Flashcards in Chapter 10: Muscular Tissue Deck (84)
What does skeletel muscle do?
Move bones or the skeleton mostly. But some attach to and move the skin or other skeletal muscles. It's striated (alternating light and dark bands) and voluntary. Although most skeletal muscles are controlled subconsciously to some extent.
What is the cardiac muscle?
Most of heart wall. Striated but involuntary. Regulated by neurons in the autonomic nervous system and by hormones
What is autorhythmicity?
Built in rhythm.
What is smooth muscle tissue?
Located in walls of hollow internal structures (blood vessels, airways, and most organs in abdominopelvic cavity) and also skin attached to hair follicles. Non striated, involuntary, some smooth muscle (like one that propel food through GI tract) has autorhythmicity. Regulated by. Neurons part of autonomic nervous system (involuntary) and hormones secreted by endocrine glands
What are the 4 functions of muscular tissue?
1) Producing body movements
2) Stabalizing body positions
3) Storing and moving substances in body
4) Generating heat
Muscular tissue contributes to homeostasis. What is electrical excitability?
Ability to respond to certain stimuli by prducing electrical signals called ACTION POTENTIALS
What are action potentials and what are the types?
Muscle action potentials. Two types: Autorhythmatic electrical signals arising within muscular tissue (like heart's pacemaker), and chemical stimuli (like nrutransmitters released by hormones, hormones distributed by blood, local changes in pH etc)
Muscle tissue contributes to homeostasis. What is contractibility?
Ability of muscular tissue to contract forcebly when stimulated by action potentials. When a skeleton muscle contracts it generates tension while pulling on attachment proteins. Sometimes muscle shortens (like when the tension generated is great enough to overcome the load of the object being moved) and other times it doesn't shorten (like holding a book in an outstretched hand)
Muscular tissue contributes to homeostasis. What is extensibility?
Ability of muscular tissue to stretch without being damaged. Connective tissue within the muscle limits the range of extensibility. Smooth muscle is subject to most stretching like each time the stomach fills with food or when cardiac muscle fills with blood.
Muscular tissue contributes to homeostasis. What is elasticity?
Ability of muscular tissue to return to its original length and shape after certain contraction/extension
What are muscle fibres?
Cells with elongated shapes
What does connective tissue do?
Surrounds and protects muscular tissue.
What is subcutaneous layer of connective tissue?
Aka hypodermis. Separates muscle from skin and is composed of areolar connecive tissue and adipose connective tissue. Provides a path for nerves, blood vessels and lymphatic vessels to enter and exit muscles
What is fascia or connective tissue?
A dense sheet and broad band of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscle and other organs. Holds muscles with similar functions together, allows free movement of muscles, carries nerves, blood vessels and lyphatic vessels and fills spaces between muscles
3 layers of connective tissue extend form the fascia to protect and strengthen skeletal muscle. What are they?
1) Epimysium: Outer layer encircling entire muscles. Dense irregular connective tissue
2) Perimysium: Dense irregular connective tissue. Surrounds groups of 10-100 or more muscle fibres. Separates them into bundles called fascicles. If you t ear a iece of meat it tears along its fascicles
3) Endomysium: Penetrates interior of each fascicle and separates individual muscle fibres. Mostly reticular fibres
What is a tendon'?
All 3 connective tissue layers may extend beyond muscle fibres to form a rope-like tendon that attaches a muscle to the periosteum of a bone (ie calcaneal tendon of the gastrocnemius (calf) muscle
What is the aponeurosis of connective tissue?
When connective tissue elements extend as a broad, flat sheet it's called aponeurosis (ie epicranial aponeurosis on top of the skull between the frontal and occipital bellies of the occipitofrontalis muscle)
What are somatic motor neurons?
The neurons that stimulate muscles to contract. A threadlike axon that extends from the brain or spinal cord to a group of skeletal fibres
What do capillaries do in muscular tissue?
Plentiful in muscular tissue. Brings in O2 and nutrients and removes heat and waste products of muscle metabolism. Muscle fibres use and synthesize lots of ATP
What is sarcolemma?
Plasma membrane of a muscle cell.
What is Transverse (T) tubules?
Thousands of tiny invaginations of the sarcolemma called TRANSVERSE (T) TUBULES, tunnel in from the surface toward the centre f each muscle fibre. Open to outside of fibre, filled with interstitial fluid, muscle action potentials travel along the sarcolemma and through the tubules.
What's the sarcoplasm?
Within the sarcolemma. It is the cytoplasm of muscle fibre. Has lots of glycogen and glycogen can be used for synthesis of ATP. Has red coloured protein called MYOGLOBIN which binds O2 molecules that diffuse into muscle fibres from interstitial fluid. Releases O2 when it's needed by mitochondria for ATP production
What are myofibrils?
Little threads in sarcoplasm. Contractile organelles of skeletal muscle. Extends entire length of muscle fibre. Why skeletal muscle fibre appear striped.
What is the sarcoplasmic reticulum (SR)>
Fluid filled system of membranous sacs. Encircles each myofibril. Stores calcium ions (Ca2++). Dilated end sacs of SR called the TERMIONAL CISTERNS. A transverse tubule and the 2 terminal cisterns on either side form a TRIAD. Release of CA 2++ from terminal cisterns of SR triggers muscle contractions
WHat are filaments and what are the two types?
Small protein structures within myofibrils. There are thin filaments mainly composed of actin and thick filaments mainly composed of myosin
What are sacromeres?
Basic functional units of a myofibril. Compartments
What are z discs?
Separate one sacromere from another
What is the M line of the sacromere?
Supporting protein that holds the thick filaments together at the centre of the H zone (middle of sacromere)
Myofibrils are built from 3 kinds of proteins. What are these 3 kinds?
1) Contractile proteins which generate force during contraction
2)Regulatory proteins which help switch contraction process on/off
3) Structural proteins that keep the thick and thin filaments in proper alignment, give the myofibril elasticity and extensibility, and link myofibrils to the sarcolemma and ECM