Exam 2 Flashcards
Functions of bone and the skeletal system
- Support
- Protection
- Assistance in Movement
- Blood Cell Formation
- Mineral Storage
- Triglyceride Storage
Bone Cell Types
Osteocytes
Osteoblasts
Osteoclasts
Osteocytes
A bone cell responsible for the maintenance and turnover of the mineral content of the surrounding bone
Osteoblasts
A cell that produces the fibers and matrix of the bone
Osteoclasts
A cell that dissolves the fibers and matrix of the bone
Compact bone
Dense bone that contains parallel osteons
Location of Compact Bone
Outer shell of all bone and the shafts in long bones
Structure of Compact Bone
The osteocytes are arranged in concentric layers around a central canal.
The lamellae form a series of nested cylinders around the central canal.
Spongy - Cancellous Bone
Composed of a network of bony struts
Location of Spongy Bone
Found in the end of long bones, and in the bones of the pelvic, ribs, vertebrae, and the skull.
Structure of Spongy Bone
Lamellae are not arranged in osteons. The matrix forms a meshwork of supporting bundles of fibers called trabeculae. These thin trabeculae branch, creating an open network.
There are no capillaries or venules in the matrix of spongy bone.
Classification of Bones
- Long Bones
- Short Bones
- Flat Bones
- Irregular Bones
- Sesamoid Bones
- Sutural Bones (Wormian)
Primary Center of Ossification
Occurs in the middle of diaphysis (shaft)
Secondary Center of Ossification
Occurs in each epiphysis of long bone.
Epiphysis
The head of a long bone
Consists largely of spongy bone
Diaphysis
The shaft of a long bone
Consists of a layer of compact bone
Epiphyseal Plate
The cartilaginous region between the epiphysis and diaphysis of a growing bone
Periosteum
A membrane with a fibrous outer layer and a cellular inner layer.
- Isolates bone from surrounding tissues
- Provides a route for the blood vessels and nerves
- Takes part in bone growth and repair
Endosteum
An incomplete cellular lining on the inner (medullary) surface of bones
This layer is active during bone growth, repair, and remodeling.
Perichondrium
The layer that surrounds a cartilage, consisting of an outer fibrous region and an inner cellular region.
Intramembranous Ossification
Bone develops directly from mesenchyme or fibrous connective tissue
Endochondral Ossification
Bone tissue replaces existing cartilage
During development, most bones originate as hyaline cartilages that are miniature models of the corresponding bones of the adult skeleton. These cartilage models are gradually replaced by bone through this process.
Types of Bones
Compact and Spongy
Haversian canal
Contains one or more blood vessels (normally a capillary and a very small vein) tha carry blood to and from the osteon
Generally run parallel to the surface of the bone
Sutural Bones
Small, flat, oddly shaped bones found between the flat bones of the skull.
Irregular Bones
Complex shapes with short, flat, notched, or ridged surfaces.
Examples: Vertebrae, Pelvic Bones, some Skull Bones
Short Bones
Small, boxlike in appearance.
Examples: carpal bones and tarsal bones.
Flat Bones
Have thin, parallel surfaces
Examples: Form the roof of the skull, the sternum, the ribs, and the scapulae.
Long Bones
Relatively long and slender
Examples: located in the arm, forearm, thigh and leg, palms, soles, fingers, and toes.
Largest long bone - Femur
Sesamoid Bones
Usually small, round, and flat.
Example: Patella
Osteons
The basic histological unit of compact bone, consisting of osteocytes organized around a central canal and separated by concentric lamellae
Lamellae
Rings of matrix that surround the central canal.
Ossification
The formation of bone, osteogenesis
Metaphysis
Connecting portion of epiphysis and diaphysis; narrow zone
Calcification
Deposition of calcium salts
Appositional Growth
Process of which the cells of the inner layer of the periosteum differentiate into osteoblasts and deposit superficial layers of bone matrix. Eventually, these osteoblasts become surrounded by matrix and differentiate into osteocytes.
This is the process in which the developing bone increases in diameter.
Increasing the Length of a Developing Long Bone
On the diaphyseal (shaft) side of the metaphysis, osteoblasts continually invade the cartilage and replace it with bone, while on the epiphyseal side, new cartilage is produced at the same rate.
The situation is like a pair of
joggers, one in front of the other. As long as they are running at the same speed, they can run for miles without colliding.
Bone Remodeling
Continuously recycles and renews the organic and mineral components of the bone matrix.
Bone remodeling goes on throughout life, as part of normal bone maintenance.
Calcitrol
Primary Source: Kidney
Promotes calcium and phosphate ion absorption along the digestive tract.
Growth hormone
Primary Source: Pituitary Gland
Stimulates osteoblast activity and the synthesis of bone matrix.
Thyroxine
Primary Source: Thyroid gland
With growth hormone, stimulates osteoblast activity and the synthesis of bone matrix.
Sex Hormones
Primary Source: Ovaries and Testes
Stimulate osteoblast activity and the synthesis of bone matrix; estrogens stimulate epiphyseal closure earlier than androgens.
