Exam 3 Ch.20-21 Flashcards
(23 cards)
What parts are needed for accommodation? Describe how the process helps you see objects up close and at a distance.
Bear chasing you
No Parasympathetic activity: eye relaxes
Ciliary body relaxes & pulls suspensory ligaments taut —>lens flattens —> see objects in distance
Looking @ watch
Parasympathetic activity (CN III):
Ciliary body contracts & suspensory ligaments relax —> lens bulges —> see objects up close
Discuss the two chambers of the eye. Where are they located? What fluid is found in each?
Anterior chamber in front of lens fillled with aqueous humor
Posterior chamber behind lens filled with vitreous humor
What cells are part of the retina?
-photoreceptors, specialized sensory cells that react to light.
-rods: simple light sensitive cells
-cones: color sensitive cells (red, blue, green)
-accessory cells: transmit action potential to actions of the optic nerve
How are rods and cones different? How are they different than other neurons in terms of resting membrane potential and stimulation?
Photoreceptors have a resting potential of about -40mV
At rest (no photon/light stimulation) sodium ions (Na+) are constantly leaking in, this is known as the ‘dark current’.
Stimulation:
Na+ no longer enters the photoreceptor.
Hyperpolarizes to -70mV and stops releasing neurotransmitters.
Results in an action potential at accessory cells and along the optic nerve.
What structures of the eye help control the amount of light entering?
• Choroid layer,is the middle layer that regulates light and includes:
– Blood vessels
– Melanin to absorb excess light
– Iris, two layers of smooth muscle that adjusts the size of the pupil.
– Pupil, the opening in front of the lens, that regulates the amount of light entering the eye.
What anatomical structures make up the external ear? What is the function of each structure?
External auditory meatus (canal) allows for the passage of sound waves to the tympanic membrane.
– The vibration is transmitted to the ossicles.
What anatomical structures make up the middle ear? What is the function of each structure?
• Ossicles, smallest bones in the body and located in
the temporal bone.
– Transmits sound waves to the internal ear.
• Malleus, attaches to the eardrum
• Incus, is located between the malleus and stapes
• Stapes, vibrates against the oval window transmitting vibrational energy to the fluid of the inner ear.
What anatomical structures make up the inner ear? What is the function of each structure?
Cochlea, is the spiral, conical, bony chamber filled with fluid.
– Contains a cochlear duct and organ of Corti (Spiral organ)
•Sounds in the hearing range goes through the cochlear duct and vibrates the basilar membrane.
– This moves the hairs (stereocilia) on the hair cells against the tectorial membrane initiating an action potential.
What are the three fluid filled chambers of the cochlear ducts?
Scala vestibuli
Scala media
Scala tympani
Describe how an object appears on the retina compared to its interpretation by the brain.
When an image enters the eye, it is inverted and reversed by the lens.
Once the brain receives the sensory input it must reorientation the perceived image / information.
Compare olfaction and gustation. What anatomical features do they have in common? What physiological features do they have in common?
Olfaction
-chemoreceptors: detect chemical substances dissolved by fluids and then perceived as odors.
-cilia: respond to dissolved chemicals, or odorants.
Gustation
-Chemoreceptors, sense chemicals that dissolve on the surfaces of the tongue, and epithelium of the cheek and throat.
Gustatory epithelial cells are the receptors that recognize dissolved chemicals.
– Have long gustatory hairs the extend out of the taste pore.
Describe the anatomy of a taste bud and where each type is located.
• Vallate papillae - Large and located on posterior aspect of the tongue in a V-shape
-Foliate papillae – Smaller and located on the lateral sides of the tongue
-Fungiform papillae - Medium-sized and located all over the tongue
-Filiform papillae
– Located all over the tongue
– Provide friction
– Do not contain taste buds
What is the purpose of the lacrimal gland? Are there any other anatomical structures associated with the eye that help it complete its purpose?
keeps the surface of the eye moist by releasing fluid that moves across the eye toward the lacrimal sac and nasal cavity.
• Relaxation of levator palpebrae superioris (CN III) results in blinking to moisturize the cornea.
• Contraction of orbicularis oculi (CN VII) results in a wink/squint. (allows for less light to enter)
List the layers of the epidermis from deep to superficial and compare the structure of each layer.
- Stratum basale:
– 1 layer of cells that undergoes mitosis to create new cells
– Closest layer to a blood supply - Stratum spinosum:
– 8-10 layers of living cells that produce pre-keratin - Stratum granulosum:
– 3-5 layers of cells that are filled with keratin
– Far from a blood vessel, start to flatten and can’t regenerate - Stratum lucidum:
– Thin layer of dead cells
– Cells are packed with a clear protein giving the cells a transparent and protective quality - Stratum corneum:
– Superficial layer of DEAD cells, 15-30 layers thick
– Protective layer
What are the different regions of hair?
• Shaft is area that is superficial to the epidermis, while the Root is the area deep to the epidermis and dermis
• Bulb is the expanded area at distal end of root
– Hair papilla is the vascular protrusion of bulb
– Matrix is the region with living cells that produce new hair cells
• Follicle is the epithelial tube that surrounds the hair root
– Arrector pili is a small band of smooth muscle attached to
follicle
Where are each of the sensory receptors of the skin located? What does each do?
Dendritic cells
– Found in the stratum spinosum
– Immune cells that patrol for foreign invaders.
Merkel cells
– Found in the stratum basale
– Fine touch receptors
• Melanocytes
– Found in the stratum basale
– Produce melanin, a pigment protein that protects keratinocytes from UV light.
What is melanin and how does it protect skin and create different skin tones?
a pigment protein that protects keratinocytes from UV light.
The amount and form of melanin produced by melanocytes differs between individuals.
Explain why stratified squamous is much better for protecting the external surface of the body than a simple columnar epithelium.
Provides protection from abrasion and is keratinized, a protein that gives skin its water-proof and protective properties.
Contrast apocrine and eccrine sweat glands.
• Apocrine – secrete milky/yellowish sweat
containing fat and proteins.
• Found in the axillary and inguinal areas
• Eccrine – secrete sweat composed of H2O, salt,
waste, vitamins
– Function to regulate body temperature
Contrast the epidermal and dermal layers of the skin. HINT: Think about the type of tissue, vascularization, types of cells present, etc.
Epidermis:
-Trans-segmental derived from epidermal ectoderm.
-4 layers
Dermis: the binder
-Segmental (repeating) strips derived from dermatome of the somite.
-CT w/ lots of collagen fibers
-2 layers
List the different types of cells found in the epidermis. What is the function of each of the cells and where are they located.
Dendritic cells
– Found in the stratum spinosum
– Immune cells that patrol for foreign invaders.
Merkel cells
– Found in the stratum basale
– Fine touch receptors
• Melanocytes
– Found in the stratum basale
– Produce melanin, a pigment protein that protects keratinocytes from UV light.
How does skin help regulate internal body temperature? Explain what the body should do if temperatures increase or decrease.
Temp increase:
1. Outside temperature increases. Body temperature increases
2. Sensory receptors for temperature send a message to the brain(hypothalamus)
3. Sweat glands release sweat. Blood vessel increase in size moving heat toward the skin.
4. Back to normal
Temp decrease:
1. Outside temperature decrease. Body temperature decreases.
2. Sensory receptors for temperature send a message to the brain
3. Blood vessel decrease in size moving heat toward the vital organs.
4. Back to normal
Compare the growth of the epidermis with the hair shaft. What do they have in common?
Exposed hair and ends of finger- and toenails, are DEAD cells like the stratum corneum.
