biospychology summary notes

Biopsychology
THE NERVOUS SYSTEM AND THE ENDOCRINE SYSTEM:

The nervous system:

- Specialised network of cells and primary internal communication system
- Two main functions: to collect, process and respond to info in environment and co-ordinate
the working of different organs and cells in body

CNS

 Brain: centre of conscious awareness. Brains outer layer (cerebral cortex) covers the brain.
 Spinal cord: extension of the brain, passes messages to and from the brain and connects
nerves to the PNS, responsible for reflex actions

PNS

 Transmits messages via millions of neurons to and from CNS
 Autonomic nervous system (ANS): governs vital functions in the body e.g. breathing, HR
 Somatic nervous system (SNS): governs muscle movement and receives info from sensory
receptors

The endocrine system:

Glands and hormones

 Endocrine system works alongside the nervous system to control vital functions. Acts more
slowly than nervous system. Most hormones affect cells in more than one body organ, key
gland is pituitary

Endocrine and ANS: fight or flight

 Stressor is perceived and hypothalamus activates the pituitary gland triggering activity in the
sympathetic branch of the ANS. ANS changes from resting (parasympathetic) to
physiologically aroused sympathetic state
 Adrenaline: released from adrenal medulla into bloodstream. Triggers physiological changes
in body creating the physiological arousal necessary for fight or flight
 Immediate and automatic: happens in an instant, acute response
 Parasympathetic action: once threat passed, returns to resting state, actions are antagonistic
to sympathetic




NEURONS AND SNAPTIC TRANSMISSION:

, The structure and function of neurons:

Types of neurons

 Sensory neurons: carry messages from PNS to CNS. Long dendrites and short axons
 Motor neurons: connect CNS to effectors (muscles and glands). Short dendrites and long
axons
 Relay neurons: connect sensory to motor or another relay. Short dendrites and short axons

Structure of a neuron

 Cell body has a nucleus containing genetic material. Dendrites from body and carry nerve
impulses from neighbouring neurons to cell body
 Axon carries impulses away from cell body down the length of neuron. Covered in a myelin
sheath (protects and speeds up transmission)
 Nodes of Ranvier allow impulse to ‘jump’ across gaps in myelin sheath
 Terminal buttons at end of axon communicate with next neuron across synapse

Location of neurons

 Cell bodies of motor neurons may be in CNS by long axons. Sensory neurons in PNS in
clusters (ganglia). Relay neurons found in rain and visual system

Electrical transmission

 When a neuron is in resting state the inside of the cell is - charged compared to outside.
When activated be a stimulus, inside becomes + charged causing an action potential to
occur. Creates an electrical impulse that travels down axon towards end of neuron

Synaptic transmission:

Chemical transmission

 Neurons communicate in groups (neural networks). Each neuron separated from the next
with synapse and signals between neurons transmitted chemically. When the electrical
impulse reaches the end of the neuron (presynaptic terminal it triggers the release of
neurotransmitter from synaptic vesicles

Neurotransmitters

 Chemicals that diffuse across synapse. Once it crosses the gap, taken up by postsynaptic
receptor site on dendrites of next neuron. Here the chemical message converted back into
an electrical impulse. Direction of travel one way. Each neurotransmitter has its own specific
molecular structure

Excitation, inhibition and summation

 Inhibition results in neuron becoming more - charged and less likely to fire e.g. serotonin.
Excitation increase + charge making it more likely to fire e.g. adrenaline. Whether a
postsynaptic neuron fire is decided by summation. Excitatory and inhibitory influences are
summed. Action potential only triggered if threshold is reached


LOCALISATION OF FUNCTION IN THE BRAIN: