaptation: all receptors other than Pupils ↑Dilates ↓ Constricts
nociceptors will adapt to sensation overtime Bladder ↓ Inhibits ↑ contracts
to avoid sensory overload (e.g., certain bladder bladder
contraction
sounds will ‘fade out’ if you don’t pay
Chemical Adrenaline Bile release (GST)
attention to them)
messages Glycogen to
Structure of The Nervous System glucose
Central nervous system: brain & spinal cord.
Communicates instructions to effectors (PNS) The brain & spinal cord
via motor neurons.
Structures in the brain
Anything coming out of the central nervous Brain: A dense collection of neurons found in
system is motor, as it will affect other things. the cranial cavity (skull). Bathed in
Integration centre. cerebrospinal fluid. Shock absorbs mechanical
force) to create space between the brain &
💡 Motor causes movement – just like boat skull. Surrounded by blood vessels for
motor. nourishment & the meninges.
Peripheral nervous system: Has a sensory
and motor arm. Meninges: layer of connective tissue
Nerve cells: technically an organ as it has surrounding brain.
supporting cells.
White matter:(corpus callosum) middle,
cabling, sending signals to grey matter or
taking information from.
Grey matter: outside is the integration centre
any signals conducted goes to white matter,
its grey when blood is removed.
Cerebrospinal fluid
Ventricles: found in the brain, forms
cerebrospinal fluid by filtering blood (CSF:
modified plasma)
Cerebrospinal fluid: bathes, nourishes,
supports, and protects the brain. Also in the
spinal cord, bathing nerves.
The spinal cord
Function Sympathetic NS Parasympathetic Spinal cord:
NS - Brain VS spinal cord: organisation internal
Heart rate ↑ HR ↓Slows HR - Encased in the spinal column.
Blood pressure ↑Increases ↓Reduces
- Protected by the meninges.
Circulation ↑Increased ↓Decreased
- Grey matter is internal and white matter is
Respiration ↑Dilates ↓Constricts
external.
bronchi bronchi
Gastrointestinal ↑stimulates ↑stimulates
system stomach, stomach, pancreas
functions
1. Define homeostasis & other body 1. Function: actions will change the variable in
components that regulate organ responses question
2. Describe structural divisions of the nervous (e.g., blood flow in skin is an effector à may
system. increase or decrease to control temperature)
3. Describe the structure & function of CNS
including structural divisions of the brain & Receptors
spinal cord.
4. Describe the major nerves in PNS and where Homeostasis is monitored by
they originate receptors: detect the levels in the
body. (e.g., blood pressure, sensors –
Homeostasis 1 outside heart and @ carotid)
Homeostasis: body’s ability to maintain Feedback loops: detection, processing
relatively stable/constant internal all sensory information, producing
environment with relation to outside response on about where things
environment. need to be changes (feedback loop)
Changes in external OR internal conditions Sensors: detect what’s going on in body (can
challenge homeostasis. be specialised to an area)
Homeostatic range exists, rather than a specific Integration centre: receives & produces
set point (e.g., core temp btwn. 36.5 and 37.8 °C) signals to maintain homeostasis
and this range can shift. Effectors: carry out change
A dynamic state of equilibrium or balance exists. These don’t always work together, sometimes
(i.e., the value will ↓ ↑ within this range), ranges only the sensors and effectors may work together
can be set or shiftable etc.
Communication within the body Sometimes these parts are all in one organ.
Positive & negative feedback
Nervous system: (electrical impulses)
Endocrine system: (chemical messengers : Negative Feedback 🙋IMPORTANT
hormones) Negative feedback loop: opposes detected
change by adjusting, and ceasing when set point
① Control mechanisms – maintaining is reached.
homeostasis.
💡 Bathtub doesn’t have 50mL of water, Eyes
Variable: is the factor or event being sense this. Brain integrates decides you need to
regulated. plug hole and put more water. Muscles are
Receptor = the sensor effector. Continue sensing – once reached desired
1. Monitors environment level you will turn the taps off!
2. Responds to changes (stimuli) Positive Feedback
3. Sends information to control centre
Positive feedback loop: Reinforces change to
Control centre = an integration point (e.g., a continue or accelerate an effect.
region of the brain) 💡 Blood clotting, at site of injury blood will
1. Analyses input from the receptor(s) simply continue clotting until hole is completely
(sensor(s)) sealed.
2. Sends signals to the effectors
REVISION – RECEPTORS IN SKIN
, Mechanoreceptors: detect sensation in the pancreas & & intestines
skin. intestines
Thermoreceptors: detect temperature Saliva flow ↓inhibits saliva ↑stimulates saliva
flow flow
Receptor adaptation: all receptors other than Pupils ↑Dilates ↓ Constricts
nociceptors will adapt to sensation overtime Bladder ↓ Inhibits ↑ contracts
to avoid sensory overload (e.g., certain bladder bladder
contraction
sounds will ‘fade out’ if you don’t pay
Chemical Adrenaline Bile release (GST)
attention to them)
messages Glycogen to
Structure of The Nervous System glucose
Central nervous system: brain & spinal cord.
Communicates instructions to effectors (PNS) The brain & spinal cord
via motor neurons.
Structures in the brain
Anything coming out of the central nervous Brain: A dense collection of neurons found in
system is motor, as it will affect other things. the cranial cavity (skull). Bathed in
Integration centre. cerebrospinal fluid. Shock absorbs mechanical
force) to create space between the brain &
💡 Motor causes movement – just like boat skull. Surrounded by blood vessels for
motor. nourishment & the meninges.
Peripheral nervous system: Has a sensory
and motor arm. Meninges: layer of connective tissue
Nerve cells: technically an organ as it has surrounding brain.
supporting cells.
White matter:(corpus callosum) middle,
cabling, sending signals to grey matter or
taking information from.
Grey matter: outside is the integration centre
any signals conducted goes to white matter,
its grey when blood is removed.
Cerebrospinal fluid
Ventricles: found in the brain, forms
cerebrospinal fluid by filtering blood (CSF:
modified plasma)
Cerebrospinal fluid: bathes, nourishes,
supports, and protects the brain. Also in the
spinal cord, bathing nerves.
The spinal cord
Function Sympathetic NS Parasympathetic Spinal cord:
NS - Brain VS spinal cord: organisation internal
Heart rate ↑ HR ↓Slows HR - Encased in the spinal column.
Blood pressure ↑Increases ↓Reduces
- Protected by the meninges.
Circulation ↑Increased ↓Decreased
- Grey matter is internal and white matter is
Respiration ↑Dilates ↓Constricts
external.
bronchi bronchi
Gastrointestinal ↑stimulates ↑stimulates
system stomach, stomach, pancreas
