Test 2 Chapter 8 Muscules Pt. 3 Flashcards
Explain Muscle (Contraction) Actions
Muscle contracts=shortens
Muscles produce force to shorten themselves.
Perform actions in antagonistic pairs
List the 3 Categories of Muscle Actions? (Contractions)
- Isometric (same length)
- Isotonic (Same tone & Same tension)
- Isokinetic (artificial Action via machine)
How are muscles arranged in pairs?
Antagonistic relationship
Isometric actions (or contractions)
Muscle produces force to shorten but remains the same length
ISO=SAME. METRIC=LENGTH
In Isometric actions what is muscle trying to do?
Muscle wants to produce force to shorten but unable to overcome resistance
***Tension=Resistance (forces are equal)
What is Isotonic Action (contraction)?
“Same tone same tension”
Force>Resistance
What are the 2 phases of Isotonic Tension?
- Concentric Action
2. Eccentric Muscle Actions
ISOTONIC Action is also known as ?
DYNAMIC ACTION
What is concentric action?
Muscle in shortening phase:
**Muscle produces more force than resistance—>Muscle shortens and elbow flexes
Force»Resistance
What is eccentric action?
Resist body or decelerate body by recruiting muscle force less than resistance. (Resisting gravity)
(Contract elbow flexors—> produce slightly less force than resistance)
Trying to shorten itself but muscle lengthens
Muscle force less than resistance
RESIST LENGTHENING AND CONTROL MOVEMENT*
What is Isokinetic Action (contraction)?
How is it performed?
- Same speed and same velocity
- Machine allows muscle joint to move at constant velocity
- Artificial environment
What are the 2 Sensory inputs (Proprioceptors) to the muscle that tells it how it is performing?
- Muscle spindles
2. Golgi Tendon Organs
What is a muscle spindle?
A Stretch receptor in the body of a muscle that detects changes in muscle length
-they are encapsulated
What are the 2 types of Muscle Spindles?
- Types:
- Intrafusal fibers-inside muscle spindle
- Extrafusal fibers-outside muscle spindle
The frequency at which most muscles reach tetanus
25-30 Hz
What are the modified muscle fibers inside the muscle spindle?
Intrafusal FIbers
First Class Lever
Lever where axis is in the middle of force & resistance. Body has a couple of these (head and neck muscles)
Second class lever
Axis on end
Resistance in middle
Force arm on opposite side of axis
Mechanical advantage Ex: Tricep
Third Class lever
Axis on one end
Force arm short and in the middle
Resistance arm on opposite side of axis
Mechanical disadvantage due to short force arm
Does increase speed and rom of joint
Another name for contractin
Action
Dynamic action what changes?
Tension changes
Extrafusal Fibers
Stimulated by what kind of neuron
Outside of muscle spindle
Normal muscle fibers
-alpha motor neuron
Intrafusal Fibers
WHAT DO THEY RECEIVE?
(Actin and myosin inside)
(2 types Nuclear chain and nuclear bag fibers)
Receive afferent neurons and
Small (Gamma motor neuron)
Do extrafusal fibers and Intrafusal fibers need to be stimulated together?
Yes so they remain sensitive to stretch.
What are Characteristics of Muscle Spindles?
They are __ receptors
Coactivated with____, so they can _______
And remain___
Functions at all
Stretch Receptors
Remain active at all lengths
Gamma motor neurons (Intrafusal fibers) so at short lengths can still detect stretch and remain sensitive
Functions at all lengths
What is the simplest movement in human function?
Explain
Myotatic (Stretch Reflex) monosynaptic reflex
-Afferent AP—>afferent neuron (muscle spindle)—>dorsal root—>1 synapse—>back down—>stimulates extrafusal fibers (alpha motor neuron) of muscle from where it came to contract
Golgi Tendon Organ (GTO)
(The 2nd proprioceptor)
- Located where?
- Located in the MUSCULOTENDINOUS JUNCTION (the point where muscle fibers end and tendon begins
and functions with muscle
Golgi Tendon Organ
Detects what?
Detects stretch of the tendon (caused by tension) due to excessive stretch of muscle
Golgi Tendon Organ stimulates what kind of interneuron?
How is it a protective reflex?
Inhibitory neuron which moves alpha motor neuron away from threshold and SHUTS DOWN MUSCLE
Detect excessive tension
What is the Inverse Stretch Reflex aka AUTOGENIC Inhibition
Tendon stretched excessively
AP—>afferent neuron—>dorsal root—>spinal cord—>INHIBITORY INTERNEURON—>moves alpha motor neuron away from threshold—>shuts down muscle by inhibiting alpha motor neuron
Muscle stimulated actually inhibits itself
Initiated by Golgi Tendon Organ
Oxidative Aerobic Metabolism
Process: Start with oxidative/Aerobic
Uses Oxidative Metabolism
Requires A lot of oxygen—>gives a lot of ATP
Glucose—>glycolysis—>TCA—>ETC—>ATP + H2O + CO2
What are the 2 Anaerobic Energy Production (Accessory Energy Pathways)?
