Chapter 10 Flashcards
Primary function of muscle?
- Transformation of chemical energy into mechanical energy to generate force perform work and produce movement
- Stabilizes body position
- Regulates organ volume
- Generates heat
- Propels food and fluid matter through various body systems
What are the three types of muscular tissue?
- Skeletal
- Cardiac
- Smooth
Myology
Scientific study of muscles
Skeletal muscle tissue
- Move bones of the skeleton
- Striated, seen under a microscope
- Works voluntarily
Cardiac muscle tissue
- Forms most of the heart wall
- Striated
- Involuntary
Autorhythmicity
Natural pacemaker/Built-in rhythm of the heart, Controlled by hormones and neurotransmitters
Smooth muscle tissues
- Walls of hollow internal structures and skin attached to hair follicles
- Non striated
- Involuntary
- Controlled by neurons and hormones
Functions of the muscular tissue
- Producing body movements
- Stabilizing body positions
- Storing and moving substances within the body
- Generating heat
Thermogenesis
When muscular tissue contracts it produces heat
What are the four special properties of muscular tissue?
- Electrical excitability
- Contractility
- Extensibility
- Elasticity
Action potentials
The ability to respond to certain stimuli by producing electrical signals
What are the two main types of stimuli triggers for action potential in muscle cells?
- Electrical signals, arises in the muscle tissue itself
- Chemical stimuli, such as neurotransmitters, hormones, and local changes in pH
Muscle fibers
Hundreds to thousands of cells that make up the separate organs of the skeletal muscles
Subcutaneous layer or hypodermis
Separates muscle from skin
Fascia
- dense sheet or broadband of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body
- holds muscles with similar functions together
- allows free movements of muscles 4. carries nerves, blood vessels, and lymphatic vessels
- fill spaces between muscles
The three layers of connective tissue?
- Epimysium
- Perimysium
- Endomysium
Epimysium
The outer layer in circling the entire muscle
consists of dense irregular connective tissue
Perimysium
Also a layer of dense irregular connective tissue but surrounds groups of 10 to 100 or more muscle fibres separating them into bundles called fascicles
Fascicles
Little bundles
large enough to be seen with the naked eye
give a cut of meat its characteristic “grain”
Endomysium
Penetrates the interior of each fascicle and separates into individual muscle fibres from one another
mostly reticular fibres
Tendon
All three connective tissue layers may extend beyond the muscle fibres to form a rope like tendon the attaches of muscle to the periosteum of a bone
Aponeurosis
Connective tissue elements that extend as a broad, flat sheet
Nerves and blood supply of the skeletal muscles
1.Well supplied With nerves and blood vessels
2. neurons that stimulates skeletal muscles to contract are somatic motor neurons
3.
Plasma membrane of a muscle cell?
Sarcolemma
Thousands of tiny invaginations of the sarcolemma ?
Transverse (T) tubules
Transverse tubules
Tunnel in from the surface towards the centre of each muscle fibre
open to the outside of the fibre they are filled with interstitial fluid
muscle action potentials travel along the sarcolemma and through the T tubules quickly spreading throughout the muscle fibre
Sarcoplasm
Within the sarcolemma the cytoplasm of a muscle fibre includes a substantial amount of glycogen and includes a red coloured protein called myoglobin found only in muscle
Myoglobin
A red coloured protein found only in muscle that binds oxygen molecules that diffuse into muscle fibres from interstitial fluid
releases oxygen when it is needed by the mitochondria for ATP production
Myofibrils
It small structures that appear in the sarcoplasm like it’s stuffed with little threads
the contractile organelles of skeletal muscle extending the entire length of a muscle fibre
giving it the striated look
Sarcoplasmic reticulum (SR)
A fluid filled system of membraneous sacs that in circles each myofibril similar to smooth endoplasmic reticulum and non-muscular cells
Terminal cisterns
Dilated Sarco plasmic reticulum
butt against the T tubule from both sides
Triad
Is formed by a transverse tubules and the two terminal cisterns on either side of it
Filaments
Smaller structures within the myofibrils consisting of thin filaments and thick filaments
Directly involved in the contract I’ll process
Arranged in compartment called sacral mirrors
Thin filaments
8nm in diameter and 1-2 um long, Composed of the protein Actin
Too thin filaments for every thick filament in the region of filament overlap
Thick filaments
16 nm in diameter and 1-2 um long, Composed of the protein myosin
Sacromeres
Basic functional units of a myofibril
Z discs
Are narrow plate shaped regions of dense protein material that separate one sarcomere from the next
Organization of a sarcomere
A band - darker middle portion
Zone of overlap - toward each end of the A band, where thick and thin filaments lie side by side
I band - Lighter less dense area that contains the rest of the thin filaments but no thick filaments and a Z disc passes through the centre of each I band
Alternating dark A bands and light I-band create the striation look
H zone - narrow, centre of each A band contains thick filaments
M line - supporting proteins that hold the thick filaments together at the centre of the H zone
The three kinds of proteins the build myofibrils
- Contractile proteins
- Regulatory proteins
- Structural proteins
Contractile proteins
Generate force during contraction
Consists of myosin and actin proteins and other components of thick and thin filaments
Myosin
Main component of thick filaments and functions as a motor proteins in all three types of muscle tissue
Motor protein
Pull various cellular structures to achieve movement by converting the chemical energy in ATP to the mechanical energy of motion which is the production of force
Shaped like to golf clubs twisted together
Myosin tail
Points toward the end line in the centre of the circle mirror tales of neighbouring myosin molecules lie parallel to one another forming the shaft of the thick filament
Myosin heads
Two projections of each meion molecule that has two binding sites
1. active binding site
2. ATP binding site
Actin
Main component of thin filament individual actin molecules join to form an actin filament that is twisted into a helix
on each actin molecule is a myosin binding site where a myosin head can attach