BIOPSYCHOLOGY
The nervous system
-consists of the central nervous system and the peripheral nervous system. Communicates
using electrical and chemical signals.
The nervous system has two main functions:
-to collect, process and respond to information in the environment
-to coordinate the working of different organs and cells in the body
The central nervous system
-made up of the brain and the spinal cord, the origin of all complex commands and
decisions.
-the brain is the centre of all conscious awareness. Its outer layer, the cerebral cortex, is only
3mm thick and covers the brain like an orange peel.
-the brain is divided into 2 hemispheres
-the spinal cord is an extension of the brain; it passes messages to and from the brain and
connects nerves to the PNS. It is also responsible for reflex actions.
The peripheral nervous system
-sends info to the CNS from the outside world and transmits messages from the CNS to
muscles and glands in the body
-transmits messages via millions of neurons to and from the central nervous system.
It is further subdivided into the:
-autonomic nervous system, which governs vital functions in the body such as breathing,
heart rate, digestion, sexual arousal, and stress responses (also further divisions of
sympathetic and parasympathetic nervous systems).
-somatic nervous system, which governs muscle movement and receives information
through sensory receptors.
The endocrine system
-one of the body’s major information systems that instructs glands to release hormones
directly into the bloodstream. These hormones are carried towards target organs in the
body.
-communicates via chemicals
-works alongside the nervous system
-most hormones affect cells in more than one body organ
-the key endocrine gland is the pituitary gland, located in the brain. It controls the release of
hormones from all the other endocrine glands in the body.
Endocrine and ANS working together: fight or flight.
-they work in parallel with one another, for example, in a stressful event.
-when a stressor is perceived, the first thing that happens is the hypothalamus activates the
pituitary gland and this triggers activity in the sympathetic branch of the ANS.
-the ANS changes from its normal (parasympathetic) state to the physiologically arouse
sympathetic state.
,Adrenaline – released from the adrenal medulla into the bloodstream. Adrenaline triggers
physiological changes in the body, which creates the physiological arousal necessary for the
fight or flight response.
Immediate and automatic – all of this happens as soon as the threat is detected. For
example, your heart beats faster, which is an acute and automatic reaction in the body. the
physiological changes explain why stress, panic, or even excitement are often experiences as
a ‘sick’ feeling.
Parasympathetic action – once the threat has passed, the parasympathetic nervous system
returns the body to its resting state. The parasympathetic branch of the ANS works in
opposition to the sympathetic nervous system – its actions are antagonistic to the
sympathetic system. The parasympathetic system acts as a ‘brake’ and reduces the activities
of the body that were increased by the actions of the sympathetic branch.
SYMPATHETIC STATE PARASYMPATHETIC
Increases heart & breathing rate Decreases heart & breathing rate
Dilates pupils Constricts pupils
Inhibits digestion Stimulates digestion
Inhibits saliva production Stimulates saliva production
Contracts rectum Relaxes rectum
NEURONS AND SYNAPTIC TRANSMISSION
Neuron- neurons are nerve cells that process and transmit messages through electrical and
chemical signals.
Sensory neurons – these carry messages from the PNS to the CNS, long dendrites and short
axons.
Relay neurons- these connect the sensory neurons to the motor or other relay neurons,
short dendrites and short axons.
Motor neurons – these connect the CNS to effectors such as muscles and glands, short
dendrites and long axons.
, The structure of a neuron
-cell body includes a nucleus, which contains the genetic material of the cell.
-dendrites protrude from the cell body, which carry nerve impulses from neighbouring
neurons towards the cell body.
-axon carries the impulses away from the cell body down the length of the neuron. It is
covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical
transmission of the impulse.
-if the myelin sheath was continuous this would have the reverse effect and slow down the
electrical impulse. So, the myelin sheath is segmented by gaps called nodes of Ranvier, which
speed up the impulse transmissions by forcing it to jump across the gaps along the axon.
-at the end of the axon are terminal buttons that communicate with the next neuron in the
chain across a gap known as the synapse.
Location of neurons
-cell bodies of motor neurons may be in the CNS, but they have long axons which form part
of the PNS.
-sensory neurons are located outside the CNS, in the PNS, in clusters known as ganglia.
-relay neurons are the most abundant and are found within the brain and the visual system.
Electrical transmission – the firing of a neuron
-when a neuron is in a resting state the inside of the cell is negatively charged compared to
the outside.
-when a neuron is activated by a stimulus, the inside of the cell becomes positively charged
for a split second, causing an action potential to occur, creating an electrical impulse to
travel down the axon towards the end of the neuron.
Synaptic transmission
-the process by which neighbouring neurons communicate with each other by sending
chemical messages across the gap that separates them.
Chemical transmission
-neurons communicate within neural networks.
-each neuron is separated from the next by a tiny gap called the synapse.
- Signals within neurons are transmitted electrically, while signals between neurons are
transmitted chemically across the synapse.
-when the electrical impulse reaches the end of the neuron (presynaptic terminal) it triggers
the release of neurotransmitter from tiny sacs called synaptic vesicles.
