Chapter 10: Muscular Tissue Flashcards
The main function of muscle tissue
converting chemical energy into mechanical energy to generate force, perform work and produce movement
Other functions of muscle tissue
Stabilize body position, regulate organ volume, generate heat, propel fluids and food matter through various body systems
Three types of muscle tissue
Skeletal
Cardiac
Smooth
This type of muscle primarly moves the bones of the skeleton
Skeletal muscle tissue
Skeletal muscle is controlled by which division of the nervous system?
somatic (voluntary)
Skeletal muscle is (striated/not striated) and (voluntary/involuntary)
Striated
Voluntary
What type of muscle makes up heart tissue?
Cardiac muscle tissue
Cardiac muscle is (striated/not striated) and (voluntary/involuntary)
Striated
Involuntary
Term for the built in rhythm of the heart “pacemaker” that causes it to beat
Autorhythmicity
These two chemicals can adjust heart rate by affecting the pacemaker
hormones
neurotransmitters
Smooth muscle tissue is (striated/nonstriated) and (voluntary/involuntary)
Nonstriated
Involuntary
Some smooth muscle (like digestive tract) has ______________________ like the pacemaker of the heart to help propel food
autorhythmicity
The smooth muscles and cardiac muscles are controlled by which division of the nervous system?
Autonomic (involuntary)
The hormones of the endocrine glands can also influence which two muscle types?
cardiac and smooth
4 key functions of muscle
- Producing body movements
- Stabilizing body position
- Storing and moving substances within the body
- Generating heat (thermogenesis)
4 special properties of mucscular tissue
- Electrical excitability (muscle action potentials)
- Contractibility
- Extensibility
- Elasticity
What limits the extensibility of muscle tissue?
the connective tissue within the muscle
Which type of muscle tissue is subject to the greatest amount of stretching?
smooth muscle (stomach, bladder)
Cells that make up skeletal muscles
myocytes or muscle fibres
What are the main functions of the adipose tissue of the subcutaneous layer of connective tissue that surrounds muscle tissue?
Stores most of the bodys triglycerides
insulation
protect muscle from physical trauma
pathway for nerves, blood vessels and lymphatic vessels to enter and exit muscles
What re the main functions of fascia?
- allows free movement of muscles
- carries nerves, blood vessels, and lymphatic vessels
- fills space between muscles
What are the three layer of connective tissue that extends from the fascia to protect and strengthen skeletal muscle?
- epimysium
- permysium
- enomysium
This is the outer layer, encircling the entire muscle and consists of dense irregular connective tissue
Epimysium
A layer of dense irregular connective tissue that surrounds groups of 10-100 muscle fibres
perimysium
These bundles are 10-100 or more muscle fibres wrapped with perimysium
Fascicles
This connective tissue penetrates the interior of each fascilcle and separates individual muscle fibres from one another. Made up of mostly reticular fibres.
endomysium
A rope like extension from a muscle that consists of the three types of connective tissue and attaches to the periosteum of a bone
tendon
Which neurons stimulate the skeletal muscle to contract?
somatic motor neurons
During embryonic development, the fusion of a hundred or more small mesodermal cells called myoblasts, arise to form?
Muscle fibres
What is the sarcolemma in a muscle cell?
The cell plasma membrane
What is sacroplasm in a muscle fibre?
The cytoplasm of the muscle fibre
What are transverse (T) Tubules?
tunnels into the muscle fibre that is open to the outside and contains interstitial fluid
increases the surface area for action potentials to actitivate all parts of teh the muscle fibre simultaneously
This is a large molecule composed of many glucose molecules; prsent in large numbers in the sarcoplams
glycogen
What is glycogen in the sarcoplasm used for?
to synthesize ATP
What is the red colored protein int he sarcoplasm?
myoglobin
What protein only found in muscle, binds oxygen molecules that diffuse into muscle fibers from the interstitial fluid
Myoglobin
When does myoglobin release the oxygen molecules
When the mitochondria needs it for ATP production
These are the contractile organelles of skeletal muscle
myofibrils
How long are myofibrils
the length of the muscle fibre
Each myofibril is surrounded by this network that is filled with fluid and is similar to smooth endoplasmic reticulum in non-muscle cells
sarcoplamic reticulum
At the end of the sarcoplasmic reticulum, these cisterns butt against the T tubule from both sides
Terminal cisterns
What is the system of two terminal cisterns on either side of a T Tubule called?
