Anatomy and Physiology Yr2 exam Flashcards
The telencephalon and the diencephalon form the…..
forebrain
the telencephalon and diencephalon start off as the….
prosencephalon
the diencephalon consists mainly of the….
thalamus and hypothalamus
endocrine cells secrete their hormones directly…..
into the blood
where does the cerebellum send the signals that representation the difference of intent?
Purkinje cells send signal from cerebellum to deep nuclei - dentate.
Deep nuclei - relayed to thalamus
thalamus to pre-motor cortex
where do upper motor neurone cell bodies lie?
In a nucleus of the brain stem, or the spinal cord
What is the name of upper neurone tracts that synapse on motor nuclei in the brainstem?
Corticobulbar tracts
What is the lateral corticospinal tract responsible for?
Fractionation of movement (independent movemnt of individual muscles)
Where does the lateral corticospinal tract decussate?
In the brainstem (medullary pyramids) to synapse directly on LMN throughout the spinal cord
That three tracts compose the corticospinal pathway?
Corticobulbar tract
Lateral corticospinal tract
Anterior corticospinal tract
what are basal nuclei?
masses of grey matter lying within each hemisphere
thalamus, caudate nucleus, putamen, globus pallidus, hypothalamus, substantia nigra, subthalamic nucleus
what does the basal nuclei do?
control and adjust muscle tone.
Eg. subconsiously the shoulder and arm is stablised to voluntarily pick up a pencil.
What can cause an increase in muscle tone characteristic of Parkinson’s disease?
Damage to the substantia nigra, or a reduction in secretion of dopamine. This causes the basal nuclei to become more active.
Parkinson’s is a hypokinetic disorder othe basal nuclei, name two hyperkinetic disorders
- Huntington’s disease - genetic disorder, degeneration of basal ganglia and thus dis-inhibition and excessive output from motor cortex
- Dystonia
Two primary functions of the cerebellum
- Adjusting the postural muscles
- Programming and fine-tuning movements controlled at the conscious and subconsious levels. Refines learned movement patterns.
What is ataxia?
Voluntary, normal strenth jerky and inaccurate movements that are not associated with hyper-stiffness.
What is Dysarthria?
Slurred poorly articulated speech
What is different about the ANS compared to the SMS regarding the motor anatomical system?
The ANS has TWO lower moto neurones in its pathway
What does the sympathetic nervous system demonstrate before reaching its target effector? And WHY?
Convergence
Allows the SNS to respond in a more generalised way.
The SNS exhibits convergence, the PNS exhibits….
Divergence.
Thus the effects are more localised and specific, the PNS is designed to respond in a specific way
What is the Corticospinal pathway composed of?
The corticobulbar tracts
The lateral corticospinal tracts
The anterior corticospinal tracts
Where does the lateral corticospinal tract decussate?
In the brainstem (medullary pyramids)
What inhibits the basal nuclei?
Neurons in the substantia nigra (via dopamine)
Huntington’s disease is an example of a……?
Hyperkinetic disorder
What are the signs of Huntington’s disease?
Involuntary jerky rapid body movements and dementia.
How does the cerebellum adjust movement?
It compares the intended motor command with the proprioceptive sensory feedback, and makes any adjustments needed to make the movement smooth.
What do the semicircular ducts detect?
Motion in one of three rotational planes
What is the name of the calcium carbonate crystals found within maculae of the utricle and saccules?
Statoconia
The statoconia on top of the macula detect what?
Changes in head position
Perception of linear acceleration
With hearing, what’s the name of the membrane that the hair cells vibrate against?
Tectorial membrane
Where do neurons from the cochlear nerve go to?
The cochlear nuclei in the medulla.
Where do neurons from the cochlear nuclei (of the medulla) go?
To the inferior colliculus
Which part of the brain processes information to determine auditory reflexes?
Inferior colliculus
Where do ascending auditory sensations synapse before reaching the auditory cortex of the temporal lobe?
Medial geniculate nucleus of the thalamus
The auditory cortex contains a map of the….
Organ of Corti
What are the two ganglion for parasympathetic nerve supply to the salivary glands?
Submandibular
Otic
Where does the vestibular nerve go?
To the vestibular nuclei at the boundary of the pons and the medulla
What are the four functions of the vestibular nuclei?
Integrating sensory information about balance and equilibrium
Relaying information to the cerebellum
Relaying information to the cerebral cortex – conscious sense of head position and movement
Sending commands to motor nuclei in the brain stem and spinal cord
What is the main neurotransmitter in the autonomic nervous system?
Acetylcholine
The main neurotransmitter in the ANS is acetylcholine, except for the ……. Sympathetic synapse, which is often ……
Postganglionic
Adrenaline
Where are the cell bodies of the preganglionic neurons of the sympathetic nervous system?
In the lateral gray horns
What does thyroid hormone do?
Stimulates ATP synthesis and energy metabolism
Where are thyroid hormones held in storage?
