Module 8 Wk 2 Flashcards
what are the 2 functional divisions of the ANS?
The parasympathetic and sympathetic
What is the other anatomical word for the parasympathetic system?
craniosacral system
what is the other anatomical name for the sympathetic system?
thoracolumbar system
What is the function of the parasympathetic division?
Day to day control of viscera
what is the function of the sympathetic division?
Active when the animal is stressed
In relation to the para and sympatheric systems what in organs is determined?
Organ function determined by the balance of input from each system
What are the two anatomical divisions of the ANS?
The CNS and the PNS
where are the main control centres of CNS located?
Hypothalamus and the midbrain
Can cerebral cortex command the control centeres?
No - They can influence
eg emotional status causing blushing
Where do the CNS decending fibers go?
Brainstem and spinal cord
In the PNS where is the outflow of the parasympathertic and sympatheric innervation?
The para outflow is via brain stem and sacral cord
The sympathetic outfloe is via thoracolumbar cord
What is the main difference in the two fibres (parasym and sym) in the PNS?
In the parasympathetic fibers the ganglia is closer to the organ they are innervating whereas in the sympathetic the ganglia is further away from the organ with a longer post-synaptic fibre
Where are the 3 different location of the neural cell body and for what kind of cell body?
- Dorsal horn for sensory cell bodies
- ventral horn for motor striated muscle
- Intermediate/lateral horm for motorneuron cell bodies of ANS in thoracolumbar and sacral cord
How do the parasymapthetic fibres innervate all viscera?
- Cranial nerves from brain
- Segmental spinal nerves from sacral spinal cord
What cranial nerves are in volved in parasympatheic fibers innervating the viscera?
- To the head via 3, 7 and 9
- To the cervical, thoracic and abdominal viscera via cranial nerve 10
What do the sacral spinal nerves innervate?
The pelvic viscera
How do sympathetic fibers innervate all viscera?
Thoracolumbar outflow from CNS
What sympathetic fibers innervates the thoracic, abdominal and pelvic cavity and the head?
Thoracic - sympathetic chain of nerves and paravertebral ganglia
Abdominal and pelvic - fusion of fibers to form prevertebral ganglia
Head - supplied by spinal nerves from C8-T7 via vagosympathetic trunk
What carries presynaptic sympathetic fibers to the sympathetic trunk in spinal segments T1-L2?
The white rami communicans
What carries post-synaptic sympathetic fibers from the sympathetic trunk to all spinal nerves?
The grey rami communicantes
Where do the preganglionic fibers of the sypathetic supply to the head synapse?
The cranial cervical ganglion
What are the two routes for the post-synaptic fibers of the sympathetic supply to the head and neck?
- Some follow arteries in the head region
- Some follow cranial nerves 9 to 12, vagal nerve branges to the laranx and pharynx
What is the function of the post-synaptic fibers of sympathetic supply?
To innervate smooth muscle
what happens to the vagus and sympathetic trunk at the chest enterence?
Near the middle cervical ganglion at the first rib the vagus and sympathetic trunk split
Why do the vagus and sympathetic trunk split?
To pass around the subclavian artery forming the Asna subclavia
T/F the lumbar region of the sympathetic trunk supply pre and post synaptic fibers to the abdominal and pelvic regions?
True
The parasympatetic supply to the body otherwise known as the craniosacral system whats a cranial and sacral orignin, describe these?
Cranial origin is nerves 3,7,9 and 10 and the sacral orignin is S1-3 spinal cord segments
What is the oculomotor nerve (CN 3) ganglion?
Ciliary ganglion
What is the function of the oculomotor nerve?
- Targets ciliary muscles regulating lens curvature
- Targets muscles of the iris to allow pupil constriction
what arterygopalatinee the two ganglions related to the facial nerve?
Pterygopalatine, sublingual and madicbular
What is the target organ from the Pterygopalatine?
Lacrimal, nasal and palatine glands for secretion and vasdilation
What is the target organ for the sublingual and mandibular ganglion?
Sublingual and mandibular glands for secretion and vasodilation
What does the glossopharyngeal nerve aid with?
Swallowing function
What is the target organ of the ganglion assocaited with the vagus nerve?
Parasympathetic supply to neck, thorax and abdomen and majority of body viscera
What are some of the responses of the vagus nerve innervating these target organs?
- heart rate
- peristalsis
- sweating
- larynx opening
Describe how vagus nerve travels?
- Comes out of brain stem
- Runs down the neck in the vagosympathetic trunk
- back up to larynx
What arises from the vagus at the middle cervical ganglion and what do they do next?
- recurrent laryngeal nerves arise
- Run back up the neck
what do the recurrent laryngeal nerves supply?
The trachea and the cervica oesophagus
what happends ro the right and left vagus just after root of the lung (oesophagus)?
They split into dorsal and ventral branches
Describe the parasympathertic supply to the pelvic viscera?
- presynaptic fibre axons travel in pelvic nerves
- synapse at terminal ganglia
- postsynaptic fibres distribute to the pelvic viscera, lower intestinal cavity and reprodutive organs
describe how the symapthetic innervates the eye?
- The first order newuron comes from brain through brainsetem down spinal cord and exits at the T1-T3 segments
- Enters into vagosympathetic trunk as second order neuron
- Synapses in cranial cervical gnaglion medial to tympanic bulla
- continues as the third order neuron to the eye
What at the level of the eye does the sympathetic supply?
The smooth muscle of the orbit and the iris dilators
What is it called when there is loss of sympathetic input to the head?
Horners syndrome
what are clinical sign of horners syndrome?
- pupillary constriction (miosis)
- prolapse of third eyelid (cherry eye)
- narrowing of the palpebral fissure
- Enophthalmos - which is your eye sinking deeper into socket
What are examples of underyling diseases of horners syndrome?
- disc herniation (neck)
- middle ear infection (otitis
Describe how the parasympathetic innervated the eye?
