Nervous System Anatomy
Tuesday, 22 April 2025 12:22 PM
Activity 1: Science 4 Fun
The pupils constrict due to the light being reintroduced to the retina. This happens so your eyes can
get the best amount of light needed to produce a clear image.
Quiz
1. Centeral and Peripheral Nervous System
2. Afferent nerves carry information to the CNS while efferent nerves carry information
outwards.
3. The somatic nervous system communicates mostly with muscle fibres to carry out voluntary
actions
4. Fight or Flight is controlled by the SNS while the Rest and Digest is controlled by the PSNS
Class Notes Page 1
,Notes
Tuesday, 22 April 2025 12:29 PM
The nervous system
• A communication network that controls all other systems in the body
• Is made up of 2 major parts
○ Central Nervous System (CNS)
▪ The CNS is made up of the brain and the spinal cord
▪ It receives information throughout the whole body, processes that information
and then sends out messages telling the body how to respond
▪ The brain is connected to the spinal cord through the brainstem
▪ The spinal cord carries signals back and forth between the brain and PNS
○ Peripheral Nervous System (PNS)
▪ The PNS is made up of the nerves that carry messages to and from the CNS and
other parts of your body
▪ Made up of sensory receptors and nerves
▪ Is divided into 2 parts
□ Somatic Nervous System (voluntary) (SNS)
Responsible for transmitting sensory information and voluntary
information
Contains 2 major types of neurons (nerve cells) ◊
◊ Sensory neurons
Takes sensory information and sends it to the CNS
◊ Motor neurons
Carry messages from the CNS to muscle fibres
□ Autonomic Nervous system (involuntary) (ANS)
Regulates involuntary bodily functions such as;
◊ Blood flow
◊ Heartbeat
◊ Digestion
◊ Breathing
Is divided into 2 components
◊ Sympathetic system
Regulates the fight or flight response
◊ Parasympathetic system
Maintains normal bodily functions (rest and digest)
Neurons
• The nervous system is made up of trillions of nerve cells called neurons
• Neurons are specialised cells that transmit electrical messages from one part of the body to
the other
• The electrical impulses are called nerve impulses, and they can only travel in one direction
• A neuron is made up of many parts
○ Neurons have a nucleus, a cell membrane, cytoplasm, dendrites, an axon and axon
terminals
▪ The cell body contains the nucleu
▪ The dendrites receive messages from other nerve cells
▪ The axon sends nerve impulses in one direction
▪ Axon terminals pass the message to the next neuron
• There are 3 types of neurons
○ Motor neurons
▪ Carry messages from the CNS to muscles and glands translating the signal to an
action
○ Connector neurons
▪ Transmits messages between neurons in the CNS
○ Sensory neurons
▪ Carry messages to the brain and spinal cord from cells in the sensory organs
▪ Have specialised receptors which are sensitive stimuli
How do neurons work?
1. An Action Potential is produced in the cell body.
○ Inside all cells there is a resting voltage
○ When the cell wants to increase the voltage to a threshold voltage the cell membrane
becomes more permeable to sodium. This means that sodium enters the cell which
makes the cell more positive. After the threshold voltage was been met then the cell
membrane becomes more permeable to potassium, which decreases the voltage
back to the resting voltage.
2. Action Potential is sent along the axon.
3. The electrical signal (action potential) activates neurotransmitters.
4. Neurotransmitters cross from one neuron to the next across the synapse.
○ The neurotransmitters recalibrate the signal for the next neuron so the signal doesn't
distort or weaken.
5. The neurotransmitters attach to the dendrites of the next neuron which triggers the next
action potential.
Homeostasis
• Homeostasis is the body's ability to regulate and maintain a stable condition within itself,
regardless of changes to the external environment.
• A constant internal environment needs to be maintained to keep an organism healthy and
functional.
○ The body functions best within an optimal range. Beyond this range, the body begins
to experience stress.
○ If a factor deviates further from the optimal range, it enters a zone of intolerance,
which can lead to illness or even death.
• Stimulus response model
○ Stimulus
▪ Any change in an organism's environment -- internal or external -- that causes
the organism to react
○ Receptor
▪ A receptor is any part of the body that can receive information from a stimulus
□ Photo
Light
□ Chemo
Chemical
□ Mechano
Touch
□ Noci
Pain
□ Thermo
Temperature
○ Coordination centre
▪ Receives information from the receptor, processes information and then
coordinates a response
○ Effector
▪ An effector is a muscle or gland that works to return the body to the optimal
range
○ Response
▪ Response is the reaction to the stimulus. It is the overall result that the
coordination centre and the effector worked to achieve.
