Homeostasis fracture scenario

Question 1

Name and describe the three stages of haemostasis

Answer 1

Vascular spasm - smooth muscle contraction in vessel walls reducing blood flow through injured vessel so platelet plug can form and coagulation can occur.

Platelet plug formation - Platelet adhesion and aggregation. Chemicals are released to bring more platelets to injured area and promote vascular spasm.

Coagulation - Platelet plug is reinforced with fibrin threads to form a mesh which traps blood cells and seals the hole until permanently healed.

Question 2

Name 2 hormones which act on the kidney to help restore blood volume. Explain the action of these two hormones and what
impact each will have on blood plasma volume.

Answer 2

Aldosterone - increases tubular reabsorption of Na+, water follows by osmosis. This increases
blood plasma volume.
Anti-diuretic hormone (ADH) decreases water lost from the collecting duct so increases blood plasma volume.

Question 3

Explain two mechanisms related to blood vessels that are used to help increase BP.

Answer 3

Constriction of arterioles to increase peripheral vascular resistance, which will increase his BP.
Constriction of veins to increase venous return. An increased the venous return will increases cardiac preload therefore increase BP.

Question 4

Define haematocrit and explain why it would be lower than normal if a patient is given IV saline.

Answer 4

Haematocrit is the percentage of blood occupied by the red cells.
Blood volume would have been restored by intravenous saline, diluting it. So haematocrit would be lower

Question 5

Name and describe the stage of bone healing that will be occurring for a patient at the time of a fracture

Answer 5

Fracture hematoma formation
Blood leaks from damaged vessels and forms a clot at the site of injury (within 6-8hrs)
Nearby bone cells die due to lack of nutrients to the tissues at the site of fracture
Swelling & inflammation occur
Phagocytosis & osteoclasts remove dead and damaged tissue (can last for several weeks)

Question 6

Name the main mineral involved in maintaining bone tissue. Also, name & describe the action of the
hormone that will enable increased deposits of this mineral in bone tissue.

Answer 6

Calcium (Ca2+)

Calcitonin stimulates deposits of calcium in bone tissue by inhibiting osteoclast activity.

Question 7

Name and describe the stage of inflammation that will be occurring at the time of fracture

Answer 7

Vasodilation & increased capillary permeability
Dilation increases the blood flow in the damaged area resulting in increased delivery of WBC,
clotting factors, nutrients & removal of wastes.