In the cytoplasmic receptors in almost every cell of the body.
What is the name of the disease associated with too much thyroid hormone? And a unique symptom
Graves’ disease (autoimmune disease)
Exophthalmos
What is the name of the disease associated with iodine deficiency , and the symptoms?
Myxedema
Oedematous, puffy appearance due to accumulation of water-holding carbohydrates in the skin
What does the adrenal cortex produce?
Corticosteroids
What are the caudate and putamen collectively known as?
Corpus striatum
Which transport protein binds to corticosteroids in the blood?
Transcortins
What does aldosterone do?
Causes the retention of Na+ ions (sodium), and prevents Na+ loss.
Secondary function … the reabsorption of Na+ enhances the osmotic reabsorption of water.
Also… increases the sensitivity of salt receptors in the tongue taste buds.
What does cortisol (glucocorticoids) promote?
Gluconeogenesis (glucose synthesis)
Glycogenesis (glycogen formation)
Lipolysis (breaking down of fatty acids)
What effect to glucocorticoids have on the immune system?
Slows the migration of phagocytic cells
Mast cells are less likely to release histamine
< swelling and irritation
How are secretory activities of the suprarenal medulla controlled? And what does it produce?
Sympathetic n.s.
Epinephrine (adrenaline)
Norepinephrine (noradrenaline)
What does gross sympathetic activation cause?
stimulation of reticular activating system ‘on edge’
> energy feeling
cv and res centre activity in brainstem… leading to?….
muscle tone (via medial and lateral pathways)
mobilization of energy stores
Gap junctions are a form of ….. communication. What are the requirements for this type of communication?
Direct
Two cells of the same type
Cells must be in physical contact
What is paracrine communication?
Use of chemical messengers to transfer information from cell to cell within a single tissue. Chemical also known as local hormones, eg. Prostaglandins.
The activity of hormones in coordinating cellular activities in tissues in distant portions of the body is called….
Endocrine communication
What do cells needs to respond to endocrine communication?
Receptors
Name the three section of an embryonic neural tube
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhomboencephalon (hindbrain)
What is the main function of the hypothalamus?
Integration of the nervous and endocrine systems
How can endocrine reflexes be triggered?
Humoral stimuli (changes in composition of extracellular fluid)
Hormonal stimuli
Neural stimuli
What does the hypothalamus secrete?
Regulatory hormones
(hormones that control endocrine cells in the pituitary gland)
How does the hypothalamus implement control?
By releasing regulatory hormones
By synthesising hormones itself
By neural control via the sympathetic NS
What is the nerve relationship between the hypothalamus and the suprarenal medullae?
Hypothalamus contains autonomic centres (sympathetic control) that cause the suprarenal medullae to release hormones in the bloodstream.
What is another name for the posterior pituitary?
Neurohypophysis
Another name for the anterior pituitary?
Adenohypophysis
What hormones does the hypothalamus produce?
ADH and Oxytocin
What hormones are released by the posterior / neurohypophysis pituitary gland?
ADH and Oxytocin
How are hormones from the anterior pituitary gland regulated?
By specific regulatory hormones secreted by the hypothalamus.
What are the 7 hormones from the adenohypophysis? (posterior pituitary)
Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH) Two gonadotropins;
follicle-stimulating hormone (FSH)
luteinizing hormone (LH)
Prolactin
Growth hormone
Melanocyte-stimulating hormone (MSH)
What does TSM (thyroid-stimulating hormone - thyrotropin) do?
From the anterior pituitary it targets the thyroid gland to release thyroid hormone
Released in reponse to thyrotropin-releasing hormone (TRH) from the hypothalamus
What does ACTH do? (adrenocorticotropic hormone), corticotropin?
Stimulates the release of steroid hormones (glucocorticoids) by the suprarenal cortex.
Released via stimulation of cortico-releasing hormone (CRH) from hypothalamus
What do the gonadotropins do (follicle stimulating hormone and luteinizing hormone?
Regulate the gonads.
Stimulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus.
What does prolactin do?
Stimulates development of the mammary gland
Also stimulates milk production during pregnancy.
What inhibits prolactin?
Dopamine, which is also known as prolactin-inhibiting hormone (PIH)
What does GH do (somatotropin)?
Stimulates cell growth and replication by accelerating the rate of protein synthesis and cell division
Which nuclei contain the neurones that manufacture ADH and oxytocin?
Supraoptic nuclei – ADH
Paraventricular nuclei – oxytocin
What does ADH do?
Decrease amount of water lost at kidneys.
What does high concentrations of ADH do?
Vasoconstriction of peripheral blood vessels – elevates BP
What happens to ADH when you drink alcohol?
ADH release is inhibited – thus increased fluid excretion
What does oxytocin do?
Stimulates smooth muscle contractions and milk let down
Promotoes labor and delivery
Where is oxytocin secreted?
Mainly uterus and fetus, not the hypothalamus
Functions of Oxytocin
the expression of love and human morality…
peaks at orgasms, and rises during sexual arousal.
whats another name for the Telencephalon?