Brain
• 2 main parts
○ Cerebellum
▪ Fine motor skills
○ Cortex
▪ Frontal
□ Rational Thoughts and Behaviour
▪ Temporal
□ Auditory and Balance
▪ Parietal
□ Sensation and Movement
▪ Occipital
□ Vision
▪ Brainstem
□ Critical involuntary processes
Endocrine System
• The endocrine system is a communication system that controls the internal environment of
the body using hormones
• Hormones are the chemical messengers in the body.
• They are produced by the endocrine glands
○ Pituitary
▪ Master gland
□ Growth
□ Water balance
○ Thalamus
▪ Master gland
○ Hypothalamus
▪ Master gland
○ Thyroid
▪ Mental growth
▪ Physical growth
○ Parathyroid
▪ Calcium levels
○ Pancreas
▪ Sugar levels
○ Adrenal
▪ Adrenalin
○ Ovaries and Testes
▪ Sex hormones
• The endocrine system is a slower process than the nervous system but the endocrine
system is more sustained.
Endotherm vs Ectotherm
• Endotherm
○ Inside Temperature
○ Endotherms can regulate their own temperature.
▪ Internal temp stays relitavly constant
• Ectotherm
○ Outside Temperature
○ Ectotherms cannot regulate their own temperature.
▪ Outside environment controls individuals temperature.
Class Notes Page 2
,Class Notes Page 3
, Quiz
Wednesday, 7 May 2025 10:58 AM
2. The temporal lobe receives the vibrations from the ear and transforms that into sounds which can
then be deciphered. Another part of it also controls your speech.
3.
a. Thermoreceptor - temperature
b. Photoreceptor - light
c. Mechanoreceptor - touch
d. Noci receptor- pain
e. Chemoreceptor - chemical
4.
a. Stimulus
b. Receptor
c. Afferent nerves
d. Spinal nerve
e. Control centre
f. Spinal nerve
g. Efferent nerves
h. Effector
i. Response
5. The brain and the spinal column
6. A gland, muscle, organ or organ system. The muscles beneath your hair follicles.
Class Notes Page 4
Tuesday, 22 April 2025 12:22 PM
Activity 1: Science 4 Fun
The pupils constrict due to the light being reintroduced to the retina. This happens so your eyes can
get the best amount of light needed to produce a clear image.
Quiz
1. Centeral and Peripheral Nervous System
2. Afferent nerves carry information to the CNS while efferent nerves carry information
outwards.
3. The somatic nervous system communicates mostly with muscle fibres to carry out voluntary
actions
4. Fight or Flight is controlled by the SNS while the Rest and Digest is controlled by the PSNS
Class Notes Page 1
,Notes
Tuesday, 22 April 2025 12:29 PM
The nervous system
• A communication network that controls all other systems in the body
• Is made up of 2 major parts
○ Central Nervous System (CNS)
▪ The CNS is made up of the brain and the spinal cord
▪ It receives information throughout the whole body, processes that information
and then sends out messages telling the body how to respond
▪ The brain is connected to the spinal cord through the brainstem
▪ The spinal cord carries signals back and forth between the brain and PNS
○ Peripheral Nervous System (PNS)
▪ The PNS is made up of the nerves that carry messages to and from the CNS and
other parts of your body
▪ Made up of sensory receptors and nerves
▪ Is divided into 2 parts
□ Somatic Nervous System (voluntary) (SNS)
Responsible for transmitting sensory information and voluntary
information
Contains 2 major types of neurons (nerve cells) ◊
◊ Sensory neurons
Takes sensory information and sends it to the CNS
◊ Motor neurons
Carry messages from the CNS to muscle fibres
□ Autonomic Nervous system (involuntary) (ANS)
Regulates involuntary bodily functions such as;
◊ Blood flow
◊ Heartbeat
◊ Digestion
◊ Breathing
Is divided into 2 components
◊ Sympathetic system
Regulates the fight or flight response
◊ Parasympathetic system
Maintains normal bodily functions (rest and digest)
Neurons
• The nervous system is made up of trillions of nerve cells called neurons
• Neurons are specialised cells that transmit electrical messages from one part of the body to
the other
• The electrical impulses are called nerve impulses, and they can only travel in one direction
• A neuron is made up of many parts
○ Neurons have a nucleus, a cell membrane, cytoplasm, dendrites, an axon and axon
terminals
▪ The cell body contains the nucleu
▪ The dendrites receive messages from other nerve cells
▪ The axon sends nerve impulses in one direction
▪ Axon terminals pass the message to the next neuron
• There are 3 types of neurons
○ Motor neurons
▪ Carry messages from the CNS to muscles and glands translating the signal to an
action
○ Connector neurons
▪ Transmits messages between neurons in the CNS
○ Sensory neurons
▪ Carry messages to the brain and spinal cord from cells in the sensory organs
▪ Have specialised receptors which are sensitive stimuli
How do neurons work?
