Question

15). Your patient asks you which cell type in the skin is the most important cell and why? How would you reply? Explain.

16). Describe the stages of intramembranous ossification and name at least one (1) bone that is formed using this process.

25). Describe the sequence of injuries to specific tissues that might occur if a patient’s knee receives blunt force trauma to the lateral side of the knee.

24). For the six (6) synovial joint classifications, identify which possess uniaxial, biaxial, or multiaxial movement. Also, identify which might be most likely to sustain injury and why that could happen.

Answer 1

Q no:15

KERATINOCYTES  are most important cell type in skin.

• Primary function of keratinocytes is the formation of a barrier against environmental damage by heat,UV radiation,water loss.
• Pathogenic bacteria,fungi,parasites, and viruses
• It constitute 90% cells of the epidermis
• It is the outermost layer of the skin
• Basal cells in basal layer of the skin
• when pathogens invading the upper layers of the epidermis can cause keratinocytes to produce proinflammatory mediators,particulary chemokines such as CXCL10 and CCL2 which attract monocytes,natural killer cells, T-Lymphocytes, and dendritic cells to the site of pathogen invasion
• A number of structural proteins (Filaggrin,keratin)
• Enzymes (proteases) , Lipids and antimicrobial peptides (defensins) contibute to maintain the important barrier function of the skin.
• Keratinization is part of the physical barrier formation (cornification)
• Keratinocytes produce more and more keratin and undergo terminal differentiation.
• The fully cornified keratinocytes that form the outermost layer are constantly shed off and replaced by new cells
• wounds to the skin will be repaired in part by the migration of keratinocytes to fill in the gap created by the wound

Q no :16

STAGES OF INTRAMEMBRANOUS OSSIFICATION

1. Starting with connective tissue mesenchyme cells diffferentiate into osteoblasts within a connective tissue (near arterioles), form ossification centers
2. Clusters of osteoblasts form osteoid that becomes mineralized
3. Small struts of bone (trabeculae) radiate out fromthe ossification centers to join with the neighbouring bone struts
4. Trabeculae just deep to periosteum thicken,becoming compactlamellar bone (the rest stays trabecular ----spongy bone----diploe)

Examles of bone formed by this process : Lower jaw (mandible), clavicle,roof of the skull.

Q no:25

Sequences of injury

• Vasoconstriction is the first response and cause clots
• Next step is vasodilation which causes edema to swell
• Vasodilation causes cells,nutrients ,and proteins to come into the injured area and waste to leave

Lateral side of knee injury causes lateral collateral ligament(LCL) injury.

Symptoms : sprain or tear of the LCL includes pain to the lateral aspect of the knee

• instability of the knee when walking
• swelling and ecchymosis at the site of trauma

Q no:24

Synovial joint classification

• Uniaxial joint

Eg : elbow joint

ie, Hinge joint

• biaxial joint

Eg:metacarpophalangeal joint (knuckle joint) of the hand

• Multiaxial joint

Eg: shoulder and hip joint
ie, ball and socket joint

  

Knee joint is more likely sustain injuyry

• anatomically largest synovial joint
• ligaments are crucial for the stability of the knee joint
• They provide mechanical reinforcement and control the range of motion
• Damage to ligaments are most common form of the knee injury