Histology - Lab Practical 2

striated muscle

presence of striations due to the regular organization of contractile proteins in the muscle cell (cardiac and skeletal muscle)

basal lamina

ensheaths each muscle fiber (muscle cell/myofibril)

smooth muscle function

involuntary movement

smooth muscle location

digestive tract, walls of arteries/veins, respiratory passageways, bladder, and reproductive system

smooth muscle fiber morphology

mononucleated, long, spindle shaped, shorter than skeletal muscle

skeletal muscle fiber morphology

long cylindrical cells, nucleus smushed to one side

satellite cells

stem progenitor cells of skeletal muscle, found within basal lamina

endomysium

connective tissue sheath that encloses a cluster of muscle fibers

perimysium

ensheaths groups of clusters of muscle fibers

epimysium

sheath of dense connective tissue that surrounds entire muscle

golgi tendon organs and muscle spindles

specialized structures for sensing muscle length

tendons

dense connective tissue, attaches muscle to bone

cardiac muscle fiber morphology

one or two central nuclei, branching, cells are joined by intercalated disks

intercalated disks

between muscle fibers, contain desmosomes, gap junctions, and adhering junctions

purkinje fibers

conduct action potential in the heart

neurons

excitable cells; receive stimuli, transmit impulses, integrate data

glia

provide nutritional and structural support, electrical insulation of axons, regulate ionic environment surrounding neurons, modulate neurotransmission by uptaking/releasing neurotransmitters/hormones, can act as macrophages (phagocytize damaged neurons)

what can be visualized in a neuron with light microscope

nucleus, rough ER + ribosomes (Nissl substance)

what does Nissl substance look like and why

granular, condensed regions within a nerve cell, Nissl substance is basophilic so it stains dark

golgi stain

frequently used to visualize neurons, randomly stains only a subset of neurons in their entirety

gray matter

composed of neuronal cell bodies

white matter

contains axons

ganglia

aggregation of neuronal cell bodies (ganglion) in PNS

nucleus

aggregation of neuronal cell bodies in CNS

nerve fibers

neuron’s axon + myelin sheath

endoneurium

loose connective tissue that surrounds individual axon

perineurium

connective tissue that surrounds bundle of axons (fascicle)

epineurium

dense connective tissue that surrounds entire peripheral nerve

central H of spinal cord

gray matter, which is prominent in neuronal cell bodies and gliocytes

surrounding central H of spinal cord

white matter, which is prominent in concentrated myelinated fibers and gliocytes, has lower capillary density than gray matter

dorsal root ganglion

transmits info from periphery to spinal cord, contains sensory neurons that send input to dorsal horns

how is the brain organized

white matter inside is surrounded by multilayered cerebral cortex of gray matter

pyramidal cells

most prominent neurons of cerebral cortex, triangle shaped with single large apical dendrite

cerebellum composition

inner white matter and outer gray matter (cerebellar cortex)

granular layer of cerebellar cortex

inner layer, has abundant cell bodies (can see lots of nuclei)

molecular layer of cerebellar cortex

outer layer, has relatively few cell bodies

purkinje cells

large flask shaped cells, there is a single layer between molecular and granular layer of cerebellar cortex

pacinian corpuscles function

touch receptors that are sensitive to pressure and vibration

pacinian corpuscles location

deep layers of skin

pacinian corpuscles composition

concentric layers of flatten schwann cells with single central nerve fiber (looks like onion)

meissners corpuscle function

touch receptor that responds to light touch

meissners corpuscle location

beneath skin epithelium of fingertips, soles of feet, and lips

meissners corpuscle composition

tapered cylinders perpendicular to skin surface, composed of flattened lamellae of Schwann cells, 1-2 axons, much smaller than pacinian

alimentary canal

esophagus to anal canal

what are the 4 layers that make up the tube wall of the alimentary canal

mucosa, submucosa, muscularis externa, serosa

mucosa

epithelium, underlying connective tissue rich lamina propria, and muscularis mucosa

submucosa

layer of dense irregular connective tissue

muscularis externa

usually two layers of smooth muscle

serosa

simple squamous epithelial membrane with some connective tissue, connective tissue wrapping called adventitia is found where structure is fixed in place

papillae

irregularities/elevations on dorsal epithelial surface of tongue

primary composition of tongue

skeletal muscle arranged in bundles that extends in three planes; allows for flexibility for speech/eating/swallowing, covered by strat squa that can be partially keratinized, rests on lamina propria

where are taste buds located

at the four different types of papillae

esophagus composition

4 characteristic layers, lumen lined by nonkeratinized strat squa that sits on connective tissue submucosa