Unit 6: Muscles and Muscle Tissues (physiology of muscle contraction (ATP…
Unit 6: Muscles and Muscle Tissues
Functions of the Muscular System
stabilize our joints
they pull on bones to cause movement, they strengthen and stabilize the joints of the skeleton.
Skeletal muscles are responsible for all locomotion and manipulation
They enable you to respond quickly
maintain our posture and generate heat during activity
Muscles generate heat as they contract, which plays a role in maintaining normal body temperature.
Smooth muscle in organs of the digestive, urinary, and reproductive tracts propels substances through the organs and along the tract.
Urine, Semen, body wastes
Maintain posture and body position
making one tiny adjustment after another to counteract the never-ending downward pull of gravity
names of all the muscles
The masseter runs from the temporal bone to the lower jaw . It lifts the lower jaw, to close the mouth. The masseter is the strongest muscle in your body.
The temporalis begins on two bones of the skull, at the front ( and at the side and base. It runs to the top of the lower jaw. Like the masseter, the temporalis helps close the mouth.
The biceps brachii runs from the shoulder to the elbow. It is attached to the shoulder blade, and extends along the front surface of the upper arm bone . When the bicep contracts, the arm bends at the elbow.
The deltoids are the triangular muscles of the shoulder. The strongest point is the central section, which raises the arm sideways. The front and back parts of the muscle twist the arm.
The pectoralis major is a large, fan-shaped muscle. It covers much of the front upper chest, beginning at the breastbone including the second to the sixth ribs.
The adductor longus is located on the inner thigh.
Located in the lower leg, the soleus runs from the lower leg bones to the heel . The soleus muscle flexes the foot by moving the foot at the ankle. It also helps circulation by pumping blood back up towards the head.
Muscle location: Some muscle names indicate the bone or body region with which the muscle is associated.
Muscle shape: Some muscles are named for their distinctive shapes.
Muscle size: Terms such as maximus largest, minimus smallest, longus long, and brevis short
3 types of muscle tissues & their major
occurs only in the heart, where it bulks the heart walls.
cardiac muscle cells are striated
contracts without being stimulated by the nervous system
usually contracts at a fairly steady rate set by the heart’s pacemaker and controls allow the heart to speed up for brief periods
found in the walls of hollow visceral organs ; the stomach, urinary bladder, and respiratory passages
force fluids and other substances through internal body channels
regulate the passage of substances through internal body openings, dilates and constricts the pupils of your eyes, and forms the arrector pili muscles attached to hair follicles
organs that attach to and cover the skeleton
fibers are the longest muscle cells and have obvious stripes ; striations
responsible for overall body mobility
must rest after short periods of activity
Characteristics of Muscle Tissues
Excitability: is the ability of a cell to receive and respond to a stimulus by changing its membrane potential
Contractility: is the ability to shorten forcibly when adequately stimulated.
Extensibility : is the ability to extend or stretch
Elasticity: is the ability of a muscle cell to recoil and resume its resting length after stretching
body movement terminology
prime mover or agonist: A muscle that has the major responsibility for producing a specific movement
antagonists: Muscles that oppose, or reverse, a particular movement
synergists: most movements involve the action of one or more
structure and organizational levels of the skeletal muscle
Discrete organ made up of several tissues
Contains blood vessels, nerve fibers, and connective tissue
one nerve, one artery, and one or more veins serve each muscle
enter or exit near the central part of the muscle and branch through its connective tissue sheaths
every skeletal muscle fiber is supplied with a nerve ending that controls its activity.
ontinuous delivery of oxygen through nutrients via the arteries
sheaths support each cell and reinforce and hold together the muscle
Each skeletal muscle fiber is a long cylindrical cell with multiple oval nuclei just beneath its sarcolemma or plasma membrane
physiology of muscle contraction
An increase in the frequency of stimulation causes temporal summation
An increase in the strength of stimulation causes recruitment
physiology of muscle contraction
Actin and myosin cross-bridge formation
Sliding mechanism of actin and myosin filaments
ATP supplies the energy to move and detach cross bridges, operate the calcium pump in the SR, and operate the Na+-K+ pump in the plasma membrane
after ATP is hydrolyzed to ADP and inorganic phosphate in muscle fibers, it is regenerated within a fraction of a second by one or more of the three pathways
direct phosphorylation of ADP by creatine phosphate
anaerobic glycolysis converts glucose to lactic acid
95% of the ATP used for muscle activity comes from aerobic respiration
Aerobic respiration requires oxygen and mitochondria, and involves a sequence of chemical reactions that break the bonds of fuel molecules and release energy to make ATP
Glucose + oxygen → carbon dioxide + water + ATP
disorders associated with the
Brody myopathy is a condition that affects the skeletal muscles, which are the muscles used for movement.
Distal muscular dystrophy is a group of rare diseases that affect your muscles. DD causes weakness that starts in the lower arms and legs