Cerebrum
Prosencephalon divides into …
telencephalon
dicencephalon
another name for the medulla oblongata
Myelencephalon
another name for the cerebellum and pons
metencephalon
the rhomboencephalon divides into …
Metencephalon
Myelencephalon
another name for columns (in the spinal tract)?
funiculi
Examples of neuroglia in the cns (4)
Astrocytes
Oligodentrocytes
Microglia
Ependymal cells
What do ependymal cells do (cns)?
Line ventricles and central canal. Assist in producing, circulating and monitoring csf
What do microglia do (cns)?
Remove cell debris, wastes, and pathogens by phagocytosis
What do astrocytes do (cns)?
maintain blood-brain barrier
provide structural support
regulate ions, nutrients, dissolved gas concentrations
absorb and recycle neurotransmitters
what do oligodentrocytes (cns) do?
myelinate cns axons
provide structural framework
What are the three broad categories of receptors?
Interoceptors
Exteroceptors
Propioceptors
what are the characteristics of free nerve endings?
stimulated by many different stimuli, and thus exhibit little receptor specificity
what’s another name for the dorsal column pathway?
medial lemniscus pathway
what and where is the solitary nucleus?
A large nucleus in the medulla.
It’s a major processing and sorting centre for visceral sensory info (VII, IX, X)
Also for dorsal roots of spinal nerves T1-S4 carrying visceral sensory info
What does a nephron consist of?
a renal Tubule (long tube) and a renal Corpuscle (contains filtrate from arterioles)
What does the filtration membrane consist of?
Fenestratad endothelium (allows all components of blood plasma to pass through, except blood cells)
Basal lamina (prevents filtration of larger proteins)
Filtration slits (slit membrane between pedicles prevents filtration of medium-sized proteins)
What passes from the glomerulus into the filtrate (via Bowman’s capsule)?
Water and small solutes
Also; glucose, free fatty acids, amino acids, vitamins, another other solutes
What is the glomerular filtration rate (GFR)
volume of fluid filtered from the renal glomerular capillaries into the Bowman’s capsule per unit time
How is GFR measured?
creatinine clearance test
* creatinine is from the breakdown of creatine phosphate in muscle tissue, and it eliminated in urine.
What is glomerulonephritis?
Inflammation of the glomeruli that affects the filtration mechanism of the kidneys
Often immune complex disorder (>>> antigen-antibody complexes) following strephococcus bacterial infection.
These complexes clog up the filtration slits
Three control mechanisms of GFR
Autoregulation - local level
Hormonal regulation - initiated by kidneys
Automonic regulation - sympathetic n.s. primarily.
What is myogenic auto regulation?
arteriole contraction or relaxation by automatic reflexes due to pressure changes
What is the juxtaglomerular complex?
a region between afferent and efferent arterioles.
An endocrine structure that secretes erthropoietin (a hormone) and the enzyme renin.
What stimulates renin from juxtaglomerular complex? (3)
- drop in blood pressure
- stimulation of juxtaglomerular cells by sympathetic inn.
- decline in osmotic conc. of tubular fluid at the macula densa.
Why and where is renin released?
By the juxtaglomerular cells.
In respond to a reduction in GFR and a number of other factors.
What does Renin do?
It converts inactive protein angiotensinogen to angiotensin I in the blood
What happens to angiotensin I (which is also inactive)?
Converted to angiotensin II by angiotensin-converting enzyme (ACE), primarily in the lung capillaries.
Angiotensin II is an active hormone. What does it do?
At nephron - Constricts the efferent arteriole (>> GFR and glomerular pressure)
At suprarenal glands - Stimulates secretion of aldosterone (cortex).
At cns - causes thirst sensation, triggers ADH release, increases sympathetic motor tone
At peripheral capillary bed - brief but powerful vasoconstriction of arterioles >> arterial pressure
Aldosterone… in the DCT and cortical portion of the collecting system
accelerates Sodium reabsorption
How does the sympathetic n.s. affect the GFR?
Powerful decrease - vasoconstriction of afferent and efferent arterioles.
- used for acute fall in BP or heart attack
What can cause proteinuria?
Endurance training because glomerular cells have been injured by prolonged hypoxia
Dorsal columns – gracilis and cuneate
Fine touch, conscious proprioception
Stays on ipsilateral side until the medulla. Decussates at medulla. Synapse to thalamus. Synpases to
What is the inn. for the ciliary muscle of the eye?
Postganglionic parasympathetic fibres from the Ciliary ganglion
what do photoreceptors detect?
photons (unit of light). Our eyes are sensitive to 700-400nm
what happens to visual nerve collaterals that don’t go to the lateral geniculate of the thalamus?
they synapse in the superior colliculi or the hypothalamus
what does the superior colliculi of the mesencephalon do with visual input?
issue commands that control unconsious eye, head, or neck movements in response to visual stimuli
what do visual inputs to the pineal gland do?
establish a daily pattern of visceral activity in the hypothalamus related to day-night cycle
what’s the difference between facilitated transport and co-transport?
