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Muscle Function
Muscle Function & Skeletal Muscles
80
Anatomy
Undergraduate 2
02/24/2013

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Cards

Term
Muscle (function)
Definition
  • Movement
  • generates heat (maintains body temp)
  • maintains posture (stability)
  • closes body openings (closing of bladder so it doesn't leak)
Term
Types of skeletal muscle
Definition
skeletal, smooth muscle, cardiac
Term
Skeletal muscle
Definition
  • Always associated with bone
  • attached to bone, primary job is to move bone

 

Term
Smooth muscle
Definition

surrounds hollow organs (ie stomach, blood vessels, intestines)

 

Term
Cardiac muscle
Definition
Muscle that is only found in heart
Term
Skeletal muscle
Definition
  • Striated
  • Long stripes running through it, bundles of nuclei, really big cells (many nuclei)
  • Typically voluntary and able to be consciously controlled (exceptions: blinking, breathing)

 

Term
Muscle cells
Definition
A bunch of microscopic proteins
Term
Muscle's version of a plasma membrane
Definition
Sarcolemma
Term
Endomysium
Definition
  • Thin layer of areolar (connective) tissue surrounding the plasma membrane of each cell (fiber)
  • allows room for capillaries and nerve fibers
Term
Perimysium
Definition
  • Slightly thicker layer of connective tissue
  • surrounds a bundle of cells called a fascicle
Term
Epimysium
Definition
Covers entire muscle
Term
Connective Tissue
Definition
Leads out to a tendon
Term
Skeletal Muscle Structure
Definition
  • Muscle cells are referred to as muscle fibers
  • plasma membrane = sarcolemma
  • T tubules = holes in the plasma membrane that allows an impulse from a motor neuron to travel through the interior of a muscle cell
  • sarcoplasmic reticulum (smooth endoplasmic reticulum): stores calcium (muscle will not contract if calcium is not there)
Term
Hypertrophy
Definition
Increase in muscle fiber size controlled by growth hormone = endocrine system
Term
Atrophy
Definition
  • Decrease in muscle cell size, always a result of lack of use
  • The end result is death of a muscle cell
  • It is replaced by connective tissue (scar tissue)
Term
Motor Unit
Definition
A single motor neuron and all the muscle fibers (cells) it connects to. It can be as few as 5-20 or as many as 1000.
Term
Precision
Definition
  • Eyes, fingers, mouth, tongue
  • Fine motor movements
  • Controlling smaller items
  • Less (fewer) fibers or cells
Term
Strength
Definition
  • Move legs, abs, shoulders
  • Larger muscle groups
  • Higher # of muscle cells
Term
Neuromuscular Junction
Definition
  • Like a synapse, but not in the CNS.
  • The connection between the end of the axon and the muscle cell.
  • Acetylcholine is the neurotransmitter.
Term
Botox
Definition
Blocks acetylcholine to smooth skin
Term
Smooth muscle
Definition
  • Not striated
  • Long, skinny
  • Spindle shaped cells
  • involuntary - no conscious control
  • Controlled by hormones or autonomic system
  • Can be stimulated to contract by the autonomic nervous system or by the endocrine system
  • ex) oxytocin & the uterus
  • Typically found around hollow organs
  • Contraction speed is very slow, but can remain contracted for long periods of time without fatiguing
Term
Cardiac Muscle
Definition
  • Only in the heart
  • Involuntary
  • Highly branched cells - brain looks at the heart as if it is one cell that is why branching is so important
  • Lock together with intercalated discs
  • Contraction rates - vary depending on need & activity
Term
Intercalated Discs
Definition
  • Desmosomes
  • Lock the cells in the cardiac muscle together so they can communicate - if they don't, the cells will die (and so will you)
Term
Muscle Contraction
Definition
  • Nerve signal stimulates the release of acetylcholine.
  • Muscle cell will depolarize.
  • Binds onto the muscle cell.