- Retina recieves light and gives info to optic nerve
- Next location is the optic chiasm where there is some cross over
- From the optic chaism there is teh optic tract that leads to the pretectal nucleus
- From the pretectal nucleus to the cranial nerve 3 parasympathetic nucleus
- From here infor travels up to ciliary ganglion which they innervates from here the eye
what is a dysfunction of the oculomotor nerve?
pupil dilation not responsive to light
What is anisocoria?
One eye smaller than other
If the left eye constricts when shine a light in the eye and right eye is also constricted is it para or symp?
Sympathetic as it cause dilation
Describe what can be see with a brain herniation?
- often see miosis initially
- midbrain swelling causing compression of cranial nerve 3 and a non functioning parasympathetic nucleus of cranial nerve 3 causing mydriasis
Describe the sympathetic innervation of the urinary tract?
Storing of urine via the hypogastric nerve which comes out about L1-4 in dogs and L2-5 in cats causeing detruser relaxion to allow filling and contration of the smooth muscle at the neck of the bladder to hold it in
Describe the parasympathetic innervation of the urinary tract?
For voiding urine via the the pelvic nerve that comes out about S1-3 and contract detruster muscle to allow release
Describe the somatic innervation of the urinary tract?
Via the pudendal nerve coming out about S1-3, it contracts the straiated sphincter muscle for urinary retention
What else does the somatic innervate?
The anal sphinter which controls the perineal reflex
what are the 3 branches of ethics and define them?
- personal ethics - right and wrong we decide for ourself
- society ethics - wide agreement forming laws
- professional ethics - special situations like medical ethics
Describe the opinion that animals have no moral standing
This view arises from the contract of mortality so liek ad people we can stand up and be heard and animals cant be a part of the agreement they dont have any rights or moral standing
Describe the opinion that animals have instrumental value?
This means that we have indirect duties towards them meaning that their value arises through their value to human
Describee the opinion that animals have intrinsic value?
Means we have direct dutues towards them meaning they ahve the capiabliity to feel and it would be unacceptable to hurt dog as the dog will suffer anf thsi matters in itself
T/F others are obligated to respcet interests that flow from animals feelings?
True
what is the definition of sentience?
The capacity to feel such as sensation or emotions
what would an animal need to do to be self conscoius?
Need to be able to think about itself and its own emotions and sensation rather than simply experiencing them
what are the 2 statagies for defending the view that animals are sentient?
Inferential and non-infrential
Define Inferntial
Inference from behaviour and neuro similarity and evolutionary continuity - problem is that you gte further away from humans with animal behavoiurs so hard to argue
Define the non-inerential argument
Knowledge of animal consciousness derives directly from our interactions with animals as conscious beings - also becomes more weak as we move away from mammals
what are the two stratagies for defending the view that animals are not sentient?
- behavioural comparisons
- higher order definition of consciousness
Describe the behavioural comparisons argument for non sceintent?
This is where they belive anaimals behaviour is automatic so not learned however there is lots of evidence if a very complexed learning capability
Describe the argument of higher order definition of consciousness argument for non sentient
This is where they believe phenomenal consciousness requires the capacity to think about ones own thoughts - prblem with this is that this level on concsciousness has not been proved to be needed for scientience
describe a mouse interms of sentuence and moral standing
- pest = no moral standing
- lab animal = instrumental value
- pet = intrinsic value
From a conteactaianisms point of view why should we act morally?
Its in your self intrest - like showing consideration is for your own sake
What do contractarains think about animals?
Due to the contactarain view being based off of agreement they do now believe animals neither create nor ahve moral duties because they cant agree
So as a contractarian any form of animal use is acceptable?
Yes
When would use of animals be ethincally desirable in a contractarians eyes?
If it benifits humans
Why might a contractarian have an indirect eithical obligation towards animals?
Due to them mattering to humans
What is an utilitarianism viw on any being suffering?
That there is no moral justification for refusing to take that suffering into consideration
How do utilitarians view animals?
Like humans they deserve moral consideration - in deciding what to do we must consider welfare consequences for animals as well as benifits to humans and animals (COST BENIFIT)
what do utilitarians think about killing animals (like for food)?
Justified if the farming conditions are not detrimental to animal welfae and the killing is humanely performed
What is the problems with the utilitarianism view?
- How so we weight the intrests for wach party? how do we know the strengths of the intest for animals
- cant really compare killing a human and an animals due to the questions like - why kill and innocent human if its going to be replaced by another living a better life - we think this about dogs and pets all time but most would not agree this can apply to humans
How does the animals right view percieve animals being used?
They believe it is unacceptable to treat a sentient being as a means to achieve a goal - no benifit can justify the violation of the right of the animal
what are the 3 types of increasing stregth of animal rights?
- The moral-status sense where the animals have at least some moral status and dont exist soley for humn use so they should be treated well for their own sake
- The equal-consideration sense where we must give equal moral weight to human and animal interest
- The utility-trumping sense where like humand animals ahve certain vital interests that we must not over ride
What are problems with the animal right view?
- we cannot protect prey without at the same time neg effecting predtors
- cant combine respect for rats and amice whilst also protecting human health
What are the 3 components of pain?
- sensory-discriminative component that refers to the capacity to analyse loaction, intensity and duration of the nocieptive stimulus
- A motivational and affective component that gives rise to the unpleaseant charater of pain perception and modifies behavoiur
- A cognitive and evaluative component involved in the phenomena of anticipation, attention, suggestion and past experiences.
what are the factors of the criteria of paIn?
Suitably complex nervous system
Protective motor reactions
Trade offs between stimulus avoidance and other motivational requirements
Having opioid receptors
Reduction of responses by local anaesthetics and analgesics
High cognitive abilities
Showing avoidance learning
What evolution can make it even more harder to identify pain in animals?
Some have evolved to hide responses to pain
What behaviors may we see in response to acute pain?
