module 9 Flashcards
Functions of the Skeletal System
Support ( framework attachment for tendons and ligs), protection( protects internal organs), movement, mineral homeostasis (blood calcium and phosphate, storing and releasing mins), hemtopoesis, Fat storage(triglycerides)
Skeletal System is What type of tissue?
Connective
Osteogenic Cell
bone stem cell and is the precursor to all other cell types
Osteoblasts:
Osteoclasts:
Osteoblasts: Dividing cells. BUILDING BONE secretes organic stuff, collagen, protein, carbohydrates
Osteoclasts: Constantly tunnel through bone, dissolving bone matrix. BREAKING BONE. or bone chewing
Osteocytes:
fill spaces in bone and maintain bone integrity
Osteogenis:
formation of bone
Bone has two components:
Inorganic:
Organic:
inorganic: this portion of bone is primarily a mineral called hydroxyapatite. a compound of calcium, phosphate and hydroxyle groups.
ORGANIC: mostly made of collagen type I. several minor proteins in the organic portion of bone.
Side note: you need both of these working together to have bone. mineral alone is to brittle, organic alone is to flexible
having mineral alone in bone create what disease?
Having organic alone is too flexible and creates what disease?
Mineral alone: OSTEOGENISIS IMPERFECTA
Organic alone: RICKETS OF OSTEOMALACIA
Where do Osteocytes live?
What is the job of the Canaliculi?
Osteocytes: live In the Lacuna
Canaliculi: pathway to communication. joins adjacent lacunae
Compact Bone:
Spongy Bone:
gives bone its strength. hard dense tissue provides structural support.
Spongy Bone:usually in the center of a long bone like the femur.
Osteon:
Lamellae
basic structural unit of compact bone
Lamellae: each osteon consists of a series of concentric rings called lamellae.
Central canal or Haversian Canal:
Perforating Canals:
canal that runs the length of the bone. CARRYING BLOOD AND LYMPHATIC VESSLES.
Perforating Canals: run radially in long bones to join adjacent central canals
Spongy Bone:
found in the marrow cavity of long bones.
- red bone marrow: where blood cells are made- hamatopoiosis.
- yellow bone marrow: storage of energy as fat
MADE OF TRABECULAE.
* structure- loosely organized rings, with lacunae containing osteocytes and with canaliculi connecting the lacunae
hematopoiesis
Trabeculae:
hematopoiesis: a process where blood cells are born.
Trabeculae: loosely organized layers form spiky projections in spongy bone called trabeculae (osteoclasts and blasts are found around the outside of trabeculae)
Cartilage functions:
forming flexilbe skeletal structures, joining bones at synarthroses (nearlyimmovable joints between bones), linging joint surfaces in synovial joints (freely moveable joints)
Hyaline Cartilage:
glass like shiny and translucent. Most cartilage in body is hyaline cartilage.
Fibrocartilage:
more fibrous in appearance and structure. chondrocytes are found in lacunae; the ground substance hsa collagen fibers running through it. found in the disks of the vertebrae in pubic symphysis and in meniscus of joints. STRONG
elastic cartilage:
has elastin fibers in place of the collagen fibers. found in the ear and epiglittis, two structures that need to be flexible and snap back into shape when moved and released.
Ligamenets:
bone to bone. band like structures that strap one bone to bone.
Dense regular connective tissue is found where?
ligaments and tendons. has a Striated appearance due to oriented collagen fibers
Dense irregular connective tissuei n the skeletal sytem is what?
Periosteum. a thin membrane that surrounds all bones. it has a rich blood supply. participates in bone repair. and has many nerve endings. SOURCE OF BOTH BLOOD AND PAIN. not on articulating surfaces.
Long bone features and location:
longer than they are wide. 3 regions: Epipysis(knobby ends of bone and form joint surfaces.) near articular sufaces. 2.in the diaphysis (middle part of bone or the SHAFT) 3. metaphysis: the transitional between the epiphysis and diaphysis.
Epiphysis (long bone feature)
& Epiphysis plate: & Epiphysis Line.
knobby ends of the bone. nearest articulating surfaces. The Epiphysis has a specialized regions inside called the epiphysis plate. this is the SITE OF BONE GROWTH in youth ( the epiphyseal plate is in charge of the human growth hormone meaning when it is present bone can grow when levels drop the plates close or become mineralized) and in adults It is a remnant of the plate called an EPIPHYSEAL LINE.
Endochondral bone formation:
this is the process by which bone growth occurs. (COMMON IN LONG BONES) this bone formation uses a cartilage bone model to shape the bone it is eventually replaced with compact or spongy bone. (in fetuses and many children many of the future bones are completely cartilaginous. ( will only take place if human growth hormone is present)
Primary ossification center:
Secondary ossification center:
primary ossification center: appears in the center of the forming bone, where diaphysis will be.
Secondary Ossification Center: will develop near the joint surface. Develops in Epiphysis.
BOTH ossification centers expand; the leftover region of cartilage between these is where the epiphyseal plate lies.
Angeogenis:
Laying down blood vessels
Epiphyseal plate:
Increases the length of long bones until the Pituitary stops the human growth hormone.
Intramembranous Bone Formation
Intramembranouse bone formation in bones of skull and other flat bones (mandilbe clavical) Spongy bone is formed in the center. compact bone eventually develops around edges. again future bone begins as cartilaginos model. but instead of primary and secondary ossification, there are MULTIPLE OSSIFICATION CENTERS. start as “islands” and spread out father. as they spread they form spongy bone.
Osteoblasts and Osteoclasts:
osteoclasts: constantly travel through bone, using acid to dissolve mineralized matrix and enzymes to dissolve organic matrix.
Osetoblasts: follow behind rebuilding bone. In this way bone is constantly remodeled.
What happens if osteoblastic activity is greater than osteoclastic activity?
calcium is deposited into inorganic matrix, bone becomes thicker and stronger
what happens if osteoclastic activity is greater than osteoblastic activity?
calcium is realeased from inorganic matrix into blood stream. bone become thinner and weaker.
Hormonal Control of bone includes what? (what hormones)
Parathyroid hormone (PTH) stimulates osteoclasts. (INCREASES blood calcium) Calcitonin (CT): stimulates osteoblasts. (DECREASE blood calcium) inhibits osteoclasts, decreases blood Ca++, increases bone formation
if blood calcium falls to low, hormones are used to stimulate brekdown of inorganic matrix. (hydroxyapatite, Ca10 (PO4)6(OH)2) this releases calcium into bloodstream. increased blood calcium levels turn hormonal switch off.
A third Hormone, what?
Calcitriol- not directly involved with bone. PTH stimulates kidneys to release calcitriol which increases absorption of ca++ from food.
Normal blood calcium is what>
8.5-10.2 mg/dl
Vitamin D in hormonal control of bone
vitamin D, important in intestinal absorption of Ca++. in the absence of Vitamin D, blood Ca++ levels drop and bones become soft and flexible. In children, RICKETS (soft bones) results from lack of Vitamin D.
Rickets:
when the organic, collagen part of bone is still made, and the resulting bones are soft and pliable. this produces that characteristic of bent bones.
Osteomalacia:
The inability to form mineralized bone called osteomalacia. may result from metabolic distrubances, cancer, or cancer chemotherapy. Scans show radioactive 99TC concentrating in areas that are making organic(collagen) bone matrix but not the inorganic.
Osteoporosis:
holes in the bone, weak bones. may be from low levels of HGH and with calcium absorption and homeostasis.
