Lecture Exam 5 Flashcards
What are the three tunics of the eyeball? What is their function?
Fibrous
- Includes Sclera and Cornea
- Sclera is white and similar to dura mater. Provides anchoring for extrinsic muscles
- Cornea allows light to enter (transparent)
Vascular
- Includes Choroid, Ciliary body, Iris, and Pupil
- Choroid is 5/6 of vasc. tunic and prevents light scatter
- Ciliary body is a thick ring of tissue made of smooth muscle that focuses lens and makes aq. humor
- Iris is the colored part of the eye with smooth muscle that allows light to enter (contains sphincter and dilator)
- Pupil is the opening of the iris allowing light to pass
Retina
- Consists of pigmented layer and neural layer
- Pigmented layer absorbs light and prevents scatter
- Neural layer contains photoreceptors, bipolar ganglia, and ganglion cells
What does a parasympathetic vs sympathetic response do to pupil dilation?
Parasympathetic - Contracts which decreases pupil size
Sympathetic - Dilates which increased pupil size
What are the accessory structures of the eye? (6)
- Eyelids
- Palpebral fissure
- Canthi
- Levator palpebrae
- Conjungtiva
- Conjunctiva sac
What is conjunctiva and conjunctival sac? What is congunctivitis? What is pink eye?
Conjunctiva - Transparent mucous membrane that covers eyelids and anterior of the eye
Conjunctival sac - Space between the eyelid and eye ball that is lined with conjunctiva to moisten and protect the eye
Conjunctivitis/Pink eye - When the conjunctiva of the eye becomes inflamed or infected causing redness, itching, and more
Know the 6 extrinsic eye muscles and their actions? What is strabismus?
Superior Rectus - Moves the eye up, contributes to medial rotation
Inferior Rectus - Moves the eye down, contributes to lateral rotation
Medial Rectus - Moves the eye toward the nose (adduction)
Lateral Rectus - Moves the eye away from the nose (abduction)
Superior Oblique - Moves the eye down and outward, contributes to medial rotation
Inferior Oblique - Moves the eye up and outward, contributes to lateral rotation
Strabismus - Condition leading to an eyes being misaligned resulting in one pointing in/out/up/down
What is the lacrimal apparatus and be able to follow the pathway of a tear.
Lacrimal Apparatus - 6 structures involved in crying
Lacrimal gland produces tears which are drained into the conjunctive sac via Lacrimal ducts. Tears are then collected in the Punctua which leads to the Canaliculi resulting in tears reaching the Lacrimal sac. After they are stored briefly they drain from the Lacrimal sac into the nasal cavity via the Nasolacrimal duct
What is glaucoma? What is Cataract?
- Glaucoma is a group of eye diseases that damage the optic nerve, often due to increased intraocular pressure, leading to vision loss
- A cataract is a clouding of the eye’s lens, which can cause blurry vision and is often age-related
Identify this structure.
Sclera
Identify this structure.
Cornea
Identify this structure.
Ciliary body
- Ciliary muscle (1st from top)
- Ciliary process (2nd from top)
Identify this structure.
Suspensory ligament
(ciliary zonule)
Identify this structure.
Iris dilator (points in) and sphincter (circular)
Identify this structure.
Cone and rod Photoreceptors
Where are vitreous and aqueous humor located
Aqueous humor is in the anterior chamber of the eye
Vitreous humor is in the posterior chamber of the eye
What is accommodation? Which structures perform this action?
Accommodation is the process of the eye focusing on objects at varying distances. This involves ciliary muscles and suspensory ligaments for muscle control of the lens which changes thickness(bulges)
What is the pupillary light reflex? What mediates this reflex?
The pupillary light reflex is a physiological response where the pupils constrict when exposed to bright light, helping to regulate the amount of light entering the eye. This reflex is mediated by the optic and oculomotor nerves
What are the specialized areas of the retina?
