How can our CNS command our bodies to move?
From signals generated from the primary motor cortex
What two organ systems are required in order for signals to generate conscious body movements?
The skeletal system and the muscular system
Is bone considered living tissue or nonliving tissue?
Living tissue
Functions of bone include?
1) Movement
2) Protection
3) Support
4) Mineral storage
5) Blood cell formation
Describe bone movement
Muscles attached to the skeletal frame can maintain or change body position by contraction
Describe bone protection
Bones can form bony compartments that enclose and protect the brain, lungs and other organs
Describe bone support
Bones support and anchor muscles (serve as a frame)
Describe bones mineral storage
Bone can be likened to “calcium-phosphate bank” for depositing and withdrawing mineral ions to maintain homeostasis and support metabolic activities
Describe bones blood cell formation
Some bones contain regions which are responsible for the body’s blood cell production
What is the structure of compact bone?
Surrounded by periosteum, dense, organized layers of parallel osteons. Each osteon has a central canal which carries blood vessels and nerves, concentric rings of dense bone with interspersed lacunae which house the living cells (osteocytes), and many small canaliculi which allows nutrients/wastes to move in/out of cells
What is the location of compact bones?
found in the outer layer of bones under the periosteum
What are the functions of compact bones
serves as the main region of bone to withstand mechanical stresses. Also the main depository of mineral ions
What is the structure of the spongy bone?
Much less calcified minerals, looks like a sponge of flattened struts fused to form a latticework. In some bones, allows room for yellow (fat) marrow and/or red marrow (blood stem cells)
What is the location of the spongy bone?
centrally located within the middle of long bone (humerus, radius, ulna, femur, tibia and fibula) shafts, and irregularly shaped bones (pelvic girdle and sternum)
What is the functions of the spongy bone?
Lightens the weight of the bone without much sacrifice of strength. Allows space for yellow and red marrow.
Osteo=
Dealing with bone
Cytes=
Dealing with cells
Early in utero, our bodies develop a?
Cartilage skeleton, which serves as a template for osteoblasts, which begins to clacify the cartilage from the outside in
At the embryonic stage of the cartilage skeleton what happens?
Because the cartilage needed vascular supply, the bone was laid down around the blood vessels. This becomes the aversion system in compact bone, and the osteoblasts become osteocytes within the lacunae of osteons
In prepubescent children what is still present?
The remnant of embryonic cartilage is still present in the epiphyseal plates of long bones
In response to growth hormone (GH), what remains cartilaginous?
Epiphyseal plates remain cartilaginous and those bones can continue to lengthen
By late adolescence, what are replaced?
The epiphyseal plates are replaced by bone and growth stops
In addition to increasing bone length, bone is?
Continually shaped and reshaped (what is called bone remodeling) by both: 1) physiological demands (calcium and phosphate) 2) physical (muscular) forces
Bone can be likened to?
Calcium bank
Calcium is essential to many body functions and if blood calcium is too low what happens?
The body will make a “withdrawal” by releasing parathyroid hormone (PTH) which stimulates osteoclasts to break dissolve some bone to release Ca++ into the blood
What happens if blood calcium is higher than needed?
The thyroid gland releases calcitonin which stimulates osteoblasts to make a deposit of Ca++ into new bone
Osteoblasts are stimulated by?
Mechanical stress to increase bone density to handle stress
What happens during orthodontic movement of teeth?
Pressure causes increased osteoclastic activity which equals bone is removed;
tension causes increased osteoblastic activity which equals bone is laid down
What is the axial skeleton?
Skull (cranial and facial bones); rib cage; and vertebral column
What is the appendicular skeleton?
Pectoral girdle (clavicle and scapula), humerus, radius, ulna, Pelvic girdle, femur, patella, fibula, tibia
Joints are?
Articulations of areas of contact or near-contact between bones
What are the types of joints?
1) Synovial joints
2) Cartilaginous joints
3) Fibrous joints
Characteristics of synovial joints
A cavity or capsule surrounds the joint and is filled with synovial fluid
Degree of movement for synovial joints
Freely movable
Examples of synovial joints
Ball and socket (hip); hinge (elbow or knee)
Characteristics of cartilaginous joints
Cartilage fills the space between bones
Degree of movement for cartilaginous joints
Only slight movement
Examples of cartilaginous joints
Between vertebrae, between sternum and some of the ribs
Characteristics of fibrous joints
Dense, fibrous connective tissue unites bones
Degree of movement for fibrous joints
Into adulthood, almost immovable
Examples of fibrous joints
Between flat cranial bones, between L and R pubis bones
Types of movement
Extension-flexion; abduction-adduction; rotation; circumduction
Replacement materials
Over the decades of use, materials used for artificial joints/bones have improved. From soft stainless steel to titanium or cobalt chromium
Replacement implementation
Surgeons and physical therapists have enhanced recovery so much that people can walk mere days after surgery
3 types of muscles
Cardiac, smooth, skeletal
Skeletal is also called
Striated
Muscles can only function by?
Contraction, shortened muscle can lengthen only by relaxation, but not active work
Muscles are?
Several bundles surrounded by an outer sheath of connective tissues
One bundle of muscle cells are?
