Physiology Exam II review Flashcards
Upper motor neuron uses what NT
Glutamate
Lower motor neuron uses what NT
Acetycholine
Renshaw cells -type of cell, location, receives branches from
Inhibitory cells in anterior horns of spinal cord
Receive branches from alpha motor neurons
Sensory fiber conduction rate from fastest-slowest
C fibers - fastest
A-d fibers
A-a or A-b
Nociceptors and thermoreceptors are related to what fibers
C or A-d
Muscle spindle is made up of what and innervated by
3-12 intrafusal fibers innervated by small gamma motor neurons
Central region of spindle functions as
Sensory receptor- no contractile fibers
Nuclear bag fibers
Detect rate of change in muscle length
Innervated by group Ia afferents and dynamic y efferents
Nuclear chain fibers
Detect static change in muscle length
Innervated by group II afferents and static y efferents
Stimulation of muscle spindle sensory fibers results in
Stimulation of a-motor neurons, contraction
Golgi tendon organ detects what
Muscle tension (contraction or stretching)
Golgi tendon organ circuitry
Type Ib afferent–> Inhibitory interneuron–> anterior motor neuron
Reciprocal inhibition
Ex. When flexing arm to move hand away from hot surface, biceps are excited and triceps inhibited
Premotor/supplementary motor areas
Create plan for movement- for more complex movements
Premotor- develops motor image
Supplementary - Programs motor sequence, mental rehearsal
Medial activation system of UMN innervate
Postural and girdle muscles
Lateral activation system of UMN innervates
Distal muscles used for fine movement
Nonspecific activating system of UMN
Facilitate local reflex arcs
Corticospinal/pyramidal tract origin
Primary motor cortex
Premotor cortex
Somatosensory area
Corticospinal/pyramidal tract pathway
Site of origin--> Internal capsule--> Medullary pyramids--> (most) Cross in lower medulla--> Lateral columns of spinal cord
Lateral corticospinal tract
Fibers that have crossed in medulla
Supplies all levels of spinal cord
Anterior corticospinal tract
Uncrossed fibers (eventually cross near LMN) Supply neck/upper limbs
Corticospinal tract functions
Add speed and agility to conscious movements, especially hands
Provides high degree of motor control
Giant pyramidal (Betz) cells are located
In motor cortex
Corticospinal muscle tract lesions cause
Reduced muscle tone
Clumsiness
Weakness
Not complete paralysis (only if both pyramidal and extrapyramidal systems are involved)
Corticobulbar tract
UMN of cranial nerves- innervate face/head neck
-Terminate in reticular formation
Fibers from _____ and _____ synapse in the _______ portion of the red nucleus
Primary motor cortex; corticospinal tract
Magnocellular portion
Stimulation of red nucleus results in
Stimulation of flexors
Inhibition of extensors
Vestibulospinal tract receives info from
Cranial nerve VIII (vestibular nerve)
Vestibulospinal tract synapses with ____ which supply ___
LMN supplying extensors
-maintain upright posture
Components of vestibulospinal tract
Utricle w/macula on horizontal plane (upright)
Saccule w/macula on vertical plane (lying down)
Semicircular canals
Macula contains
Calcium carbonate crystals, cilia etc…
Cerebellum functions
Planning, timing, adjusting muscle movements -mainly when they have to be rapid
Not essential for locomotion
Cerebellar vermis zone
Location for control functions of muscle movements of body, neck, shoulders, hips
Intermediate zone of cerebellum
Muscle contractions in distal portions of upper/lower limbs
Lateral zone of cerebellum
Planning of sequential motor movements w/cerebral cortex
Dentate, emboliform, globose nuclei (intracerebellar) lesions result in
Extremity ataxia
Fastigial nuclei (intracerebellar) lesions result in
Trunk ataxia
Granular layer
Innermost layer of cerebellar cortex
Golgi II cells, glomeruli, mossy fibers
Purkinje cell layer
Middle layer of cerebellar cortex
Purkinje cells
Molecular layer
Outermost layer of cerebellar cortex