 

Term
After the nerve is stimulated in muscle contraction,
Definition
  • Binding of acetylcholine to the muscle cells open Sodium and Potassium Channels
  • ACh makes muscle bend and sends response
Term
After the ACh binds to the muscle cell,
Definition
  • Depolarization occurs - impulse for contraction travels through the cell.
  • If no acetylcholine released, no polarization, no muscle contraction.
Term
After depolarization,
Definition
  • The impulse for contraction spreads over plasma membrane and enters T tubules causing Calcium gates to open in SR (sarcoplasmic reticulum)
Term
Calcium moves from high to low concentration through the muscle cell by
Definition
diffusion
Term
Calcium moves back through
Definition
Active transport via calcium pumps
Term

After the calcium gates open

 

Definition
Calcium released by the SR (sarcoplasmic reticulum) binds to troponin.
Term
After calcium binds to troponin,
Definition
The troponin-tropomyosin complex changes shape and exposes active sites on actin.
Term
After the active sites on actin are exposed,
Definition

The myosin head gets ahold of actin, it builds a chemical bond called cross-bridge attachment.

Binds onto an active site on actin.

Term
Once the cross bridge attachment is made,
Definition

Power Stroke takes place. The myosin head falls over, still attached to actin (was standing upright), pulls on actin thats what makes muscle cells shorter.

Now ATP must come break the crossbridge attachment.

Term
After the power stroke,
Definition
Crossbridge detachment takes place. This requires ATP to break the bond (need an input of energy).
Term
Once crossbridge detachment takes place,
Definition

The myosin head must be reset. Because it had fallen over, it has to stand back up. The energy is required to break the bond and reset itself. If no calcium is available or present, the muscle will not move at all.

When the nerve impulse ends for a contraction, the calcium gets pumped back into the SR.

Term
Without ATP
Definition
you are dead
Term
When calcium leaks out
Definition

Forms crossbridges, causes rigormortis

 

Term
Myoglobin
Definition
Muscle cells store oxygen on a receptor
Term
Why do muscle cells store glycogen?
Definition

It is a carbohydrate; polysaccharide, use for energy

To burn anything; you need fuel and oxygen

Term
Why does a muscle become fatigued?
Definition
  • Too much carbon dioxide and lactic acid
  • Not enough oxygen, not enough energy source (glucose, glycogen)
Term
Oxygen debt
Definition
  • Replacing oxygen that was used during exercise; recharging blood
  • Oxygen helps breakdown lactic acid
  • The quicker it is paid back; the better
  • Winded, panting - have to payback other body systems for borrowed amounts

 

Term
Slow twitch muscle fibers
Definition
  • Large amounts of mitochondria, myoglobin and blood
  • Slow to contract, but do not fatigue easily
Term
Fast twitch muscle fibers
Definition
  • Smaller amounts of mitochondria, myoglobin, and blood
  • Contract quickly, but fatigue quickly.
  • Ex) short distance runner, sprinter, eyes (skeletal muscles)
Term
Flex
Definition
Decrease the angle of the joint
Term
Extend
Definition
Increase the angle of the joint
Term
biceps
Definition

bend arm at the elbow

origin: scapula

insertion: radius

Term
triceps
Definition

straighten arm

antagonist of biceps; posterior side

origin: humerus, scapula

inserts: olecranon of ulna (elbow)

Term
flexors
Definition

bend the wrist, pulling hand toward elbow

ventral surface of forearm and hand muscles for flexing

(inside of hand and arm)

Term
extensors
Definition

straighten the wrist

antagonist of flexors, dorsal surface of forearm and hand muscles

(outside of arm) used for extending

Term
deltoid
Definition

raise arm to horizontal position or higher

triangular shape

origin: scapula, clavicle

inserts: humerus

Term
pectoralis major
Definition

pull arm forward

origin: clavicle, sternum, ribs

inserts: humerus

synergist with latissimus dorsi to work together to pull arm down

antagonists to latissimus dorsi by itself

muscle that moves humerus

 

