A succinct and complete summary of the Biopsychology topic of AQA
A-level Psychology. Using only this material when revising for the Biopsychology section of Paper 2 I was able to achieve an A* in psychology.
Biopsychology Revision Notes
Biopsychology: The nervous system and the endocrine system
The nervous system in brief:
Central nervous system - Control behaviour and physiological processes
Peripheral nervous system - Relays nerve impulses from CNS to the rest of the body, and from the body
to CNS
Somatic nervous system - Carries sensory and motor signals to and from the CNS
Autonomic nervous system - Controls involuntary body function
Sympathetic nervous system - Emergency response: fight or flight
Parasympathetic nervous system - Calm and restore: rest and digest
The nervous system
The nervous system is divided into two subsystems:
- Central nervous system
- Peripheral nervous system
The CNS is made up of the brain and the spinal cord
- The brain is the centre of all conscious awareness and regulates physiological processes
- The brain's outer layer, the cerebral cortex, is only 3 mm thick and covers the brain
like an orange peel covers and orange
- The spinal cord transfers messages to and from the brain to the rest of the body amd
connects nerves to the PNS
- It is also responsible for reflex actions such as pulling your hand away from a hot
plate.
The peripheral nervous system (PNS)
The PNS transmits messages to and from the CNS, via millions of neurons. The PNS is further
subdivided into:
- The somatic nervous systems (SNS) - This is the part of the PNS that is responsible for
muscle movement and receives information from sensory receptors
- The autonomic nervous system (ANS) - Plays an important role in homeostasis, which
maintains internal processes like body temperature, heart rate and blood pressure.
The two main divisions of the ANS (their actions are mostly antagonistic)
- The sympathetic nervous system - fight or flight - impulses travel from the ANS to organs in
the body to help us prepare for action when faced with a dangerous situations
- The parasympathetic nervous system - ‘rest and digest’ - to relax the body, and return us
to our resting state.
The opposing actions of the sympathetic and the parasympathetic nervous system
Heart Increases heart rate Decreases heart rate
Eye Dilates pupils Constricts pupils
Gut Slows digestion Increases digestion
These two systems are at work constantly shifting your body to more prepared states and more
relaxed states depending on the situation.
,The Endocrine System
- It is a network of glands that regulate bodily functions. Act by secreting chemical messengers
called hormones.
- Uses blood vessels to carry hormones around the body
- Most hormones affect more than one organ
Chemical signaling
- The process of glands releasing hormones
3 stages:
1. Gland Stimulation - gland is ‘excited’ in preparation for hormone release. Stimulated by
chemical changes and electrical impulses.
2. Hormone release - once exited, glans release hormones into the bloodstream. Hormones
travel around the body in the circulatory system.
3. Effector Binding - hormones bind to receptors on target cells - leaving the bloodstream
Hypothalamus
- Links the Nervous System to the Endocrine System in combination with the pituitary
gland. Maintains homeostasis. Hormone: CRH (corticotropin-releasing hormone)
The Endocrine and the ANS
- In a fighting situation the hypothalamus triggers activity in ANS (causing sympathetic arousal)
and then the pituitary gland sends a message to the adrenal glands to release the hormone
adrenaline (and noradrenaline) into the bloodstream.
- Adrenaline leads to increased heart rates, faster breathing, sweating, inhibits digestion
- All of this happens immediately and automatically when a threat is detected
- Body returns to parasympathetic state once threat has passed, body returns to ‘rest and
digest’
Major glands - PTGA
Ps:
- Pituitary Gland: “Master gland”. Releases hormones that control the entire
system. Hormone: ACTH
- Pineal Gland: In control of sleep. Hormone: Melatonin
- Pancreas: in control of blood sugar levels. Hormone: Insulin
Ts:
- Thyroid Gland - In control of the body’s metabolic rate and regulates growth
and maturation. Hormone: Thyroxine
G:
- Gonads (Ovaries and Testes) - Produce sex hormones and aid
devlopment of sex organs and secondary characteristics. Hormones:
Testosterone and Oestrogen
A:
- Adrenal Glands - regulates biological effects of the fight or flight response.
Hormone: Adrenaline and cortisol
, Biopsychology: Neurons and synaptic transmission
Overview
Neurons - neurons are nerve cells that process and transmit messages through electrical and
chemical signals (80% of neurons are located in the brain).
Synapse - the site of contact between nerve cells. Synapses convert electrical signals into chemical
information, which is conveyed between neurons at this site. The synapse consists of both pre- and
post-synaptic elements.
Neurotransmitter - brain chemicals released from synaptic vesicles that relay signals across the
synapse from one neuron to another. Neurotransmitters can be broadly divided into those that perform
an excitatory function and those that perform an inhibitory function.
Key terms and their functions
Nucleus - The control centre of a cell, which contains the cell's chromosomal DNA
Dendrite - Receives the nerve impulses from neighbouring neurons
Axon - where the electrical signals pass along away from the cell body (action potential)
(axons take signals to the synapse, dendrites take signals away)
Myelin sheath - insulates/protects the axon from external influences that might affect the
transmission
Nodes of Ranvier - These speed up the transmission of the impulse by forcing it to ‘jump’
Terminal buttons - end of axon containing vesicles
The structure of a neuron
- The cell body (or soma) includes a nucleus, which contains the genetic material of the cell. Branchlike
structures called dendrites protrude from the cell body. These carry nerve impulses from neighbouring
neurons towards the cell body.
- The axon carries the impulses away from the cell body down the length of the neuron. The axon 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. Thus, the myelin sheath is segmented by gaps called nodes of Ranvier. These speed up the
transmission of the impulse by forcing it to jump' across the gaps along the axon.
- Finally, 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.
Three main types of neurons: motor neurons, sensory neurons and relay neurons
Sensory Neurons: Relay Neurons: Motor Neurons:
Role of neuron: Carry messages from Connect the sensory Connect the CNS to
the PNS to the CNS neurons to the motor effectors such as
or other relay neurons muscles and glands
Description of Long dendrites Short dendrites Short dendrites
dendrite:
Description of Axon Short axons Short axons Long axons
Location Sensory neurons are found Make up 97% of all Cell bodies lies in the CNS
outside the CNS, in the neurons and most are but they have long axons
PNS in clusters known as found within the brain and which form part of the PNS
ganglia the visual system
“action potential” - a neuron is in a resting state the cell is negatively charged, when a neuron is
activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an
action potential creating an electrical impulse that travels down the axon
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