Chap 5: Skeletal System Flashcards
Axial skeleton
A division of the skeletal system consisting of the skull, the rib cage, and the vertebral column.
Appendicular skeleton
A division of the skeletal system consisting of the arms, legs and pelvic girdle.
Levers
Rigid rods where muscles attach
Remodeling
The process by which bone is constantly renewed by the resorption and formation of the bone structure.
Osteoclasts
Special cells that break down and remove old bone tissue.
Osteoblasts
Special cells that form and lay down new bone tissue
Wolff’s law
Scientific explanation of how remodeling (new bone growth) occurs along the lines of stress placed on the bone.
How many bones in the human skeletal system?
206, approximately 177 are used in voluntary movement.
How many bones are in the axial skeletal system?
80 bones
How many bones are in the appendicular skeleton system?
Approximately 126 bones
What’s an example of a long bone?
- Hemerus
* femur
What’s an example of a short bone?
- carpals of the wrist
* tarsals of the ankle
Joints
The sites where two bones meet and movement occurs as a result of muscle contraction.
What’s an example of a short bone?
Similar in length and width and appear somewhat cubical in shape
•carpals of the wrist
•tarsals of the ankle
What’s an example of a flat bone?
Thin, protective surfaces that provide broad surfaces for muscles to attach
•scapulae (I.e., the shoulder blades)
•sternum (I.e., the breast plate)
•ribs
What’s an example of an irregular bone?
Unique shape and function from all other bone types
•vertabrae (I.e., the spinal column)
What’s an example of a sesamoid bone?
Small, often round bones embedded in a joint capsule or found in locations where a tendon passes over a joint.
•patella (I.e., the kneecap)
Articulate (hyaline) cartilage:
Cartilage that covers the articulate surfaces of bones
Epiphysis (epiphyses):
The end of long bones that contains red marrow that produces red blood cells and is also one of the primary sites for bone growth.
Diaphysis:
The shaft portion of a long bone
Epiphyseal plate
The region of long bone connecting the diaphysis to the epiphysis
Medullary cavity:
The central cavity of bone shafts where marrow is stored
Periosteum:
A dense fibrous membrane that covers the bone, provides an attachment site for tendons, and contains nerves, blood vessels, and bone-producing cells.
Depressions
Flattened or indented portions of bone
Processes
Projections protruding from the bone where tendons and ligaments can attach.
Vertebral column
Bones that house the spinal cord; consists of the cervical, thoracic, and lumbosacral regions.
Spinal cord
Bundle of nerves housed within the vertebrae.
Intervertebral discs
Fibrous cartilage structures between vertebrae that act as shock absorbers and assist with movement
Neutral spine
Represents a position in which the vertebrae and associated structures are under the least amount of load and can most optimally support functional movement.
What are the 3 major curvatures of the adult human spine?
- Posterior (concave) cervical curve (hollowed or rounded inward).
- Posterior (convex) thoracic curve (curved or rounded outward).
- Posterior (concave) lumbar curve (hollowed or rounded inward).
Osteokinematics
Movement of a limb that is visible
Arthrokinematics
The description of the joint surface movement; consists of three major types: roll, slide and spin.
Synovial joints
A joint with a fluid-filled joint capsule. Synovial joints are the most common joints associated with human movement. They comprise approximately 80% of all the joints in the body and have the greatest capacity for motion.
Nonaxial
A gliding joint that moves in only one plane, either back and forth or side to side
Nonsynovial joints
Joints that have no joint capsule, fibrous connective tissue, or cartilage in the uniting structure.
Ligament
A fibrous connective tissue that connects bone to bone
Collagen
A protein found in connective tissue, muscles, and skin that provides strength and structure it is the most abundant protein in the human body.
Elastin
A protein that provides elasticity to skin, tendons, ligaments, and other structures.
Growth plate
A specialized cartilage disc located in the epiphysis that is responsible for longitudinal bone growth.
What are the most common joints in the human body?
Synovial joints
Skeletal muscle
The type of muscle tissue that connects to bones and generates the forces that create movement.
Fascia
Connective tissue that surrounds muscles and bones
Epimysium
Inner layer of fascia that directly surrounds an entire muscle, commonly referred to as the “deep fascia”.
Fascicles
Largest bundles of fibers within a muscle. Fascicles are surrounded by perimysium
Perimysium
Connective tissue surrounding a muscle fascicle.
Endomysium
Connective tissue that wraps around individual muscle fibers within a fascicle.
Glycogen
Glucose that is deposited and stored in bodily tissues, such as the liver and muscle cells; the storage form of carbohydrate.
Myoglobin
Protein-based molecule that Carries oxygen molecules into the muscles.
Myofibrils
The contractile components of a muscle cell; the myofilaments (actin and myosin) are contained within a myofibril.
Myofilaments
The filaments of a myofibril;include actin and myosin.
Actin
The thin, stringlike, myofilament that acts along with myosin to produce muscular contraction.
Myosin
The thick myofilament that acts along with actin to produce muscular contraction.
Sarcomere
The structural unit of a myofibril composed of actin and myosin filaments between two Z-lines.
Z-line
The meeting point of each sarcomere
Neural activation
The nervous system’s signal that tells a muscle to contract
Neuromuscular junction
The specialized site where the nervous system communicates directly with muscle fibers
Synapse
A junction or small gap between the motor neuron and muscle cells
Motor unit
A motor neuron and all of the muscle fibers that it innervates
What are two protein structures that are important to muscle contraction?
Tropomyosin and troponin
Tropomyosin
Located on the actin filament and blocks myosin-binding sites located on the actin filament, keeping myosin from attaching to actin when the muscle is in a relaxed state.
Troponin
Located on the actin filament, plays a role in muscle contraction by providing binding sites for both calcium and tropomyosin when a muscle needs to contract.
Action potential
Nerve impulse that is relayed from the central nervous system, through the peripheral nervous system, and into the muscle across the neuromuscular junction.
Neurotransmitters
Chemical messengers that cross the synapse between neuron and muscle and assist with nerve transmission.
Acetylcholine (ACh)
A neuron transmitter that helps the action potential cross the synapse into the muscle, which initiates the steps in a muscle contraction.
Sliding filament theory
The series of steps in muscle contraction involving how myosin (thick) and actin (thin) filaments slide past one another to produce a muscle contraction, shortening the entire length of the Sarcomere.
Excitation-contraction coupling
The physiological process of converting an electrical stimulus to a muscle contraction.
Power stroke
The myosin heads bind to actin and pull them toward the Sarcomere center, which slides the filaments past each other, shortening the muscle.
Adenosine triphosphate (ATP)
A high-energy molecule that serves as the main form of energy in the human body; known as the energy currency of the body.
Resting length
The length of a muscle when it is not activity contracting or being stretched.
Type l muscle fibers
Muscle fibers that are small in size, generate lower amounts of force, and are more resistant to fatigue.
Type ll muscle fibers
Muscle fibers that are larger in size, generate higher amounts of force, and are faster to fatigue.
All or nothing principle
Motor units cannot vary the amount of force they generate; they either contract maximally or not at all.
Capillaries
The smallest blood vessels and the site of exchange of elements between the blood and tissues.
What are the three types of muscles?
Skeletal, cardiac and smooth
Muscle fibers contain:
Glycogen, fats, minerals and myoglobin
