T1: Functional Anatomy Flashcards
What is the pupillary light reflex?
The size of the pupil at rest represents a balance between two antagonistic forces
1. amount of light stimulating the retina
2. the emotional status of the patient
Describe the importance of the light amount got the pupillary light reflex
the amount of light stimulating the retina and influencing the oculomotor neurons to constrict the pupil
- miosis: parasympathetic innervation through CN III
Describe the importance of the emotional status of the patient for the pupillary light reflex
the emotional status of the patient influences the sympathetic system and causes pupillary dilation (mydriasis)
Describe the resting pupil
both pupillary dilator (sympathetic) and antagonistic pupillary sphincter (parasympathetic)
-the relative resting parasympathetic/sympathetic innervation and resulting muscle tone determine the size of the pupil
What is the pupillary sphincter
-constrictor/ the more powerful muscles
Dilated pupil?
- sympathetic
- mydriasis
-muscle contraction increases pupil size
Constricted pupil?
- parasympathetic
-miosis
What is the pupillary light reflex (PLR)?
bright light shone into one eye at a time
- both pupils should constrict
-Direct response: tested eye
-Consensual/indirect response: opposite eye
When/how does a blink response occur?
- the dazzle reflex
-Facial nerve CN VII
-When a bright light is initially flashed into the eye
what is the pupillary escape?
If a poor-quality light source is used the stimulated pupil may dilate slightly with continued stimulation
What is a clinical response?
The direct response in the eye which is stimulated by light
- pupil constriction is stronger in this eye than in the opposite eye (consensual/indirect response)
What is the afferent pathway?
stimulation of the retinal receptors by light
- optic nerve (CN II) to optic chiasm to optic tract to CN III Nucleus (oculomotor nerve)
What is the efferent pathway?
begins in the parasympathetic nucleus of CN III in the mesencephalon on the stimulated side – the CN III — leaves the skull via the orbital fissure — synapses behind the eye (ciliary ganglion) — the pupillary constrictor muscles to cause constriction of the pupil (miosis)
How does the consensual/ indirect PLR pathway occur?
stimulation of the contralateral CN III parasympathetic nucleus results from some fibers of the CN II (optic nerve) that cross over (decussation at the optic chiasm)
The PLR evaluate _____reflex …
subcortical reflex/ no cerebral cortex function, menace response yes!
What is the menace response?
This is a cortically mediated eyelid closure produced by a threatening or unexpected gesture suddenly appearing in the near visual field
When does the menace response appear?
it is a learned response, not a reflex, to a perceived threat
What pathway does the menace response use?
visual stimulus is relayed contralaterally in CN II (optic nerve) to the occipital cortex via thalamus.
- motor cortex stimulates the ipsilateral facial nerve (CN VII) to cause eyelid closure
Pupillary reflex check what?
Menace response check what?
PR: Subcortical structures
MR: cerebral cortex
What are the 4 basic tissues in the body?
- epithelial tissue
- connective tissue
- muscle tissue
- nervous tissue
special distinction of epithelium
tissues is not penetrated by blood vessels but rather they receive nutrition and discharge waste by diffusion via blood vessels in the underlying or neighboring connective tissue
Names of the epithelium
simple: one layer
stratified: two or more layers
squamous: thin and plate like
cubical: equal in height and width
columnar: cells are taller than they are wide
What makes up connective tissue?
loose connective tissue (collagen, elastic fibers) fibrous tissues, fat, cartilage, bone, bone marrow, blood
What is Ehlers-Danlos Syndrome (cutaneous asthenia)
a group of connective tissues disorders, fragile, stretchy and loose skin caused by a genetic defect in the production of collagen fibers/prone to damage
What is the role/definition of glands?
Selectively removes materials from the blood, concentrates or alters them, and secretes them for further use in the body or for elimination from the body
What is exocrine?
