Human Anatomy Midterm Review

Question 1

Describe the importance of a standard anatomical position.

Answer 1

A standard anatomical position is a universal position or common point of reference for all who study the human body.

It allows all who study the body to discuss the parts of the body within the same frame of reference and experience.

Question 2

What is the standard anatomical position?

Answer 2

The person is:

• standing upright
• facing the observer
• feet flat on the floor
• arms to the sides
• palms turned and facing forward (supinated)

Question 3

What are the major planes and what type of section do they produce?

Answer 3

The major planes are:
Sagittal Plane, Frontal Plane, Transverse plane/Horizontal/Cross-sectional
The sagittal plane produces left and right sections.
The frontal plane produces anterior and posterior sections.
The transverse plane produces superior and inferior sections.
Parasagittal - uneven sections
Midsaggital/median - even halves

Question 4

Describe the structure of a serous membrane. Identify the location of the 3 serous membranes of the body.

Answer 4

Serous membranes are thin membranes that line body cavities not open to the outside (ventral body cavities).
Composed of simple squamous epithelium called the mesothelium.
Serous membranes are composed of two continuous layers; the parietal and visceral layer.
The parietal layer lines the walls of cavities.
The visceral layer covers the viscera within these cavities.
The serous fluid in the space between the two layers reduces friction and allows the membranes to slide past each other.

Location:
Pleural cavity
- Parietal pleura - lines the thoracic cavity
- Visceral pleura - covers the lungs

Pericardial cavity

• Parietal pericardium - lines the pericardial sac
• Visceral pericardium - covers the heart

Peritoneal cavity

• Parietal peritoneum - lines abdominal wall
• Visceral peritoneum - covers the abdominal viscera

Question 5

How is epithelial tissue classified?

Answer 5

Epithelial tissue is classified by the number of layers, simple (1 layer) or stratified (2 or more layers) and, by the shape of the cells constituting the epithelium. These can be squamous, cuboidal or columnar.
The first name designates the number of layers, the second name designates the cell shape.
Squamous - flat
Cuboidal - cube shape
Columnar - column shaped
Furthermore, when it comes to stratified epithelia, the second name is based on the cell type on the superficial surface.
Finally, stratified can also be keratinized or non-keratinized, indicated at the beginning of the name.

Question 6

Name the 6 special characteristics of epithelial tissue.

Answer 6

1 - Highly cellular
2 - Overlying connective tissue
3 - Avascular but innervated
4 - High capacity for regeneration
5 - Polarity
6 - Specialized contacts

Question 7

Contrast simple epithelia with stratified epithelia.

Answer 7

Differences:
Simple epithelium consists of only a single layer of cells, stratified epithelia is composed of multiple layers, 2 or more.

Simple epithelium has a function more suited for filtration, diffusion, lining viscera, secretion and absorption and propelling substances across membranes.
-Stratified epithelium has a function more suited for protection.

Stratified epithelia is more durable than simple epithelia

Simple epithelium is found lining the alveoli, as mesothelium and endothelium.
Stratified epithelium is found in locations subject to abrasion.

All the cells of simple epithelia are attached to the basement membrane
- Only the basal cells of stratified epithelia are attached to the basement membrane

All the cells of simple epithelium are the same (usually)
- Cells can be different throughout stratified epithelia

Question 8

Why is areolar connective tissue considered to be the main battlefield in the fight against infection?

Answer 8

Areolar connective tissue underlies all epithelial tissue and is thus the first line of defense between the epithelial tissue and the blood stream.
Furthermore, areolar connective tissue contains multiple cells involved in immunity, including macrophages, WBC’s and mast cells of the inflammation response.
Moreover, they contain all three fibre types (collagen, elastic, reticular) which function as a mesh to slow down the travel of invading microbes.

Question 9

Compare and contrast dense regular and dense irregular CT.

Answer 9

Similarities (Compare):
Both derive from a similar embryonic origin (mesenchyme)
Both are a subset of CTP; Both are dense connective tissues.
Both contain fibroblasts and some elastic fibres
Both are connective tissues and thus are composed mostly of ECM rather than cells
Both are primarily composed of collagen fibres

Differences (Contrast):
Dense regular connective tissue consists of collagen fibres primarily arranged parallel to each other.
Dense irregular connective tissue on the other hand has collagen fibres arranged in perpendicular irregular arrangements.

Dense regular connective tissue is adapted to handle stress in only one direction
Dense irregular CT is adapted to handle tension in multiple directions.