Facilitated transport - passive transport across a membrane by carrier proteins. There is no continuous channel, just a temporary change in protein structure.
Co-transport - carrier protein transports two substances in the same direction simultaneously.
What happens if the Transport Maximum of glucose out of the lumen is exceeded?
hyperglycaemia
permeability characteristics of the descending limb of the nephron loop?
Permeable to water but relatively impermeable to solutes.
Permeability characteristics of the ascending loop of the nephron
relatively impermeable to both water and solutes.
Contains active transport mechanisms that pump Na+ and Cl- ions from the tubular fluid to the peritubular fluid of medulla.
What controls the permeability of the DCT and CCD (cortical collecting duct)
Aldosterone from the adrenal gland and ADH from the pituitary
What does aldosterone do in the nephron?
It controls sodium (Na+) ion pumps along most of the DCT and the proximal portion of the collecting system. (Cl- ions follow Na+ because positive attracts negative).
one line summary of pathology of Parkinson’s disease
‘progressive degeneration of cells within the pars compacta of the substantia nigra iin the midbrain’
How is the hypothalamus stimulated? (3)
- Sensory info from the cerebrum, brain stem, spinal cord
- Changes in the composition of csf and interstitial fluid
- chemical stimuli in the circulating blood that enters the hypothalamus
Damage to the lateral geniculate nuclei of the thalamus would affect what?
vision
what is the releasing hormone for TSH (from hypothalamus?
TRH (thyrotropin-releasing hormone)
what stimulates the release of ACTH (adrenocorticotropic hormone)
hypothalamus - cortico-releasing hormone
what is special about the spinothalamic tract?
Decusses at same segment, or one close by
where is ADH made, and where is ADH stored?
made in hypothalamus, stored in posterior pituitary gland
how to hormones get from the hypothalamus to the anterior pituitary gland?
portal blood system
Monoaminergic neurons have which neurotransmitters? (3)
Dopamine
Noradrenaline
Serotonin
What is the crus cerebri?
A continuum with the internal capsule witihin the brainstem. Primarily motor; corticospinal and corticobulbar tracts.
where do the first order neurones of the dorsal columns terminate?
at the mid-medulla, namely the gracile and cuneate nuclei, they then decuss.
What is the name of the fibres in the medulla that the 2nd order neurones become?
internal arcuate fibres
What is the name of the tract that the dorsal column neurons follow after decussing in the mid-medulla?
medial lemniscus (runs through rostral medulla, pons and midbrain). Terminates at 3rd order neurons at the thalamus
Where are the superior and inferior colliculus found?
In the midbrain
The ascending auditory projection goes to the….
lateral lemiscus and then the inferior colliculus.
After the interior colliculus, where do the auditory fibres go?
medial geniculate nucleus of the thalamus, and afterwards to the auditory cortex of the temporal lobe.
The superior colliculus of the rostal midbrain is part of the…..
visual system (more specifically eye movements with smooth pursuit or saccadic eye movements)
What is a crossed extensor reflex?
Association neurones connecting to motor neurones that innervate the extensor muscles in the opposite leg. These muscles contract and extend the opposite leg, preventing the animal from collapsing when it lifts its other leg off the sharp object.
What happens in the PCT? (4)
Reabsorption. 99 percent of the glucose, amino acids, and other organic nutrients in the fluid. A combination of facilitated transport and co-transport.
- Active/Passive Reabsorption of Ions. The PCT actively transports several ions, including sodium, potassium, and bicarbonate ions The ion pumps may be influenced by circulating ion or hormone levels.
- The PCT indirectly recaptures roughly 90 percent of the bicarbonate ions from tubular fluid. Bicarbonate is important in stabilizing blood pH.
Reabsorption of Water. Osmosis pulls water out of the tubular fluid and into the peritubular fluid. Along the PCT, this mechanism results in the reabsorption of roughly 108 litres of water each day.
Secretion. Active secretion also occurs along the PCT.
What happens with diabetes?
High levels of glucose in the filtrate exceeds the Tm (transport out of the lumen) of the carrier proteins so sugar is excreted in the urine (hyperglycaemia)
What is reabsorbed in the nephron loop?
Roughly half of the water, and2/3 of the Na+ and Cl- ions, remaining in the tubular fluid
What is the chacteristic of the descending limb?
Permeable to water but relatively impermeable to solutes
What are the characteristics of the thick ascending limb?
Relatively impermeable to both water and solutes, contains active transport mechanisms that pump Na+ and Cl- ions from the tubular fluid into the peritubular fluid of the medulla.
what happens down the descending loop?
water diffuses out and the filtrate concentration of NaCl builds up.
It is highest at the bottom of the loop
What happens in the ascending loop?
