Bio Unit 3 part 2

Question 1

how is the tenstion excerted by a muscle during a single twitch influenced by

Answer 1

1;. the muscle type
2. sarcomere length at the start of contraciotn

Question 2

what is sarcomere lenghth

Answer 2

the degree of overlap between the thick and thin filaments

Question 3

what happens with too little overlap in sorcomere lenghth, too much over lap and way too much overlap

Answer 3

too litle: few crossbridges, little force can be generated

too much:actin filaments start to interfere with each other, less force generated

way too much overalp; thick filaments collide with Z disk, force rapidly decreases

Question 4

how can the force of a muscle five be increased

Answer 4

a single twitch does not prepresent the maximum force the muscle fibre can develop, it is increased by increasing the rate of action potentials that stimulate the fibre

Question 5

Summation

Answer 5

increase in force generated by a muscle, increase tenstion level

due to repeated stimulation from action potentials that occur before the muscle has fully relaxed

Question 6

tetanus, incomplete (unfused) tetanus, and complete (fused tetanus

Answer 6

from summation

term for the state of muscle when it reaches maximmum force of contraction

incomplete (unfused) tetanus, slow sstimulation rate, fibre relaxes slightly between stimuli

complete (fused) tetanus; fast stimulation rate, fibre does not have time to relax

Question 7

what is the motor unit and the two components

Answer 7

the basic unit of contraction in an intact skeletal muscle, muscle made up of many fifferent motor units

1. a group of muscle fibers
2. the somatic motor nueron that controls them, by action potental and contracts all muscle fibers

motor uni contracts in an all or none fashion

Question 8

how is the contracction of the muscle baried

Answer 8

• changing the type of motor unit that is activated
• changing the number of motor units that are active

Question 9

which will have more muscle fiberes per motor unit fine or cource movements

Answer 9

cource

Question 10

what are all the fibres in a motor unit

Answer 10

they are all one type

Question 11

isotonic

Answer 11

creates force and mocves a load, the load is ussually constant, and the muscle length changes

Question 12

isometric

Answer 12

creates force without movement, muscle lenghth is constant and the load is usually greater than the force that can be applied

Question 13

whaere is smooth muscle found in the body?

Answer 13

walls of hollow organs and tubes, bot attached to bones of skeleton

Question 14

how are smooth muscles arrangess,single unit and multi unit

Answer 14

single unit, cells coupled by gapp junctions, not cessary to electrically stimulate each individual fibre and are found on walls of internal organs

multi-unit, no gap junctions, each individual musce fibre is separately innervated

Question 15

on a whole muscle level what are teh differences betweeen smooth and skeletal muscle

Answer 15

contraction of smooth muscle changes muscle shape, not just lenghth

smooth muscle develops tension (force) slowly

smooth muscle can maintain contraction longer withought fatiguing, important because some are conracted most of the time

Question 16

differences between smooth and skeletal level in a cellular level

Answer 16

page 79

Question 17

what is the effect of not having T-tubles

Answer 17

page 80

Question 18

difference between skeletal and smooth muscle in a molecular level

Answer 18

page 80

Question 19

explain smooth muscle contraction

Answer 19

page 80

Question 20

what are the 3 channells that Ca2+ enters through

Answer 20

voltage-gated channels , open when cell depolarizes

stretch-activated channels, open when membrane stretched

chemically-gated channels, open in response to hrmones

Question 21

explain relaxation in smooth muscleq

Answer 21

page 81

Question 22

what are cardiac msucle

Answer 22

specialized muscle cells of the heart, shares features with both smooth and skeletal msucles

Question 23

most myocardial cells are typically……

Answer 23

striated and contractile fibers organixed into sarcomeres

Question 24

how are cardiac muscle different from sckeletal muscle:

Answer 24

cardiac muscle cells are much smaller with single nucleus with about 1/4 of the cell volume is occupied by mitochondria, allows for sommunication in both direction

T-tubles are much alarger and branched and the sarcoplasmic reticulum is smaller

adjecent cells are joined by intercalated discs with desmosomes

Question 25

how much is not incoleced in conractio of the cardiac muscle cell, but what are they iinvolved in

Answer 25

1% they are involved int he electrcal excitation of the heart, known as the electrical conducting sustem of the heart

they initiate heartbeat and allow the elecctrical excitation to spread rapidly throught the heart

they are connected to other cardiac cells via gap junctions

Question 26

explain cardiac muscle contraction

Answer 26

page 83

Question 27

what are teh factors influencing cardiac muscle contraction force

Answer 27

1. changes in (Ca2+)
   explained in 83

Question 28

cardiac muscle is also what

Answer 28

an excitable tissue and can generate action potientions

Question 29

explain the major sequence of evetnts of a cardiac muscle

Answer 29

page 86

Question 30

why does sustained depolarization occur

Answer 30

because of the slow opening of the voltahe-gated Ca2+ channels