Transcript PP – Skeletal System

The Skeletal System
Anatomy & Physiology
OMHS
Learning Targets: I can…
• identify the skeletal subdivisions, major
bones, and joints of the human body.
• describe the functions of the skeletal
system.
• compare and contrast different types of
bone tissue and bone cells.
• explain homeostasis of the skeletal system.
• describe different skeletal disorders.
1. Support – provides framework,
supports soft tissues and provides
points of attachment for skeletal
muscles
2. Protection – internal organs are
protected by skeleton, ex. Heart
and lungs are protected by ribs
Functions - continued
3. Movement –
when muscles
contract, they pull on bones and
produce movement
4. Mineral Storage – homeostasis
mechanism that deposits and
removes calcium and phosphorus
on demand
Functions - continued
5. Blood Cell production – red
bone marrow produces blood
cells; a process called
hematopoiesis
6. Storage of energy – yellow bone
marrow stores lipids, an important
source of chemical energy
• Bones are grouped according to
their shape
1. Long – legs, toes, arms, fingers
2. Short- wrist, ankle
3. Flat – cranial, sternum, ribs,
scapulas
4. Irregular – vertebrae
• The matrix consists of mineral
salts (calcium phosphate and
calcium carbonate)
• Bone may be classified as
compact or spongy
• Compact Bone – dense layer of
bone containing Haversian canal,
lamellae (rings of matrix); between
lamellae are lacunae that house the
osteocytes.
• Spongy bone – has irregular
spaces that help reduce the weight
of the bone; the site of hemopoiesis
Hemopoiesis (or Hematopoiesis)
The process through which blood cells
are formed and differentiated into …
• red cells (erythrocytes) – most abundant
• white cells (leukocytes) – defense system
• platelets (thrombocytes) – clotting agents
• Diaphysis – shaft of bone; contains
compact bone surrounding yellow
marrow (fat storage)
• Epiphysis –ends of bone; made of
spongy bone (site of hematopoiesis)
• Periosteum- tough connective
tissue that covers the bone;
continuous with tendons and
ligaments
1. Osteoprogenitor cells (bone stem cells)
give rise to osteoblasts. (baby bone cell)
2. Osteoblasts - cells that form bone; when
they become isolated in the matrix, they
become mature bone cells (teenager)
Osteocytes – mature bone cells
(grandfather)
3. Osteoclasts - function in reabsorption of
bone (they destroy bone) (cut down bone)
• Osteoblasts lay down the osteiod matrix
(protein) in lamellae or layers.
• The calcified or hard salts of the matrix are
laid down later. The salts come from the
blood supply (Haversian canal) and move
through the lamallae using the canaliculi
(small tubes throughout matrix).
• Bone growth & hardening is stimulated by
stress. Therefore, exercise is important to
maintain bone health.
• Osteoclasts and osteoblasts are
constantly reforming and restructuring
bone; but the total mass of bone
remains fairly constant
• When the body needs calcium,
osteoclasts destroy bone to release
calcium into the bloodstream
• Therefore, you must include calcium
in your diet so that osteoblasts can reform bone
• Minerals – calcium and
phosphorus must be included in
the diet
• Vitamins – vit. D is required for
the absorption of calcium; vit. C
is required to maintain the matrix;
vit. A regulates bone remodeling
activity; vit. B12 may also help
Hormones needed for bone tissue activity:
1. Human growth hormone is responsible
for the growth of bones
2. Estrogen & testosterone aid in new
bone growth
3. Calcitonin promotes bone formation
and decreases blood calcium level
4. Parathyroid hormone increases blood
calcium level (promotes destr. of bone)
• Osteoporosis is caused when a person’s bone
density drops significantly.
• Osteoporosis happens when osteoclast activity is
greater than osteoblast activity.
• It is especially prevalent is post-menopausal
women because of the drop in estrogen.
• Treatments – increase in hormones such as
calcitonin, testosterone, & estrogen.
• Exercise is also beneficial because increases stress
on the bone which aids in bone development.
3 types of joints:
A.Fibrous- skull
B. Cartilaginousvertebrae
C. Synovialarticulating
bones
1.
2.
3.
4.
5.
6.
6 Different Types of
Synovial Joints:
Ball and socket (hip)
Ellipsoidal (metacarpals)
Gliding (wrist)
Hinge (elbow)
Pivot (ulna & radius)
Saddle (wrist & thumb)
• 1: Ball and socket joint;
• 2: Ellipsoid joint (Condyloid); 3: Saddle joint;
• 4 Hinge joint; 5: Pivot joint;
• When bone marrow is transplanted it is
taken from the donor during surgery using a
long needle inserted into the superior end of
the femur (2% of bone marrow is taken).
• The bone marrow is then given
intravenously (IV- through the vein) into the
circulatory system.
• The bone marrow then travels to the bones,
since it is a stem cell it replicates quickly
and takes root in all of the bones.