Secretion outside the body via ducts
What is endocrine?
secretions within the body via the bloodstream
What is the sagittal plane?
runs the length of the body and divides it into left and right parts that are not necessarily equal halves
Median plane (mid-sagittal plane)
runs down the center of the body lengthwise and divides it into equal left and right halves
transverse plane
divides into cranial and caudal parts that are not necessarily equal
horizontal (dorsal) plane
divides the body into dorsal and ventral parts that are not necessarily equal
what is included in the dorsal cavity
cranial: brain
vertebral: spinal
what is included in the ventral cavity
- thoracic cavity
- parietal and visceral
-pleura: lungs
-mediastinum and mediastinum pleura: heart, thoracic part of esophagus, trachea, vessels, nerves - Abdominal cavity
- Pelvic cavity
what is the peritoneum
a serous membrane similar to that surrounding the heart and lungs in the abdominopelvic cavity
what is the peritoneal cavity
space between parietal peritoneum (attached to abdomen wall) and visceral peritoneum
what is ascites or abdominal effusion
medical term referring to the accumulation of fluid in the peritoneal cavity that exceeds 25 mL or buildup of fluid in the abdomen
what are the specific terms of ascites for species
dilated cardiomyopathy: dogs
feline infectious peritonitis: cats
water belly: poultry pulmonary hypertension
what is transudate
accumulation of fluid due to a hydrostatic imbalance between the intravascular and extravascular compartments despite normal vascular permeability; little protein or blood cells
- endothelium is not damaged
what is exudate
accumulation of fluid due to increased vascular permeability; high protein content, numerous cells
-leukocytes directly damage vessels or cause tissues to produce chemical signals that alter vascular permeability
what are the functions and roles of skin
- grows and regenerates
-protection from environment
-barrier against loss of water, electrolytes, cells
-flexibility
-temperature regulation
What does the integumentary system do?
storage
pigmentation, immunosurveillance, production of vitamin D, sensory perception,
excretory secretions
What is the case with Vitamin D
cats and dogs cannot synthesize vitamin D efficiently/ they must receive it in their diet
What are the three levels of the skin
epidermis: upper (shed and replaced every 22 d for dogs)
dermis: lower
hypodermis: right below the dermis, muscles for piloerection
(epidermal appendages: hair, sweat glands, sebaceous glands)
what are the characteristics of Dog’s skin?
-epidermis for dog, 3-5 cells thick
-canine hairs grow in bundles
-grows in cycles
-when hair reaches a certain length (dog’s genetic makeup) it stops growing, dies, and is shed
what are the apocrine glands?
help seal the outer layer of the epidermis, pheromone secretion
the merocrine (eccrine) glands are?
- the the pads of the paws
-watery secretion similar to sweat in humans
What is the annual rate of hair production for animals
- dogs: produce 60 to 180 g hair/kg annually
- cats: produce 30 to 40 g hair/kg BW
- hair follicles are 20-60 angle to the skin to help shed water
-hair growth influences by photoperiod, hormones, genetics and general health
What are the types of hair for dogs
-secondary hairs: short fluffy hairs
-primary hairs: longer/stiffer outer hairs
-whiskers (tactile hairs)
Do all dogs shed?
yes, all dogs shed. The degree depends on
- thickness of undercoat
- rate of which growth of hair occurs
poodles: single coated dogs, have long growth cycle and are classified as “non-shedding”
most dogs/cats regrow a normal appearing coat 3 month after being shaved
as day length shortens
-rate of growth decreases and maturity of hair is slowed
-winter coat
as day length increases
-rate of growth increases
-shedding occurs at a faster rate (loss of winter coat)
-if dogs are kept inside, growth rate and shedding occur throughout the year
Describe the skin and coat of a cat
-loose skin from the body
– aids in temperature regulation
– protection during fighting
- if a cat does not groom itself, indicating of a illness or problem
–all cats shed: depends on photoperiod (indoor cats are not as seasonal)
