Exam 5 Flashcards
Eye
- *Palpebrae**-eyelids
- *Palpebral fissure**-space between eyelids
- *Canthi**- angle at which where eyelids meet
- *Levator palpebrae superioris**- muscle that lifts of the eyelid
- *Orbicularis oculi**- closes your eye (innervated by CN7)
- *Conjunctiva**- transparent mucous membrane (stratified columnar epithelium)
- *Palpebral conjunctiva**-under eyelid
- *Bulbar (ocular) conjunctiva**- anterior of eye
- *Conjunctival sac**- where contact lense lies
- *Lacrimal apparatus**
- *Lacrimal gland**-creates tears that sweep down and to the middle to lacrimal sac.
- *Lacrimal caruncle**-pink thing in the medial corner of the eye.
- *Lacrimal puncta**- tiny holes in medial eye that send tears to canaliculi.
- *Lacrimal canaliculi**- one way valves take tears from puncta to lacrimal sac
- *Lacrimal sac**- take tears to nasolacrimal duct
- *Nasolacrimal duct**- tears to nasal cavity
- *Nasal cavity-** when you cry, your nose runs with tears (lacrimal fluid) made up of mucus, antibodies, and lysozymes
Extrinsic Eye muscles
& Superior Levator
Innervated by CN 3 Ocularmotor (LR6/SO4/3)
Strabismus- affected eye turns either medially or laterally with respect to the normal eye (some people call this “lazy eye”)
Fibrous Tunic
- *Lens**- helps focus light.
- *Anterior cavity**-lens to cornea (aqueous humor)
- *Posterior cavity**- lens to retina (vitreous humor)
- *Fibrous tunic**- sclera
- *Vascular tunic**- choroid
- *Nervous tunic**-retina
- *Fibrous Tunic**
- *Sclera**- white of the eye (dura mater of brain); provides anchoring for extrinsic eye muscles
- *Cornea**- light enters here, transparent (avascular, only pain receptors gets oxygen & nutrients from air and aqueous humor)
- *Limbus**- renews the corneal epithelium, and is where sclera and cornea merge (border between the corneal epithelium and the bulbar conjunctiva)
Aqueous humor- is renewed continuously and is in constant motion- formed as filtrate of the blood from capillaries in ciliary processes, flows through pupil into anterior chamber, drains into veins scleral venous sinus and returns to blood
Scleral venus sinus- fluid from the posterior chamber to the anterior chamber of the anterior cavity. too much produces glocoma.
Iris
Involuntary:
parasympathetic- pupil constriction
sympathetic- dialation (fight or flight)
Vascular Tunic
Choroid-forms most of vascular tunic, continuous with ciliary body; prevents light scatter, pigmented with Melanin
Ciliary body- encircles the lens- consists of smooth ciliary muscle– focuses the lens w/ suspensory ligaments (CN3).
• Accomodation-focus on what you need to.
• Makes aqueous humor
Iris- visible, colored part of eye. Allows light to enter. Has smooth muscle fibers (sphincter- constriction(parasympathetic) and dilator- dilates (sympathetic)
• Pupil- opening of iris (pupillary light reflex)-opening for light
Nervous Tunic
Consists of two layers
Pigmented layer(deep to choroid)-like choroid, prevents light scatter.
Neural layer (deep to pigmented)
Photoreceptors cells:
Cones-color in light (lots in ML)
Rods-(night vision)don’t pick up color
• Bipolar neurons- receive action potential from PR cells, pass it on to ganglion cells
• Ganglion cells- axons form the optic nerve which runs to visual cortex.
- *Specialized parts of the Retina**
- *Optic nerve**
- *Optic disc**-blind spot
- *Ora serrata**: junction between the ciliary body and the neural layer of the retina
- *Macula lutea**-best vision
- *Fovea centralis**-center of ML (only cones)
Detached retina: separation of pig layer from neural layer which can be due to low eye pressure.
When stimulated by light (photons), the photoreceptor neurons signal the bipolar cells which then signal the ganglion cells to generate action potentials. Axons from the ganglion cells run along the internal surface of the retina and converge at the optic disc to leave the posterior eye as the optic nerve (remind yourself: what is a nerve?).