- escape and avoidence
- volalistaion
- defensive behaviours
- direct attention towrads site of their pain
- might look normal but if you chnage hoe you are observing/ palpating you will see chnage
what behavioural respones might you see in chronic pain?
- protective or gaurding behaviours
- posture may be chnaged
- depression and learned helplessness
Decribe the physiological response to noxious stimulation
Results in stress responses - allow an animal to allocate bodily resources
Decribe the physiological response to activation of sympatho-adrenal catecholamine release
Changes in blood pressure, increased heart rate, changes in respiration, changes in muscle tone, defecation and urination
Decribe the physiological response to activation of hypothalamo-pituatary-adrenocortical axis
There is a glucocorticoid release
Why is there a problem with visual injury being a sign of pain?
- Injury can occur without pain
- Pain can occur without injury
- internal damage may be missed by human observation
Where else apart from relieveing pain are analgesics and anaesthetics used?
For pain assessment - like nerve blocks in horses
What are the problems with analgesic treatment?
- important that substances that prevent the animla from expressing pain rather than relieveing pain are not mistaken for analgesics
- analgesic drugs may have behavioural effects unreleated to pain and nociception
- drugs can also have nast side effects which is not good welfare practice
what methods of pain assesment are most likley to give the most accurate results?
Ones that combine objective and subjective elements
What are the two parts of the external ear?
- The Pinna which is the projection outside the skull
- External acoustic meatus (ear canal) connecting pinna to typanic membrane
Describe the shape of the pinna
Funnel shaped - wide distally to receive sound and narrows to connection with external acoustic meatus
What is the movility of the pinna?
It can oreintate towards sounds
What determines the pinna shape?
The articular cartilage which has different stiffeness so different shaped produced
what anchors pinna to skill so stays in place?
annular catilidge
where does skin and vessels adherev on external ear?
- skin adheres more firmly to concave surface (inner)
- vessels run on convex (outer) surface
where do the vessels which run on convex surface branch from?
caudal auricular artery
where does the external ear canal run from and too?
Runs from closure of auricular cartilidge to ear drum
What glands secrete wax?
sebaceous and tubular ceruminous glands
Describe the shape of the external ear canal?
curve ventrally then angle rostromedially
Is it true that sometimes you have to sedate to examine external canal with an otoscope?
Yes in cat and dog
Where is the middle ear found?
Within the tympanic cavity (bulla)
what is the tympanic bulla filled with?
gas
Descibe how the tympanic cavity is divided in the cat
- dorsal = epitympanic recess
- ventral - tympanic bulla
How does the tympanic membrane divide in ear?
Divides external acoustic meatus from the middle ear
where does the medial surface of the tympanic membrane attach?
To ossicles
What does the tympanic membrane attach to on temporal bone?
They tympanic ring of temporal bone
Laterally to medially name the aufitory ossicles
- Malleuse
- incus
- stapes
where does the handle of malleus attach too?
Eardrum
Is there an articulations at the level of the auditory ossicles?
Yes called malleus-incus-stapes
T/F the base of stapes inserts into vestibular window?
True
What are the two muscles that tense eardrim and ossicle chain?
- Tensor tympani
- Stepedius
what does sound cause to the middle ear?
- Vibration of the tympanic membrane
- Motion transmitted through ossiicle chain
- This causes vibration in the inner ear fluid at vestibular window
What connects tympanic cavity to nasopharynx?
The auditory tube
Describe the pathway of the auditory tube?
- openings in lateral wall of nasopharanx
- runs in cartilage trough
T/F is the auditory tube normall open?
False - usually collapsed
What does the opening of the auditory tube allow?
Equalisation of pressure on either side of the tympanic membrane and drainage of material ferom tympanic cavity
At the inner ear level what happens to sound?
Transformation of the sound into nerve impulses to be interperated by brain
What is the inner completely inclosed by?
Petrous temporal bone - osseous labyrinth
T/F there is a system of me,branous ducts and cavities in the inner ear?
True
What are the central cavities of the inner ear?
- utriculus
- sacculus
What are the ducts of the inner ear?
- 3 semicircular ducts from utriculus
- Spiral cochlear duct from sacculus
What ducts in inner ear are for balance?
The 3 semicircular ones from utriculus
what ducts in the inner ear are for hearing?
The spiral cochlear one from the sacculus
What stimulates sensory hair on receptor cells in wall of mebranous labyrinth?
Movement of endolymph
Within the utriculus and sacculus there are further receptors, name them and decribe their function?
Maculae - they have little crystals adhere to sensory hairs that determine position of the head relative to gravity triggering a response from said hairs
What angle are semicircular canals at?
Orientated at right angles
What is nystagmus?
“flicking” movement of eyes in response to movement of fluid in semicircular canals
What are the 3 parts of the osseous labryinth?
- central chamber
- semicircular canals
- cochlea
Describe the structure of the cochlea?
- It has spiral shape
- central osseous pyramid with canal running around and projecting spiral lamina
What three channals does the membrane from spiral lamina divide into?
- scala vestibuli
- cochlear duct
- scala tympani
Describe hearing at the inner ear
- vibration at vestibular window and cochlear window
- transmtted through perilymphatic space
- cause vibrations at basement membrane and movement of sensory cilia
- regestered by NT
- transmitted to vestibulocochlea nerve (8)
Name the 3 nerves that supply to ear?
- vestibulocochlear nerve
- facail nerve
- mandibular nerve
What does the ebstibulocochlear nerve divide into?
- Vestibular - balance
- Cochlear - hearing
Describe vascular supply to the external ear
- arterial supply from external carotid via caudal auricular
- venous drainage to maxillary vein
Describe the vascular supply to the middle and inner ear
- arterial supplu from occipital artery
What is an aural heamatoma?
Heamatoma in pinna under skin
Describe the 3 ways to image the ear?