Triad
What does the sarcoplasmic reticulum store in relaxed muscle fibre?
Ca+
The release of what from the terminal cisterns of the sarcoplasmic reticulum triggers a muscle contraction?
Ca+
What are the two tpes of filaments or myofilaments within myofibrils?
Thin filaments and thick filaments
These filaments are 8nm in diameter, 1-2 um long and made of actin
thin filaments
actin
These filaments are 16nm in diameter and 1-2um long and are composed of myosin
Thick filaments
myosin
How many thin filaments for each thick filament?
2 thin for every 1 long
What are the compartments or structures that the thin and thick filaments are arranged in in a muscle fibre?
Sarcomeres
What is the basic functional unit of a myofibril?
A sarcomere
These are narrow, plate shaped regiong of dense protein material that seperate one sarcomere from another
Z discs
The A band is the middle section of the sacromere and extends the length of the….
Thick filamanets
What zone is found near the ends of the A band where the thick and thin filaments lie side by side?
The zone of overlap
This is lighter, less dense area that contains the rest of the thin filaments but no thick filaments
I Band
What passes through the center of each I Band?
Z disc
What creates the striations in skeletal muscle tissue?
the dark A Bands and LIght I bands
What is contained in the H zone in the centre of each A Band?
Only thick filament, no thin filament
What does the M Line in the centre of the A Band consist of?
Supporting proteins holding two thick filaments togetherW
What are the three kinds of proteins that make u myofibrils?
- Contractile Proteins
- Regulatory Proteins
- Structural Proteins
What is the function of contractile proteins?
To generate force during contraction
What two proteins are contractile proteins?
Myosin and actin
What does myosin function as in all three types of muscle tissue?
A motor protein
These type of proteins pull various cell structures to achieve movement by converting the chemical energy in ATP to the mechanical energy of motion (force)
Motor proteins
(myosin)
How many myosin molecules form a single thick filament?
About 300 myosin molecules form a thick filament
Describe the structure of the mysoin molecules
Shaped like two golf clubs twisted together
What is the myosin tail?
The two twisted golf club handle end
Where does the myosin tail point in the sarcomere?
Towards the M LIne
What composes the myosin heads?
The two golf club heads of the myosin molecule
What are the two myosin head binding sites?
- Actin binding site
- ATP-binding site
What is another function of the ATP binding site on the myosin heads?
Functions as ATP-ase - an enzyme that hydrolyzes ATP to generate energy for muscle contraction
What shape do individual actin molecules combine to form?
A helix
What part of myosin binds to the myosin binding site on each actin?
The myosin head
What are the two regulatory proteins found in a myofibril?
- tropomyosin
- Troponin
What filament do the tropomyosin and troponin belong to?
THe thin filaments
What does tropomyosin do?
Blocks the myosin binding sites on actin in relaxed musclesW
What holds tropomyosin strands in place?
troponin
What causes troponin to undergo a shape change that results in the tropomyosin being moved away from the myosin binding site on the actin?
Ca+ calcium ions
What happens when myosin binds to actin myosin binding site?
muscle contraction
What do the dozen structural proteins found in muscle contribute to?
Alignment
Stability
Elascticity
Extensibility of myofibrils
What is the third most plentiful protein in skeletal muscle?
Titin
How big is a titin molecule
half a sarcomeere; from z disc to m-line
What role does titin molecule play
Connects to zdisc and m line for stability of the the position of the thick filament
Also accounts for elasticity and extensibility in myofibrils - can stretch 4 x its length
What mechanism describes the process of muscles contracting?
Sliding filament mechanism
What happens when thin filaments slide inward during muscle contraction?
The I Band and H zone narrow and eventually disappear altogether when the muscle is maximally contracted
What are the four steps of the contraction cycle?
- ATP hydrolysis
- Attachment of myosin to actin
- Power stroke
- Detachment of myosin from actin