Ora serrata - Neural layer meets ciliary body
Macula Lutea
Fovea centralis - Center of Macula
Optic Disc - Blind spot
What is the visual pathway of light passing onto photoreceptors to the primary visual cortex?
- Light reaches the pigmented layer
- Photoreceptor is triggered turning the signal into an electrical signal
- Signal travels to bipolar cell -> Ganglion cell -> Axon ->Optic nerve -> Optic chiasma (medial decussation) -> Optic tract ->Thalamus -> Optic radiation -> Visual cortex (occipital lobe)
What happens if a retina is damaged? Optic chiasma? Visual cortex/optic tract?
- Retina or optic nerve damage can lead to blindness in affected eye
- Damage to Optic chiasma can lead to loss of vision in both vision fields
- Damage to right visual cortex/optic tract can lead to blindness in the left visual field of both eyes
How is the ear divided into external, middle, and internal ear?
External:
- Involved in hearing
- Consist of Auricle, helix, lobule, external auditory meatus, and external auditory canal
- Ends at tympanic membrane
Middle:
- Involved in hearing
- Consists of ossicles (malleus, incus, stapes), round window, Auditory tube, and reflexive muscles
Internal:
- Involved in equilibrium and some hearing
- Consist of Semicircular canals (and ducts), Vestibule (utricle and saccule), and cochlea (and duct)
What foramina of the skull bones are related to ear and ocular function?
Ear:
- External auditory meatus
- Internal acoustic meatus transmits Facial and vestibulocochlear nerve (7 and 8)
Ocular:
- Optic canal allows optic nerve (2) to pass
- Superior orbital fissure allows oculomotor, trochlear, and abducent nerve (3,4,6) to pass
What are the structures of the inner ear involved in hearing?
Scala Vestibuli: Upper chamber, filled with perilymph, receives vibrations from the oval window.
Scala Media (Cochlear Duct): Middle chamber, filled with endolymph, contains the organ of Corti.
Scala Tympani: Lower chamber, filled with perilymph, ends at the round window.
Organ of Corti: Located in the scala media, contains hair cells that convert sound vibrations into electrical signals.
Hair Cells: Sensory cells in the organ of Corti, detect vibrations and generate electrical signals.
Tectorial Membrane: Above the hair cells, bends the hair cells when sound vibrations move the basilar membrane.
Basilar Membrane: Vibrates in response to sound, stimulating hair cells based on pitch.
What are the structures of the inner ear related to equilibrium?
Semicircular Canals: Three loop-shaped structures, filled with endolymph, detect rotational movement of the head (angular acceleration).
Ampulla: Enlarged region at the base of each semicircular canal, contains crista ampullaris, which has hair cells that detect rotational movement.
Utricle: Located in the vestibule, detects horizontal linear acceleration and head position relative to gravity.
Saccule: Located in the vestibule, detects vertical linear acceleration and head position relative to gravity.
Macula: Sensory area in the utricle and saccule, contains hair cells that respond to changes in head position and linear motion.
Otoliths: Tiny calcium carbonate crystals in the macula, move with head position changes, bending the hair cells and triggering nerve signals.
Label the image. What is the function of the external ear?
- Helix, auricle, External acoustic canal, External auditory meatus, Lobule (descending order)
- The function is to funnel sound toward the eardrum and protect the inner ear of debris
Label the image. What is the function of the middle ear?
- Auditory ossicles (Malleus, Incus, Stapes), Tympanic membrane, Round Window, pharyngotympanic tube
- The middle ear transmits sound from the external ear to the inner ear, amplifies sound, equalizes air pressure, and protects from loud noises
Label the image? What are their membranous components and what is their function?
- Semicircular canals: Contains semicircular ducts responsible for equilibrium for angular rotation
- Vestibule: Contains utricle and saccule responsible for static and linear equilibrium
- Cochlea: Contains cochlear duct responsible for hearing
What is endolymph and perilymph? Where are they found?
