A+P Exam 2

“chondr-”

Cartilage

“osteo-”

bone

Functions of bones

• Support

• protection

• attachment point

• Storage

• blood cell formation

• hormone production

What do bones store

minerals and fats in yellow bone marrow

hematopoiesis

formation of red blood cells in red bone marrow

osteocalcin

a hormone produced by bones that regulates insulin release, glucose homeostasis and energy expenditure

Perichondrium

fibrous ct that surrounds skeleton in embryo, contains blood vessels for cartilage tissue, resists excessive outward expansion of cartilage

Three types of cartilage

• hyaline

• elastic

• fibrocartilage

hyaline cartilage

most abundant type, contains collagen fibers

fibrocartilage

contains rows of chondrocytes alternating with thick collagen bands

two types of cartilage growth

appositional growth and interstitial growth

appositional growth

laying down new cartilage on top of old cartilage, occurs at the surface of cartilage, causes cartilage to grow in width

interstitial growth

cells divide and secrete matrix within pre-existing cartilage, occurs deeper in cartilage tissue, causes cartilage to expand from within and grow in length

sesamoid bones

bones that form in a tendon

all bones contain an outer layer of ___ and an inner layer of ___

compact bone, spongy bone

spongy bone

has open spaces with needle-like pieces of bone called trabeculae, open spaces are filled with marrow, trabeculae is found in greatest concentration along lines of stress

Structure of flat, irregular, and short bone

Thin plate of spongy bone covered by compact bone, no large cavities for bone marrow (all bone marrow found around trabuculae)

Diaphysis

Shaft of long bones, composed of compact bone collar with internal medullary cavity (contains bone marrow), served by nutrient artery and nutrient vein

Epiphysis

Ends of long bones, compact bone externally and spongey bone internally, covered with articular cartilage

Periosteum

Membrane on long bones covering external bone surface except at bone ends

Endosteum

Membrane of long bones covering internal bone surfaces

Vascularization and innervation of long bones

nerve travels with blood vessels

Hemapoietic tissue

red bone marrow and yellow bone marrow

red bone marrow

produces red blood cells, in cranial skeleton, axial skeleton, and heads of femur and humerus

yellow bone marrow

medullary cavity of long bones, contains more fat and less blood supply than red bone marrow, can be converted back to red bone marrow

organic chemical composition of bone

cells and osteoid

inorganic chemical composition of bone

mineral salts (mostly calcium phosphate salts packed around collagen fibers)

Four primary types of cells responsible for bone growth

• osteoprogenitor cells

• osteoblasts

• osteocytes

• osteoclasts

osteoprogenitor cells

mitotically active cells, can change into osteoblasts

osteoblasts

bone forming cells, secrete unmineralized ecm/osteoid that forms bone tissue, secrete matrix until surrounded

osteocytes

mature bone cells, monitor and maintain bone matrix, respond to mechanical stress and chemical signals(calcium levels)

osteoclasts

secrete collagenase to break down collagen in bone matrix, bone degrading cells that maintain repair and remodel bones

Microscopic anatomy of compact bone features

• osteon

• central canals

• circumferential lamellae

osteon

structural unit of compact bone, helps withstand pressure, concentric circles with calcium salts inbetween

central canals

run thru center of each osteoblasts, contain nerve and blood vessels, connect neighboring osteons and medullary cavity

circumferential lamellae

wrap around osteons to form outermost layer of bone

Endochondral ossification

bone formation, hyaline cartilage is used as blueprint, occurs in most bones below the skull

step 1 of Endochondral ossification

formation of a poc (primary ossification center, in diaphysis center) and bone collar, osteoblasts lay down bone against cartilage diaphysis to form a collar

step 2 Endochondral ossification

cavity forms in diaphysis center, cavity cells in poc die off, cartilage outside of cavity grows to elongate bone

step 3 Endochondral ossification

formation of initial spongy bone in diaphysis, periostea bud invades cavity (bus contains nutrients and osteoblasts), osteoblasts secrete bone matrix inside cavity, initial formation of spongy bone is bone covered cartilage trabeculae

step 4 Endochondral ossification

formation of medullary cavity and elongation of diaphysis, spongy bone is broken down by osteoclasts to form medullary cavity, cartilage in remaining diaphysis is calcified broken down and replaced with bone, secondary poc is formed in epiphysis

step 5 Endochondral ossification

secondary ossification continues in epiphysis, similar to to primary ossification but spongy bone is retained in bone ends, still some areas with cartilage

bone growth in length

1) new cartilage laid down in epiphyseal plate, occurs on epiphyseal side

2) cartilage is calcified at center of plate

3) calcified cartilage is broken down by osteoclasts and osteoblasts lay down new bone tissue, occurs on diaphysial side

Bone growth in width

1) osteoblasts secrete new matrix at the periosteum

2) osteoclasts break down bone tissue at the endosteum

When bone growth stops in adolescence

re4amining cartilage in plate is calcified and replaced by bone, bone of diaphysis fuses with bone of epiphysis

Importance of bone remodeling

• maintenance of ca homeostasis (calcium is essential for excitability of cells)

