Bone&BioMechanics

Question 1

What does appositional bone growth involve?

Answer 1

The periosteum and the endosteum

Appositional bone growth involves two bone coverings: the periosteum on the outside and the endosteum on the inside.

Question 2

How does the diameter of a bone enlarge?

Answer 2

Through appositional growth at the outer surface

In this process, osteogenic cells in the inner layer of the periosteum produce daughter cells that differentiate into osteoblasts.

Question 3

What do osteoblasts do during appositional growth?

Answer 3

Add bone matrix to the surface

Osteoblasts produce bone matrix and are trapped between circumferential lamellae, differentiating into osteocytes.

Question 4

What are circumferential lamellae?

Answer 4

Successive layers of bone added to the outer surface

These layers are produced by osteoblasts during appositional growth.

Question 5

What happens to the deeper lamellae over time?

Answer 5

They are recycled and replaced with osteons

Osteons are typical of compact bone.

Question 6

What role do osteoclasts play during appositional growth?

Answer 6

Remove and recycle lamellae at the inner surface

This process allows the medullary cavity to enlarge as the bone increases in diameter.

Question 7

Fill in the blank: As a bone increases in diameter, the _______ gradually enlarges.

Answer 7

medullary cavity

Question 8

What is the primary function of osteogenic cells in appositional growth?

Answer 8

Produce daughter cells that differentiate into osteoblasts

These cells contribute to the formation of new bone matrix.

Question 9

True or False: Appositional growth only occurs on the inner surface of the bone.

Answer 9

False

Appositional growth occurs at the outer surface, while osteoclasts work on the inner surface.

Question 11

What is the periosteum?

Answer 11

The periosteum is a superficial layer of compact bone that covers all bones, consisting of a fibrous outer layer and a cellular inner layer.

It isolates the bone from surrounding tissues and provides routes for blood and nerve supply.

Question 12

What are the three functions of the periosteum?

Answer 12

• Isolates the bone from surrounding tissues
• Provides a route for blood and nervous supply
• Actively participates in bone growth and repair

These functions are crucial for maintaining bone health and integrity.

Question 13

What are perforating fibers?

Answer 13

Perforating fibers are collagen fibers from tendons, ligaments, and joint capsules that are cemented into the circumferential lamellae by osteoblasts from the periosteum.

This attachment method is extremely strong.

Question 14

What happens when there is excessive pull on a tendon or ligament?

Answer 14

An excessive pull on a tendon or ligament will usually break a bone rather than snap the collagen fibers at the bone surface.

This illustrates the strength of the attachment between the bone and surrounding structures.

Question 15

What does the endosteum line?

Answer 15

The endosteum lines the medullary cavity and covers the trabeculae of spongy bone.

It is an incomplete cellular layer that is active during bone growth, repair, and remodeling.

Question 16

What is the primary composition of the endosteum?

Answer 16

The endosteum consists of a simple flattened layer of osteogenic cells that covers the bone matrix, generally without any intervening connective tissue fibers.

This structure allows for direct interaction with the bone matrix.

Question 17

Where do osteoclasts typically occur?

Answer 17

Osteoclasts generally occur in shallow depressions called osteoclastic crypts or Howship’s lacunae that they have eroded into the matrix.

This highlights the role of osteoclasts in bone resorption.

Question 18

What is appositional bone growth?

Answer 18

Appositional bone growth is the process that increases the diameters of existing bones but does not form the original bones.

It involves the addition of new bone tissue to the outer surface.

Question 19

When does bone formation begin during embryonic development?

Answer 19

Bone formation begins roughly 6 weeks after fertilization when the embryo is 12 mm (0.5 in.) long.

This marks a critical phase in skeletal development.

Question 20

What are the two major processes involved in bone formation?

Answer 20

• Endochondral ossification
• Intramembranous ossification

These processes are essential for the development of the skeletal system.

Question 21

True or False: The periosteum is involved in bone growth and repair.

Answer 21

True

It actively participates in these processes, making it vital for bone health.

Question 22

Fill in the blank: The _______ is an incomplete cellular layer that covers the medullary cavity.

Answer 22

[endosteum]

The endosteum plays a key role in bone remodeling.

Question 25

What is the study of tissues called?

Answer 25

Histology ## Footnote Histology is the microscopic study of tissue structure and function.

Question 26

Define a tissue.

Answer 26

Collections of similar cells and cell products that perform specialized functions. ## Footnote Tissues are formed by cells working together for a specific purpose.

Question 27

What are the four basic types of tissue?

Answer 27

* Epithelial tissue * Connective tissue * Muscle tissue * Nervous tissue ## Footnote These tissue types are essential for the structure and function of the body.

Question 28

What are the functions of epithelial tissue?

Answer 28

* Covers exposed surfaces * Lines internal passageways and chambers * Forms secretory glands ## Footnote Epithelial tissue plays a crucial role in protection and secretion.

Question 29

What does connective tissue do?

Answer 29

* Fills internal spaces * Provides structural support * Stores energy ## Footnote Connective tissue is vital for maintaining the body's structure and energy reserves.