Internal Chambers, Fluids and the Lens
- *Posterior cavity**- vitreous humor(collagen, ground substance, and water)-transmits light, supports lense, and maintain intraocular pressure
- *Anterior cavity- anterior chamber (aqueous humor**) and posterior chamber
- *Aqueous humor**- is renewed continuously and is in constant motion- formed as filtrate of the blood from capillaries in ciliary processes, flows through pupil into anterior chamber, drains into veins scleral venous sinus and returns to blood.
- *Lens-** a thick transparent, biconvex disc that changes shape to allow focusing of the light on the retina
Visual feild
Note: the L occipital lobe is going to interpret, process R visual field.
*each eye perceives a portion of the other visual field(biocular vision).
hemi-decussation- at the optic chiasma only the median half the of the axons cross over.
Entire visual pathway
(@ 25:30min eye part 2)
Light enters through the cornea, travels through the aqueous humor of the anterior chamber of the anterior cavity and then travels through the pupil of the iris, then enters the posterior chamber of the anterior cavity which is also filled with aqueous humor, then through the lens which is bent to ensure the photon will land on the fovea centralis for the best acuity. As the photon travels through the vitreous humor of the posterior cavity to the retina, where photreceptor cells are stimulated, which stimulates bipolar cells, which stimulate ganglion cells whose axons run through the optic disc and out posteriorly forming Optic nerve (CN2) to the optic chiasma where hemi-decussation occurs, only medial axons cross over, the action potential continues and synapses in the Thalamus, and then to the Primary visual cortex of the occipital lobe, where you have conscious awareness of what you see.
ANS
Efferent visceral motor
Only corresponds to Visceral reflexes
Effectors:
Smooth muscle
Cardiac muscle
Glands
Viceral motor (compared to SM)
-thinner mylen-slower
-2 synapses
-1st cell body starts in the lateral horn
-2nd cell body outside CNS, unmylenated (ganglionic neuron) to effector
ANS- 2 Divisions
- same innervations, different actions
Parasympathetic
Resting and digesting
AKA-Cranial-sacral division
Cranial nerves (3, 7, 9, 10)
CN3-eye
CN 7, 9-salivary glands
CN 10- thoracic visera
Sacral nerves (S2-S4)
-bladder, genitals, and last of digestive tract
Sympathetic
Flight, fight, freeze, sex
Thoracolumbar division
Comes off spine at (T1-L2)
Commonalities & Differences in Divisions
Common properties
*Both have a two neuron chain
-Preganglionic neuron
-Postganglionic neuron
*Both preganglionic cells releases ACh as neurotransmitter
Differences
*Location of preganglionic cell bodies- (all in CNS- but in different areas)
Sympathetic-lateral horn
Parasympathetic- Lateral gray column
and cranial nerve nuclei (3, 7,9,10)
*Synapse of Preganglionic cell (location of ganglion):
Symp- near CNS
Para-far from CNS
* Length of preganglionic fiber:
Symp-shorter
Para- longer
* Type of neurotransmitter used by 2nd neuron on effectors:
Symp- norepinephrine
Para- Ach
Amount of terminal branching:
Symp- widespread innervation
Para- acute
Sympathetic the only to innervate blood vessels, erector pili, and sweat glands, think about when you get scared, blood vessels constrict, hair stands on end, and you sweat.
Parasympathetic two neuron chain
Parasympathetic- long preganglionic fiber; short postganglionic fiber. Preganglionic fiber synapses on ganglia in head (CNs) or terminal ganglia (organ of innervation)
Review Cranial Nerves 3, 7, 9, and 10
- *CN 3**- postganglionic fiber innervates smooth muscle of ciliary body (pupil constriction)
- *CN 7**- Postganglionic fiber innervates lacrimal gland, submandibular (salivary) glands.
- *CN IX**- postganglionic fibers terminate on parotid gland (big salivary gland)
- *CN X**- postganglionic fibers terminate on viscera (heart, lungs, liver, stomach, SI, and part of the LI until the Left Colic Flexure.
Sympathetic two neuron chain
Sympathetic- short preganglionic fiber; long postganglionic fiber. Preganglionic fiber synapses on paravertebral (sympathetic trunk ganglia) or on prevertebral ganglia (collateral ganglia).
