Zoology Chp 38- Muscular System

skeletal, smooth, cardiac

types of muscle tissue

muscle tissue

tissue that contracts when stimulated by signal then relax and lengthens

composed of cylindrical cells often called “muscle fibers” (muscle cells)

skeletal muscle

type of muscle

helps move the body and its parts

made of cells that can contract when stimulated

attached to bones

cardiac muscle

type of muscle

found only in the wall of the heart

plasma membranes of cells fused together so all cells contract as a unit

skeletal muscle

what kinds of muscle are voluntary muscle control

smooth and cardiac

what kinds of muscle are involuntary muscle control

skeletal muscle

muscle type that helps move body and parts

built of cells that can contract when stimulated attaches to bones

found in the arm

smooth muscle

muscle type found in internal organs

cardiac muscle

muscle type found only in the heart wall

skeletal muscle

striated

voluntary control

long, cylindrical cells

multinucleated

multiple cells (muscle fibers) fused together to meet cellular demands

attached to bones via tendons

location of skeletal muscles

myoblasts (stem cell)

muscle fiber is formed from…

myoblasts

what fuses together to form one long cell for the skeletal muscle

tendons

ties muscles to bones

ligaments

links bone to bone

cardiac muscle

striated

involuntary control

branched cell with intercalated discs

pumps blood through the heart

smooth muscle

non-striated (smooth appearance)

involuntary control

spindle-shaped cells

single nucleus per cells

moves substances through organs (peristalsis)

peristalsis

in smooth muscle

movement that squeezes and pushes things down a tube

organs, blood vessels, and airways

locations of smooth muscles

sarcolemma, sarcoplasm, myofibrils, sacroplasmic recticulum

structures within a skeletal muscle fiber

sarcolemma

plasma membrane of a muscle fiber

forms inward folds called T tubules

T tubules

carry electrical signal into the interior of muscle fiber

extensions of the sarcolemma

sarcoplasm

cytoplasm of muscle fiber

myofibrils

long, cylindrical structures inside muscle fiber

responsible for muscle contraction

made of myofilaments (thick and thin filaments)

sarcoplasmic recticulum

specialized form of smooth ER

surrounds each myofibril

myosin

what kind of protein does thick myofilaments contain

actin

what kind of protein do thin myofilaments contain

endomysium

thin layer of connective tissue that surrounds each individual muscle fiber (muscle cell)

helps mind muscles fibers together and transmit force

perimysium

connective tissue that surrounds each fascicle (bundle of muscle fibers)

helps organize fibers into functional bundles

contains blood vessels and nerves that supply muscle fibers

epimysium

entire muscle surrounded by a dense connective tissue

muscle → fascicle → muscle fiber → myofibril → sarcomere → myofilaments

levels of muscle organization in order

origin

one end of the muscle that attaches to bone and stays relatively motionless

insertion

one end of the bone that attaches to bone and moves the most

when the forelimb is pulled up the bicep contracts and the tricep relaxes

when the forelimb is pulled down the tricep contracts and the bicep relaxes

explain how muscles move bones using a lever system

bursa

small, fluid-filled sacs often found between tendons and bones

act as cushions and allow ease of movements

fascia

a type of connective tissue that extends beyond the muscle and becomes tendon

sarcolemma

plasma membrane surrounding muscle fiber

muscle fiber

cluster of myofibrils

surrounded by sarcolemma (plasma membrane)

fascicle

bundle of muscle fibers surrounded by perimysium

contains blood vessels and nerves

organizaes muscle fibers for coordinated contraction

myofilaments

actin and myosin

entire muscle

bundles of fascicles surrounded by epimysium then fascia

muscle fiber → endomysium → perimysium → epimysium → fascia

order from inside to outside of connective tissue layers

shorten

muscle contracts when cells…

sarcomere

basic unit of contraction

made up of thick and thin filaments arranged in overlapping array

glucose, glycogen, triglycerides, fatty acids

identify the four major fuel sources used by muscle cells

decreases

as length of exercise period increases, use of muscle energy stored…

increases

as length of exercise period increases use of energy sources from blood…

cellular respiration, fermentation, creatine phosphate pathway

the three pathways used to regenerate ATP

creatine phosphate pathway

ATP production pathway

simplest and most rapid way to produce ATP

immediate burst of energy that only lasts about 10 seconds

transfers phosphate to ADP→ produces ATP quickly

used for short explosive movements

fermentation

ATP production pathway- anaerobic metaboslism

produces ATP without oxygen

breaks down glucose to form lactic acid

short-term energy, leads to fatigue

process:

hormones signal muscle cells to break down glycogen making glucose available

glucose broken down through glycolysis into pyruvate (produces small amount of ATP)

pyruvate converted to lactic acid

cellular respiration

ATP production pathway- aerobic metabolism

requires oxygen

slower but efficient

produces large amounts of ATP

supports long-term, sustained activity

Slow-twitch fibers (Type I)

contract slowly, but keep going for a long time

use aerobic respiration for energy

rich in mitochondria, myoglobin (redder color), and blood supply

best for endurance activities

Fast-twitch fibers (Type II)

contract quickly and powerfully

use mostly anaerobic respiration

fatigue quickly, accumulate lactate

fewer mitochondria and less myoglobin (whiter in color)

best for short bursts of power

actin (thin) and myosin (thick) filaments, I band, A band, H zone, Z disc, m line, myosin heads

structures of a sarcomere

thin filaments

structure of the sarcomere

two strands of beads

beads are actin molecules which can contract

thick filaments

structure of the sarcomere

made of myosin molecules

sliding filament mechanism

When a sarcomere contracts, the Z lines move closer together and the I band and H zone get smaller. The A band stays the same width and, at full contraction, the thin filaments overlap.

fascia

sheet-like connective tissues that surround and separate muscles, muscle groups, bones, organs, and blood vessels throughout the body

one muscle (the agonist) contracts to create movement while the other muscle (the antagonist) relaxes and is being pulled

(biceps contracting while triceps relax)

Describe how antagonistic muscle pairs work together to produce movement.