Parathyroid Hormone
Primary Source: Parathyroid glands
Stimulates osteoclast activity; increases blood calcium ion concentrations
Calcitonin
Primary Source: Thyroid gland
Inhibits osteoclast activity; promotes calcium loss by kidneys; decreases blood calcium ion concentrations.
Fracture
A break or crack in a bone.
Paget’s Disease
A chronic disorder that can result in enlarged
and misshapen bones due to abnormal bone destruction and
regrowth
Axial Skeleton
80 Bones; Forms the longitudinal axis of the body; 40% of the bones in the human body
Skull - 8 Cranial, 14 Facial
Bones associated with the Skull - 6 Auditory ossicles and the Hyoid
Vertebral Column - 24 Vertebrae, Sacrum, Coccyx
Thoracic Cage - Sternum, 24 Ribs
Primary Functions of Axial Skeleton
Provides a framework that supports and protects the brain, spinal cord, and the thoracic and abdominal regions.
Also provides an extensive surface area for the attachment of muscles that (1) adjust the positions of the head, neck, trunk; (2) perform respiratory movements; and (3) stabilize or position parts of the appendicular skeleton.
Suture
A synarthrotic joint located only between the bones of the skull.
Does not move
Types of Sutures
- Lamboid Suture
- Coronal Suture
- Sagittal Suture
- Squamous Suture
Lamboid Suture
Connects the occipital bone with the two parietal bones
Coronal Suture
Attaches the frontal bone to the parietal bones of either side
Sagittal Suture
Extends from the lamboid suture to the coronal suture, between the parietal bones.
Squamous Suture
On each side of the skull joins the temporal bone and the parietal bone of that side
Hyoid Bone
Supports the larynx and is the attachment site for muscles of the larynx, pharynx, and tongue.
3 Bones of the Sternum
- Manubrium
- Body
- Xiphoid Process
Synarthroses
NO MOVEMENT
The bony edges are quite close together and may even interlock. These extremely strong joins are located where movement between the bones must be prevented.
Examples: Suture, gomphosis, Synchrondrosis, Synostosis
Gomphosis
A synarthrosis that binds the teeth to bony sockets in the maxillae and mandible.
Does not move.
Synchondrosis
A rigid, cartilaginous bridge between two articulating bones.
Synostosis
A totally rigid, immovable joint created when two bones fuse and the boundary between them disappears.
Happens in infants.
Amphiarthrosis
LITTLE MOVEMENT
Permits a little movement, but is much stronger than a freely movable joint. The articulating bones are connected by collagen fibers or cartilage.
Examples: Syndesmosis, Symphysis
Syndesmosis
Bones are connected by a ligament.
Example: Distal joint between the tibia and fibula.
Symphysis
The articulating bones are connected by a wedge or pad of fibrocartilage.
Example: The joint between the two pubic bones.
Diarthrosis
FREE MOVEMENT
Subdivided according to the movement permitted.
Example: Synovial joints
Monoaxial, biaxial, triaxial.
Monoaxial
Movement in one plane
Elbow, ankle
Biaxial
Movement in two planes
Ribs, wrist
Triaxial
Movement in three planes
Shoulder, hip
Synovial
Permits a wider range of motion than do other types of joints. They are typically located at the ends of long bones, such as those of the upper and lower limbs.
Flexion
Movement in the anterior-posterior plane that decreases the angle between the articulating bones.
Extension
Movement in the anterior-posterior plane that increases the angle between the articulating bones.
Hyperextension
Extension past the anatomical position
Abduction
Movement away from the midline of the body
Adduction
Movement towards the midline of the body
Circumduction
A movement in which the distal end of the bone moves in a circular direction, but the shaft does not rotate.
Supination
The palm is turned back over into anatomical position
Pronation
The palm is turned inwards towards the midline of the body
Elevation
Moves in a superior direction
Closing of the mouth
Depression
Moves in an inferior direction
Opening of the mouth
Inversion
Twisting movement of the foot that turns the sole inward, elevating the medial edge of the sole.
Eversion
Twisting movement of the foot that turns the sole back outward.
Dorsiflexion
Flexion at the ankle joint and elevation of the sole, as when you dig in your heel.
Plantar flexion
Extends the ankle joint and elevates the heel, as when you stand on your tiptoes.
Opposition
Movement of the thumb towards the surface of the palm or the pads of other fingers.
Reposition
Movement that returns the thumb and fingers from opposition
Protraction
Moving a body part anteriorly in the horizontal plane
Retraction
Moving a body part posteriorly in the horizontal plane
Lateral flexion
Occurs when your vertebral column bends to the side
Gliding Joint
Have flattened or slightly curved surfaces that slide across one another, but the amount of movement is very slight.
Examples: Intercarpal joint, verterbrocostal joint, sacroiliac joint
Hinge Joint
Permit angular motion in a single plane, like the opening and closing of a door
Examples: elbow joint, knee joint, ankle joint, interphalangeal joint
Condylar Joint
Have an oval articular face nestled within a depression on the opposing surface.