Dense regular CT is poorly vascularized.
Dense irregular CT is vascularized.

Dense regular CT is found in ligaments and fascia.
Dense irregular CT is found in articular capsules.

Both have fibroblasts and some elastic fibres.

Question 10

What do the 3 types of cartilage have in common? Name 1 location in the body where each would be found.

Answer 10

The three types of cartilage are: Fibrocartilage, Hyaline cartilage, Elastic cartilage.
They have the following in common:
- ECM is composed mostly of water (60-80%)
- Ground substance is gel-like
- Firm, flexible tissue
- Avascular and non-innervated
- Cell types are chondrocytes and chondroblasts

Fibrocartilage - pubic symphysis, intervertebral discs
Elastic cartilage - pinna of ear, epiglottis
Hyaline cartilage - articular cartilage, fetal skeleton

Question 11

What type of CT underlies the epithelia in a mucous membrane? What is its specific name?

Answer 11

Areolar connective tissue.

Specifically named: lamina propria

Question 12

Name the five strata in the epidermis, from top to bottom.

Answer 12

Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

Question 13

Describe, in detail, the stratum corneum.

Answer 13

23-30 cell layers thick of flat, dead keratinocytes filled with keratin
Cells are continuously shed
Topmost layer of skin
Protects the skin against abrasion and penetration

Question 14

Describe, in detail, the stratum lucidum.

Answer 14

Composed of a few layers of flat, dead keratinocytes.
Only present in thick skin of the soles of the feet and palms of the hands.
See through under microscope.

Question 15

Describe, in detail, the stratum granulosum.

Answer 15

1-5 cell layers of flat, dying keratinocytes
Third deepest skin strata
Contains lamellar granules that release waterproofing glycolipid

Question 16

Describe, in detail, the stratum spinosum.

Answer 16

8-10 layers thick
Contains thick bundles of intermediate filaments
Contains star-shaped Langerhan’s (macrophages) cells
Some mitotic division occurs here
Melanocytes are found here
Second deepest strata

Question 17

Describe, in detail, the stratum basale.

Answer 17

Deepest strata
Single layer of youngest keratinocytes that actively divide to replenish above cell layers
Receives nutrients and gases and removes wastes with the blood supply of underlying connective tissue
Attached to underlying dermis by dermal papillae
Contains some melanocytes

Question 18

Name 1 function of the papillary layer and 1 function of the reticular layer of the dermis.

Answer 18

Papillary layer:

• contains dermal papillae which function to provide a blood supply for the overlying epidermis and increase surface area for exchanges and attachment between the two layers.
• composed of areolar connective tissue
• 20%

Reticular layer:

• 80%
• Composed of dense irregular connective tissue with interlacing collagen and elastic fibres
• this layer functions to provide the elasticity, strength, recoil and extensibility of the skin

Question 19

What connective tissue is found in hypodermis?

Answer 19

Areolar CT

Adipose CT

Question 20

Compare and contrast osteoblasts, osteocytes and osteoclasts.

Answer 20

Osteoblasts:

• bone forming cells
• do not divide
• secrete matrix and collagen fibres
• initiate calcification
• once surrounded by their secretions, differentiate into osteocytes

Osteocytes:

• do not undergo cellular division
• mature cells that no longer secrete matrix
• lie in lacunae and are linked to one another through canaliculi
• Maintain the metabolism of the osteon

Osteoclasts:

• Bone degrading cells
• Large cells with many nuclei and a ruffled
• Secrete concentrated HCl and release lysosomal enzymes for bone desorption
• originate from monocytes and macrophages

Similarities

• All of these cells are actively involved in bone tissue
• Osteoclasts and osteoblasts are both involved in bone remodeling
• All of these cells do not divide
• Osteoblasts and osteocytes both are derived from osteoprogenitor cells (although osteocytes are derived from osteoblasts)

Question 21

Identify 3 features of compact bone that contribute to its strength.

Answer 21

1 - Osteons within compact bone are arranged longitudinally and act as weight bearing pillars that reinforce the bone against compression and tension
2 - Lamellae are calcified collagen fibres that impart strength and are present in alternating clockwise-counterclockwise arrangements. These function to prevent torsional strain and crack propagation.
3 - Circumferential lamellae run along the circumference of the entire diaphysis in a similar anti-directional arrangement as lamellae. These function to resist torsion of the entire bone.
4 - Periosteum: contains dense irregular connective tissue which wraps around the compact bone. Imparts ability to withstand stress in multiple directions.
5 - Bone is a densely packed tissue
6 - Ground matrix is calcified, hard and provides structural strength

Question 22

Compare and contrast the pectoral and pelvic girdle.