Endolymph: Fluid found in the cochlear duct and the semicircular canals, where it helps with the transmission of sound and balance signals
Perilymph: Fluid found in the space between the bony labyrinth and the membranous labyrinth of the inner ear, surrounding the cochlea and semicircular canals, providing cushioning and support
What is the vestibule, utricle, and saccule? What is their function?
Vestibule: Middle part of the inner ear responsible for static equilibrium and linear acceleration. Also houses the Utricle and saccule
Utricle: Fluid-filled sac within vestibule responsible for detecting horizontal movements and changes in head position contributing to equilibrium during linear acceleration
Saccule: Fluid-filled sac located in vestibule detects vertical movements and changes in head position allowing for detection of up and down acceleration and spatial orientation
What allows for balance and detection of head position in the inner ear? What innervates this?
- Both Utricle and Saccule have macula which is a special sensory epithelium that has receptor hair cells allowing for detecting head position and equilibrium. Innervated by CN VIII
What are the semicircular ducts? What is their function? What is the ampulla?
- Composed of anterior, posterior, and lateral semicircular ducts
- Allow for detecting rotational movement
- Open onto utricle
- Ampulla is an opened space containing Crista ampullaris and cupula. These structures are moved as endolymph moves while we rotate our heads allowing the signal to be sent to the brain so we can detect spatial awareness and head movement
What is the cochlear duct? What is its function?
The cochlear duct is a fluid-filled structure in the cochlea containing endolymph. It is located between the scala vestibuli and scala tympani. It houses the organ of Corti, sensory organ that converts sound vibration into neural signal, which conducts signal to brain for hearing. Crucial for auditory transduction
What is the pathway of hearing and triggering of the auditory cortex?
- Sound wave reaches and vibrates tympanic membrane
- Auditory ossicles vibrate intensifying pressure
- Pressure waves created by stapes push on oval window move through fluid in scala vestibuli
4a. Sound with frequencies below hearing travel through helicotrema and do not excite hair cells
4b. Sound in hearing range goes through cochlear duct, vibrating basilar membrane deflecting hairs on inner hair cells
What are the three ways to control hormone secretion
Humoral:
- Secretion in direct response to changing ion or nutrient levels in blood
Neural:
- Secretion of endocrine glands controlled by neural stimuli
- sympathetic nerve fibers stim. cells in adrenal medulla which release epinephrine and norepinephrine
Hormonal:
- Stimuli received from other glands
- Certain hormones signal secretion of other hormones
What are two common characteristic of secretion in endocrine glands?
- Always secrete hormones into the bloodstream
- Always controlled by feedback loops
- Negative: Blood concentration drops -> hormone secreted -> Blood cc increases -> hormone stops being secreted
- Positive : Oxytocin in women during labor -> contractions -> oxytocin release
What is positive/Negative feedback and how does it regulate hormone levels?
- Feedback loops are cycles that respond to changing conditions. There is positive and negative feedback loops to help regulate hormone levels and processes
Positive feedback example:
- During labor a woman will begin to produce oxytocin which in turn will result in contraction. This contraction will then result in the production of more oxytocin and continue the cycle until the baby is delivered and the loop is broken
Negative feedback example:
- When blood sugar levels drops below a set point, glucagon is released which causes the breakdown of glycogen which increases blood sugar levels. Then the blood sugar will surpass the set point resulting in no more glucagon production until the blood sugar drops below set point once again
What is the location of the hypophysis? What is the difference in tissue origin in the two portions of the gland? How are these differences related to the hypothalamus (how does the hypothalamus affect both of these differently)?
- Hypophysis (pituitary gland) sits in the hypophyseal fossa of the sphenoid bone
- Adenohypophysis (anterior) consist of glandular tissue
- Neurohypophysis (posterior) consist of neural tissue (part of brain)
- Adenohypophysis is indirectly controlled by hypothalamus due to hormones released into bloodstream via hypophyseal portal system which regulates anterior pituitary secretion
- Neurohypophysis is directly controlled by the hypothalamus. It stores and releases hormones produced by the hypothalamus which are transported via nerve fibers to the posterior pituitary for release into the bloodstream.