Water is retained in the filtrate and NaCl is actively pumped out
Ionic exchange - study this diagram
The cells of the DCT and cortical collecting duct regulate water and ion permeability under the control of ……
Aldosterone (from adrenal cortex) &
ADH (from pituitary gland)
What does Aldosterone do?
Controls Na+ pumps along most of the DCT and the proximal portion of the collecting system
What does ADH do?
Inserts water channels into the cells of the DCT and CCD. Water is therefore absorbed down the concentration gradient created by aldosterone
Age-related changes affect kidney function (2) and the micturition reflex (3)
A Reduction in the GFR.This reduction results from fewer glomeruli, cumulative damage to the filtration apparatus in the remaining glomeruli, and diminished renal blood flow.
A Reduced Sensitivity to ADH. Reabsorption of water and sodium ions occurs at a reduced rate, and more sodium ions are lost in urine.
Problems with the Micturition Reflex.Three factors are involved in such problems: (1) The sphincter muscles lose muscle tone and become less effective at voluntarily retaining urine.
(2) The ability to control micturition can be lost after a stroke, Alzheimer disease, or other CNS problems affecting the cerebral cortex or hypothalamus.
(3) In males, urinary retention may develop if enlargement of the prostate gland compresses the urethra and restricts the flow of urine.
what’s another name for the dorsal column pathway?
medial lemniscus pathway
what does the medial lemniscus pathway (dorsal columns) detect?
discriminative touch, conscious proprioception, vibration
where do the 1st order neurons of the lemniscus tract decussate?
dorsal medulla - gracilis and cuneate nuclei
what is the crus cerebri?
The anterior portion of the cerebral peduncle which contains the motor tracts
what are the names of the two speech areas in the brain?
Broca
Wernicke
whats the triad of clinical symptoms of Parkinson’s disease?
Tremor - resting/ pin-rolling
Rigidity - ‘lead-pipe’
Bradykinesia (also affects the face)
IMP: signs are strikingly asymmetric
Other signs; stooped posture, shuffling, asymmetric arm swing, micrographia
What is chorea?
Rapid, irregular, unpredictable, ‘fidgety’ like movements.
Long term complication of Parkinson’s treatment with L-Dopa
Function of oligodendrocytes
Production of myelin sheath in cns axons
where is the dentate nucleus?
in the cerebellum. Largest nuclei in cerebellum.
what is the ophthalmic artery a branch of ?
internal carotid artery
name the four arteries in the diagram
anterior inferior cerebellar artery
vertebral artery
anterior spinal artery
posterior inferior cerebellar artery
primary motor cortex is also known as the….
precentral gyrus
structures in the pyramidal tract (corticospinal) - 6
motor cortex
corona radiata
internal capsule
crus cerebri (in midbrain)
pons
medulla - pyrimidal decussation
label structures
caudate nucleus
putamen
globus pallidus
thalamus
Diagram of embryological development of neural tube
what is the diencephalon composed of?
thalamus
hypothalamus
what nuclei is the neurohypophysis produce ADH and oxytocin?
supraoptic nuclei - ADH
paraventricular nuclei - oxytocin
Four main characteristics of insulin
- stimulates glucose utilization
- enhances ATP prduction
- Stimulates carbodydrates storage (glycogen)
- Stimulates lipid (triglyceride) storage in adipose tissue
Four important facts about glucagon
- reduces glucose consumption
- stimulates breakdown of glycogen stores (carbodydrates)
- stimulates breakdown of triglycerides
- stimulates glyconeogeneis (a.a. > glucose in Liver)
How are insulin and glucagon levels controlled?
They respond to change in glucose levels. Indirectly by hormones that affect glucose levels.
Insulin is stimulated by parasympathetic, inhibited by sympathetic
The suprarenal medulla has four main actions that supplement the sympathetic n.s. via the action of noradrenaline and adrenaline, what are they?
- Mobilization of glycogen stores in skeletal muscle and acceleration of glucose breakdown to provide ATP. Increases musclar strength and endurance.
- Adipose tissue - fats - fatty acids - into bloodstream for ATP production
- Liver - glycogen - glucose for neural tissues
- Heart - increase in rate and strength of cardiac muscle contractions
Name some complications of diabetes mellitus (6)
- diabetic retinopathy
- diabetic neuropathy
- diabetic nephropathy
- degenerative cardiac changes
- problems with blood flow to feet
- cataracts
What do Delta and F cells do in the pancreas?
Produce inhibiting hormones that reduce gut absorption and gallbladder contraction
How is the cerebellum connected to the brainstem?
Via the interior, middle and superior cerebellar peduncles.
The functions of the cerebellum are entirely….. and it functions at an …… level
motor
unconscious
In a sentence, what does the cerebellum do?
Controls maintenance of equilibrium (balance), influences posture, and muscle tone and coordinates movement.
Gross external anatomy of the cerebellum
two laterally located hemispheres joined in the midline by the vermis.
