lecture 1 - homeostasis & autonomic nervous system Flashcards
what is physiology?
the study of the functioning of living things
bodys internal working
what are the different organ systems?
circulatory digestive endocrine immune integumentary (skin) musculoskeletal nervous respiratory reproductive urinary
what is homeostasis?
consistency of the internal environment
maintenance of equilibrium within limited ranges
what happens if homeostasis isn’t maintained?
disease - pathophysiology
what is negative feedback regulation?
when the effector leads to a reduction in the stimulus
physiological examples:
• blood pressure
• plasma osmolarity
• pupil diameter
control of light entering the eye by pupil diameter
changes in pupil diameter regulate the amount of light reaching the retina and allow the eye to automatically adapt to varying levels of light
can show if someone is braindead if no response to light
what is the major function of the autonomic nervous system?
to maintain homeostasis
organisation of the ANS
sensory afferent nerve fibres
control centres
• hypothalamus
• brain stem
• spinal cord
efferent pathways
• sympathetic NS - fight or flight
• parasympathetic NS - rest and digest
• 2 systems are antagonistic
common features of the 2 efferent pathways in the ANS
- 2 neurons in series
- preganglioic neurones originate in the CNS
- postganglionic neurones originate in autonomic ganglia
- 1 preganglionic neurone can synapse with may postganglionic neurones
structure of parasympathetic NS neurones?
preganglionic neurone = LONG
postganglionic neurone = SHORT
structure of sympathetic NS neurones?
preganglionic neurone = SHORT
postganglionic neurone = LONG
neurotransmitters of the ANS
acetylcholine - ACh
noradrenaline - NAdr
adrenaline - Adr
non-adrenergic, non-cholinergic (NANC) transmitters
2 types of synapses
cholinergic - nicotinic or muscarinic
adrenergic - alpha or beta
nicotinic cholinergic receptors
neuromuscular junction
blocked by curare
SNS and PNS ganglionic synapses
muscarinic cholinergic receptors
target organs in PNS some exceptions (sweat gland innervation by SNS)
blocked by atropine - dilutes pupils to allow retina to be seen
parasympathetic organ synapse
