Muscle, Smooth, and Cardiac Tissue Flashcards Preview

Histology > Muscle, Smooth, and Cardiac Tissue > Flashcards

Flashcards in Muscle, Smooth, and Cardiac Tissue Deck (28):
1

Sarcolemma

-Cell Membrane
-Nuclei exist under sarcolemma (towards outside because high # of mitochondria and proteins push it to outside

2

Sarcoplasm

-aka cytoplasm
-Made up mostly of myofibrils

3

Sarcosomes

mitochondria

4

Sarcoplasmic reticulum

endoplasmic reticulum

5

Another word for muscle fiber?

Muscle cell

6

Order from smallest to biggest:
myofibril, fascicle, filament, muscle, sarcomere, fiber

FILAMENT < SARCOMERE < MYOFIBRIL < FIBER < FASCICLE < MUSCLE

7

Difference between muscle cell nuclei and fibroblast (when viewing in a slide)?

Muscle cell nuclei: toward edge of cell border
Fibroblast: see a little cytoplasm around it and found in the CT between cells

8

Role of connective tissue between muscle cells?

-Holds muscle fibers together to make a bundle that can have force
-Attaches muscle to bone
-Provides a supply of blood vessels and nerves
-Structures: Endomysium, perimysium, and epimysium

9

Endomysium

-Structure in CT that surround individual muscle fibers
-Fine layer of reticular fiber

10

Perimysium

-Structure in CT that surrounds group of fibers (fascicle)
-Collagen fibers

11

Epimysium

-Structure in CT: sheath that surrounds a group of fascicles
-Lots of collagen fibers
-Surround whole muscle (every muscle fiber is surrounded by epimysium)

12

Three ways muscles utilize energy?

1) Metabolism of fatty acids and glucose produces energy from ATP
2) Glucose can be taken from circulating stores or from breakdown of glycogen
3) Oxidative phosphorylation provides energy when muscle is recovering from contraction

13

TYPE 1: Muscle skeletal fibers

-Small fibers
-RED fibers in charge of slow twitch fatigue-resistant moter units
-Lots of myoglobin, mitochondria and blood vessels
-Found in back (long fibers)
-Endurance

14

TYPE IIA: Muscle skeletal fibers

-intermediate fibers
-Fast-twitch fatigue-resistant motor units
-Lots of myoglobin and glycogen

15

TYPE IIB: Muscle skeletal fibers

-Glycolytic
-Fast-twitch fatigue-prone moto units
-Contain less myoglobin and mitochondria
-WHITE Fiber
-Fine motor skills: Finger and eyes.

16

Myofibril

-Run length of a muscle cell
-Myoibrils are made up of bundles of myosin II and actin (individual polymers of myosin II and actin are myofilaments)
-Myofibrils are a repeating chain of tiny sarcomeres or small contractile units: myofibrils are bundles
-Surrounded by sER or sarcoplasmic reticulum

17

Subunits of Troponin

1) TnC: Binds Calcium to initiate contraction
2)TnT: binds tropomyosin
3) TnI binds actin (not static)

18

Why are accessory proteins in muscle important?

Regulate spacing, attachments, and alignment of the myofilaments (thick and thin filaments)

19

Thick filaments (aka Myosin II)

Two heavy chains: each have a small globular head (cross bridges) that is at a 90 degree angle to the rest of the molecule. The head has two bindings sites: one for ATP and one for actin

Four light chains:2 essential, 2 regulatory light chain.

20

Muscular dystrophies

-Cause: gene deletions create frameshifts that result in an absence of dystrophin
-Dystrophin and associated complexes join the muscle cytoskeleton to the extracellular matrix

21

Botulinum Toxin

-Inhibits the release of acetylcholine at the presynaptic end
-No muscle contraction
-Used as a treatment for focal dystonia
-Doesn't cure; just relieves the symptoms
-Thought to improve blood flow and release of nerve fibers under compression y contracting muscles
-Used for cosmetic purposes: Botox, etc.

22

Neuromuscular spindle

-receptor units within muscle to send info on muscle tension and position to central nervous system
-Encapsulated sensor that contains both sensory and motor components
-2 types: nuclear bag fiber (nuclei in bunch) and nuclear chain fiber (nuclei in row)

23

Muscle repair

-Myoblasts are stem cells that orginiates in mesoderm
-express myogenic regulatory factors (MRFs)
-Satellite cells are myogenic precursors that lie between plasma membrane of fiber and external lamina

24

Smooth muscle

Found as sheets or bundles in walls of the gut, ureter, urinary bladder, resp tract, uterus, and blood vessels
-Central nucleus (cork-screw appearance if in contracted state)

25

Structural elements of smooth muscle

-Connected by gap junctions (cell-to-cell signalling)
-invaginations of the plasma membrane act as primitive t-system
-Contractile apparatus: Thin filaments attached to dense bodies and thick filaments oriented differently

26

Smooth muscle initiation of contraction

Three ways:
1) Mechanical impulses: when lumen of a blood vessel expands, smooth muscle cells contract; passive stretching
2) Electrical depolarization: release of norepinephrene/acetylcholine: stimulate receptors on plasma membrane to change membrane potential
3) chemical stimuli: bind specific cell membrane receptor

27

REgulation of smooth muscle

-Postganglionic neurons of the autonomic nervous system
-Sympathetic and parasympathetic nerves
-Nerve pass through connective tissue and not always close to smooth muscle (neurotransmitter must travel by diffusion; signal occurs through gap jxn bc not all cells receive neurotransmitter)

28

Chronic Asthma

Acute attack is when spasms of smooth muscle with excessive mucous secretion closes off airways