Divided into three lobes; anterior, posterior and flocculonodular lobes
There are four nuclei in the cerebellum, what is the name of the one that is most visible?
dentate nucleus
The grey matter of the cerebellar cortex is divided into three layers
outer fibre rich - molecular layer
intermediate - Purkinje cell layer
inner - granular layer
Where do afferent fibres to the cerebellum come from ? (4)
spinal cord (spinocerebellar fibres)
inferior olivary nucleus (olivocerebellar fibres)
vestibular nuclei (vestibulocerebellar fibres)
pons (pontocerebellar fibres)
What are the functional subdivisions of the cerebellum?
Archicerebellum. The oldest and associated with the flocculonodular lobe
Paleocerebellum
Neocerebellum; the majority of the cerebellum
What is the function of the archicerebellum?
Maintenance of balance
Extensive connections with vestibular and reticular nuclei. Vestibulospinal and reticulospinal connections.
What is the function of the neocerebellum?
muscular coordination, including trajectory, speed and force of movement.
mainly connected with pontine nuclei.
What happens with a midline lesion of the cerebellum?
Loss of postural control
Symptoms usually ipsilateral.
intention tremor
nystagmus
if bilateral (alcohol); dysarthria, cerebellar ataxia
What is Charcot’s triad?
nystagmus
dysarthria
intention tremor
- triad of symptoms commonly associated with m.s.
What is the central sulcus?
The boundary between the frontal and parietal lobes
What type of hormone is aldosterone and where is it produced?
Steroid (mineralocorticoid)
Adrenal cortex
What stimulates the secretion of aldosterone?
Main one – rise in K+ levels
Also; drop in Na+ content, blood volume, or blood pressure (monitored by stretch receptors in atrium), or a rise in K+ concentration.
Also – released in response to angiotensin II
why get you get raising of the eyebrow in UMN lesion, and not with Bell’s Palsy?
what does the brainstem consist of?
The amygdala is part of the …..
limbic system
Something important about the basal ganglia and the limbic system….
They interface with the limbic system, this confering a role in the physical expression of behaviour driven by affective and motivational states
What is the lentiform nucleus?
Putamen and Globus Pallidus grouped together
what is another name for the caudate nucleus and putamen?
Striatum
the nucleus accumbens is part of the …..
caudate nucleus (basal ganglia)
diagram of the basal ganglia
What are the current concepts of the role of the basal ganglia?
Their function is to facilitate behaviour and movements that are required and appropriate in any particular context and to inhibit unwanted or inappropriate movements.
Cellular organisation of the retina - diagram
What is the choroid of the eye?
Dark pigmented cells that line the inner surface of the sclera and reduce reflection by absorbing light.
What is the Meyer’s loop?
Part of temporal lobe that represents the upper part of the visual field
What does the kinetic labyrinth consist of?
semi-circular canals and ampullary organs
How do vestibular hair cells function?
mechano-sensitive stereocilia which respond to directional bending by opening K+ channels to cause depolarisation and release of neurotransmitter onto sensory axons of the VIIIth cranial nerve at the cell base.
How is tilt detected in the macula?
Stereocilia are orientated in opposite directions. Deflection stimulates, opposite direction inhibits.
Networks from Vestibular apparatus
(reflex pathways - 3)
steady gaze during head movement
spinal output to extensors - help maintain upright posture
visceral control - including vomiting centres of brainstem
How does the cerebellum help the vestibular apparatus?
It fine tunes vestibular reflexes
Vestibular reflexes (3)
Postural
Increase tonus in extensor muscles via the lateral vestibulo-spinal tract. Vestibular nuclei - medial longitudinal fasciculus - neck muscles, keep the head upright.
Vestibulo-ocular
coordinates head and eye movements to keep gaze centred on visual objects.
Visceral
Mismatch between the vestibular and other sensory inputs can cause vertigo, nausea and vomitting, etc. This can also occur in hyperactivity of the labyrinth (labyrinthitis, Meniere’s disease) and brainstem lesions.
What is oogenesis and when does it occur?
Ovum production
Begins before a woman’s birth
Accelerates at puberty
Ends at menopause
What is in suspended development before birth?
primary oocytes
Primordial follicles are activated by?
rising levels of FSH
At puberty, primordial follicles degenerate via a process called?
atresia
What are the cells called around a growing primary oocyte?
Granulosa cells
granulosa cells and ……. cells produce …….
thecal
oestrogens
Step one of ovarian cycle is….
activation of primordial follicles into primary follicles.
Also… growth of granulosa cells (oestrogen production)
Ovarian cycle step two is…..
primary follicles developing into secondary follicles
what develops in stage two of ovarian cycle?
mainly the follicle due to secretion of liquor folliculi. Not much primary oocyte development
ovarian cycle - day 10 to 14. Step three.
What has happened?
follicles become tertiary follicles or mature graafian follicles.