- otoscope
- radiograph
- advanced imaginf - CT + MRI
If an animal dosent have a full orbit like a dog what is it called and what supports this?
Incomplete orbit and ligaments connect the two bits
T/F blindness can only come from the brain?
Flase - can be an obstruction to one of the structures of the eye which will restrict light getting in to form image
Name the three layers/Tunics of the eye from outer most to inner most
- fiberous tunic
- Vascular tunic
- neural tunic
What is the functions of the fiberous tunic?
- gives shape to eyeball
- protection to structures of the eye
What are the components and dunction of the vascular tunic?
- Blood vessels
- smooth muscle
- nutreint supply
- Control lens and pupil shape and size
What is the function of the neural tunic?
- Translation of visual signal into nerve impulses and transmission to brain - so light into ap
What are the two parts of the fiberous tunic?
- cornea and sclera
where do the cornea and sclera meet?
limbus
What can cause odema in cornea?
- build up of intersitual fluid in the CT of cornea and blocks vision
What is the main oart of the cornea?
Substania propria
what is substania propria inbetween?
The anteroir and prosteria lining epithelium
What is the anterior epithelium and what is it in continuation with?
- bowmans layer in continuation with conjunctival epithelium
What is the prosterior epithelium and what is it in continuation with?
The basement membrane in continuation with anteroir surface of iris
What is the sclera an entry point for?
for nerves and vessels
What attaches to the sclera?
Ocular muscles anteroir to the equator
What is the name of the thin membrane covering the cslera and what is its function?
- vagina bulbi
- Seperates eyeball from retrobulbar fat allowing eyeball free movement in socket
What does the vascular tunic consist of?
- Choroid
- Ciliary Body
- Iris
What are the functions of the vascular tunic?
- Vascular supply
- lens suspension
- control shape of lens and pupil
Where does the iris attach too?
Peripheral attachment to sclera and ciliary body
What is the central opening called in the iris?
Pupillllll
What controls the pupil size?
The smooth sphincter (parasympatetic) and Radial dilator (sympathetic) muscles
What does the iris divide?
Anteroir and prosterior chmabers of the eye
What are the Iridic Granules?
Projections from dorsal border across pupil seen in horses and ruminants
What is the ciliary body?
Thickened ridged ring around lens
What does the ciliary body produce?
Produces and drains of aqueous humour
What are the functions of the ciliary body?
- anchors lens
- chnages size of lens through contraction/ dilation of the cilary muscles
What is the structure in choroid that increases night vision?
Taptum lucidum
How does the tapetum lucidum?
Sends light back through retina passing through again allowing it to be picked up more
What are the cell types from outside to inside in the nervous tunic of the eye?
- retinal pigmant epithelium
- photoreceptor cells (rods BW and night, cones colour and day)
- bipolar ganglion cells
- multipolar ganglion cells
What is the most inner tunic of the eye?
The retina
Where does the retina line?
chroroid from optic nerve to pupillary margin
Where can light reach in retina?
prosterior 2/3 as contains receptor cells
What is the Ora serrata?
The junction between optic and blind parts
What enters at the optic disc?
The optic nerve
What is the macula?
Greater density of receptor cells
T/F lens is transparent?
Trueee
Where does aqueous humor enter and exit?
Enters at anterior chamber via pupil and exits via iridocorneal angle
If there is failure to drain aquous humour what happens?
Glaucoma - damage to the optic nerve
What is the function of the viterous body?
To maintain contact between retina and choriod
T/F viterous body volume fluctuates?
Flase - constant
What is the function of eye adnexa?
To protect and move eye
What is included in the eye adnexa?
Orbit
Orbital Fasciae – 3 conical layers
Ocular Muscles
Eyelids
Conjunctiva
Lacrimal Apparatus
What are the 4 rectus muscles?
Dorsal, Ventral, Medial, Lateral
What are the 2 oblique muscles of the eye and where do they run through?
- Run through trochlea
- Dorsal and ventral
Where do the upper and lower eyelids meet?
Comasures
What is teh functions of eyelids?
Close to eclude light and blink away foreign bodies
Describe the innervation of the eyelids
Motor - CN 7 and 3
sensory - CN 5
what is conjunctiva?
A thin membrane layer that protects the eye
what is the name of the conjunctiva that lines eyelids?
Palpebral
what is the conjunctiva that refelcts over sclera?
Bulbar
Where can forgein bodies be trapped in conjunctiva?
The space between lids and eyeball called the conjunctival sac
T/F the thirs eye can fully cover eyeball?
True when fully retracted into orbit
what gland of the third eyelid collapses causing cherry eye?
Nictitans glands
What are the glands of the lacrimal apparatus?
- lacrimal
- Nictitans gland
What is the function of the lacrimal apparatus?
Tear production
Where do tear film drain?
Via punvta lacrimalia feeding ino lacrimal sac and sca drains into nasolacrimal duct then into nasal cavity
What is the main supply to the eye and adnexa?
External ophthalmic artery and drainage mainly satillite to arteries
What are the 3 mechanisms the hypothalamus uses to regulate the endocrine system?
- ANS centers exert nervous control on adrenal medulla
- Vasopressin/Antidiuretic hormone (ADH) and Oxytocin production (released from the pituitary gland)
- Regulatory hormone production (RH and IH) controls pituitary gland directly and all other endocrine glands indirectly
What are the inhibitory neurohormones produced in the hypothalamus?
- GnRH
- Corticotropin relaesing hormone
- Thyrotropin releasing hormones
- Prolactin inhibiting factor and releasing factor
- Growth hormone releasing hormones and somatostatin
What are the activatory neurohormones produced in the hypothalamus?
- Oxytocin
- Antidiuretic hormone
What is the function of oxytocin and where in hypothalmaus is it produced?
- milk let down, luteolysis and sexual function
- magnocellular neuron of the paraventricular nucleaus
What is the function of Antidiuretic hormone and where in hypothalmaus is it produced?