Stellate cells, basket cells, purkinje dendrites, granule cell axons
Granular cells form
Parallel fibers in cortex
Golgi cells project from and to
Parallel fibers to granular cell bodies
Basket cells project from and to
Parallel fibers to purkinje axon hillock (lateral inhibition)
Stellate cells project from and to
Parallel fibers to purkinje dendrites (lateral inhibition)
Purkinje cells
Project to intracerebellar nuclei
-They are ONLY output from cerebellar cortex, and always inhibitory
Climbing fibers
Afferent from cerebellar cortex- cause complex spikes
Play role in motor learning, condition purkinje cells
Mossy fibers
Afferent from cerebellar cortex
Make simple spikes
Vestibulocerebellum
Control of balance and eye movements
Contains flocculonodular lobes
Loss of flocculonodular lobes results in
Extreme disturbance of equilibrium and postural movements
Changes that occur when cerebellum is removed
Movements are slow to develop and turn off, force is weak
Vestibulocerebellum syndrome
Progressive genetic disease of flocculonodular lobe
Nystagmus
Vertigo, tinnitus
Spinocerebellum
Vermis/intermediate zone
Receives info from motor cortex and red nucleus
Sends corrections back to them via thalamus
Cerebrocerebellum
Lateral parts of hemispheres
Receives corticopontocerebellar projections
Coordination of speech
Corticopontocerebellar tract
Major link b/w cortex and cerebellum
Lesions result in weakness
Vestibulocerebellar tract terminates
In flocculonodular lobes
Reticulocerebellar tract terminates
In vermis
What tracts form the mossy fibers
Corticopontocerebellar
Vestibulocerebellar
Reticulocerebellar
Spinocerebellar
Axons from what form climbing fibers
Olivocerebellar tract
Cerebelloreticular tract begins
Fastigial nuclei –> reticular
Cerebellothalamocortical and cerebellorubral tracts begin
Dentate, emboliform, globose nuclei
Basal nuclei functions
Plan/execute motor commands w/cerebral cortex
Modulate thalamic output to motor cortex
Basal nuclei putamen circuit (direct pathway)
Cerebral cortex (+Ach)--> Putamen (-GABA)--> Internal Globus pallidus (IGP) (-GABA)--> Thalamic relay nuclei (+Glutamate)--> Primary motor cortex
Dopamine D2 receptors vs D1 receptors
D2 inhibitory
D1 excitatory
Lesions in globus pallidus
Inability to maintain postural support
Spontaneous movements of hand/arm etc- ethetosis
Lesions in subthalamic nuclei
Sudden flailing movements of an entire limb- hemiballismus
Lesions in striatum (putamen)
Flickering movements of hands/face/elsewhere- Chorea
-Occurs w/huntingtons
Lesions in substantia niagra
Caused by destruction of dopaminergic neurons
Parkinsons
Tremors
Dopamine effect on direct and indirect pathway
Dopamine inhibits the indirect pathway and excites the direct pathway
Direct (putamen) pathway function
Excitatory
Subconscious execution of learned movements
Indirect (caudate) pathway function
Inhibitory
Planning of sequential/parallel motor patterns
Where can you find neurons that are directly sensitive to chemical/physical variables (temperature etc)
Hypothalamus
Brain areas affecting body temp
Anterior preoptic hypothalamus
Warm sensitive neurons
30% of neurons in APH
Activate neurons in paraventricular nucleus and lateral hypothalamus – Parasympathetic
Cold sensitive neurons
5% of neurons in APH
Activate neurons in posterior hypothalamus –Sympathetic
What is the brain area involved in shivering
Posterior hypothalamus
Posterior hypothalamus normally inhibited by _____, when activated it sends signals to
Inhibited by heat center in APH
Sends signals to activate a/y-motor neurons in lateral horns
IL-1/prostaglandins effect on fever
Increases it
Aspirin effect on fever
Decreases by reducing prostaglandin synthesis
Active transport of glucose occurs via ___ and where
Sodium glucose cotransport
GI tract, renal tubules
End products of Citric acid cycle
16 hydrogens
2 ATP
4 CO2
Increased blood glucose leads to
Increased osmotic pressure
Increased urine output
Damage to tissues/vessels
When 2 electrons pass through for oxidative phosphorylation, how much ATP is produced
