All Histology - Exams 1, 2, and 3 Flashcards
Difference between thick and thin skin
Difference is only between the thickness of the epidermal layer.
Thick skin has thicker epidermis. It’s only on palmar surfaces of hand and plantar surfaces of foot. It LACKS hair follices, sebaceous glands, and arrector pili mm
Thin skin has thinner epidermis. It covers most of body surface. It CONTAINS hair follices, sebaceous glands, and arrector pili mm
Meissner’s corpuscle
Encapsulated nerve endings in the papillary dermis. Sensitive to light touch. Blind people who read brail have more than typical amount of Meissner’s corpuscles.
Pacinian corpuscle: function and appearance
Encapsulated nerve endings in the reticular dermis. Detect pressure changes and vibrations on skin surface. If you press hard on your skin, can feel it deep in the skin. That’s b/c Pacinian are located in the deep dermis layer.
Have onion pattern-appearance around the axon
eccrine v. apocrine sweat glands
eccrine sweat glands are NOT associated w/ hair follicles; over entire body EXCEPT lips and external genitalia. Thermoregulatory sweating
apocrine are LARGE sweat glands. Don’t begin to function until puberty and are responsive to hormonal influence = ‘nervous sweating.’
Name the 5 layers of the epidermis from most superficial to deepest and important features
- s. corneum: anucleated, flat cells that are dead
- s. lucidum: only in thick skin
- s. granulosum: lots of keratin, so stain much darker. First cell layer that has live cells!
- s. spinosum: prickly/spiny intercellular junctions
- s. basale: most mitotically active; has stem cells and melanocytes
Where would you most likely find stratum lucidum?
THICK skin. S. Lucidum is not readily apparent in thin skin.
Keratinization. Distinguishing features of 5 layers of keratinocytes.
Keratinization takes 2-6 hours, which is the amount of time it takes for keratinocytes to leave s. granulosum and enter s. corneum. (5) levels of keratinocytes:
-s. basale = basophilic b/c of lots of ribosomes making keratin protein
-s. spinosum = cells begin to synthesize keratohyalin granules and lamellar bodies
-s. granulosum = dark b/c of lots of keratinohyalin granules not surrounded by a membrane
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What type of sweat gland is known for its location in the odor-producing areas of the body?
apocrine sweat glands. Found in axilla, areola, and perianal regions.
Explain the 3 types of secretions and which gland goes with each.
holocrine glands: release their entire cytoplasm upon secretion. Sebaceous glands are holocrine
mericrine glands: no loss of cytoplasm associated with their secretion. Apocrine sweat glands are believed to actually be mericrine.
eccrine: secretion by exocytosis
What kind of epithelium would most likely make up the walls of a sweat duct?
Duct of eccrine sweat glands is lined by stratified cuboidal epithelial cells
What two glands secrete directly into the hair follicle?
- sebaceous glands: sebum coats the hair follice and skin surface for protective function
- apocrine glands
What kind of granules do you find in the s. granulosum layer?
keratinohyalin granules
Sliding filament theory of muscle contraction
During contraction, thick and thin filaments do not shorten, but increase the degree in which they overlap
muscle spindles
stretch receptors. They are modified muscle fibers that contain both sensory (afferent) and motor (efferent) fibers. They detect a muscle’s degree of stretching.
Nissl substance
basophilic staining of the cytoplasm due to high [ ] of RNA (both free and bound ribosomes). Nissl substance is the ergastoplasm of neurons.
bipolar neurons
confined to special sense, such as vision, hearing, and smell
What type of tissue is hypodermis?
white adipose
3 types of skeletal muscle
Type I = red, slow oxidative, means lots of mito and fatigue resistant
Type II A = pink, fast, oxidative
Type II B = fast, glycolytic. Has lots of glycogen and gets tired very quickly b/c produces a lot of lactic acid
2 layers of cerebellum (gold, neuron pic)
outer = molecular layer middle = Purkinje cell layer deep = granular cell layer
What does axon hillock look like on slide (pink one)?
white/clear b/c devoid of organelles, so doesn’t pick up stain.
structure of sensory ganglion. Where is it located? What type of nerves are in sensory ganglion?
top layer is CT capsule. lower bunch of neurons with central nucleus and then a bunch of small satellite cells around, which are dark-staining and kind of look like nuclei
**Tend to cluster together b/c no fibers running through them
Located in dorsal root and nerves are PSEUDOUNIPOLAR
Autonomic nerves
- cell bodies are scattered (b/c fibers running through them)
- nucleus is not centered = eccentric
- don’t have satellite cells all tightly around like with sensory ganglion
lipofuscin
related to lysosomes = residual bodies that don’t get degraded and just accumulates. aka Age Pigments
what cell is melanin formation in?
melanocytes