- Water balance
- magnocellular neuron of the Supraoptic nucleaus
What is the function of GnRH and where in hypothalmaus is it produced?
- reproductive function
- rostral hypothalamus in preoptic area
What is the function of CRH and where in hypothalmaus is it produced?
- stress
- parvocellular neurons of the paraventriculat nucleus
What is the function of TRH and where in hypothalmaus is it produced?
- Metabolism
- parvocellular neuron of the paracentricular nucleus
What is the function of Prolactin inhib factor and releasing and where in hypothalmaus is it produced?
- lacttaion
- acruate nucleus
What is the function of GHRH and where in hypothalmaus is it produced?
- growth, metabolism and lactation
- arcuate nucleus
Describe the gross structure of the piuatary gland
- sits within hypophysial fossa of the cranial floor
- Completely covered in dura
- venous channals either side linking the ophthalmic plexus rostrally and external jugular anf ventral venous plexus caudally
- lateral to cavernous sinus are cranial nerves that spply the eye
What are the two parts of the pitautary gland and how wrae they formed?
- Pars nervosa (prosterior) - down growth of nervous tissue from hypothalamus
- Pars distalis (anterior) - upgrowth of epithelium of the roof of the oral cavity
What is a portal system?
Two capillary beds linked in series
What are portal veins?
Blood vesseks that link two capillary networks
What happens to hormones found in the hypophyseal portal system?
Capillaries transport them to pitaury
T/F we can measure the level of hormones at the level of the pituarty
Trueeeee
What is the pituatory gland suspened by from the hypothalamus?
narrow fragile stalk infundibulum
What does the anteroir pituatory produce?
Trophic and direct action hormones which direct and regulate other hormones around the body
What is the anteroir pituatory regulated by?
HYpothalamus vua a unique system of portal veins
What is the main cell type you see in anterior pituitary?
Secretory cells - chromopils and chromophores
What does the prosterior pitautary release?
Oxytocin and antidiuretic hormone into circulation
Where are the hormones produced in the prosteroir pituatory?
In the magnocellular neurons
What are the hormones of the prosterior pituatory released in response too?
Nervous impulses from other brain areas
what kind of axons does the prosteroir pituatory have?
Non myelinated axons
What are herring bodies?
Dilations of nerve fibers filled by small vesicles containing the neurosecretory products of the hypothalamic cells
What is seen histologically at the pars intermedia?
- basophilic cells
- Irregular clumps
- cells contain secretory granules
What is the pineal gland?
Small, dark, pigmented outgrowth from prosteroir roof of the 3rd ventricle
What is the most abundant thing you see when looking at the pineal gland histologically?
Pinealocytes
What other cell types do you see?
astrocytes
What is pineal sand?
Mineral deposits seen with age
what does maturation of the hypothalamo-pituatary axis lead to?
puberty
what kind of feedback is seen at the hypothalamo-pituatory-thhyroid axis?
Classic negative
What is there excess of when there is hyperthyroidism?
T3 and T4
What is the function of the anteroir assocaiation cortex?
Personality
If there is damage to the visual cortex what is the outcome?
Dizziness
What are the main things the libic system is in control of?
Emotion, learning and memory
What is the hippocampus responsible for?
Spatial memory and the transfer of some types of info for long term memories
what kind of memories is the hippocampus involoved in?
Explicit
Describe what would happen if you removed medial temporal regions like hippocampus?
Result sin anterograde amnesioa , unable to recall anything that happended since surgery and working memory was intact
What is the amygdala?
It is a collection of nucleiW
what is the role of the amygdala?
A role in affective behaviors and other species typical behavoiur
Where does sensory information go after coming through thalamus?
To amygdala and tries to make sense of it
Describe amgdala neurons?
multimodal and respons to more than one sensory modality
In cats what will lesions of the amygdala result in?
Undisturbed by thigs that would usually destress them
What is the Fornix?
It is a bundle of fibres along the medial aspect of the hemispheres that has inter-connections with the hippocampi on both sides of the hemispheres
What is the function of the fornix?
Primarly connects the hippocampus to mammillary body of the hypothalamus
Other fibers connect directly to the anteroir nucleus of the thalamus
How is the fornix been related to cognitive dysfunctions like dementia?
When there is demylation of fibre bundles of the fornix
What is the mammillary body?
It is Intricately connected with the hippocampal formation, fornix, amygdala and midbrain
What is the primary function of the mammillary body?
Associated with recollective memory but also involved with emotion and goal-dirceted behavoiurs (contributes but also comes from elsewhere)
What can cause significant damage to the mammillary body?
Trauma, stroke, tumours and alcoholism
What is the speptum involved in?
Emotional behavoiurs, sexual behavior, agressive behaviour, modulation of the autonomic functions, attention and memory functions
Where does the septum recieve input from and where does it project too?
- Receives from Hippocampus, amygdala, hypothalamus and midbrain
- Projects to the hippocampus and denate gyrus, the thalamus and severall hypothalamic nuclei
What do septal regions induce?
Rage - exaggerated reacrions to both appropriate and innnocuos stimuli
What is the cingulate cortex?
Neural interface between emotion, sensation and action
What does the cinguate cortex connect with?
The limbic thalamic nuclei and with other limbic areas including the subiculum and entohinal cortex
What is the cingulate cortex involved in?
Planned motor movements
What doe lesions to the cingulate cortex cause?
Lesions here result in indifference to pain and other sensations that have strong emotional connotations like socail infidderence and apathy, no emeotional intonation in speech and personality chnages
What kind of lesion woul result in diminished ability to perform spatial navigation?
Lesions to the posterior cingulate cortex
How many nuclei does the basal ganglia have?
It has 4 nuclia that are involved in volubtary movement - caudate nucleus, putamen, globus pallidus and substantia nigra
They do not have direct input or output with the spinal cord so what happens instead?