The nervous system
-consists of the central nervous system and the peripheral nervous system. Communicates
using electrical and chemical signals.
The nervous system has two main functions:
-to collect, process and respond to information in the environment
-to coordinate the working of different organs and cells in the body
The central nervous system
-made up of the brain and the spinal cord, the origin of all complex commands and
decisions.
-the brain is the centre of all conscious awareness. Its outer layer, the cerebral cortex, is only
3mm thick and covers the brain like an orange peel.
-the brain is divided into 2 hemispheres
-the spinal cord is an extension of the brain; it passes messages to and from the brain and
connects nerves to the PNS. It is also responsible for reflex actions.
The peripheral nervous system
-sends info to the CNS from the outside world and transmits messages from the CNS to
muscles and glands in the body
-transmits messages via millions of neurons to and from the central nervous system.
It is further subdivided into the:
-autonomic nervous system, which governs vital functions in the body such as breathing,
heart rate, digestion, sexual arousal, and stress responses (also further divisions of
sympathetic and parasympathetic nervous systems).
-somatic nervous system, which governs muscle movement and receives information
through sensory receptors.
The endocrine system
-one of the body’s major information systems that instructs glands to release hormones
directly into the bloodstream. These hormones are carried towards target organs in the
body.
-communicates via chemicals
-works alongside the nervous system
-most hormones affect cells in more than one body organ
-the key endocrine gland is the pituitary gland, located in the brain. It controls the release of
hormones from all the other endocrine glands in the body.
Endocrine and ANS working together: fight or flight.
-they work in parallel with one another, for example, in a stressful event.
-when a stressor is perceived, the first thing that happens is the hypothalamus activates the
pituitary gland and this triggers activity in the sympathetic branch of the ANS.
-the ANS changes from its normal (parasympathetic) state to the physiologically arouse
sympathetic state.
,Adrenaline – released from the adrenal medulla into the bloodstream. Adrenaline triggers
physiological changes in the body, which creates the physiological arousal necessary for the
fight or flight response.
Immediate and automatic – all of this happens as soon as the threat is detected. For
example, your heart beats faster, which is an acute and automatic reaction in the body. the
physiological changes explain why stress, panic, or even excitement are often experiences as
a ‘sick’ feeling.
Parasympathetic action – once the threat has passed, the parasympathetic nervous system
returns the body to its resting state. The parasympathetic branch of the ANS works in
opposition to the sympathetic nervous system – its actions are antagonistic to the
sympathetic system. The parasympathetic system acts as a ‘brake’ and reduces the activities
of the body that were increased by the actions of the sympathetic branch.
SYMPATHETIC STATE PARASYMPATHETIC
Increases heart & breathing rate Decreases heart & breathing rate
Dilates pupils Constricts pupils
Inhibits digestion Stimulates digestion
Inhibits saliva production Stimulates saliva production
Contracts rectum Relaxes rectum
NEURONS AND SYNAPTIC TRANSMISSION
Neuron- neurons are nerve cells that process and transmit messages through electrical and
chemical signals.
Sensory neurons – these carry messages from the PNS to the CNS, long dendrites and short
axons.
Relay neurons- these connect the sensory neurons to the motor or other relay neurons,
short dendrites and short axons.
Motor neurons – these connect the CNS to effectors such as muscles and glands, short
dendrites and long axons.
, The structure of a neuron
-cell body includes a nucleus, which contains the genetic material of the cell.
-dendrites protrude from the cell body, which carry nerve impulses from neighbouring
neurons towards the cell body.
-axon carries the impulses away from the cell body down the length of the neuron. It is
covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical
transmission of the impulse.
-if the myelin sheath was continuous this would have the reverse effect and slow down the
electrical impulse. So, the myelin sheath is segmented by gaps called nodes of Ranvier, which
speed up the impulse transmissions by forcing it to jump across the gaps along the axon.
-at the end of the axon are terminal buttons that communicate with the next neuron in the
chain across a gap known as the synapse.
Location of neurons
-cell bodies of motor neurons may be in the CNS, but they have long axons which form part
of the PNS.
-sensory neurons are located outside the CNS, in the PNS, in clusters known as ganglia.
-relay neurons are the most abundant and are found within the brain and the visual system.
Electrical transmission – the firing of a neuron
-when a neuron is in a resting state the inside of the cell is negatively charged compared to
the outside.
-when a neuron is activated by a stimulus, the inside of the cell becomes positively charged
for a split second, causing an action potential to occur, creating an electrical impulse to
travel down the axon towards the end of the neuron.
Synaptic transmission
-the process by which neighbouring neurons communicate with each other by sending
chemical messages across the gap that separates them.
Chemical transmission
-neurons communicate within neural networks.
-each neuron is separated from the next by a tiny gap called the synapse.
- Signals within neurons are transmitted electrically, while signals between neurons are
transmitted chemically across the synapse.
-when the electrical impulse reaches the end of the neuron (presynaptic terminal) it triggers
the release of neurotransmitter from tiny sacs called synaptic vesicles.