What is the follicular arrangement of thyroid cells? What is colloid material and what is its function?
- Thyroid follicles consist of outer areolar CT layer with parafollicular cells and capillaries close to the surface and follicle cells in the innermost part close to colloid
- Follicle cells make TH (T4 and T3) which regulate metabolic rate and protein synthesis
- Parafollicular cells make calcitonin which depresses blood calcium levels (promotes calcium deposition in bone) via osteoclasts and kidney function (childhood)
- Colloid is located centrally and is made of thyroglobulin which is a precursor of T4 and T3
Where are the parathyroids found? What hormone is produced and what is its action?
- Lies on posterior surface of thyroid gland
- Parathyroid hormone (PTH) - Acts on bone, kidney, and GI tract. Stim. osteoclasts, decrease kidney excretion, Activate Vit.D and stim. calcium uptake
What are the two different glandular tissues of the adrenal glands? Which portion is a branch of the nervous system?
Adrenal Medulla
- Part of Sympathetic Nervous tissue
- Chromaffin cells are modified postganglionic sympathetic neurons
- Secrete (aa) (nor &)epinephrine
- Active in fight or flight response
Adrenal Cortex
- Bulk of adrenal gland composed of three cortex layers
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
What is a steroid hormone? What type of molecule is it derived from? What are two types of steroids (ex.?)?
- Steroids are hormones derived from cholesterol
Glucocorticoids
- Cortisol - Secreted by zona fasc. and reti. in response to ACTH. Stimulates Fat and protein breakdown and gluconeogenesis (glucose production)
- Stress response during fasting, trauma, anxiety
Mineralocorticoids
- Aldosterone - Secreted by zona glom. causing sodium and water to be reabsorbed to maintain blood volume and pressure
What are the endocrine cells of the pancreas? Where are they found and what is their action. What happens in hyposecretion of insulin?
- Pancreatic islets (islets of Langerhans)
- They are scattered throughout the pancreas
- Contain α (80%) and β(20%) cells
- α cells - Secrete glucagon. Signals liver to release glucose from glycogen raising blood sugar
- β cells - Secretes insulin. Signals body cells to take up glucose from the blood and lower blood sugar
- Diabetes mellitus
- T1 Autoimmune response leads to body destroying its beta cells
- TII (adult onset) Cells have lowered sensitivity to insulin, can be controlled through diet and exercise
What is the autonomic nervous system and what is it’s relationship with the PNS?
- Autonomic nervous system is one of the two branches of the Peripheral nervous system (the other is somatic nervous system.
- Controls involuntary processes of smooth muscle, cardiac muscle, and glands
- Heart rate, digestion, respiratory rate, blood pressure
- ANS composed of two branches, Sympathetic (fight or flight) and parasympathetic (rest and digest). These two systems balance each other out to maintain homeostasis
What division of sensory and motor neurons does the ANS use?
- Uses visceral sensory neurons
- Hunger, pain, irritation
- Uses visceral motor neurons
- Innervate smooth muscle, cardiac muscle, and glands. These are further subdivided into sympathetic and parasympathetic
Compare ANS neurons with somatic motor neurons. (Control, # neurons, neurotransmitter, target response, regulation)
Compare and contrast parasympathetic and sympathetic nervous system. Where are pre- and postganglionic cell bodies found? What neurotransmitter is used. Where are cell bodies? What structures are innervated?
How do the lengths of fibers compare in sympathetic and parasympathetic divisions?
Sympathetic:
- Short preganglionic fiber
- Long postganglionic fiber
Parasympathetic:
- Long preganglionic fiber
- Short postganglionic fiber
What structures only occur between T1-L2? Why are they important?