Input from the cortex instead and outputs to the midbrain, thalamus prohects to the frontal, premotor and motor cortices
Describe the neural basis of parkinsons disease?
There is a loss of the dopamine in parkinsons disease leading too increase in output from the basal ganglia
The overreactivity of the indirected pathway results in hypokinetic disorderssss
so basically the more output the more involuntary respose
describe motor control?
4 brain regions project down in spinal cord
muscle action causes info back into thalamus for feedback
If there is a lesion at the higher centers of moto control what is the result?
There is a loss of integrated function and there is abnormal responses
Describe the hierarchy of motor control
- sensory info comes in/ beinf processed at higher centres
- these higher centres regulate lower centres
- sensory input to limbic system (motivation, goal)
- then this goes to basal ganglia ( movment initaition)
- then to cerebellum ( coordination of the movement)
- then to motor cortex (rifining that movement
- then spinal cord for actual movement
As spinal cord expects this input from higher centers if it si cut what happens?
Spinal shock
Where do pyramidal tracts that are the motor neurons originate and terminate?
- frontal cortex
- spinal cord or brain stem
Where are extrapyramidal tracts located and involved in?
Located in the pons and medulla of the midbrain and involved in involuntary movements
What is pyramidal tract syndrome characterised by?
Spasticity and paralysis
Whats is extrapyramidal tract syndrome characterised by?
Involuntary movements, muscular rigidity and immobility without paralysis
What is the corticospinal tract required for?
Fine, skilled movements
where do the cortocospinal tracts fibers terminate?
On inter-neurons in the spinal cord
What tracts do the extrapyramidal tracts go onto be?
- Reticulospinal tract
- Vestibulospinal tract
- Rubrospinal tract
- Tectospinal tract
What is the function of the reticulospinal tract?
Basic posture and initaition of locomotion
What is the function og th vestibulospinal tract?
Postural acting
What is the function og the rubrospinal tract?
Acts mainly on flexors and postural
What is the main function of the tectospinal tract?
Acts on cervical vert and orientates head
What are the effects of lesions in the decending tracts?
- IN spinal cord it results in complete paralysis
T/F snout gives rise to the size of binocular vision
True
Describe Cat vs Horse binocular vision?
- Cat has smaller snout so has bigger binocular vision also aided by eyes being more to the front of the head
- Horse has smaller binocular vision and larger monocular vision as eyes on side of the head and big snout meaning there is also overlap of vision
What is the role of the lacrimal gland?
They secrete saline tear. This fluid cleans and lubes the front of the eye during blinking. It also prevents cornea from drying out and frost injury during cold weather.
What does the lacrimal fluid contain to protect against infections?
Lysozyme and immunoglobulin A
What are the 2 axis of the eye and their functions?
- Optical axis gives most optically clear image
- Visual axis to fovea gives best colur vision
What happens to light when it passes from across the cornea, lens and viterous humor?
It bends
When going through the lens of the eye what happens to the light?
The light info is refrected and focused at a focal point
what determines the distance from the focal point behind the lens?
The distance to the image
How do we maintai the image at the back of the retina?
Achieved through ciliary bodies that contract and relax muscles
What is seen when there is relaxion of ciliary bodies?
Expansion of the lens where it narrows leading too an enchanced image detection
What is seen when there is contraction of the ciliary bodies?
The muscles relax which decreases wlongation of the lens leading to the ability to adjust visual detection
Why must horses move their heads to see things near and far?
As they dont have the ability to adjust ciliary muscles
It objects are close to horse how will the horse move its head?
Raise its head
It objects are distant to horse how will the horse move its head?
Head depressed
What does retinal detachments mean?
LOss of blood supply to retina and rods/cones will start to die unless re-attachment is quick
Describe what happens to light at the retina?
- pass through anumber of different cells
- BInd to photoreceptor (rods and cones)
- light info back to the front of the eye via bipolar cells and retinal ganglion cells
What is the type of photoreceptor cell that retinal ganglion cells express and its function?
Melanospins and they are critical for the integration of ligh informations used for biological rhythms
In rods what happens once light is detected?
It is detected at the outer segment, info then travels down inner segment through nucleus to synaptic endings where neurotransmitters are being released
What is rhodopsin involved in?
- Involved in light detection and irradiance
- It had retinol and when lught is beinf detected there is a shape chnage in protein making it a tri isomer
What happens when light hits rhodopsin?
- Isomerisation of retinal
- Activation of alpha subunit of transducin
- Activation of phosphodiesterase (PDE)
- Decreases cGMP levels and closes ion channels
- Tbis all hyperpolarises the receptor cell
In retina what is the blind spot of photoreceptors?
It is whre all the axons of different ganglion cells are converging to form optic nerve
What are rods and cones more senstive?
- Rods are much more sensitive to light (irradiance)
- Cones provide much more detailed info like colour
What happens when light is provided to the centre of recptive feild?
You will have a higher activity to stimulus and the outer bit has inhibition of ap
What does the pulpillary reflex indicate?
A functional state of the affernet and efferent that control the pupil - allows you to identify damage to visual pathway
How do you know from pupillary reflex if optic nerve is intact?
If light into left eye elicits a consensual constriction in the right eye we can be sure the optic nerev is intact as its info is being convey to reposnse
What does the dazzle reflex test?
Cranial nervels 2, 7 and part of midbrain
What does an absence in response to dazzle reflex indicate?
Blindness
Describe the neural circuit from retina to lateral geniculate nucleus
Light - retina - down optic nerve - projects into lateral geniculate nucleus in thalamus
What are parvocellular cells?
They are small and integrate signals from cones and are neccessory for colour to form
What are magnocellular cells?
They are large, integrate signals from rods, involved in movement, depth and irradiance
From the LGN what cells project into the primary visual cortex at the back of the brain and what are their function?
