Stimulus

A stimulus is a change in the environment (internal or external) that is detected by a receptor and elicits a response.

A rapid, unconscious response

Innate behaviour develops independently of the environmental context, whereas learned behaviour develops as a result of experience.

Use the following examples. • Excitatory drugs: nicotine, cocaine and amphetamines • Inhibitory drugs: benzodiazepines, alcohol and tetrahydrocannabinol (THC).

Cocaine acts at synapses that use dopamine as a neurotransmitter Cocaine binds to dopamine reuptake transporters, which pump dopamine back into the presynaptic neuron Dopamine builds up in the synaptic cleft The postsynaptic neuron is continually excited, giving feelings of euphoria not related to any activity

Dopamine Secretion --associated with feelings of well-being and pleasure. Many addictive drugs, including cocaine and alcohol affect dopamine secreting synapses. Overstimulation of dopamine receptors decreases their efficiency 2. Genetic Predisposition The gene DRD2 codes for the dopamine receptor --deficiency of dopamine receptors predisposes humans to alcoholism People with certain alleles consume less alcohol 3. Social Factors peer pressure, cultural traditions, poverty, social deprivation

controls automatic and homeostatic activities, such as swallowing,digestion and vomiting, and breathing and heart activity

coordinates unconscious functions, such as movement and balance.

maintains homeostasis,coordinating the nervous and endocrine systems,secreting hormones of the posterior pituitary, and releasing factors regulating the anterior pituitary.

the posterior lobe stores and releases hormones produced by the hypothalamus and the anterior lobe, and produces and secretes hormones regulating many body functions.

act as the integrating centre for high complex functions such as learning,memory and emotions.

Limit this to: • passage of impulses from pain receptors in the skin and other parts of the body to sensory areas of the cerebral cortex • feelings of pain due to these areas of the cerebral cortex • endorphins blocking transmission of impulses at synapses involved in pain perception.