Shared Flashcard Set

Details

Lecture 11 - Muscle II
All-or-none, Motor Units, Smooth Muscle, Cardiac Muscle, Levers, Muscle use and disuse
27
Anatomy
Undergraduate 1
09/30/2010

Additional Anatomy Flashcards

 


 

Cards

Term
subthreshold stimulus
Definition
a weak stimulus not able to contract a muscle
Term
threshold stimulus
supratheshold stimulus
Definition
-stimulus needed for a muscle fiber to contract
-more than enough stimulus for a muscle to contract,
Term
Motor Unit
Definition
The motor neuron together with all the muscle fibers it connects to
Term
Motor recruitment
Definition
The addition of more motor units by adding more stimulus the whole muscle
Term
Muscle tone, posture and maintenance of balance
Definition
In the body, a muscle may be in state of partial contraction. At any time, some fibers in such a muscle are contracted while others are relaxed. This generates what is called muscle tone. Muscle tone is essential for maintaining posture and balance.

When you faint, you lose our muscle tone and colapse.
Term
"Treppe" Staircase Effect
Definition
A muscle that is stimulated repeatedly, allowing sufficient time for relaxation between stimuli, responds with a corresponding series of separate twitch. Each twitch gets stronger until maximum.
Term
Tetanus
Definition
When a skeletal muscle is stimulated so frequently that it cannot relax after the previous twitch, the individual contraction merge together and produce a sustained contraction.
Term
Clostidium toxin (tetanus shot)
Definition
This bacterial toxin prevents the breakdown of acetylcholine at the neuromuscular junction, and muscles therefore remain in a state of continual contraction.
Term
Isotonic contraction
Definition
Muscles shorten, the tension remains constant
Term
Isometric contraction
Definition
Muscle doesn't change, but Tension rises
Term
Smooth muscle
Definition
- Involuntary and Nonstriated.
- Shorter than skeletal muscle fibers
- Each fiber has just one, centrally located nucleus.
Term
Components of smooth muscle
Definition
-contains myosin and actin
- are not organized so they lack striations
-lack T-tubules and do not have the proteins troponin and topomyosin.
Term
Multi-unti Smooth Muscle
Definition
- Muscle the cells are not well organized, and occur as separate fibers rather than sheets.
-These separate fibers may contract independently of each other, but contraction is initiated by signals from the nerves of the autonomic nervous system.

Examples: iris of eye, in the walls of blood vessels, in the large passageways of the lungs and the arrector pili muscle
Term
Visceral (Single Unit) Smooth muscle
Definition
Cells are arranged in wraparound sheets and are in very close contact of each other, this allows for gap junction. allows for peristalic movements

Example: in hallow places such as the stomach, intestine, urinary tract (bladder), reproductive tract (uterus) and blood vessels.
Term
Pacemaker cells
Definition
Initiate waves of excitation in Visceral smooth muscle. This activity is modulated and regulated by the autonomic nervous system.
Term
Calmodulin
Definition
a calcium-binding protein that mediates excitation contraction coupling
When calmodulin binds calcium, the combination activates an enzyme called myosin light chain kinase (MLCK). The activated enzyme phosphorylates part of the myosin molecule. The phosphorylated myosin then binds to actin. Relaxation is brought about by removal of the phosphate group by another enzyme called myosin light-chain phospatase.
Term
Smooth Muscle Contraction: Nervous input from the autonomic nervous system.
Definition
Smooth muscle in many parts of the body is innervated by autonomic branch of the nervous system. release acetylcholine or norepinephrine
Term
First Class Levers
Definition
OFI

-lifting the head
- straightening the arm at elbow
- movement of foot around the ankle
Term
Second Class Levers
Definition
FOI

-do not exist in body
Term
Third Class Levers
Definition
FIO
-most common lever
-flexing the forearm at the elbow
Term
Agonist (prime mover)
Definition
Muscle that causes a desired action and is responsible for most of the movement
Term
Antagonist
Definition
Muscle that is relaxing when the agonist is contracting
Term
Synergists
Definition
Helper muscles
Term
Muscle Repair
Definition
Satellitte cells divide and form myoblasts that can fuse to form new muscle cells to replace the damaged muscle fibers
Term
Muscular Hyperplasia
Definition
increase in the number of muscle fibers in a muscle
Term
Muscular Hypertrophy
Definition
Repeated forceful contractions (weight lifting) cause the muscle fibers to increase in size
Term
Muscular Atrophy
Definition
"wasting away"

Disuse Atrophy- don't use muscles so you lose them
Supporting users have an ad free experience!