Health and Disease Week 8 Flashcards
What are the 4 major regions of the brain?
cerebral cortex, cerebellum, midbrain, brain stem
What are the 4 lobes of the cerebral cortex?
frontal, pariental, temporal, occipital
What further regions are the lobes of the cerebral cortex divided into?
Brodmann’s areas that are responsible for different functions and emotions
What is the somatosensory cortex responsible for?
processes sensory information including touch and pain
What are the steps involved in the ascending pathway into the somatosensory cortex?
- mechanoceptors detect a signal
- send action potential
- action potential comes into spinal cord through dorsal root
- reaches synapse
- crosses to other side of the body
- reaches another synapse
- reaches the somatosensory cortex
What is the prefronal cortex invovled in?
personality and traits
What is the function of the cerebellum?
motor memory and movement of skeletal muscle
What are 2 examples of ‘fast’ neurotransmitters in the brain?
glutamate and GABA
What does glutamate do?
excitatory neurotransmitter than opens ligand-gated Na+ ion channels
What does GABA do?
inhibitory neurotransmitter than opens ligand-gated chloride ion channels Cl-
What are examples of ‘slow’ neurotransmitters?
5-HT, acetylcholine, dopamine, noreadrenaline
What do ‘slow’ neurotransmitters do?
activate G protein-coupled receptors
What does the autonomic nervous system do?
act on tissue that is NOT under voluntary control
What are examples of tissues that are NOT under voluntary control?
smooth muscle, cardiac muscle, glandular tissue
What 2 divisions make up the autonomic nervous system?
sympathetic and parasympathetic
How are efferent neurones arranged in the somatic nervous system?
the somatic motor neurone connects the CNS to skeletal muscle
What is different about the autonomic nervous system?
there are 2 motor neurones that exist in collections of cell bodies called ganglion
define ganglion
a collection of neuronal cell bodies found in the autonomic division of the peripheral nervous system
What is the structure of motor neurones in the sympathetic nervous system?
- short preganglionic neurones
- long postganglionic neurones after the synapse
- preganglionic neurones usually project to the paravertebral sympathetic chain
- postganglionic neurones in the sympathetic chain send long axonal projections that synapse on the target organ
What is the structure of motor neurones in the parasympathetic nervous system?
- long preganglionic neurones
- short postganglionic neurones
- preganglionic neurones send long axonal projections to parasympathetic ganglia (near or in target organ)
- postganglionic neurones send short axonal projections which synapse on the target organ
What are physiological effects of activation of the sympathetic nervous system?
- pupils dilate
- inhibits saliva
- relaxes airways
- heart rate increase
- blood pressure increase
- blood vessels constrict except going to skeletal muscle
- liver converts glycogen to glucose
- secretions of epinephrine and norepinephrine from adrenal medulla
What are physiological effects of activation of the parasympathetic nervous system?
- stimulates digestion
- dilates blood vessels in the gut
- stimulates pancreas to release insulin and digestive enzymes
- stimulates sexual arousal
Which neurotransmitters and receptors work in the sympathetic nervous system?
- preganglionic neurones release acetylcholine
- acetylcholine acts on nicotinic receptors
- postganglionic neurones release noradrenaline
- acts on adrenoceptors
What are the two exceptions to this?
sweat glands and adrenal medulla
Which neurotransmitters and receptors are involved in the parasympathetic nervous system?
- preganglionic neurones release acetylcholine
- acetylcholine acts on nicotinic receptors
- postganglionic neurones release acetylcholine
- acetylcholine acts on muscarinic receptors
What are the 3 main types of G protein-coupled receptors?
- Gs-coupled receptors
- Gi/Go-coupled receptors
- Gq-coupled receptors
What do Gs-coupled receptors do?
activate adenylate cyclase, which produces cAMP
What do Gi/Go-coupled receptors do?
inhibit adenylate cyclase and affect ion channels
What do Gq-coupled receptors do?
activate phospholipase C, which leads to production of IP3
Which 2 subtypes are adrenoreceptors in the sympathetic nervous system divided into?
alpha and beta
What are the subdivisions of alpha adrenoreceptors?
a1 and a2
Which hormone has more influence on alpha receptors?
noradrenaline over adrenaline
What are the main actions of alpha 1 adrenoceptors?
- vasoconstriction
- relaxation of GI tract
What are the main actions of alpha 2 adrenoceptors?
inhibit noradrenaline release
What is the main action of beta 1 adrenoceptors?
increase heart rate
What are the main actions of beta 2 adrenoceptors?
- bronchodilation
- vasodilation
What is the main function of beta 3 adrenoceptors?
lipolysis
What are the 3 subtypes of muscarinic receptor in the parasympathetic nervous system?
M-1, M-2, M-3
What type of receptor is M1? Where is it located?
neural, CNS
What type of receptor is M2 and where is it located?
cardiac, heart
What type of receptor is M3 and where is it located?
glandular, smooth muscle
What do M1 and M3 receptors do?
increase IP3
What do M2 receptors do?
decrease cAMP
Which receptors are responsible for change in heart rhythm in sympathetic and parasympathetic nervous system?
beta 1 and M2
Which type of receptor is responsible for affecting blood vessels in the sympathetic NS?
alpha 1
What are the 2 muscles on each side of a limb called?
agonist and antagonist muscles
How does the knee jerk reflex work with agonist and antagonist muscles?
- there is still a monosynaptic network provide input to the agonist muscle to contract, but also input to an inhibitory interneurone
- input to inhibitory interneurone causes the inhibition of motor neurone on antagonist, decreasing acetylcholine release
- antagonist muscle relaxes
What is an example of a reflex involving the eyes?
the pupil constriction reflex
What is different about the pupil constriction reflex compared to the knee jerk reflex?
involves the cranial nerves instead of the spinal cord as eyes are above the neck
How does the pupil constriction reflex work?
- eyes are exposed to bright light
- the optical tract innervates the pretectal nucleus in the brain stem
- the pretectal nucleus innervates the oculomotor nerve
- this causes a reflex that changes the pupil size in response to light to protect the retina
How is sight interpreted by the brain?
- the brain receives input from the eyes into the visual cortex
- the association cortexes interpret feedback from the eyes
How do touch receptors work?
- in each nerve ending, there are touch receptors called mechanoceptors
- mechanoceptors respond to pressure and touch opens ligand-gated ion channels which causes depolarisation
How do taste receptors work?
there are specialised cells in taste buds that respond to chemicals in food
How many different taste receptors are there and what are they?
5 = salt, sour, bitter, sweet, umami
Where are action potentials from taste receptors received in the brain?
the primary gustatory cortex
How do smell receptors work?
- odorants move into the nasal cavity and come into contact with olfactory receptors cells -> like taste
- the odorants activate G protein-coupled receptors
How do sound receptors work?
- soundwaves vibrate the eardrum at same frequency as the sound
- the vibration is passed to the inner ear and bone, which causes hair cells in the cochlea that are mechanosensitive neurones to vibrate
- action potentials generated
Which nerve do action potentials from sound go down?
the vestibulocochlear nerve