Which provides more flexibility? More stability?

Answer 22

Compare (Similarities):

• Both are ball and socket joints for limb articulation
• Both are girdles, i.e. they connect the appendicular skeleton to the axial skeleton
• Both are part of the appendicular skeleton

Pectoral girdle:
- consists of the clavicle and scapulae
- Does not completely encircle the body (i.e. the scapulae do not attach to one another or to the axial skeleton)
- Girdle is light and the limbs are mobile
-The socket of the shoulder joint (glenoid cavity) is hollow
Great for flexibility and mobility.
Poor for stability.

Pelvic girdle:

• consists of paired hip bones, (sacrum and coccux)
• attached to the axial skeleton by strong ligaments
• Completely encircles the body
• Heavier than the pectoral girdle
• Acetabulum is deep
• Provides less flexibility but more stability

Question 23

How are joints classified functionally? Structurally? Give examples.

Answer 23

Joints are classified functionally by the amount of movement they allow. Functional classifications include:
Synarthrotic joints - immovable (ex: sutures)
Amphiarthrotic joints - partially movable (ex: interosseus membrane between radius and ulna)
Diarthrotic joints - freely movable (all synovial joints, eg. shoulder joint)

Joints are classified structurally by the material that binds the bones together as well as by the presence/absence of a joint cavity. Structural classifications include:
Fibrous joints:
- Syndesmoses - amphiarthrotic, short or long
–eg. short - ligament between tibia and fibule
–eg. long - interosseus membrane between radius and ulna
- Gomphoses - synarthrotic
–eg. Periodontal ligament that holds teeth in jaw
- Sutures - synarthrotic
–eg. sutures in cranium

Cartilaginous joints:
Synchondroses - synarthrotic
-eg. epiphyseal plate
Symphyses - amphiarthrotic
--eg. pubic symphysis

Synovial joints - diarthrotic and contain a joint cavity
- eg. shoulder joint

Question 24

What is an articular disc? Give an example of a location in the body.

Answer 24

An articular disc or meniscus, is a disc of fibrocartilage which functions to:

• allow bones of different shapes to fit snuggly (eg. femur and tibia)
• makes joints more stable and minimizes wear and tear on joint surfaces
• distributes the load more evenly
• can partially or completely divide the joint cavity

Menisci are found in the knee for example.

Question 25

Describe the 6 angular movements of synovial joints.

Answer 25

Abduction - movement of a limb along the frontal plane away from the midline

Adduction - movement of a limb along the frontal plane towards the midline

Flexion - movement along the sagittal plane that decreases the angle of the joint and brings the two articulating bones closer together

Extension - movement along the sagittal plane that increases the angle of the joint and brings the two articulating bones further apart

Hyperextension - movement along the saggital plane that involves bending a joint past its regular range of motion, past anatomical position.
eg. thorax, neck, shoulder, hip

Circumduction - combination of flexion, extension, abduction and adduction in no particular plane.

Question 26

Describe the organization of skeletal muscle and its connective tissue sheaths.

Answer 26

Muscle fibres or cells, are surrounded by a fine sheet of endomysium, composed of areolar CT.

Muscle cells are then wrapped into fascicles, which are surrounded by a dense irregular CT layer called the perimysium.

Fasciscles are then wrapped together into a whole muscle. This is surrounded by a dense irregular connective tissue layer called the epimysium.

Question 27

What is a sarcomere? Describe its components. How does it change during contraction?

Answer 27

A sarcomere is the function unit of contraction of a muscle cell.

Each sarcomere is composed of two Z-discs or Z-lines, marking its border.
- Each sarcomere contains overlapping arrangements of thick and thin filaments.
Thin filaments extend from the Z-disc towards the centre of the sarcomere and contain actin myofilaments.
Thick filaments are held by titin and other proteins and extend from the centre of the sarcomere towards the Z-discs on either side. These contain myosin myofilaments.
Titin is an elastic protein that anchors the thick filaments and provide elasticity.

The different zones of the sarcomere are:
- A band - extend the whole length of the thick filament
- I band - extend from one sarcomere to another and consists of the areas where thin filament does not overlap thick filament.
H-zone: zone were only thick filaments occur, in the centre of the sarcomere.
M-line middle of the H zone.

During contraction, The A band stays the same length, the I band gets smaller, the H zone potentially disappears (based on amount of contraction)) and the Z-discs of a sarcomere come closer together.