Sympathetic trunk ganglia (T1-L2)
Off ventral rami are grey & white rami communicans attach to Sympathetic trunk ganglia (T1-L2)
- *Grey RC**- (unmylenated) post-ganglionic fibers
- *White RC**- (mylenated) pre-ganglionic fibers
- *Sympathetic trunk ganglia** have Thoracic Splanchnic nerves that run anteriorly which innervate sympathetic organs
Pathways of sympathetic autonomic reflex arcs
“at level” option
“up or down” option
Thoracic viscera option
Abdominal vicera
- only one that doesn’t synapse in the sympathetic ganglion
- instead goes out a splanchnic nerve an synapses in a colatteral ganglion (prevertebral), then the post-synaptic nerve travels a nerve plexus to the organ of innervatiion.
The Adrenal Medulla
(sympathetic)
- It produces and releases two NTS: norepinephrine and epinephrine
- It is stimulated by sympathetic preganglionic cells of the ANS
The Endocrine System
A system of ductless glands
• Secrete messenger molecules called hormones
• Hormones travel to distant body cells and signal characteristic physiological responses
*Interacts closely with the nervous system
*Controls and integrates the functions of other organ systems in the body, slower process, but longer lasting than nervous system
Maintains homeostasis, controls growth, metabolism, stress defenses, blood chemistry
The Pituitary Gland (Hypophysis)
Secretes 9 major hormones
Sits in hypophyseal fossa (sella turcica)
Connected to hypothalamus by stalk of tissue called the infundibulum
Two basic divisions of the pituitary gland
Adenohypophysis (anterior)- originates from hypophyseal pouch (glandular tissue) Pars distalis-large part where hormones come from.
Neurohypophysis (posterior)- originates from brain (nervous tissue)
Hypothalamic Control of Hormone Secretion from the Adenohypophysis
Hypophyseal portal system- double capillary bed system
Adenohypophysis
- *Hormones**:
- *Thyroid Stimulating(TSH)**: (T:Thyroid gland)(E: Stim. Thyroid to release Thyroid hormone)
- *Adrenocorticotropic hormone (ACTH)**:(T:Adrenal Cortex) (E:signals adrenal cortex to release stress hormones (glucocorticoids)
- *Follicle-stimulating(FSH)**: (T:gonads) (E: maturation of sex cells (sperm/ovaries)
- *Luteinizing Hormone (LH)**: (T:gonads) (E: Prod/Secret. of sex hormones)
- *Growth Hormone (GH)**: (T: epiphyseal plates & body cells) (E: protein synthesis & body growth)
- *Prolactin**: (T: mammary glands) (E: stimulates milk production)
- *Melanocyte-stimulating hormone (MSH)**: (T: fetus) (E: darkens skin)
Neurohypophysis
Does not make any hormones, just secretes them
- *Hypothalamo-hypophyseal tract-** hormones are neurotransmitters from the hypothalamus, stored & released here
- *Secretes two hormones**
- *Antidiuretic (ADH):** (T: kidneys and arterioles) (E: Kidneys reabsorb water/ arterioles constrict-up blood pressure)
- *Oxytocin:** (Uterus: contraction & mammary glands: milk secretion)
Pineal
Pineal
Has calcium phosphate and carbonate granules- easy to see on X-rays.
melatonin (monoamines)
• Regulated by day/night cycles
• Seasonally fluctuates
• Regulates seasonal breeding in animals
• Maybe involved in mood disorders
• Powerful antioxidant (up to 5 mg/day take at night)
Thyroid
- Located in the anterior neck-inferior to larynx
- Two lateral lobes connected by isthmus
- Largest pure endocrine gland
- *Hypothyroidism**-person always cold, gains weight but doesn’t feel hungry.
- *Hyperthyroidism**- Person is “hot”, loses weight, very hungry, anxious. Must ablate thyroid (radioactive iodine).
Goiter-lack of iodine
Thyroid follicles:
- *Follicular cells**
- *Thyroid hormone** (TH)- controls metabolic rate and protein synthesis
- *Parafollicular cells**
- *Calcitonin**- depresses blood calcium levels (via osteoclasts and kidney function).
