PSC1002/L01 Homeostasis Flashcards
Give 3 things that are controlled by homeostasis.
Internal environment (ECF)
Equilibrium through compensation
Variables (bp)
Define negative feedback.
Effector leads to reduction in stimulus
Give 2 physiological examples of negative feedback.
Blood pressure
Plasma osmolarity
Pupil diameter
What 2 muscles work to constrict/dilate pupil diameter?
Sphincter pupillae
Dilator pupillae
What 3 control centres make up the autonomic nervous system?
Hypothalamus
Brain stem
Spinal cord
What kind of nerve fibres are in the autonomic nervous system?
Sensory Afferent Nerve Fibres
What 2 efferent pathways make up the autonomic nervous system?
Sympathetic - fight or flight
Parasympathetic - rest and digest
Name the common features of the 2 efferent pathways. (4)
2 neurons in series
Preganglionic neurons originate in CNS
Postganglionic neurons originate in autonomic ganglia
1 preganglionic neuron can synapse with many postganglionic neurone
Give 3 examples of effects of the parasympathetic nervous system.
Constricts pupil
Stimulates salivation
Inhibits heart
Constricts bronchi
Stimulates digestive activity
Stimulates gallbladder
Contracts bladder
Relaxes rectum
Give 3 examples of effects of the sympathetic nervous system.
Dilates pupil
Inhibits salivation
Relaxes bronchi
Accelerates heart
Inhibits digestive activity
Stimulates glucose release by liver
Secretion of epinephrine from kidney
Relaxes bladder
Contracts rectum
What hormones are involved in flight or fight response? (4)
Adrenaline
Noradrenaline
Cortisol
Potentially osteocalcin
Describe the osteocalcin pathway of flight or fight response. (5)
Stimulus -> amygdala centre -> bone osteoblasts -> osteocalcin -> inhibits PNS
Describe the preganglionic origin of the cranial nerve III (oculomotor).
Eye
Describe the preganglionic origin of the cranial nerve VII (facial). (3)
Lacrimal
Nasal
Submandibular
Describe the preganglionic origin of the cranial nerve IX (glossopharyngeal).
Parotid
Describe the preganglionic origin of the cranial nerve X (vagus). (2)
Thorax
2/3 abdomen (75%)
Describe the origin of the pelvic nerve.
Rectum
Bladder
Describe the length of neurons in the parasympathetic nervous system.
Preganglionic = long
Postganglionic = short
Describe the length of neurons in the sympathetic nervous system.
Preganglionic = short
Postganglionic = long
Describe the preganglionic origin of the sympathetic nervous system.
Thoracic T1 - Lumbar 2/3 (L2/3)
Describe the postganglionic origin of the sympathetic nervous system.
2 paravertebral sympathetic chains
What is special about innervation of the adrenal medulla?
Directly innervated by preganglionic neuron of the SNS
Give 4 neurotransmitters of the ANS.
Acetylcholine
Noradrenaline
Adrenaline
Non-adrenergic, non-cholinergic neurotransmitters (NANC)
What 2 kinds of receptors are found in the ANS?
Cholinergic
Adrenergic
Give 3 features of nicotinic receptors.
In ganglia SNS & PNS
Neuromuscular junction
Blocked by curare
Give 2 features of muscarinic receptors.
Target organs in PNS
Blocked by atropine
Give an exception to muscarinic receptors in target organ PNS.
Sweat gland innervation by SNS
What is attached to muscarinic receptors?
G-protein
What is attached to a nicotinic receptor?
Alpha and beta component
Describe the action of alpha1 postsynaptic receptors.
NAdr > Adr
Vasoconstriction and smooth muscle contraction
Describe the action of alpha2 presynaptic receptors.
NAdr > Adr
Reduction in adrenergic and cholinergic transmission
What are alpha receptors blocked by?
Phentolamine
Describe the action of beta1 receptors.
Adr = NAdr
Increase in heart rate and force of contraction
Describe the action of beta2 receptors.
Adr > NAdr
Vasodilation and smooth muscle relaxation
What compounds block beta receptors?
Propanolol
What is associated with adrenoreceptors?
G-protein
