Chapter 10 - muscle tissue Flashcards
muscular abilities (4)
excitable- respond to a stimulus
contractable - shorten in length
extensible - extend or stretch
elastic - return to original shape
5 main functions of muscular tissue
- create motion by working with nerves, bones, and joints
- maintain posture
- sphincters - keep substances in one place
- peristatic contractions - move substances through tubes by waves of contractions
- generate heat - thermogenesis (shivering = involuntary muscle contraction)
skeletal muscle
function, appearance, control
location - skeleton
function - movement, posture, health generation
appearance - started, multi-nucleated, parallel fibres
control - voluntary
components of a skeletal muscle
-CT covering muscle units
-Under fascia is the epimysium (surrounds muscles)
Perimysium - fascicles
Endomysium - fibers
components of a skeletal muscle fiber
- Fiber - a muscle cell
- Sarcolemma - PM of muscle cell
- T-tubules - continuation of sarcolemma
- Sarcoplasmic Reticulum - creates mesh-like structure that ends in the terminal cisternae.
- Terminal Cisternae holds calcium
- Sarcoplasm - cytoplasm for muscle cells
what are muscle fibres built from? name and describe these 3 components.
- contractile proteins
- made up of actin and myosin
- generate muscle contraction - Regulatory proteins
- troponin and tropomyosin
- switch the calcium process on and off - structural proteins
- connectin and dystrophin
- link MF to PM of sarcolemma
- keep thick and thin filaments together
name and describe the 2 contractile proteins
- thin filaments - made of the protein actin
2. thick filaments – made of the protein myosin
How do regulatory proteins work?
Ca2+ binds to troponin which changes the shape of the troponin-tropomyosin complex and uncovers the myosin binding sites on actin
what is the sliding-filament mechanism?
thick and thin filaments slide past one another during muscle contraction
explain the process of the sliding0filament mechanism.
- Contraction is initiated when Ca2+ is released into the sarcoplasm
- Calcium binds to Troponin, moves Tropomyosin off the myosin binding sites
- Thick and thin can now “slide on one another
- Sarcomere is shortened
what produces tension in a muscle?
sarcomere shortening produces tension
Explain Excitation - Contraction coupling
- EC coupling involves putting it all together
- Thought process in the brain
- Action Potential (nerve signal) arrives at the neuro-muscular junction
- regeneration of action potential alone the sarcolemma
- Release of calcium from sarcoplasmic reticulum
- Sliding of thick on thin filaments
- Generate muscle tension = work
what occurs at the neuromuscular junction
- activation of motor neuron -acetylcholine (Ach) is released
- Ach broken down by acetylcholinesterase
- Breakdown and diffusion of Ach out of synaptic cleft
- motor endplate has many ligand-gated sodium channels
* CHECK*
sources of muscular energy and duration of produced contraction.
- stored ATP - 3 secs
2. energy from stored creatine phosphate (easily available) - 12 seconds
describe aerobic ATP production
- oxidative
- cellular respiration in mitochondria (1 glucose = 36 ATP)
- requires oxygen
- slow
Using anaerobic glucose for energy
- glycolosis
- glucose + 2 pyruvate = 2 atp
- no o2, faster, 30-40 seconds
characteristics of red muscle fibers
- numerous mitochondiras
- lots of myoglobin (protein that binds 02)
- lots of energy stores
- lots of blood supply
characteristics of white muscle fibers
- less myoglobin and mitochondria
- les blood supply
characteristics of slow oxidative muscle fibres.
- small
- dark red
- least powerful
- fatigue resistance
characteristics of oxidative-glycolytic fibres (FOG)
- Intermediate in size
- appear pink
- moderately resistant to fatigue
characteristics of fast glycolytic fibres (FG)
-Large
-white
-powerful
-Fatigue quickly
(many of these present in body builders)
Cardiac Muscle
location, function, appearance, control
location - heart
function - continuously pump blood
appearance - striated, one central nucleus
control - involuntary
true or false:
In response to a single AP, cardiac muscle contracts 10-15 times longer than skeletal muscle due to prolonged delivery of Ca2+
true
Visceral (smooth) muscle
location, function, appearance, control
location - GI Tract, uterus, eye, blood vessels
function - peristalsis, BP, pupil size, erects hair
appearance - no striations, one central nucleus
control - involuntary
cardiac and smooth muscle are both involuntary and _______.
autorhythmic
- not controlled by nervous control
In terms of energy, how is smooth muscle different from cardiac and skeletal muscle?
has a low capacity for generating ATP
what is a motor unit composed of?
motor neuron and all of the muscle cells it innervates
what makes cardiac and smooth muscles contract for long periods of time
No Transverse tubules and slow Ca2+ removal = long contractions
explain high precision movements
- fewer muscle cells per neutron
ex) Extraocoular muscles (Eyeball)
ex) Laryngeal (voice box)
explain low precision movements
- more muscle cells per neutron
ex) Thigh muscles (2000-3000 MC innervated by 1 neuron)
how does exercising build muscle?
- After intense exercise there is muscle damage including torn sarcolemmas and disrupted Z-discs
- Responds by building more proteins
- Muscle fibers undergo repair and more muscle proteins are synthesized
- More thick and thin filaments (larger, stronger)
- Don’t get more muscle cells but each cell grows
what affect does aging have on muscles?
- slow, progressive loss of skeletal muscle mass that is replaced largely by fibrous connective tissue and adipose tissue
- Muscle strength at age 85 is about half that at age 25