The Parathyroid Gland
Lie on the posterior surface of the thyroid gland
Contain two types of endocrine cells
Chief cells – produce parathyroid hormone (PTH)
3 important actions on bone, kidney, and GI tract
Adrenal Glands
-Located on surface of the kidneys
-Nerve supply is almost exclusively sympathetic fibers
-Two endocrine glands in one
• Adrenal medulla – a knot of postganglionic sympathetic nervous tissue
Chromaffin cells – modified postganglionic sympathetic neurons
• Secrete - norepinephrine and epinephrine).
• Active in “fight or flight” response
• Adrenal cortex – bulk of the adrenal gland
Cortex-3 layers:
• Zona glomerulosa
• Zona fasciculata
• Zona reticularis
The Adrenal Cortex
-Secretes a variety of hormones- all are steroids and are grouped into two main classes:
• Glucocorticoids
Cortisol – stimulated by ATCH secreted by zona fasciculata and zona reticularis -stimulates fat and protein catabolism and gluconeogenesis.
• Helps the body deal with stressful situations
- **Mineralocorticoids**
- *Aldosterone**- is secreted by the zona glomerulosa - Sodium/water reabsorbed to maintain blood volume and pressure.
Cushings disease: prolonged exposure to inappropriately high levels of the hormone cortisol.
The Pancreas
Located in the posterior abdominal wall
Contains both endocrine and exocrine cells
• Exocrine cells – acinar cells – secrete digestive enzymes into small intestine(ducts)
• Endocrine cells – pancreatic cell clusters (islets of Langerhans) contains both α and β cells
Main endocrine cell types
• Alpha cells (α cells-20%) – secrete glucagon
Signals liver to release glucose from glycogen
Raises blood sugar
• Beta cells (β cells-70%) – secrete insulin
Signals most body cells to take up glucose from the blood
Lowers blood sugar
• G cells – secrete gastrin (stimulates digestive activity)
Disorders of the Pancreas: Diabetes Mellitus
Type I diabetes – develops suddenly, usually before age 15
T cell-mediated autoimmune response destroys beta cells
Type II diabetes – adult onset
Usually occurs after age 40
Cells have lowered sensitivity to insulin
Controlled by dietary changes and regular exercise
Middle ear
• Ossicles- malleus, incus, stapes (merge onto oval window)- transmit sound from external ear to internal ear.
• Round window – dissipates left-over energy in cochlea Oval window (stapes)
• eustachian tube/ auditory tube- equalizes air pressure (connects middle ear to the nasopharynx)
• Reflexive muscles that anchor/ protect ossicles from loud sounds (tympanic reflex)
-Stapedius (stapes)(CN7)
-Tensor tympani (malleus)(CN5)
Inner ear
3 boney structures:
cochlea- purely sound
vestibule- static equilibrium, linear equilibrium
semi-circular canals-equilibrium
Soft membranous structures within each:
Cochlea (Cochlear duct)
Vestibule (Utricle and Saccule)
Semi-circular canals (semi-circular ducts)
- *Perilymph**-fluid inside boney structure
- *Endolymph**- fluid inside soft membrane, inside boney structure
Utricle and Saccule-vestibular apparatus
Concerned with balance and position of head while stationary
Acceleration (linear)
Endolymph
Has special sensory epithelium called Macula
Receptor hair cells
Innervated by CN VIII (vestibular division)
Maculae
Horizontal (utricle) and vertical (saccule)
Receptor hair cells
Otolithic membrane- responsible for “triggering” hair cells
Otoliths- calcium carbonate crystals
Semicircular Ducts (semicircular canals)-Vestibular apparatus
Rotational movement
Anterior, posterior, and lateral semicircular duct.
Opens onto utricle
Ampulla
Crista ampullaris- (crest with hair cells)
Cupula- jelly-like pointed cap
Cochlea
- A spiral blind tube
- Innervated by CN VIII- cochlear division
- Perilymph-filled chambers:
scala vestibuli (starts from oval window) and scala tympani (continuous with each other-_helicotrema_). Merge onto round window
– Vestibular membrane
– Basilar membrane
• Endolymph
Cochlear duct- scala media
• Organ of Corti
– Stereocilia- hair cells
– Supporting cells
• Tectorial membrane-roof of organ of corti
