chap 45 - animal movement

______ ______ is found in every organ

muscle tissue

what are the four functions of muscle tissue

resist movement, maintain posture, maintain blood pressure, generate heat

all muscle cells have mechaism of action - they _______ then ______

contract (shorten) relax (lengthen)

group of muscle cells with same origin, insertion, and function consisting of multiple fascicles

skeletal muscle

bundles of muscle cells are wrapped with connective tissue (fascia)

fascicles

multinucleated muscle cell, consisting of many myofibrils

skeletal muscle fiber

cylindrical contractile structures inside muscle cells that contain the proteins acting and myosin

myofibrils

fiber is ____

fibril is _____

cell, tube inside cells

the contractile unit of a skeletal and cardiac myofibril extending from one z line to the next

sarcomere

attachment points between sarcomeres made of many proteins include alpha-actin

z lines

what are the two main contractile proteins

myosin and actin

protein that forms thick filaments in muscle

myosin

protein that forms thin filaments in muscle

actin

specialized muscle cell membrane

sarcolemma

invaginations of the cell membrane in cardiac and skeletal muscle

t-tubule

specialized muscle cell endoplasmic reticulum

sarcoplasmic reticulum (SR)

a?

fascicle

b?

muscle fiber

c?

z line

d?

sarcomere

e?

myosin

f?

actin

all the muscle cells innervated by a single neuron

motor unit

synapse with and can stimulate

innervate

at rest there is a slight _____ ___ concentration on the inside of the muscle cell membrane

negative ion

a higher ________ Na+ concentration outside the muscl ecell

positive

a motor neuron releases the neurotransmitter acetylcholine at the neuromuscular junction (NMJ)

1st step of neurons initiating contraction

acetylcholine binds receptor proteins on muscle that open Na+ channels

2nd step of neurons initiating contraction

action potential Na+ rushes into the muscle cell depolarizing the membrane which opens a cascade of ion channels along the muscle membrane

3rd step of neurons initiating contraction

action potential passes into membrane extensions called t-tubules (transverse tubules)

4th step of neurons initiating contraction

impulse reaches the sarcoplasmic reticulum which opens calcium (Ca2+) channels

5th step of neurons initiating contraction

Ca2+ binds troponin, which moves tropomyosin, opening myosin binding sites on actin

6th step of neurons initiating contraction

two inhibitor proteins that surround actin filaments preventing myosin from interacting

troponin and tropomyosin

myosin heads bind actin to form cross-bridges (this shortens the sarcomere)

7th step of neurons initiating contraction

•ATP binds Myosin “heads” to ______ ____ from actin during contraction.

detatch them

when nerve activation ends, _____ ____

activation ends

membrane transport protein that uses ATP to pump calcium ions from the cytosol back into the sarcoplasmic reticulum

Sarcoplasmic / Endoplasmic Reticulum Ca²⁺ ATPase (SERCA):

muscles require ___ to contract and relax

ATP

_______, ___, and _______ are broken down into components that can enter the mitochondria & the TCA cycle that makes ATP.

glucose, fats, protein

a molecule that transfers a phosphate molecule to ADP during strenuous exercise when ATP levels are low

phosphocreatine

short, intense resistance training that builds more myofibrils (NO NEW MUSCLE CELLS)

strength training

cells near muscles receive signals to become myofibrils

satellite cells

builds endurance by signaling cells to increase production of mitochondria, myoglobin, and capillaries to muscle cells

aerobic trainin

protein that stores oxygen in muscle cells

myoglobin

muscle composition depends on:

aerobic v anaerobic respiration use, myoglobin levels, mitochondria number, myosin isoforms

Muscle cells that have slow contractions, primarily use aerobic respiration for ATP, have more mitochondria, and have more capillaries supplying myoglobin.

slow twitch (type 1) muscle fibers

Muscle cells that have fast contractions, rely on anaerobic respiration, and creatine phosphate for energy.

fast twitch (type 2a) muscle fibers

Cells have fast contractions,  primarily use anaerobic glycolysis but also use aerobic respiration.

intermediate (type 2b) muscle fibers

proteins derived from the same gene but are spliced into different amino acid sequences

isoforms

myosins spliced such that they have different ATPase activity (break down ATP at different rates)

myosins isoforms

Muscle cells that have myosin isoforms that break down ATP slowly.

-The cells also have more mitochondria, and increased blood supplies. 

slow twitch (type 1) muscle fibers

Muscle cells that have myosin isoforms that break down ATP quickly.

-They rely on more anaerobic respiration and creatine phosphate for energy.

fast twitch (type 2a) muscle fibers

the end of the muscle that is attached to the non moving bone

origin

the end of the muscle that is attached to the movable bone

insertion

groups of muscles that work in opposition to each other

antagonistic muscle groups

muscles that pull bones closer together, decreasing joint angles (eg hamstring)

flexors

muscles that increase the angle of a joint, straightening it out (eg quadriceps)

extensors

what are the three types of skeletal systems

hydrostatic, endo and exoskeletons

use hydrostatic pressure of enclosed body fluids (or soft tissues) to support body

hydrostatic skeletons

have rigid structures inside the body

endoskeletons

have rigid structures on the outside of the body (often made of the carbohydrate chitin)

exoskeletons

squeeze coelomic fluid, and pressure pushes outward, extending longitudinal muscles and lengthening the segment

circumferential muscles contract

pull the body forward (for hydrostatic skeletons)

longitudinal muscles contract

alternating contractions of longitudinal and circumferential muscles pass down earthworm in waves

peristalsis

cells that secrete collagen and the organic matrix of bone (osteoid) which becomes calcified (bone)

osteoblasts

osteoblasts that become trapped in the matrix they secrete, that form star shaped canals to exchange nutrients and waste

osteocytes

bone cells responsible for removing and reabsorbing of old bone during remodeling

osteoclasts

bands of fibrous connective tissue that binds bones to other bones

ligaments

tissue with cells in a gelatinous matrix of polysaccharides and protein fibers that provides a smooth surface for bones to move against each other

cartilage

tissue with hard extracellular matrix that stores minerals

bone