Simple - responds to stimulus with correct orientation
Complex - respond to moving stimulus of correct oreintation
Hyper-complex - shows end stopping and responds to objects of a particular size
What does happens to these LGN cells in the primary visual cortex?
They are integrated and then try to form visual perception
In absence of light what do you get with LGN cells?
None other than basement membrane
What LGN cells have an on off response?
Simple and complex
Decribe the neural circuit for vision?
LGN - V1 - can go dorsally to partietal lobe and have a higher level of visual perception or can go ventrally to temporal lobe
what does the dorsal stream from V1 to V5 elicit?
Guides moevemnts such as the hand postures for grasping a mug or pen
What happens if there is damage to the ventral stream?
Prevents identification of objects
What happens if there is damage to the dorsal stream?
Results in optic ataxia
what are the 4 pathways that arise from the optic tract?
- LGN = visual cortex = visual feild
- Rostral collliculi = dazzle relfex = blink
- pretectum, pons = pupillarilary light relex
- suprachiasmatic nucleus = hypothalamic pineal gland = control of movement systems
Whys is dogs colour vision restricted?
Due to the number of cones in retina
What is colour vision represented by in the cortex?
Blobs
What are the two measures in which a pure tone is described?
- Amplitude or intensity as sound pressue
- Frequency or number of cycles per second of vibration
What is amplitude measured in and what is it percieved as?
- decibels
- percieved as loudness
What is frequency measured in and what is it percieved as?
- Hertz
- Percieved as pitch
T/F most animals can chnage orientation of ears to maximise sound
True
What muscles allow pinna to move?
Auricularis muscles
What is the function of ossicles?
They connect the typmainc membrane to the inner ear via oval window
What effect does sound have on tympanic membrane?
sounds moves membrane and That moves ossicles which amplify pressue communicated to inner ear
What are the two muscles that act to improve perception and sound protection?
- tensor tympani
- stapedius
How do tensor tympani and stapedius percept and project?
Contract and stop bones from moving when loud sounds are made and when your talking so you dont hear yourself
What are the three parallel fluid flilled cavities of the cochlea?
- vestibulo
- media
- tympani
What causes the fluid within the cavities of the cochlea to move?
The staples vibrations against the oval window
Whats is the round window?
A moveable membrane that is required to accomodate pressure that arises when the oval window is pushed
What Is the structure responsible for converting the vibrations produced by the ossicles into nural activity?
Organ of corti
What are the three componebts of the organ of corti?
- The sensory cells (hair cells)
- The auditory fibers that mak up the vestibulocochlear nerve
- other supporting cells
T/F there are inner and outer hair cells in organ of corti?
True
What do the hair cells of the organ of corti transmit?
- Transmit the perturbation in the basilar membrane
- Transmit this info to the vestibulocochlear nerve
Describe the differences between the inner and the outer hair cells?
Inner
- assocaited with many auditory nerves
- invoved in sound perception
outer
- associated with few auditoru nerves
- Not primarily involved in sound detection but instead they fine tune by changing tension in basilar membrane
Describe what inner ear hair cell movement causes?
- fluid moves so the hair cells move
- when hair cells move it causes rapid chnages in ion channels
- respond with graded potentials
How can the auditory nerve respond to specific frequency?
It has cells that selectively respond to specif freqencies
Describe how the auditory pathways link the brain stem to brain
- The superior olivary nucleus is the first stage - when inputs from both R and L cochear nuclei are integrated
- The inferior colliculus is the primary auditory center in the midbrain which sends outputs to the medial geniculate nuclei in the thalamus
- The MGN then projects to the auditory cortex
What do females display more of in activity patter?
Display greater activation in the right proterior temporal lobe
What does intensity differences result from?
The differences in loudness that reaches the ears
What sounds are more susceptible to intensisty differences?
HIgher frequency sounds
What does latency differences result from?
The difference in the arrival times of the sound waves
What is onset disparity?
Difference in two ears
What is ongoing phase disparity?
Continouos mismatch of all frequency peaks
What causes the onset of disparity and ongping phase disparity?
One ear aleays beinf a little closer to the sound than the other
What are the two divisions of the superior olivary nucleus?
- Lateral superior olive processes intensity differences
- Medial superior olive processes latency differenes but encodes sound by relative activity (l and r)
What are common causes of conduction deafness in the external ear and middle ear?
E - cerumen and otitis externa
M - fluid accumulation in the eustachain tube
Where does densorineural deafness originate from?
Cochlear or auditory nerve lesions
What is central deafness and hearing loss caused by?
Brain lesions
two types of central deafness?
word and cortical
Define word deafness
Unable to recognise spoken words, speech production and simple sound discrimination are still functional
Define cortical deafness?
- Difficulty in recognising audiitory stimuli
- rare bilateral damage to the auditory cortex
what is the function of the vomeronalsal organ?
Detection of olfactory info
Describe the structure of the olfactory epithelium
- bowmans glands secrete mucous that lines epithelium
- odorants receptors on the cilia
- basal stem cells instead of receptor cells
Describe the detection and intracellular activation of odorants
- receptors detect odour
- opens up Na and K channals
- Ions come in and bind
- This results in a graded response
At the olfactory bulb decribe the cells and receptors
There are large numbers of receptors and small number of mitral cells
What happens at the olfactory bulb?
It is the primary process in which physiological response becomes neurological responses and representaion of odours start to occur
What does olfaction detect?
- Prey
- Predators
- Poisons
- Mates
why do dogs have better sense of smell?
- They have larger olfactory epithelium so more receptors
- Twice as many active receptor porteins
- olfactory bulb is much larger
- vomeronasal organ show low functionality in humans
what are the two types of taste receptors?
- small uncharges particles or ions for salty or sour
- molecules bind to receptors for sweet and bitter
what is vision?
It is the consciuos perception of infro from the eyes
What is the visual system?
The part of the CNS which gives organisms the ability to process information that is conatined in visible light
what 4 things can we use to asses vision?