Question 30

What is the primary function of muscle tissue?

Answer 30

Contracts to produce movement. ## Footnote Muscle tissue includes skeletal, cardiac, and smooth muscle types.

Question 31

What is the role of nervous tissue?

Answer 31

Conducts electrical impulses and carries information. ## Footnote Nervous tissue is essential for communication within the body.

Question 32

Fill in the blank: The human body contains trillions of cells, but only about _______ different types of cells.

Answer 32

200 ## Footnote This diversity allows for specialization in functions across different tissues.

Question 33

What is the tissue level in the organization of the human body?

Answer 33

Tissues are formed from cells working together. ## Footnote Tissues are a higher level of organization than cells and represent a collection of similar cells.

Question 34

True or False: Histologists can identify some tissues without using a microscope.

Answer 34

True ## Footnote Based on laboratory experiences, some tissues may be recognizable to trained individuals.

Question 35

What are the three types of muscle tissue?

Answer 35

* Skeletal muscle * Cardiac muscle * Smooth muscle ## Footnote Each type of muscle tissue has distinct functions and locations in the body.

Question 36

What is microscopy?

Answer 36

The use of microscopes to study cells and tissues ## Footnote Microscopy began about 400 years ago.

Question 37

What types of microscopes were invented 400 years ago?

Answer 37

* Simple microscopes with one lens * Compound microscopes with more than one lens ## Footnote These early light microscopes had limited magnification capabilities.

Question 38

What is the maximum magnification of a typical light microscope in a lab?

Answer 38

Up to 1000 times ## Footnote This is the maximum magnification achievable when using light.

Question 39

What can modern electron microscopes magnify up to?

Answer 39

Over 1 million times ## Footnote Electron microscopes use beams of electrons instead of light.

Question 40

What does 'resolution' refer to in microscopy?

Answer 40

The amount of fine detail that can be seen in an image ## Footnote Resolution varies with magnification and the type of microscope used.

Question 41

List the approximate magnification for a human heart using a microscope.

Answer 41

× 100 ## Footnote This is an example of the magnification range for different objects.

Question 42

What is the approximate magnification for a red blood cell?

Answer 42

× 1000 ## Footnote This indicates the level of detail visible for red blood cells.

Question 43

What is the approximate magnification for a mitochondrion?

Answer 43

× 100,000 (10^5) ## Footnote This level of magnification allows for viewing of cellular organelles.

Question 44

How do early microscopes compare with modern microscopes in terms of magnification?

Answer 44

Early microscopes magnified objects only 10 to 20 times actual size ## Footnote Modern microscopes offer significantly higher magnification capabilities.

Question 45

What is the size range for viruses in nanometers?

Answer 45

Typically in the range of nanometers (nm) ## Footnote This indicates the small size of viral particles compared to cells.

Question 46

Fill in the blank: The unaided human eye cannot see objects smaller than _______.

Answer 46

[key learning term] ## Footnote This emphasizes the limitations of human vision in anatomical studies.

Question 47

What is a compound light microscope?

Answer 47

An optical instrument that directs visible light through a thin section of tissue.

Question 48

How is total magnification calculated in a compound light microscope?

Answer 48

By multiplying the magnification of the objective lens times that of the ocular lens.

Question 49

What is the maximum resolution of a light microscope?

Answer 49

About 200 nm (0.2 m).

Question 50

What does the resolution of a microscope measure?

Answer 50

The ability to distinguish between two separate points or objects.

Question 51

What is a transmission electron microscope (TEM)?

Answer 51

A microscope that uses magnets to direct a beam of electrons through a finely sectioned object.

Question 52

What is the maximum resolution of a transmission electron microscope?

Answer 52

About 0.2 nm (0.0002 um).

Question 53

What distinguishes a light micrograph (LM) from a transmission electron micrograph (TEM)?

Answer 53

A light micrograph is taken with a light microscope, while a TEM provides sharper details of cells and organelles.

Question 54

What is the key difference in specimen preparation between scanning electron microscopy (SEM) and TEM?

Answer 54

SEM specimens are not sectioned and are coated with an electron-dense material.

Question 55

What type of image does a scanning electron microscope produce?

Answer 55

A three-dimensional image of the specimen.

Question 56

What is the maximum resolution of a scanning electron microscope?

Answer 56

About 10 nm (0.01 um).

Question 57

What is the first step when using a compound light microscope?

Answer 57

Begin by using the objective lens with the lowest magnifying power.

Question 58

Fill in the blank: The image taken with a scanning electron microscope is called a _______.

Answer 58

scanning electron micrograph (SEM).

Question 59

If the LM is magnified 400 times (400x) and the ocular lens is 10x, what is the magnification of the objective lens?

Answer 59

40x.

Question 60

What type of image is created when a specimen is bombarded with electron beams in SEM?

Answer 60

A three-dimensional image.

Question 61

What is the role of the ocular lens in a compound light microscope?

Answer 61

To further magnify the image after it has been magnified by the objective lens.

Question 62

True or False: The wavelength of the electron beam in a TEM is larger than that of ordinary white light.

Answer 62

False.