Do Now
• Use the Socrative App to answer the
questions!
• Room # 981663
Objectives
1. Identify the different structures and fuctions
of the Skeletal system.
2. Label a long bone and internal structures of
bone.
3. Explain bone development and growth.
4. Apply knowledge of homeostatic
mechanisms to explain the regulation of
blood calcium levels.
Skeletal System
Chapter 7
Skeletal System
Components
• Bone
• Tendons- connect
bones to muscle
• Ligaments- connect
bones to bones
Functions
• Muscle attachment
• Protection
• Contain blood-producing
cells
• Storage of inorganic salts
• Passageway for nerves &
blood vessels
Bone Classification
• Long
• Ex:
– Humerus
– Femur
– Ulna
– Radius
– Clavicle
– Phalanges
Bone Classification
• Short
– Wrist bones
– Foot bones
Bone Classification
• Flat
Bone Classification
• Irregular
Bone Classification
• Sesmoid
Long Bone Anatomy
Microscopic Structure
• Compact (Cortical)
Bone: osteocytes and
layers of ECM are
concentrically clustered
around a Haversian
Canal (Osteon).
– Haversian Canals contain
blood vessels and nerve
fibers which nourish the
bone cells.
Microscopic Structure
Bone Development
• Intramembranous
Bones:
– Originate between
sheetlike layers of
connective tissue.
• Endochondral Bones:
– Begin as masses of
cartilage that bone tissue
replaces.
Bone Development
• Bone Development Animations
• Bone Development Explanation (YouTube)
Bone Development
• Intramembranous Ossification:
1. Connective tissue appears a the sites of future
bones.
2. Connective tissue cells differentiate into osteoblasts.
3. Osteoblasts deposit bony material around
themselves and form spongy bone.
4. Membranous tissue cells give rise to the periosteum.
5. Osteoblasts inside the periosteum form compact
bone.
Bone Development
• Endochondral Ossification (Condensed Version):
1.
2.
3.
4.
5.
6.
7.
Cartilage breaks down in the center of the diaphysis. (primary
ossification center)
Periosteum forms around the developing dipahysis from connective
tissue.
Blood vessels and osteoblasts from periosteum invade the cartilage and
form spongy bone.
Epiphysis remain cartilaginous and later secondary ossification centers
appear and form spongy bone.
Epiphyseal plate undergoes mitosis and produces new cells which
enlarge , while calcium salts accumulate in the extracellular matrix, they
calcify, and the cartilage cells die.
Osteoclasts secrete acid that dissolves part of the calcified matrix and
osteoblasts deposit new bone tissue in place of the calcified cartilage.
Bone continues to grow at the epiphyseal plate until adulthood.
Endochondral
Ossification
Do Now
• Complete the questions using Socrative (you
will get participation points for this so make
sure you do it! Use someone’s phone when
they are done or the computer if necessary)
Objectives
• To explain the different functions of bone in
detail.
• To apply your knowledge of homeostasis and
negative feedback loops to explain hormonal
regulation of bone calcium resorption and
deposition.
7.4- Bone Function
• Aside from movement and protection, bones
are involved in…
– Red blood cell formation
– Storage of inorganic salts
Hematopoiesis
• Hematopoeiesis=Red blood cell formation
• RBC’s form in the liver, spleen, and bone marrow
– Red Marrow:
• Found in infants as well as in spongy bone of skull, ribs,
sternum, clavicles, vertebrae, and hip bones of adults
• Produces red blood cells (erythrocytes), white blood cells
(leukocytes), and platelets.
– Yellow Marrow:
• In adults
• Stores fat
• *doesn’t produce RBC’s
Inorganic Salt Storage
• ECM of bone is rich in calcium
• Calcium is required for muscle contraction,
nerve impulse conduction, blood clotting, and
other physiological processes.
• Our bodies must maintain a sufficient bloodcalcium level using a homeostatic mechanism.
Calcium Regulation
• How is calcium regulated?
Calcium Regulation
Low calcium levels
• Causes Parathyroid Hormone (PTH) to be
released
– PTH causes stored calcium in bone to be released
– PTH causes calcium reabsorption in the kidney
(not excreted in urine)
– PTH causes the synthesis of Vit. D. which increases
Ca+ absorption in the small intestines.
High calcium levels
• Causes the release of calcitonin from the
thyroid gland
– Calcitonin Inhibits Ca2+ absorption by the
intestines
– Inhibits osteoclast activity in bones
– Inhibits renal tubular cell reabsorption of Ca2+
allowing it to be excreted in the urine
Hypo vs. Hypercalcemia
• Hypocalcemia: can cause muscle stiffness and
seizures
• Hypercalcemia: too much calcium, causes
kidney stones or even kidney failure, could
cause heart problems
Quiz on Friday!
• There will be a quiz on 7.1-7.4 on Friday. This
will include the main bones of the skull as well
as the notes we have covered so far.
• #’s 1-13 (not the features just bones!)
Do Now
• If you have not done so already, complete the
quiz on socrative!
• If you have already completed it, come up
with 3 questions you might see on your quiz
that you did not see on the practice quiz.
Objectives
• To Identify the major bones of the skull.
• To label the major features of the bones of the
skull.
The Skull!!
Frontal Bone
Parietal Bone(s)
Occipital
Temporal
Ethmoid
Sphenoid
Mandible
Maxilla
Zygomatic
Volmer
Palatine
Nasal
Lacrimal
Hyoid
Coloring Activity
• *Color all of the bones that we just covered!