- observation of animal in unfamiliar enviroment
- ability to track
- visual placing
- menence response
summerise the visual pathway
Retina - optic nerve - optic chiasm - optic tract - lateral geniculate nucleus gets information - optic radiation is the axon that connects LGN and optical cortex
What is the optic chaism?
Where there is a cross over of information
Define visual feild
The total area in which objects can be seen in the peripheral vision as you focus your eyes on a central point
what is the difference between predtor and preys visual fields?
Prey have a smaller visual fleild seen by both eyes compared to predator
Why is the PLR a reflex?
There is no cortical involvement
Describe how the Pupillary light relex works?
- Its starts at the retina when there is a flash of light
- Info goes to optic nerve (CN 2)
- Then it goes via iptic chiasm where there is some cross over
- Then onto the optic tract
- Does not go to cortex from here rather the pretectal nucleus in the brain stem
- Then efferent pathway via the parasympathetic nucleus of cranial nerve 3
- This creates bilateral pupil constriction
Describe how the menence response works?
- The beginning is the same as pupillary relfex pathway until at the level of the optic tract info goes to LGN
- From LGN it goes to the optic cortex then to motor cortex
- This activates the pontine nucleus
- Cerebellum is then involved to make everyting smooth
- Then goes to the facial nerve nuclei which closes eyelid
What can distrupt the results of the menenece response?
If you make too much air as it will cause them to blink becuase of that and not hand
What is the type of blindness without apparent lesion of the eyes and involves processing system?
Central cortical blindness
Where are the lesions in Central blindness?
- LGN
- Optic radiation
- Occipiral cortex
What can be seen clinically when there is central blindness?
- normal PLR as in 1st part of pathway
- absent menance response as it is 2nd part of pathway
- blind
What is the type of blindness where it involves collection and distrubtion system so eye and 1st part of pathway?
peripheral blindness
Where would you see lesions in peripheral blindness?
- eye
- optic nerve
- optic chiasm
- optic tract
What clinically would you see with peripheral blindness?
- absent PLR as in frist part of pathway
- absent Menence response
- blind
Describe the dazzle reflex?
- First bit same as PLR but the differnece comes when it goes to pretectal nuclues it goes to cranial nerve 3 to constrict pupil and goes through facial nerve nuclei to close eye lid
- results in bilateral blinking
what nerve innervates the dorsal, medial, ventral rectus muscles, ventral oblique muscle and levator plapbrae muscles of the eye?
Cranial nerve 3 - occulomotor
what innervates the dorsal oblique muscle of the eye?
Cranial nerve 4 - trochlear
What innervates the lateral rectus muscle and the retractor bulbi muscle of the eye?
Cranial nerve 6 - abductant
what happens when a cranial nerve becomes damaged and what is it called?
It decreases the tone of the muscles that it innervates so that the ones still working pull eye in one direction
what is it called when you get abnormal alingment of eyes?
strabismus
What are semicircular ducts cirtical for?
Our control of balance and acceleration and deacceleration
What induces change of fluid in the semicircular canals?
head movement
What does a change of fluid lead to in semicircular canals?
Leads to change in hair cells involved in the sense of chnages of rotation
what happens when head moves to the left?
- Fluid goes to the right and orientation of hair cells in the ampulla will be pushed to right
- leads to excitation and increase in firing
what happens if the head moves to the right?
- Fluid moves right to left but orientation of the haie cells is different
- leads to inhibition of hyperpolaristation and decrease of firing
What is specific about macula in each urticle?
Has specificity for different horizontal accelerations - if in opposite direction it inhibits hair cell
What way are sacular macula orientated?
Vertically and are senstive to accesleration thats vertical and highly sensitive to gravity
What does the bilateral orgnaisation of the vestibular system provide?
Ample information to CNS that conveys both rotation of the head, accesleration and anatomy.
What are the 4 major nuclei of the vestibular tract?
Inferior, lateral, medial and superior
What nuclei conveys info about head rotation?
Everything but inferior
What nuclei conveys info about accelaration and gravity?
Everything but superior
What does the lateral nucleus send down the cervical and lumbar section of the spinal cord and to regulate what?
- lateral vestibulospinal projections
- To regulate flexor and extensor muscles
What does the medial nucleus send to cervical regions of sponal cord and to regulate what?
- medial vestibulospinal projections
- To regulate axial muscles
Describe what happens when the head turns in an anti clockwise rotations
- excites horizontal semi-circular canal
- output signals via lateral and medial vestibular nuclei to same side oculomotor nucleus and opposite side abducens nucleus to produce eye movemtn to the right
When are vestibular reflexes activated?
When the position of the head is changed relative to the vertical axis
When are tonic reflexes activated?
When the position of the head relative to the rest of the body is altered
what would you look to see in vestibulospinal reflexes?
There should be no difference between head and trunk position - both rotation induces left leg extension and rught leg flexion (or opposite)
What is the righting reflex in cats?
Where normal posture is restored in an animal that has fallen or unbalanced
what is postural equilibrium?
The regulation of posture with respect to gravity
What is static equilibrium?
State in which all forces acting on the body are balanced so that body rests in an intended postition
What is dynamic equilibrium?
The ability to progress through an intended movement without losing progress
To maintain balance what must happen to voluntary movements?
must be procedeed by counterbalance movement
What do decending projections from cerebral cortex regulate?
Regulates spinal cord either directly or indirectly
why does the basal ganglia interact with the thalamus?
To incorporate sensory feedback for motor plans like learning
what are medial brain stem pathways essential for?
activation of movement
What are lateral brainstem pathways essentail for?
Adjustments of movements
describe the anatomy of muscles spindles?
Encapsulated sensory receptors and function to signal chnage in the length of the muscle
What are the 3 intrafusal muscke fibres?
- single la sensory fibre
- static motor neurons
- dynamic motor neuron
what is la sensory fibers response dependent on?
Motor neuron stimulation
