Integumentary System & Coagulation: Functions, Layers, Receptors, and Wound Healing

What are the main functions of the integumentary system?

Barrier protection, cutaneous sensation, temperature regulation, blood reservoir, biological protection, metabolic functions (vitamin D3), and waste excretion.

What happens when large portions of the body are burned?

Loss of barrier function, increased risk of infection, fluid loss, and impaired temperature regulation.

What are the three main layers of the skin?

Epidermis, dermis, and hypodermis.

What are the key cell types in the epidermis?

Keratinocytes, melanocytes, dendritic (Langerhans) cells, and tactile (Merkel) cells.

What is the function of melanocytes?

Produce melanin to protect nuclei from UV damage.

What layer of the epidermis is responsible for fingerprints?

Stratum basale via dermal papillae.

What are the two layers of the dermis?

Papillary layer (thin, areolar tissue) and reticular layer (thick, irregular connective tissue).

What is the hypodermis composed of and what are its functions?

Vascularized adipose and areolar tissue; functions include fat storage, insulation, and cushioning.

Which mechanoreceptor detects vibration and tapping and adapts very rapidly?

Pacinian corpuscle.

Which receptor detects stretch and joint rotation and adapts slowly?

Ruffini corpuscle.

What do free nerve endings detect?

Pain (nociception), temperature, and harmful chemicals (chemesthesis).

What are TRP receptors and what do they detect?

Transient receptor potential channels; detect chemical stimuli like capsaicin and menthol.

What initiates vasoconstriction during hemostasis?

Neurogenic reflex and endothelin.

What are the steps of primary hemostasis?

Platelet adhesion (via vWF and collagen), activation, secretion of granules (ADP, TxA2), and aggregation.

What is the key event in secondary hemostasis?

Thrombin cleaves fibrinogen into fibrin to form a stable clot.

What limits clotting to the injury site?

Tissue plasminogen activator (t-PA) from endothelial cells.

What platelet receptor binds to vWF for adhesion?

Glycoprotein Ib (GpIb).

What receptor forms bridges between platelets for aggregation?

Glycoprotein IIb/IIIa (GpIIb/IIIa).

What stabilizes the platelet plug?

Thrombin and fibrin formation.

What vitamin is essential for coagulation?

Vitamin K.

What is the most important factor in vivo for coagulation?

Thrombin.

What lab test assesses the extrinsic pathway?

Prothrombin time (PT).

What lab test assesses the intrinsic pathway?

Partial thromboplastin time (PPT).

What are the four phases of wound healing?

Hemostasis, inflammation, proliferation, and remodeling.

What is granulation tissue composed of?

Fibroblasts, capillaries, loose ECM, and macrophages.

What distinguishes first intention from second intention healing?

First intention: clean, small wounds with minimal inflammation. Second intention: large, irregular wounds with marked inflammation and contraction.

Name three systemic factors that impair wound healing.

Diabetes, smoking, and immunocompromised conditions.

What (for the purposes of this class) is the most important factor of the coagulation cascade and why?

Thrombin because it converts fibronogen into fibrin.

What two factors of the coagulation cascade form the "extrinsic pathway?"

TF and F VII

What is the most serious deficiency in the coagulation cascade?

prothrombin. A deficiency is incompatible with life.

What is the importance of factor X in the CC?

converts prothrombin to thrombin

What is the importance of the Factor IXa and Factor VIIIa complex?

Activates factor X

What is the importance of the Factor VIIa and tissue factor complex? most important activator if factor IX

but can also activate factor X directly.