• bone health

Two factors that control deposition and reabsorption

• parathyroid hormone, released in response to decreasing blood ca levels

• mechanical stress

effects of pth release

number of osteoclasts at bone increase and become more active, once blood ca returns to normal pth decreases

wolffs law

bones will remodel to adapt to mechanical stress

the more stress placed on a bone…

the more trabeculae will be found at that location and the thicker the compact bone will be

bone repair steps

1) hematoma forms

2) fibrocartilage callous forms

3) bony callus forms

4) bone remodeling occurs

Structural types of joints

fibrous, cartilaginous, and synovial

Functional types of joints

synarthroses (no movement), amphiarthroses (some movement), diarthroses (free movement)

Fibrous joints

Composed of collagen fibers of CT, no joint cavity present, mostly synarthroses and some amphiarthroses

Types of fibrous joints

• Sutures

• Sydesmoses

• Gomphoses

Sutures

Bundles of extremely strong and short collagens fibers

Syndesmoses

Bones connected only by ligaments

Gomphoses

Periodontal ligament joins bone to tooth, fibers of joint are short and limit movement

Cartilaginous joints

bones joined by cartilage, synarthroses or amphiarthroses

• synchondroses (hyaline cartilage, mostly synarthroses)

• Symphyses (fibrocartilage, mostly amphiarthroses)

Synovial joints

diarthroses, possess a joint cavity, most joints in body and almost all in appendicular skeleton

six structures in synovial joints

• articular cartilage

• joint cavity

• articular capsule

• synovial fluid

• reinforcing ligaments

• innervation and vascularization

articular capsule

two layered capsule that encloses joint cavity, outer fibrous layer and inner synovial membrane

When joint is active, synovial fluid becomes

watery

Structures associated with synovial joints

bursae and tendon sheath

bursae

flattened sacs that contain a little synovial fluid, reduce friction

tendon sheath

elongated bursa that wraps around a tendon, prevents excessive friction for a particular tendon

Three factors influencing joint stability

articular surfaces, ligaments, and muscle tone

Movement allowed by synovial joints

• non axial movement

• uniaxial movement

• biaxial movement

• multiaxial movement

Non axial movement

gliding movement, plane joint

uniaxial movement

flexion/extension and rotation movement, hinge and pivot joint

biaxial movement

flexion/extension and adduction/abduction movement, condylar and saddle joint

multiaxial movement

flexion/extension abduction/adduction and rotation movement, ball and socket joint

Temporomandibular joint

• hinge joint

• articular disc divides synovial cavity into superior and inferior portions

• superior - allows later excursion

• inferior - allows elevation and depression

Glenohumeral joint

• mostly freely moving joint in the body

• reinforcing ligaments are very thin and loose

• glenoid labum - rim of fibrocartilage providing stability

elbow joint

• stability provided by trochlea/trochlear notch, muscle and tendon of arm muscles, and ulnar collateral ligament/radial collateral ligament

coxal joint

• stability provided by articular surfaces and strong ligaments

knee joint

• single joint cavity shared by 3 separate joints: femoropatellar joint, medial and lateral tibiofemoral joint

• Stabilized by menisci and intrascapular ligaments (anterior and posterior cruciate ligaments)

Acute form of arthritis

bacterial and inflammatory

chronic arthritis

inflammatory and degenerative

Osteoarthritis

• most common form of chronic

• more articular cartilage is being destroyed than replaced, exposed bone rubs together

Rheumatoid arthritis

• autoimmune chronic inflammatory disporder, bilateral condition

• joints of fingers, wrists, ankles, and feet

• synovial membrane becomes inflamed, lymphocytes and macrophages flood area to destroy cause of inflammation, synovial fluid accumulates and a pannus forms

Functions of the NS

• Sensory input

• Integration (processing and interpreting info)

• Motor output

Neuroglia

cell that provides support and maintenance to neurons

Types of neuroglia

• Astrocytes

• microglial cells

• ependymal cells

• satellite cells

• oligodendrocytes

• schwann cells

astrocytes

• cns

• projections from membrane surface connect to and wrap around neurons, nerve endings, and surrounding blood capillaries

• provide nutrients to neurons, allows migration of young neurons, clean up surrounding neurons

microglial cells

• cns

• contact nearby neuron cells to monitor neuron health

• migrate towards injured neurons and transform into a macrophage and phagocytize the neuron

ependymal cells

• cns

• most have cilia

• lines central cavities of cns to circulate csf

satellite cells

• pns

• support and protect neurons

oligodendrocytes and schwann cells

• oli are cns, schwann are pns

• wrap around nerve fibers

• create myelin sheath, insulate neurons

Characteristics of neurons

longevity, amitotic (don’t undergo mitosis), metabolism

ganglia

cluster of cell bodies in pns

axon

conducting region of neuron, transmits neurons away from cell body, bundles in cns are called tracts, bundles in pns are called nerves

afferent/sensory neuron

transmit signals to cns

efferent/motor neuron

transmit motor signals away from cns and towards effector organs

interneuron

found in between sensory and motor neurons, pass signals through cns pathways where integration occurs

what’s required to change the permeability of the plasma membrane to or more ions

the use of ion channels in the plasma membrane

types of electrical signals that can be produced by a change in resting membrane potential

graded potential and action potential

Depolarization

when the inside of the cell becomes more positively charged compared to the rmp, excites a neuron

hyperpolarization

when the inside of the cell become more negatively charged compared to the rmp, inhibits a neuron

graded potential

• graded mean magnitude varies directly with the stimulus strength

• only occur over short distances

• can be depolarizing or hyperpolarizing

• necessary to initiate a nerve impulse