No oxygen or not enough oxygen available to meet energy demands
- Creatine Phosphate (Phosphocreatine)
- Anaerobic Glycolysis-Lactic Acid System
Creatine Phosphate or Phosphocreatine
High energy compound to put ATP back together in 1 step
1 step: Creatine Phosphate + Adenosine Di Phosphate—>Creatine + Adenosine Triphosphate
Muscle can produce work w/o oxygen at very high levels for a short period of time
Anaerobic Glycolysis aka ____
What accumulates?
Give an overview of anaerobic glycolysis
What happens to pH?
Lactic Acid System
Occurs when no oxygen is available allows us to perform glycolysis without being dependent on mitochondria & oxygen to run Electron transport chain
Limit 30-120 seconds at high speeds
Accumulates lactate and Hydrogen ions
Anaerobic glycolysis—>glucose->pyruvate—>lactate and; H
**pH drops
What is Fatigue?
What are the 2 types?
When a muscle cannot sustain a given performance
- Peripheral Fatigue
- Central Fatigue
Peripheral Fatigue
Occurs in periphery muscle and; primarily catabolism
Fails to function because can’t recycle ATP fast to keep up with demand—>force drops
MOST FATIGUE OCCURS HERE
Central Fatigue
Nervous system is not stimulating muscle
(Can’t pinpoint why/how it happened)
No stimulation=no force produced
What are the 3 characteristics of skeletal muscle fibers?
- Speed (Twitch)
- Color
- Biochemical Properties
What are the speeds of the following twitches?
Fast Twitch
Medium Twitch
Slow Twitch
Fast Twitch 60 ms
Medium 100 ms (Skeletal muscle)
Slow Twitch 120 ms
Color is due to?
2 types?
Myoglobin levels which traps and; binds oxygen but is found in the muscle
Red Fiber
White Fiber
Compare myoglobin levels in
Red Fibers
White Fibers
Red fibers: high myoglobin
White fibers: less myoglobin
Biochemical properties what are the two types and explain them
- Oxidative—>Use oxygen more readily
- Glycolytic—>function better anaerobically with Creatine phosphate, lactic acid system
(Anaerobic glycolysis, lactic acid system or Phosphocreatine)
What are the 2 Muscle Fiber Types?
- Type 1: Slow oxidative
- Type IIa: Fast oxidative
- Type IIb: Fast glycolysis
What are the two Fast fibers?
Type IIa—fast oxidative
Type IIb: fast glycolytic
Explain Type 1 muscle fiber
(Slow oxidative)
Slow, red, oxidative.
Cross bridges @ slow rates & lots of myoglobin
Describe the Type IIa fiber
(Fast oxidative)
Fast, Red, Oxidative
Works best in both anaerobic and aerobic
Describe Type IIb fibers
(Fast glycolytic)
Fast, white, glycolytic
Characteristics of Smoot Muscle
What type of shape? Size?
Develops from?
Number of nuclei?
Presence of myofibrils?
Striated?
Presence of regulatory Proteins and organelles?
Has a bit of
Presence of ___ different than skeletal muscle
Threadlike, spindle shaped, much smaller
Develops from single myocyte cell
***SINGLE NUCLEUS
Has actin; myosin but LACKS MYOFIBRILS (so no STRIATIONS)
Lacks Troponin and T-Tubules
Little bit of:Tropomyosin and Sarcoplasmic Reticulum
Dense body: Smooth muscle is similar to Z-line in which actin connects to
In Smooth muscle, a dense body is similar to what?
Z-line in which actin connects to
What are the 3 (4) phases of contraction in Smooth Muscle?
- Activation
- Phosphorylation
- Latch Phenomenon
- Relaxation
Explain Activation phase in contracting smooth muscle
-Myosin head is unloaded have to cock and load it
(skeletal muscle is already loaded)
Activation: calcium influx from extracellular fluid (different from Skeletal Muscle where Ca comes from Sarcoplasmic)
**Calcium interacts with Calmodulin—>results in Phosphorylation (loading of myosin head)—>signal transduction pathway
Explain Phosphorylation:
Load myosin head—>forms cross bridge—>power stroke—>
(Phosphorylation of myosin head) which loads myosin head
(No tropomyosin)
Explain Latch Phenomenon
Prolonged power stroke…Hangs on for a while
**Myosin head is attached for prolonged amount of time
Explain Relaxation in Smooth Muscle
Pump calcium out of the cell into extracellular fluid space
Compare Twitch Length in skeletal muscle to smooth muscle length
Skeletal Muscle Twitch length: 100ms
Smooth Muscle: 3000ms (3 seconds)
Hella slow
Characteristics of Smooth Muscle
Negative: Twitch Time?