Bulging on surface of ovary ready for ovulation
What hormone stimulates the primary oocyte to complete meiosis I? (stage three)
LH
What happens on day 14
Secondary oocyte released
Ovulation marks the end of the ….. phase
follicular
ovulation - the ….. follicle releases the …… oocyte
tertiary
secondary
remaining granulosa cells of follicle (after ovulation) forms the …..
corpus luteum
what does the corpus luteum do?
secretes progesterone
What does progesterone do?
maturation of uterine lining
secretion of uterine glands
Step six - what happens if ovulation doesn’t occur?
corpus luteum dies
Drop in levels of progesterone and oestrogen
definition of upper motor neurone
cell body lies in cns processing centre
definition of lower motor neurone
cell body lies in a nucleus of the brainstem or spinal cord
The motor area devoted to a specific region of the cortex is proportional to ………
the number of motor units involved in the region’s control
What does the internal capsule do?
It links the cerebral cortex to the diencephalon, brain stem, cerebellum, and spinal cord
As you begin a voluntary movement, the basal nuclei ……
control and adjust muscle tone.
If the substantia nigra is damaged or the neurons secrete less ……., basal nuclei become more ……..
dopamine
active
Chorea consisting of ……. ………. rapid movements and …….. are signs of Huntingtons disease.
This genetic disorder causes degeneration of the basal ganglia resulting in …………. and excessive output from the motor cortex.
involuntary jerky
dementia
dis-inhibition
What is the movement disorder common to all lesions of the cerebellum?
Ataxia
Ataxia describes voluntary, normal strength jerky and inaccurate movements that are not associated with hyper-stiffness
Cerebellum symptoms (4)
Ataxia
Nystagmus
Dysequilibrium
Dysarthria
What are the GENERALIZED actions of the sympathetic nervous system (4)
Increased alertness via stimulation of the reticular activating system, causing the individual to feel “on edge.”
Increased activity in the cardiovascular and respiratory centres of the pons and medulla oblongata, leading to elevations in blood pressure, heart rate, breathing rate, and depth of respiration.
A general elevation in muscle tone through stimulation of the medial and lateral pathways, so the person looks tense and may begin to shiver.
The mobilization of energy reserves, through the accelerated breakdown of glycogen in muscle and liver cells and the release of lipids by adipose tissues.
Three divisions of neural tube
The Prosencephalon divides into the…..
The rhomboencephalon divides into the….
The diencephalon is composed of the ….
thalamus and hypothalamus
What does the suprachiasmatic nucleus of the hypothalamus do?
It receives input from the retina to control the diurnal (of the day) rhythms and the sleep/ waking cycle.
What do the autonomic centres of the hypothalamus do?
control medullary nuclei that regulate heart rate and blood pressure
Locations of the lateral and medial geniculate and the inferior and superior colliculus
There are some important nuclei in the midbrain - mesencephalon, what do they do?
Process visual and auditory information and control reflexes triggered by these stimuli
(superior and inferior colliculi)
Remember that the medulla oblongata also contains major centers that regulate autonomic function: (3)
Heart rate
Blood pressure
Digestion
What do association fibres do? (in neural cortex)
They interconnect areas of neural cortex within a single cerebral hemisphere.
What do anaxonic neurones do?
They form the interneurons of the CNS, and, outnumber all other types of neurones combined.
eg. purkineje cells, pyramidal cells, globus pallidus cells
What are interneurons involved with? (anaxonic cells)
All higher functions, such as memory, planning, and learning.
In terms of the nervous system, what is adaptation?
A reduction in sensitivity in the presence of a constant stimulus.
Tonic receptors adapt slowly.
Phasic receptors adapt fast
What is it called, the link between peripheral receptor and cortical neurone?
Labeled line
What are the three major somatic sensory pathways? (3)
- Posterior column pathway
- Spinothalamic pathway
- Spinocerebellar pathway
What sensation does the dorsal column/ medial lemniscus pathway carry?
fine touch,
pressure,
vibration,
& proprioception
Dorsal column pathway is broken down into… (2)
gracilis fasciculus
cuneatus fasciculus
What sensation does the spinothalamic tract carry?
poorly localized (“crude”) touch,
pressure,
pain,
and temperature
Further differentiate the spinothalamic tracts (anterior and lateral). What sensations are involved with each?
Anterior spinothalamic tract ; crude touch and pressure
Lateral spinothalamic tract; pain and temperature
Give some examples of interoceptors
nociceptors,
thermoreceptors,
tactile receptors,
baroreceptors,
chemoreceptors,
Which cranial nerves carry visceral sensory information mostly from organs above the diaphragm ?
VII - facial
IX - glossophargyneal
X - vagus
Where does visceral sensory information go?
To the solitary nucleus, a large nucleus in the medulla oblongata.
What is the solitary nucleus?
It is a major processing and sorting centre for visceral sensory information
What’s the relationship between T1-S4 dorsal roots and visceral sensory information?
They also carry visceral sensory information to the solitary nucleus and the thalamus
Therefore; overlap of somatic and visceral input at the spinal segment (spinothalamic tract)
What is referred pain?
