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Summary AQA alevel psychology biopsychology notes
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Biopsychology Poppy StoneBiopsychology
The nervous system and the endocrine system
The Nervous System
It is a specialised network of cells in the body with the 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
It is divided into two sub-systems:
Central nervous system (CNS)
o Made up of the brain and spinal cord
o Brain is the centre of all conscious awareness and the outer layer, cerebral cortex is
what distinguishes our mental functions
o Spinal cord is an extension of the brain and is responsible for reflex actions
Peripheral nervous system (PNS)
o The PNS transmits messages via neurons to and from the CNS
o It is further divided into the:
Autonomic nervous system (ANS)- governs vital functions in the body such
as breathing, heart rate, digestion, and sexual arousal
Somatic nervous system (SNS)- controls muscle movement and receives
information from sensory receptors
The Endocrine System
Glands and hormones:
Hormones are secreted into the bloodstream and affect any cell in the body that has a
receptor for that particular hormone
The endocrine system is a network of glands throughout the body that secrete chemical
messengers called hormones
Hormones are required to regulate bodily functions
A required amount of a specific hormone is released from an endocrine gland which
regulates physiological processes of the human body e.g. growth
The endocrine system works closely with the nervous system to regulate these processes,
but the endocrine system uses blood vessels to deliver hormones to target sites in the body
Endocrine glands:
Special group of cells within the endocrine system.
Function is to secrete hormones, which are chemical substances that regulate activity of cells
The major endocrine glands are: the pituitary gland, adrenal glands and the reproductive
organs
Hormones:
Chemical messengers that travel through the bloodstream and carried to target sites
throughout the body
Only affect a limited number of cells called target cell which respond to particular hormones
because they have receptors for that hormone
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, Biopsychology Poppy Stone
Hormones influence many processes including mood and the stress response
Regulation of the endocrine system
It is regulated by feedback and one set of signal releases hormones #
As levels of the hormone rise in the bloodstream a second set of signals slows down
secretion of that hormone
This results in stable concentrations of hormones circulating in bloodstream
Fight or flight response
When a stressor is perceived the hypothalamus triggers activity in the sympathetic branch of
the ANS
The ANS changes from its resting state to aroused state
Adrenaline is released from the adrenal medulla into the bloodstream which triggers
physiological changes in the body which creates the arousal needed for fight or flight
All of this happens in the instant a threat is detected
Once the threat has passed the PNS returns body to resting state
Neurons and synaptic transmission
Neurons
Neurons are cells of the nervous system that process and transmit messages through
electrical and chemical signals
They are specialised cells whose function is to move electrical impulses to and from the CNS
The electrical impulses are called action potentials
3 types of neurons:
o Sensory- carry messages from PNS to CNS and have long dendrites but short axons
o Relay- connect sensory to motor neurons and have short dendrites and short axons
o Motor- connect CNS to effectors such as muscles and have short dendrites and long
axons
Structure of a neuron
The cell body includes a nucleus which contains the genetic material of the cell
Dendrites are branch like structures which extend from the cell body which carry nerve
impulses from neighbouring neurons towards the cell body
The axon carries 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
The myelin sheath is segmented by gaps called nodes of Ranvier which speed up the
transmission of the impulse 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
Electric transmission- the firing of a neuron
When a neuron is in resting state the inside of the cell is negatively charged
When neuron activated by stimulus the inside becomes positively charged for split second
causing action potential to occur
This creates an electrical impulse that travels down the axon towards the end of the neuron
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