1. An Action Potential is produced in the cell body.
○ Inside all cells there is a resting voltage
○ When the cell wants to increase the voltage to a threshold voltage the cell membrane
becomes more permeable to sodium. This means that sodium enters the cell which
makes the cell more positive. After the threshold voltage was been met then the cell
membrane becomes more permeable to potassium, which decreases the voltage
back to the resting voltage.
2. Action Potential is sent along the axon.
3. The electrical signal (action potential) activates neurotransmitters.
4. Neurotransmitters cross from one neuron to the next across the synapse.
○ The neurotransmitters recalibrate the signal for the next neuron so the signal doesn't
distort or weaken.
5. The neurotransmitters attach to the dendrites of the next neuron which triggers the next
action potential.
Homeostasis
• Homeostasis is the body's ability to regulate and maintain a stable condition within itself,
regardless of changes to the external environment.
• A constant internal environment needs to be maintained to keep an organism healthy and
functional.
○ The body functions best within an optimal range. Beyond this range, the body begins
to experience stress.
○ If a factor deviates further from the optimal range, it enters a zone of intolerance,
which can lead to illness or even death.
• Stimulus response model
○ Stimulus
▪ Any change in an organism's environment -- internal or external -- that causes
the organism to react
○ Receptor
▪ A receptor is any part of the body that can receive information from a stimulus
□ Photo
Light
□ Chemo
Chemical
□ Mechano
Touch
□ Noci
Pain
□ Thermo
Temperature
○ Coordination centre
▪ Receives information from the receptor, processes information and then
coordinates a response
○ Effector
▪ An effector is a muscle or gland that works to return the body to the optimal
range
○ Response
▪ Response is the reaction to the stimulus. It is the overall result that the
coordination centre and the effector worked to achieve.
Brain
• 2 main parts
○ Cerebellum
▪ Fine motor skills
○ Cortex
▪ Frontal
□ Rational Thoughts and Behaviour
▪ Temporal
□ Auditory and Balance
▪ Parietal
□ Sensation and Movement
▪ Occipital
□ Vision
▪ Brainstem
□ Critical involuntary processes
Endocrine System
• The endocrine system is a communication system that controls the internal environment of
the body using hormones
• Hormones are the chemical messengers in the body.
• They are produced by the endocrine glands
○ Pituitary
▪ Master gland
□ Growth
□ Water balance
○ Thalamus
▪ Master gland
○ Hypothalamus
▪ Master gland
○ Thyroid
▪ Mental growth
▪ Physical growth
○ Parathyroid
▪ Calcium levels
○ Pancreas
▪ Sugar levels
○ Adrenal
▪ Adrenalin
○ Ovaries and Testes
▪ Sex hormones
• The endocrine system is a slower process than the nervous system but the endocrine
system is more sustained.
Endotherm vs Ectotherm
• Endotherm
○ Inside Temperature
○ Endotherms can regulate their own temperature.
▪ Internal temp stays relitavly constant
• Ectotherm
○ Outside Temperature
○ Ectotherms cannot regulate their own temperature.
▪ Outside environment controls individuals temperature.
Class Notes Page 2
,Class Notes Page 3
, Quiz
Wednesday, 7 May 2025 10:58 AM
2. The temporal lobe receives the vibrations from the ear and transforms that into sounds which can
then be deciphered. Another part of it also controls your speech.
3.
a. Thermoreceptor - temperature
b. Photoreceptor - light
c. Mechanoreceptor - touch
d. Noci receptor- pain
e. Chemoreceptor - chemical
4.
a. Stimulus
b. Receptor
c. Afferent nerves
d. Spinal nerve
e. Control centre
f. Spinal nerve
g. Efferent nerves
h. Effector
i. Response
5. The brain and the spinal column
6. A gland, muscle, organ or organ system. The muscles beneath your hair follicles.
Class Notes Page 4