Example: Radiocarpal joint, metacarpophalangeal joint, metatarsophalangeal joint
Saddle Joint
Have complex articular faces and fit together like a rider in a saddle. Each face is concave along one axis and convex along the other.
Example: Thumb
Pivot Joint
Only permit rotation
Examples: Atlantoaxial joint (neck), proximal radioulnar joint
Ball-and-socket Joint
The round head of one bone rests within a cup shaped depression in another.
Example: Shoulder joint, hip joint
Oxygen debt results from:
Prolonged anaerobic metabolism
The correct anatomical name for the lower jaw is the mandible. True or False?
True
The organic component of the bone is primarily:
Collagen
The inorganic component of the bone is primarily:
Hydroxyapatite
Which of the following is NOT a part of the axial skeleton?
a. Hyoid
b. Ilium
c. Sternum
d. Sacrum
e. Ethmoid
Ilium
True or False: Serum calcium levels are elevated by vitamin D and calcitonin.
False
True or False: The articulating surfaces of bones are covered by fibrocartilage.
False; hyaline cartilage covers the articulating surfaces of the bones.
Muscle relaxation occurs when:
Calcium has returned to the sarcoplasmic reticulum
Skeletal Muscle Tissue
Cells are long, cylindrical, striated, and multinucleated.
Voluntary
Location of Skeletal Muscle Tissue
Combined with connective tissues and neural tissues in skeletal muscles.
Function of Skeletal Muscle Tissue
Moves or stabilizes the position of the skeleton
Guards entrances and exits to the digestive, respiratory, and urinary tracts
Generates heat
Protects internal organs
Cardiac Muscle Tissue
Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected with intercalated discs
Involuntary
Location of Cardiac Muscle Tissue
Heart
Functions of Cardiac Muscle Tissue
Circulates blood
Maintains blood pressure
Smooth Muscle Tissue
Cells are short, spindle-shaped, and nonstriated, with a single central nucleus.
Involuntary
Location of Smooth Muscle Tissue
Found in the walls of the blood vessels and in digestive, respiratory, urinary, and reproductive organs.
Functions of Smooth Muscle Tissue
Moves food, urine, and reproductive tract secretions
Controls diameter of respiratory passageways
Regulates the diameter of blood vessels
Striations
A series of ridges, furrows or linear marks
Sarcolemma
The plasma membra of a muscle cell
Sarcoplasmic Reticulum
Network of channels that runs the long axis of the muscle cell and stores calcium for muscle contraction
Myofibril
Runs the whole length of the skeletal muscle, composes each muscle, elongated, non-branching, subdivided into sarcomeres which are the contractile unit.
Myofilaments
Fine protein filaments composed primarily of the proteins actin (thin) and myosin (thick)
Myosin
The protein component of thick filaments
Actin
The protein component of microfilaments
that forms thin filaments in skeletal muscles and
produces contractions of all muscles through
interaction with thick (myosin) filaments
Canaliculi
Small channels in the lamellae that provide passageways through the solid matrix for diffusion of nutrients and wastes.
A Band
Broad dark band in middle of sarcomere
I Band
Broad light band on the ends of the sarcomere
M Line
In the center of the A band `
H Band
Lighter region on either side of the M line
Zone of Overlap
Dark region where thin filaments are located between the thick filament
Z Line
Bisects the I bands and mark the boundaray between adjacent sarcomeres
Steps in Muscle Contraction
- Excitation of fiber - the impusle comes to the cell
- Action potential comes to the t-tubule and into the cell from the t-tubule
- Calcium comes out of the sarcoplasmic reticulum and frees the actin binding sites.
- The cross bridge cycle
- Cessation of Contraction - muscle contraction stops when calcium is back in the sarcoplasmic reticulum, and the troponin moves back causing the tropomyosin to cover the binding sites returning the muscle to its original length.
Cross Bridge Cycle
- Phosphorylated myosin head attaches to an actin myofilament
- ADP and Phosphate ions are released from the myosin head. Myosin head changes to bend, low energy state. Shape change pulls the actin towards the M line.
- Cross bridge detachment - ATP attaches to myosin breaking the cross bridge
- Cocking of the myosin head - attached ADP is hydrolyzed by myosin ATPase into ADP + Phosphate ions, bringing it back to a high energy state.
Energy for Muscle Contraction
Creatine Phosphate reacted with ADP to created Creatine and ATP which is used for energy.
Glucose (from glycogen breakdown or delivered from blood) => 2 ATP, Pyruvic acid, and Lactic acid (which gets released to the blood)
Oxidation of Glucose - Pyruvic acid leads to aerobic respiration in mitochondria which splits into CO2, H2O and 38 ATP
Oxygen Debt
Blood vessels in muscles dilate and blood flow is increased in order to increase the available oxygen supply. Up to a point, the available oxygen is sufficient to meet the energy needs of the body.
Fatigue
Decline in ability of a muscle to generate force
Functions of Muscular System
- Movement
- Provides protection and support for other tissues
- Generate heat that maintains body temperture