- Gray ramus communicans carries postganglionic sympathetic fibers from sympathetic ganglia to the spinal nerves, allowing fibers to reach target organs
- White ramus communicans carries preganglionic sympathetic fibers from spinal nerves to sympathetic ganglia, synapse with postganglionic neurons
Describe the anatomy of parasympathetic division. What cranial nerve is the primary parasympathetic nerve?
- Parasympathetic division is in the craniosacral region which means the preganglionic neurons originate in the brainstem and the sacral spinal cord (S2-S4)
- Preganglionic neurons originate from lateral horns of sacral spinal cord
- Parasympathetic ganglia are located on or very near target organs
- Have very short postganglionic neurons
- CN X (Vagus) nerve is the primary parasympathetic nerve because it carries about 75% of parasympathetic fibers that reach heart, lungs, and GI
Describe the anatomy of the sympathetic division.
- Sympathetic division is in the thoracolumbar region (T1-L2). Its preganglionic neurons are in the lateral horns of the spinal cord (T1-L2)
- Preganglionic fibers exit via ventral roots ->spinal nerve ->White rami communicantes -> sympathetic ganglia near the spinal cord -> Gray rami communicantes -> spinal nerve -> target cell
- Preganglionic fibers synapse on sympathetic trunk ganglia (paravertebral ganglia) or collateral ganglia (prevertebral ganglia)
- Sympathetic trunk ganglia
- Collateral ganglia - Not paired or segmentally arranged. Abdomen and pelvis only (anterior to vertebral
- Long postganglionic neurons extend to target and may travel through gray rami communicantes
- Preganglionic use acetylcholine at synapse
- Postganglionic use norepinephrine at synapse (sweat uses ACh)
What is the adrenal medulla? What is its role in the ANS?
- Adrenal medulla is an extension of the ANS
- Produces and releases norepinephrine and epinephrine
- Stimulated by preganglionic cells of ANS
How do signals in the sympathetic division travel at level?
Lateral horn -> Ventral root ->White ramus communicans -> Sympathetic trunk ganglia -> Gray ramus communicans -> Ventral ramus of spinal nerve -> Effector
How do signals in the sympathetic division travel up/down?
Lateral horn -> Ventral root ->White ramus communicans -> Sympathetic trunk ganglia -> Sympathetic trunk -> Sympathetic trunk ganglia -> Gray ramus communicans -> Ventral ramus of spinal nerve -> Effector
How do signals in the sympathetic division travel through collateral ganglion?
Lateral horn -> Ventral root ->White ramus communicans -> Sympathetic trunk ganglia -> Splanchnic nerve -> Collateral ganglion -> Target
How do signals in the sympathetic division travel through thoracic viscera?
Lateral horn -> Ventral root ->White ramus communicans -> Respective Sympathetic trunk ganglia -> Target
Draw a visceral reflex
Micturition (urine)
- Bladder fills stretching bladder walls activating receptors
- Signal sent to spinal cord
- Signal is processed and initiates micturition reflex causing smooth muscle in bladder wall to contract
- Smooth muscle contraction allows internal urethral sphincter to relax and allow urine to flow
- External sphincter is controlled by skeletal muscle so we have more control over when we pee
What are the effector cells of the two divisions?
- Cardiac muscle in the heart
- Smooth muscle in blood vessels, GI, and more
- Glands such as sweat, thyroid, hypothalamus, and more
Draw the different sympathetic pathways to various effectors
- Sympathetic division shows norepinephrine which can increase heart rate, vasoconstriction, bronchodilation, sweating and more.
- All pathways follow a similar setup
- Sympathetic preganglionic neurons → sympathetic chain ganglia → postganglionic neurons → heart (via the cardiac plexus)
- Sympathetic preganglionic neurons → sympathetic chain ganglia → postganglionic neurons → smooth muscle in blood vessels
- Sympathetic preganglionic neurons → sympathetic chain ganglia → postganglionic neurons → bronchiolar smooth muscle
- Sympathetic preganglionic neurons → sympathetic chain ganglia → postganglionic neurons → radial muscles of the iris
