BIOS 255 ANATOMY AND PHYSIOLOGY III EXAM 2 COMPREHENSIVE TEST PAPER 2026 QUESTIONS WITH SOLUTIONS

BIOS 255 ANATOMY AND PHYSIOLOGY III
EXAM 2 COMPREHENSIVE TEST PAPER
2026 QUESTIONS WITH SOLUTIONS

⫸ Platelets Answer: Cell fragments
-From megakaryocytes
No nucleus
Some organelles
-Granules
-Vesicles with hemostatic chemicals
-Lysosomes


⫸ What can platelets do? Answer: Can:
Crawl
Pseudopods
Stick together (clots)
Dissolve clots
Secrete
Fight infection


⫸ Hemostasis: Steps Answer: Injury to vessel
Vascular spasm
Platelet plug formation

,Clot forms


⫸ Vascular Spasm Answer: Vasoconstriction
Caused by:
Nerve impulses (Short-term)
Vasoconstrictors (Chemicals)
Ex) Serotonin
-From platelets


⫸ Platelet Plug Formation:Upon activation Answer: Grow pseudopods
-Crawling
-Adhesion
-Contraction


Degranulation
-Release chemicals
~Vasoconstrictors ,Platelet activators, Procoagulants


⫸ Platelet Plug Formation Answer: Platelets
Do NOT stick to endothelium
DO stick to collagen
Damage → exposed collagen

,Sticking to collagen
(or other platelets)→Platelet Activation


⫸ Coagulation Answer: Platelet plug
Not a clot (yet)
Loose
Weak


Clot formation
-Main event: fibrin formation
Note: RBCs help Passively


⫸ Purpose: Fibrin Formation Answer: Complicated process
Fibrin: like spider web
-Catches more platelets & RBCs
Prthrombin→Thrombin→Fibrinogen→Fibrin→clot


⫸ Thrombin Answer: Prothrombin
-Inactive form


Thrombin = Enzyme
Fibrinogen → Fibrin
Chops pieces off

, ⫸ Fibrin formation Answer: Fibrinogen → fibrin
Pieces chopped off
By thrombin


Fibrin proteins polymerize
make fibers


⫸ Coagulation cascade Answer: Series of reactions
-Reaction cascade


Reactants
-Proteins
-Already in plasma
-OR Released
~Especially by platelets


⫸ Coagulation cascade:2 activation paths Answer: Extrinsic
Started by molecules released by damage


Intrinsic
Started by activated platelets