Positive:
Force Production?
Best length of functioning?
Slow Twitch=Big Negative (3000ms)
Positive: energy efficient (doesn’t require as much ATP as skeletal muscle)
Too slow for human movement but conserves energy
**moves food through stomach
Produces force equal to skeletal muscle
Works equally well at all lengths
Does smooth muscle have sarcomeres?
At What lengths does smooth muscle work well?
Presence of Length Tension Relationship?
No sarcomeres=no overlaps
All staggered out therefore…
WORKS well at all lengths
No length tension relationship because smooth muscle works EQUALLY WELL AT ALL LENGTHS
What are the 2 types of smooth muscle & how are they classified (how are they turned on)?
- Multi-unit smooth muscle=neurogenic
2. Unitary-Visceral (single unit)=Myogenic
Define Myogenic
What are the 2 myogenic ways of stimulation?
Myogenic stimulates itself and doesn’t require external stimulus
- Pacemaker Activity-results in pacemaker potential (regularly reaches threshold)
- Slow Wave Potential-results in slow wave potentials. Irregular and Dependent upon Na/K pump
Characteristics of Multi-Unit Smooth Muscle
How are multi-unit smooth muscles excited?
Where are they located?
Similar to skeletal muscle in that it has UNITS
Units allow us to grade tension—>Fine TENSION Gradation
Neurogenic->excited or imitated by nerve cell
-More units—>more force
not the norm
Located in large arteries and bronchiole tubes in circulatory and respiratory system.
Best examples: Smooth muscle in eye which adjusts the lens via ANS (involuntary)
Characteristics of Unitary or Visceral or Single Unit Smooth Muscle
What makes unitary smooth muscle unitary?
What does Unitary Mean?
How is it turned on/Excited?
Fibers are connected to each other Via gap junctions-makes it unitary
Meaning that once 1 fiber is stimulated all cells eventually become stimulated this is known as FUNCTINAL SYNCYTIUM
Myogenic
What is Slow Wave activity?
Regular rate or irregular?
Slow wave potentials
-Speeding up and slowing down of Na/K pump
Pump speeds up- pushes membrane potential away from threshold
Pump slows down-pushes membrane potential toward threshold
**slows down enough and reaches threshold it produces action potential.
IRREGULAR Action Potentials* (off beat) due to Na/K pump
Define Myogenic Activity(again)
Do Myogenic unitary muscle fibers receive ANS input?
Definition: stimulates itself..does not require external stimulus to initiate own contraction
Does not require ANS input but receives it to slow down or speed up properties
Describe Pacemaker Potential
Ex: Cell membrane has leaky membrane (Na)—>gradually hyper-polarizes until it reaches threshold—>Action Potential
*stimulates self from within due to leaky cell membrane**
Regularly reaches threshold (AP reached on regular basis-heart)
What is the most PLASTIC tissue in the body?
What does that mean?
Skeletal Muscle
It can adapt and change to its function.
Adapts to more work being placed on it or less work being placed on it
What are the 3 types of muscle adaptation?
Hypertrophy
Hyperplasia
Atrophy
What is Hypertrophy?
How does it happen?
Muscle has to produce more force than normal—>Adapts to stress of force put on it
How does this happen?
-Increased actin and myosin in fiber which increases cross sectional area of Fiber.
Increases Size and Number of Myofibrils
Hyperplasia
When does it happen?
- Increased number of muscle fibers
- under abnormal conditions due to steroid use, and taking growth hormone and supplements can induce hyperplasia
Don’t believe it really occurs
Atrophy
Muscle decreases in size
Ex: cast around muscle
Produces less force than used to
Don’t use it…Use it
In hypertrophy, does the number of muscle fibers increase?
NO, because muscles and nerve cells are unable to reproduce!
Increases size and number of myofibrils (bundles of actin and myosin
100s-1000s of them in a myofiber)
What does Aerobic & Anaerobic Muscle training do?
Teaches the muscle to adapt.
Can train muscle to function more aerobically—>enhances aerobic metabolism
Can train muscle to function more anaerobically—> adapts to perform more anaerobically
What is a functional Syncytium?
What does it produce (what is the result of functional Syncytium?
Functionally, Unitary smooth muscles works as 1 big unit or cell.
Peristalsis (unitary wave)
How are Myogenic Properties Influenced?
List 2 Autonomic ways
List 3 other ways
- Autonomic Input-can speed up or slow down 2. ANS: Can make twitch larger or smaller in smooth muscle
- Hormones (epinephrine-speed up)
- Metabolic factors (enhance/decrease) arterioles-contraction
- Stretch
- Leaky membranes to calcium (continuous leak->continuous state of tone (or continual contraction) due to calcium leak.
Where is Unitary Smooth Muscle found?
- Hollow organs in the body
GI tract
Ureters
Uterus
Bladder
All are myogenic
