Summary Psychology A-level AQA - Biopsychology

Biopsychology 1


Key features of the nervous system:

• A specialised network of cells and our primary communication system
• It has two main functions
o To collect, process and respond to information in the environment
o To coordinate the working of different organs and cells in the body
• It is divided into the central nervous system (CNS) and the peripheral nervous system (PNS)
Structure and function of the CNS:

• Made up of the brain and spinal chord
• Brain is the centre of all conscious awareness
• Outer layer of the brain, cerebral cortex, is highly developed in humans and is what
distinguishes our higher mental functions from those animals
• Spinal chord – an extension to the brain and is responsible for reflex actions
• Passes messages to and from the brain and connects nerves to the PNS
Structure and function of the PNS:

• PNS transmits messages, via millions of neurons, to and from the nervous system
• The PNS is further sub-divided into the autonomic nervous system (ANS) and the somatic
nervous system (SNS)
• The ANS governs vital bodily functions, including bbreathingg, heart rate, digestion, sexual
arousal and stress responses
• The SNS controls muscle movement and rreceiives information from sensory receptors




The endocrine system:

• Key features:
o Works alongside the nervous system to control vital functions in the body through the
action of hormones
o Works much more slowly than the nervous system, but has widespread and powerful
effects
• Glands:
o Organs in the body that produce hormones
o Major endocrine gland is the pituitary gland located in the brain – called the master
gland because it controls the release of hormones from all other endocrine glands in
the body

, Biopsychology 2


• Hormones:
o Secreted in the bloodstream and affect any cell in the body that has a receptior for
that particular hormone
o For example, thyroxine produced by the thyroid gland affects cells in the heart and
also cells throughout the body which increase metabolic rates
The endocrine system and ANS work together:

• Often endocrine and autonomic nervous system work in parallel, for instance in stressful
situations:
o When a stressor is perceived, the hypothalamus triggers activity in the sympathetic
branch of the ANS
o ANS changes from the normal resting state (parasympathetic state) to the
psychologically aroused sympathetic state
o The stress hormone, adrenaline, is released from the adrenal medulla into the
bloodstream
o Adrenaline triggers psychological changes in target organs and causes
▪ Increased heart rate
▪ Dilation of pupils
▪ Decreased production of saliva
o This is called the light or flight response
o Once the threat passes, the parasympathetic nervous system returns the body to its
resting state (rest and digest response) - acts as a ‘brake’ and reduces activities of the
body that were increased by the actions of the sympathetic branch
Structure and functions of neurons:

• Over 100 billion neurons in the human nervous system, 80% of which are located in the brain
• By transmitting signals electrically and chemically, these provide the nervous system with its
primary means of communication
• There are three types of neurons
Motor neurons:

• Connect the CNS to the effectors such as muscles and glands
• Short dendrites along long axons
Sensory neurons:

• Carry messages from PNS to CNS
• Long dendrites and shory axons
Relay neurons:

• Connect sensory neurons to motor and other relay neurons
• Short dendrites and short axons
The structure of a neuron:

• Vary in size but all share the same basic structure
• Cell body (soma)
o Includes a nucleus which contains the genetic material of the cell
• Dendrites
o Branch-like structures that protrude from the cell body
o Carry nerve impulses from neighbouring neurons towards the cell body