3 ATP
ATP formed per glucose molecule per cycle
efficiency is %
Glycolysis-2 CAC-2 OP-34 38 total per glucose 66% efficiency
Pentose phosphate pathway
Synthesis of triglycerides from glucose
Uses NADPH
Uptake of triglycerides
They are first digested into monoglycerides/fatty acid
Intestinal cells resynthesize them into triglycerides that enter lymph as chylomicrons
-Bile salts form micelles w/lipids for absorption
Lipoprotein lipase
Adipose/heart/skeletal muscle
Hydrolyzes triglyceride/chylomicron to fatty acids and glycerol
VLDL
High concentration of triglycerides, moderate amount of phospholipids and cholesterol
Transports lipids from liver to adipose
LDL
High concentration cholesterol, moderate amount of phospholipids
HDL
High concentration protein, low cholesterol/fatty acid
What happens to ketones
Converted to acetyl CoA
Conditions favoring ketosis
Starvation
Diabetes
Fatty diet
Ornithine cycle mitochondrial steps
Ammonia + CO2–> Carbamoyl phosphate
Carbamoyl phosphate + Ornithine–> Citrulline
Ornithine cycle cytoplasmic steps
Citrulline + aspartate–> arginosuccinate
Arginosuccinate –> arginine + fumarate
Arginine–> urea + ornithine
Fumarate can enter CAC
What is the best known stimuli for increasing rate of thyroid stimulating hormone
Cold
Thyroxine and metabolic rate
Increases metabolic rate
Testosterone and metabolic rate
Can increase 10-15% due to anabolic effect of increasing muscle mass
Malnutrition and metabolic rate
Reduces it significantly
Propulsive movements
Contractile ring occurs at point of stimulation in gut and can move orally or rectally (usually dies out orally)
Myenteric plexus is needed
Mixing movements
Can be caused by peristaltic contractions themselves
What cells generate slow waves and what are they
Cells of Cajal
- slow waves are not action potentials;they spread through gap junctions and occur spontaneously
- set maximum frequency of contraction
Spike potentials
Action potentials when GI membrane > +40mV
Opens calcium-sodium channels in GI smooth muscle
Reflexes integrated entirely within gut wall- function
Much of GI secretion
Peristalsis
Mixing contractions
Local inhibitory
Reflexes from gut to prevertebral sympathetic and back to gut
Long distance signals
Evacuation of colon
Inhibit stomach motility/secretion
Empty ileal contents
Gastrin activation/actions
Eating/Phe/Trp
Stimulates gastric acid secretion by parietal cells
Stimulates mucosal growth
Inhibited by acid (negative feedback)
Zollinger-Ellison syndrome
Gastrin secreting non-b cell tumors of pancreas
What secretes cholecystokinin and what is its action
I-cells of small intestine
Controls feedback of duodenum
Pancreas functions
Inhibit appetite
What secretes secretin and what are functions
S cells of small intestine
Stimulates pepsin, inhibits gastric acid secretion
GIP secreted by, action
Only GI hormone secreted in response to fat/carb/protein
K cells of duodenum/jejunum
Stimulates insulin release, inhibits gastric acid secretion
Motilin secreted by/actions
M-cells of duodenum/jejunum
Stimulates gastric motility
Secreted during fasting
Saliva secretion regulated by
Mostly parasympathetic, but also sympathetic- both result in increased saliva
Cranial nerves VII and IX
Parasympathetic saliva receptor/ second messengers
Cholinergic
IP3 and Calcium
Sympathetic saliva receptor/ second messengers
B-adrenergic
cAMP
Direct parasympathetic stimulation of H+
CN X innervates parietal cells to release H+
Ach is NT
Indirect parasympathetic stimulation of H+
CN X innervates G cells
G cells secrete gastrin which stimulates H+ secretion
GRP is NT
Histamine secretion action
Stimulates H+ secretion by activating parietal cells
Somatostatin secreted by/functions
Delta cells of pancreas
Inhibits secretion of insulin, glucagon, gastrin
Decreases motility/secretion/absorption of GI tract
Crypts of Lieberkuhn
Goblet cells
Enterocytes-absorptive
Paneth cells-antimicrobial
Enteroendocrine cells-peptide hormones