Each surround by connective tissue
One muscle cell (many myofibrils) are?
Multinucleated cell, also called muscle fiber
Myofibrils can?
See striations (that’s why skeletal muscle is also called striated muscle)
Muscle unit of contraction?
Sarcomere
Each sarcomere goes from?
z-line to z-line
Sarcomere is principally made up of 2 types of protein macromolecules
Actin and myosin
Most current understanding of muscle contraction is called>
The sliding-filament model
What happens to the sliding filament model when stimulated?
The heads of the thicker filament of myosin will form cross bridges with the thinner filaments of actin. If there is adequate ATP, the myosin heads will power stroke, detach, reattach and power stroke again. This shortens each sarcomere and thus the entire muscle
The primary motor cortex initiates what for conscious movement?
The neural signal
The axon of the motor neuron exits the?
Spinal cord eventually branching off and ending at the neuromuscular junction, also called the motor end plate
The axon ending release?
Acetylcholine (ACh) into the synaptic cleft
During the neural control of muscles, signals are carried along the?
Muscle cell plasma membrane and end up in small extensions of the muscle cell plasma membrane.
Where do the extensions of the muscle cell plasma membrane penetrate into?
These extensions or T tubules penetrate into the interior of the muscle cell. Connecting with the internal smooth endoplasmic reticulum (SER)
In muscle cells (SER) is called the?
sarcoplasmic reticulum, and it’s function is to store Ca++ and then release it when the nerve signals hits
What happens when Ca++ hits myofibrils
The myosin can form those cross-bridges with actin and the contraction can commence
During contraction, ATP utilization can exceed
20 to 100 times as when the muscle is resting. Because of the potentially high ATP demand, skeletal muscle cells must have additional sources of ATP
What are the additional sources of ATP?
1) Pathway 1: Dephospharylation of creatine phosphate (rapid)
2) Pathway 2: Aerobic respiration (slow)
3) Pathway 3: Glycolysis (rapid but not as much ATP produced)
4) Anaerobic respiration: With intense exercise, the need for ATP production can exceed the above 3 pathways. The muscle will begin to accumulate and O2 debt, by borrowing off of anaerobic pathways, which also results in the accumulation of lactic acid
Term used to describe the mechanical force a contracted muscle can exert. But only if this force overcomes the load, does the muscle actually shorten
Muscle tension
Isometric is
Contraction results when muscles contract but do NOT shorten
Isotonic is
(Concentric) contraction results when muscles contract AND shorten under a constant load
Motor units equal
The motor neuron and the muscle cells it controls
The muscle twitch is
From a single stimulation of a single motor unit
Temporal summation is
When repeating stimulations enter before the relaxation phase from the the previous twitch is completed
Tetany occurs?
Occurs near or at maximum temporal summation. Over the whole muscle, different motor units will take turns to postpone muscle fatigue
All or nothing principle
For individual muscle cells, just like nerve axons
Muscle tone is
A steady low level contracted state-even a resting muscle has a few motor units contracted, help to stabalize joints, and maintain general muscle health
Fast vs. Slow muscle
Fast or white muscles have fewer capillaries and less mitochondria and myoglobin, low endurance but contract rapidly and powerfully over short periods.
Slow or red muscles have more capillaries and more mitochondria and myoglobin, high endurance but slower contractions (e.g postural muscles that aid in body support)
The human musculoskeletal system has how many muscles?
600+
What is synergism-Antagonism
Some of the muscles contribute to the same movement along a joint, these muscles are synergistic
What are examples of four synergistic muscles working together to extend the leg at the knee joint
The quadriceps
What are antagonistic muscles?
Muscles whose contractions work counter other muscles
What are some examples of antagonistic muscles?
The hamstring are antagonistic to the quadriceps femoris in that they flex the leg at the knee joint
Muscles can only work by what?
Contraction
What is origin?
The bone on one side of the muscle, which is relatively motionless is called the origin
What is insertion?
The attachment of the other side of the muscle is on the bone which is relatively mobile during contraction, this is called insertion
What is an example of insertion?
The pectoral girdle (the shoulder end of the scapula) is the origin of the biceps brachial, but the insertion is on the forearm bones (the radius)
What is required for health in order to maintain muscle tone and sufficient skeletal strength?
A certain amount of activity is required
Increasing aerobic exercise level benefits health by
Increasing metabolic efficiency (they can work longer without becoming fatigued)
What are some things that increasing aerobic exercise does?
1) Increase the number and size of mitochondria
2) Increase the number of blood capillaries supplying muscle tissue
3) Increase amount of O2-binding pigment myoglobin in muscle tissue
What does increase in strength training do?
“Pumping iron” increases the number of myofibrils in fast muscle cells, but does NOT increase metabolic efficiency. Muscles can get larger and stronger, but they fatigue rapidly
What are anabolic steroids
They are prescription drugs of synthetic testosterone and/or its derivatives, used to treat impotence in men and menopausal symptoms in women, as well as part of hormone replacement therapy when needed
What are some side effects of anabolic steroids
Acne, baldness, shrinking testes, infertility, cardiovascular disease, kidney damage, increase risk of testicular cancer and psychological effects (increase irritability to roid rage and bodybuilder’s psychosis)