Histology: Muscles and Neuro Flashcards
Why do you need calcium for muscle contration?
Actin’s binding sites for myosin are blocked by tryposymsin filaments. On these filaments is a protein called troponin, that can bind with calcium. When it binds with calcium, it moves the trypomyosin out of the way so that myosin can then bind to the actin and the sacromere can contract.
What are the major components of smooth muscle to look for in a histology slide?
Cells: they are fusiform (taper) shaped and the nuclei are central. It will be more cell dense than connective tissue
Draw out a sarcromere with all the components: A band, I band, Z line, H zone, M line.
Which bands change size with contraction? Which ones stay the same?
A band: does not change
I band: gets smaller
H zone: gets smaller
What is the sacroplasmic reticulum and what does it do?
It is a network of channels surrounding myofibril units allowing calcium to get into each sarcromere
What are T tubules?
channels connecting the muscle cells (myocytes) to the outside world; they are separate from the sarcroplasmic reticulum
In cardiac muscle, what are the functions of the gap junctions and the fascia adherens?
gap junctions: let calcium and other ions pass through
fascia adherens: a bundle of proteins to combat forces, similar to demosomes
What are some things to look for when identifying cardiac muscle?
central nuclei, branched myofibers instead of fusifrorm, intercalated dicsc
What are some thing to look for when identifying skeletal muscle?
weird looking nuceli(they look stretched out and flat, the cels are syncytial (multiple cells becoming one so appears multinuclear), very clear organized myofibers, not branched at all
What is the difference between fast and slow twitch muscles?
Fast: (white meat) is built for speed, low myoglobin
SLow twitch: built for endurance, high myoglobin
What is the function of dystrophin in skeletal muscle?
It is an anchor complex that binds the mucle proteins (actin) with the cytoskeleton, preventing membrane damage
What is a myotendonous junction?
Where the collagen fibers in muscles joint together and fuse to create a tendon that connects muscl to bone. (think of the onion bag)
What are intrafusal fibers?
fibers that allow spatial awareness, proprioception, sense strecth, identify length and position
How do intrafusal fibers work?
They wrap around the bag of muscles and sense the diameter
Where are muscle satellite cells located?
under the endomysium
What are the arrows pointing to and how can you tell?
You can see there is skeletal muscle on the bottom, and the top looks like regular dense connecive tissue, so we can say this is a myotendonous junction. Not only is there the color change, but we loose the striations and get more of a collagen crimp.
The central nervous system consists of what two things?
Brain and spinal chord
What are the 4 action targets of neurons?
other neurons
muscles (both smooth and striated)
glands (autonomic nervous system)
Circulation (smooth muscle)
What is the law of dynamic polarization?
neural signals only travel in one direction from dendrites to axon
What is the function of the kinesins proteins?
they are motor proteins that drag vesicles from the cell body along the axon
What are the two categories of neurons?
Sensory (Afferent) and Motor (Efferent)
the somatic (body) afferent neurnos are sensitive to what?
How about the visceral (guts) afferent nuerons?
pain, vibration, fine touch, position, temperature
deep stretch, pain, pressure
The motor (efferent) neurons are divided into somatic and visceral. WHat actions fall under each category?
somatic: voluntary skeletal muscle movememt
visceral: involuntary autonomic system (parasympathetic and sympathetic)
List the functions of glial cells
supporting
nurturing
insulating (myelin)
phagocytosis (get rid of stuff)
clean up the neurotransmitters to prevent over stimulation
stem cells?
What are the different types of glial cells?
astrocytes (in the peripheral nervous system, satellite cells)
microglia (macrophages)
Ependymal cells
Oligodendrocytes (in the peripheral system schwann cells)
What are astrocytes?
they are large star shaped cells, help with the blood brain barrier, they have foot processes that support the endothelial cells in capillaries, and they signal neurons through calcium dependent release of glutamate
What is the function of astrocytes?
structural support
supply neurons with nutrients
supports synaptic activity
reuptake of neurotransmitters
stimulate oligodendrocytes to initiate myelination
component of glial scars
What is a myelin?
concentric wrappings of lipid membrnes that are interupted periodically by nodes of ranvier
How does salatory conductance happen?
the ion channels are located at the nodes of ranvier and the myelin shealth acts as the electric insulator. this icnreases the transmission speed of the action potential
what are ependymal cells and what do they do?
they are a part of the neuroepithelium, they are simple cuboidal cells that have cilla and microvilli, lines the ventricles of the brain, secrete and absorb CSF
What is the difference between white and grey matter in the brain and spinal chord?
white matter contains lots of myelin, mostly axons and glia
gray matter is mostly cell bodies and glia (less
What kind of tissue is this? What identifiable features confirm the tissue identity?
This is smooth muscle. the cells are fusiform with central nueculi
Explain the difference between a myofibril and a myofiber
a myofiber is a single multinucleate cell, and a myofibril is the bundle of actin and myosin
What is a triad?
the T tubule in a myofiber sandwhcihed between two terminal cisterna of the sarcoplasmic reticulum
What kind of tissue is this? What are the structures labelled A, B, and C?
This is cardiac muscle
A: intercalated disc
B: neucleus (centralized)
C: branched fiber
What kind of tissue is this? What structure give it away?
skeletal muscle. You can see the individual sarcromeres (A bands and I bands), the nuceli are peripheral and not centralized, and the structure is very organized
What is the differences between type 1, type 2a and 2b?
type 1 muscle: slow oxidative, smaller diameter, more capillaries, more mitochondira, endurance
type 2a: fast oxidative, intermediate (in between the two)
type 2b: fast glycolytic, larger diameter, fewer capillaries, less mitochondira, explosive power like sprinting
Which slide shows slow oxidative muscle and which shows fast glyolytic? How do you know?
the one on the left is slow oxidative and the one on the right is fast glycolytic. The slow oxidative fibers are stained dark blue and the one on the left has more slow fibers, so this muscle would be better for endurance and is likely a muscle that is working constantly. The muscle on the right has less slow fibers and is likely a muscle more involved with faster movements and less endurance
What are the 3 muscle layers?
epimysium, perimysium, and endomysium
What is nissl substance?
the RNA and proteins in aggrugate with the rough endoplasmic reticulum in the nueral cell body and dendrites but NOT the axon
What are the arrows pointing to in this photo?
nissl substance in the nueral cell body and dendrites
What are the arrows pointing to? A and B?
A: astrocyte
B: capillary
What are the arrows pointing to?
Nodes of Ranvier
What is the structure labelled A?
it is the neural epithelial cells, ependymal cells
What is the arrow pointing to? Which side of the slide is the white matter and how do you know?
Arrow: nueral cell body
the left side is the white matters because you can see the myelinated axons (white circles are the myelin, pink circles inside the white circles are the axons) from the transverse cut
What are the elements of the meninges?
CNS: dura mater, arachnoid mater, pia mater
PNS: epinerium, perinerium, endonerium
identify the structures labelled A, B, and C
A: epinerium
B: perinerium
C: endonerium
Identify A, B, and C
A: pia mater
B: arachnoid mater
C: dura mater
