Do Now• Use the Socrative App to answer the

questions!• Room # 981663

Objectives1. 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. Cartilage breaks down in the center of the diaphysis. (primary ossification center)

2. Periosteum forms around the developing dipahysis from connective tissue.3. Blood vessels and osteoblasts from periosteum invade the cartilage and

form spongy bone.4. Epiphysis remain cartilaginous and later secondary ossification centers

appear and form spongy bone.5. 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.

6. Osteoclasts secrete acid that dissolves part of the calcified matrix and osteoblasts deposit new bone tissue in place of the calcified cartilage.

7. 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 blood-calcium 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

(The Orange)

Sphenoid

Mandible

Maxilla

Zygomatic

Volmer

Palatine

Nasal

Lacrimal

(The Green)

Hyoid

Coloring Activity• *Color all of the bones that we just covered!