Strong visceral pain sensations arriving at a segment of the spinal cord can stimulate interneurons that are part of the spinothalamic pathway.
Activity in these interneurons leads to the stimulation of the primary sensory cortex, so the individual feels pain in a specific part of the body surface unrelated to the visceral stimulus
Liver and GB referred pain
Heart referred pain
Referred pain - ureters
The basal ganglia are important in the facilitation of appropriate motor behaviour and the ……. of unwanted movements.
inhibition
Each side of the cerebellum coordinates movements of the ….. side of the body.
Ipsilateral
(spinocerebellar tract)
Remember the symptoms of
cerebellar syndrome (4)
nystagmus
dysarthria
ataxia
intention tremor
symptoms on ipsilateral side
NO weakness or loss of sensation
Nuclei of the hypothalamus (7)
paraventricular - oxytoxin
supraoptic - ADH
suprachiasmatic - coordinates day/ night cycles of activity
autonomic centres - control medullary nuclei that regulate HR and BP
Tuberal - releases hormones that control endocrine cells of adenohypothesis
mamillary - controls feeding reflexes (licking, swallowing, etc)
preoptic - regulates BT
What do the mesencephalic nuclei do?
(inferior and superior colliculus)
The nuclei process visual and auditory information and control reflexes triggered by these stimuli
ALSO - contains centres that help maintain consciousness
What is adaptation (in context of sensory receptors)?
A reduction in sensitivity in the presence of a constant stimulus.
Tonic receptors adapt slowly.
Phasic receptors adapt fast
thalamus - labelled lines - what is the relationship?
Processing in the thalamus determines the specificity of the sensation according to the appropriate labelled line.
The anterior spinothalamic tracts carry….
crude touch and pressure sensations
The lateral spinothalamic tracts carry ….
pain and temperature sensations
Conductive deafness is caused by….
Earwax, damage to ear-drum,
otosclerosis of the middle ear, trauma,
middle ear infections - travelling from the nasopharynx, genetic defects
Sensorineural deafness is caused by…..
Cochlea – infection, trauma, noise, age, ototoxic drugs, genetic defects (myosins, gap junction mutations etc), tumours.
Central deafness is caused by…..
Vascular accident, trauma, MS,
infection, tumour, neonatal distress
What are the four systems that control excretory exchange?
urinary system
respiratory system
digestive system
integumentary system
What are the three functions of the urinary system?
regulates volume and solute concentration of blood plasma
excretion of nitrogenous waste
elimination of waste products into the environmnt
ammonium ion (from breakdown of nitrogen) is combined with …… to produce …..
CO2
urea
Which level are the kidneys located ?
between T12 and L3
What holds the kidneys in position?
The fibrous capsule, a layer of collagen fibers that covers the outer surface of the entire organ.
The perinephric fat capsule, a thick layer of adipose tissue that surrounds the fibrous capsule.
The renal fascia, a dense, fibrous outer layer that anchors the kidney to surrounding structures.
The vestibular and reticular nuclei form tracts, what are they called? And function?
Vestibulospinal
and reticulospinal
- muscle tone & posture
What are the two groups of basal ganglia pathways?
direct - initiates/facilitates movement
indirect - stops/inhibits movement
Globus pallidus consists of two….
segments - medial and lateral
Why are the caudate nucleus and putamen important?
They receive afferent fibres from the cerebral cortex, the thalamus, and the pars compacta of the substantia nigra
Disorders of movement and the basal ganglia - General features (a list)
No paralysis,sensory loss or ataxia
Abnormal motor control,alterations in muscle tone
Abnormal involuntary movements
Slowness - bradykinesia
Loss or absence - hypokinesia, akinesia
Problems of stopping and starting
Abnormal postures, arm swinging in walking can be absent
Rigidity to passive movement is constant as opposed to spasticity
Cog-wheel v continuous
Tremor at rest
Chorea - fragmented purposeful components of a real movement
Dystonia - sustained contractions producing abnormal postures
Athetosis - slow sinuous writhing movements of axis
Myoclonus - short sharp movements
Tics
Simple overview of cerebellar function
Motor cortex sends command to lower motor neurons in spinal cord
Simultaneously the command is recorded in cerebellum
Cerebellum receives information via spino-cerebellar tracts
This is information of what has actually happened
Cerebellum compares “intention” & “achieved”- computes difference
Purkinje cells send output from cerebellum to deep nuclei - dentate
Deep nuclei relay to thalamus to pre-motor cortex
Pre-motor cortex corrects motor cortex with difference
Error is corrected
Basal ganglia lesions - signs
Contralateral signs
No paralysis or sensory loss
Abnormal control of posture & movement Parkinsons - tremor at rest
Slowness starting,carrying out movement - hypo/brady/akinesia
Abnormal involuntary movements
Rigidity to passive movement
Cerebellar lesions (5 signs)
Ipsilateral signs
Nystagmus
Intention tremor
Dysarthria
Ataxia
