Muscular System Flashcards
Functions of muscle three tissue types?
- Smooth muscle- Moving food through the digestive tract, emptying the uniary bladder, regulating blood vessel diameter, changing pupil size, contracting many gland ducts. moving hair.
- Skeletal muscle-Body movement
- Cardiac muscle- Pumping blood; contractions provide the major force propelling blood through blood vessels.
Smooth muscle
The most widely distributed type of muscle in the body. Found in the walls of hollow organs (stomach, uterus, tubes; blood vessels, ducts of certain glands, and iris for pupil dilation). They propel urine through the urinary tract, mixing food in the stomach and small intestine, dilating and contracting the pupil of the eye, and regulating the flow of blood through blood vessels.
pg 269
Cardiac muscle
Found only in the heart, and its contractions provide the major force for moving blood through the circulatory system. Can contract spontaneously and rhythmically. This property is autorhythmicity; nervous or hormonal stimulation is not always required for them to contract. They are controlled involuntarily., by autonomic nervous and endocrine systems
pg 269
Major functions of all three types of muscles
- Movement of the body- Most skeletal muscles are attached to boned and are responsible for the majority of body movements, including walking, running, chewing, and manipulating objects with the hands.
- Maintenance of posture- Skeletal muscles constantly maintain tone, which keeps us sitting or standing erect.
- Respiration-Skeletal muscles of the thorax carry out breathing movements.
- Production of body heat- When skeletal muscle contract, heat is given off as a by-product. This released heat is critical for maintaining body temperature.
- Communication- Skeletal muscles are involved in all aspects of communication, including speaking, writing, typing, gesturing, and smiling or frowning.
- Constriction of organs and vessels- The constriction of smooth muscle within the walls of internal organs and vessels causes those structures to constrict. This constriction can propel mixe food and water in the digestive tract; remove materials from organs, such as the urinary bladder or sweat glands; and regulate blood flow through vessels.
- Contraction of the heart- The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body.
pg 269-270
Excitability
The capacity of muscle to respond to an electrical stimulus. Normally, the stimulus is from nerves that we consciously control. Smooth and cardiac muscle also respond to stimulation by nerves and hormones but can sometimes contract spontaneously.
pg 270
Extensibility
A muscle can be stretched beyond its normal resting length and still be able to contract.
pg 270
Where are skeletal muscle found?
Attached to bones
pg 269
Where are smooth muscle found?
Walls of hollow organs, blood vessels, eyes, glands, and skin
pg 269
Where are cardiac muscle found?
Heart
pg 269
Fasciculus
A muscle is composed of numerous visible bundles
What is Epimysium?
The entire muscle is surrounded by a layer of dense irregular collagenous connective tissue
pg 270
What is Perimysium
Each fasciculus is surrounded by a connective tissue layer
pg 270
Fasciculus
A muscle is composed of numerous visible bundles
pg 270
Epimysium
The entire muscle is surrounded by a layer of dense irregular collagenous connective tissue
pg 270
Perimysium
Each fasciculus is surrounded by a connective tissue layer
pg 270
Endomysium
Second layer that consists of reticular fibers, but is much thicker
pg 272
Muscle fiber
Develop from less mature, multinucleated cells called myoblasts. The mutiple nuclei found skeletal muscle fibers result from the fusion of myoblast precursor cells, not from the division of nuclei within myoblasts. Muscle fibers differentiate into functional muscle fibers as contractile proteins accumulate within their cytoplasm. Shortly after the myoblasts form, nerve begins to innervate the developing muscle fibers.
pg 272
Myofilament
Actin filaments (thin myofilaments) are about 8 nanometers in diameter and 1000 nm in length.
Myosin myofilaments (thick myofilaments) are about 12 nm in diameter and 1800 nm in length.
They are arranged in a highly ordered units called sarcomeres, which join end to end to form the myofibrils.
The arrangments actin and myosin myofilaments gives myofibrils its banded/striated look.
pg 272
Myofibril
Sacroplasm contains numerous bundles of myofibrils. Each one a threadlike structure, about 1-3 um in diameter, that extends the length of the muscle fiber. Contains two kinds of protein filaments, called myofilament. Actin and myosin myofilaments
pg 272
bnm,
*Actin filaments- small fibrils, an=bout 8nm in diameter, that form bundles, sheets or networks in the cytoplasm. Provide structure to the cytoplasm and mechanical support for microvilli. Actin filaments also support the plasma membrane and define the shape of the cell. Changes in shape involve breakdown and reconstruction of actin filaments. These changes in shape allow some cells to move about. Responsible for muscle contractile capabilities.
Muscle fiber structure
The plasma membrane of the muscle fiber is called a sarcolemma.
Two delicate connective tissue layers are located just outside the sarcolemma. The deeper and thinner of the two is the external lamina. Consist mostly of reticular (collagen) fibers. The second layer also consists of reticular fibers but is a much thicker layer, called endomysium.
Along the surface of the sarcolemma are many tublike invaginations of the sarcolemma, called transverse tubules, or T tubules. They occur regular intervals along the muscle fiber and extend inward, connecting the extracellular environment with the interior of the muscle fiber.
The T tubules lie adjacent to the highly organized smooth endoplasmic reticulum, called sarcoplasmic reticulum, in skeletal muscle fibers.
Other organelles, such as mitochondria and energy storing glycogen granules, are packed into the cell and constitute the cytoplasm, which in muscle fibers is known as the sarcoplasm.
Sarcoplasm also contains numerous bundles of protein filaments called myofibrils. A myofibril contains both actin and myosin and myosin myofilaments.
The two myofilament are arranged into sarcomeres
Muscle fiber structure
The plasma membrane of the muscle fiber is called a sarcolemma.
Two delicate connective tissue layers are located just outside the sarcolemma. The deeper and thinner of the two is the external lamina. Consist mostly of reticular (collagen) fibers. The second layer also consists of reticular fibers but is a much thicker layer, called endomysium.
Along the surface of the sarcolemma are many tublike invaginations of the sarcolemma, called transverse tubules, or T tubules. They occur regular intervals along the muscle fiber and extend inward, connecting the extracellular environment with the interior of the muscle fiber.
The T tubules lie adjacent to the highly organized smooth endoplasmic reticulum, called sarcoplasmic reticulum, in skeletal muscle fibers.
Other organelles, such as mitochondria and energy storing glycogen granules, are packed into the cell and constitute the cytoplasm, which in muscle fibers is known as the sarcoplasm.
Sarcoplasm also contains numerous bundles of protein filaments called myofibrils. A myofibril contains both actin and myosin and myosin myofilaments.
The two myofilament are arranged into sarcomeres
pg 272
Thick filament
Myosin
Z-disc
Separates one sarcomere from the next. It is a filamentous network of protein that forms a stationary anchor for the attachment of actin myofilaments.
Z-disc
Separates one sarcomere from the next. It is a filamentous network of protein that forms a stationary anchor for the attachment of actin myofilaments.
pg 273