Term
latissimus dorsi
Definition

pull arm backward

origin: starts on thoracic vertebrae continues down to ilium

inserts: humerus

synergist with pectoralis major to work together to pull arm down

also antagonizes deltoid

muscle that moves humerus

Term
trapezius
Definition

pulls scapulas together, shoulders back

origin: occipital bone continuing down to the thoracic vertebrae

inserts: scapula

scapula movement

Term
serratus anterior
Definition

pull scapulas laterally and forward

origin: ribs

inserts: scapula

scapula movement

strong muscle to keep scapula in place

Term
levator scapulae
Definition

raise scapula, pull head back (raise up)

deeper muscle

origin: cervical vertebrae

inserts: scapula

 

Term
sternocleidomastoid
Definition

pull head forward

origin: sternum & clavicle

inserts: mastoid process (bump behind the ear)

Term
masseter
Definition

close jaw

origin: zygomatic

inserts: mandible

works with temporalis to chew (synergist)

Term
temporalis
Definition

close jaw

origin: temporal bone

inserts: mandible

works with masseter to chew (synergist)

 

Term
platysma
Definition

open jaw, pull lip down

mouth down to chest

open mouth, pout

very thin, not strong

antagonist of temporalis and masseter

 

Term
orbicularis oris
Definition

round of mouth

purse lips

assists with eating

movement of skin

 

Term
obicularis oculi
Definition

close eyelids

squint

round of eye

movement of skin

Term
buccinator
Definition

drink through straw

cheek muscle

important for eating, tightening skin, create vacuum

keeps food from squirting out of mouth

Term
rectus abdominus
Definition

bend forward

flex @ hip

covered with other muscle and connective tissue

origin: pubic bone

inserts: sternum @ xiphoid process (distal end of sternum) and small amt of ribs

 

Term
erector spinae
Definition

stand erect

extend spine

pull on spine to straighten us up

long thin strap-like muscles going up spine

Term
diaphragm
Definition

inhale

separates chest cavity from abdomen

breathing muscles, does not have antagonist

exhale passively

Term
intercostals
Definition

raise/lower chest wall

external: pull ribs up and out as we take a breath

internal: pull ribs back down and in during forceful exhale - in between ribs

Term

external obliques

 

Definition

bend forward, twist torso

run at an angle until they catch iliac crest

origin: lateral side of ribs

inserts: low/medial iliac crest, top of rectus abdominus

Term
internal obliques
Definition

bend forward, twist torso

origin: iliac crest

inserts: ribs, connective tissue

these muscles are responsible for rotation

Term
transversus abdominus
Definition

pull abdominal wall in

run horizontal

deepest of 3 abdominal muscles

important for birth, bladder, and bowels

compresses abdomen

"picture taking muscle"

Term
gluteus maximus
Definition

pull leg back

origin: ilium, sacrum, coccyx

inserts: femur

Term
iliopsoas
Definition

raise thigh or pull it forward

origin: lumbar vertebrae, ilium

inserts: femur

antagonist to rectus abdominus

comprised of 2 muscles; iliacus, psoas major

located right under sartorius

Term
tensor fasciae latae
Definition

pull thigh laterally

origin: ilium

inserts: femur - connective tissue (IT band) on top of femur

 

Term
adductors
Definition

pull thigh medially

functional group

antagonize tensor fasciae muscle

inside groin muscle

origin: pubis

inserts: femur

Term
hamstring group
Definition

bend knee

flex from back side

origin: several muscles

inserts: tibia

 

Term
quadriceps group
Definition

straighten knee

antagonist to hamstrings

origin: bit of ilium, femur

insert: tibia (tibial tuberosity)

Term
sartorius
Definition

raise leg, pulling knee medially

rolls thigh out so medial surface comes up

very skinny muscle

origin: lateral side of ilium

inserts: medial side of tibia (inside)

Term
gastrocnemius
Definition

stand on tiptoe; raises heel up

calf muscle

origin: distal end of femur

inserts: calcaneus (heel bone); long strap of connective tissue, calcaneal tendon

Term
tibialis anterior
Definition

raise toes

point toes up

origin: on tibia

inserts: metatarsals

part of normal walking motion

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