PT7111 - Midterm #1 Study Guide

Clinical Medicine Review Topics for Exam 1

What is homeostasis?

• Maintain a relatively stable internal condition despite harsh external conditions

• Precisely controlled on a second-by-second or minute-by-minute basis

What is a receptor or sensor?

• Detects level (quantity or amount) of a variable

• Detects changes in a variable

• Communicates with the control center

Where is the temperature control center located?

Hypothalamus

What is the control center?

• Takes current data acquired by sensors

• Compares levels/changes of a specific variable to the normal level or “set point”

• If there is a difference between the “set point” and the current status, the control center can activate effectors to return to the desired level

What is the “set point” or “set range”?

The “normal” or “typical” level/range of a variable

What are effectors?

Responders that help return the internal condition variable back to the “normal” or “set point”

What is acute inflammation?

(Good) natural processing, part of our bodies immune defense (prepares injured area for healing)

Acute inflammation prepares the body for….

Healing

What are some potential triggers of acute inflammation?

• Trauma

• Laceration, abrasion, puncture, avulsion

• Burns

• Toxic or irritating chemicals

• Infectious agents

• Abnormal immune reactions

• Allergies

• Autoimmunity

Acute inflammation triggers ______ cells.

Acute inflammation triggers mast cells

What is the function of mast cells during acute inflammation?

• Lie within the connective tissue

• The body’s “security guards” made to respond to injury by “sounding the alarm”

• Contains vesicles (granules) filled with histamine and other inflammatory mediators (cytokines) which dilate nearby blood vessels (redness, warmth) and make them more permeable (swelling, edema) which stimulates nociceptors because it irritates nerves

Mediators stimulate ____________ which releases _________ and ________ to the wound.

Mediators stimulate bone marrow which releases neutrophils and monocytes to the wound

What is the function of histamine?

Increased capillary blood flow and permeability and is a chemical mediator

What are five manifestations of acute inflammation?

1. Swelling

2. Redness (erythema)

3. Warmth

4. Pain

5. Limitation of Motion/Function

Attraction of neutrophils and monocytes from bone marrow are stimulated by ________ and led to the location by _________.

Stimulated by mediators and led to the location by chemotaxis

Which white blood cell(s) are part of the 1st wave of phagocytes?

Neutrophils

Which white blood cell(s) are part of the 2nd wave of phagocytes

Monocytes

What is the main purpose/function of phagocytosis?

• To “clean up” and “sterilize” the wound of contaminating bacteria

• Removes the dead tissue

• Prepares for proper healing

What are the main steps of phagocytosis?

1. Phagocyte adheres to the pathogen/debris

2. Phagocyte forms pseudopods that eventually engulf the particles → forms a phagosome

3. Lysosome fuses with phagocytic vesicle → forms phagolysosome

4. Lysosomal enzymes digest the particles, leaving a residual body

5. Exocytosis of the vesicle removes indigestible and residual material

Much of healing is triggered/signaled by _________ secreted by ___________.

Much of healing is triggered/signaled by mediators secreted by macrophages

What are two of the “growth factors” important in healing?

• Fibroblast Growth Factors (FGFs)

• Vascular Endothelial Growth Factors (VEGFs)

• These stimulate angiogenesis and the recruitment of fibroblasts to the area

How does angiogenesis, fibroblast, and collagen deposition occur?

1. The outer (most superficial) layer of the wound must be covered by regenerating (new) epithelial tissue

   • Epithelial cells can grow across a defect but below it is collagen and ECM

   • Long period of time in which you have a blood clot/scab on top of wound; takes a long time for ground substance in the ECM to heal the wound below

2. Deeper tissue in the wound must be “rebuilt”

3. New blood vessels must develop throughout the depth of the wound (“angiogenesis”)

   • New blood vessels sprout from existing blood vessels (neovascularization); as they sprout, they carry fibroblasts which secrete collagen molecules and ECM which can help to rebuild tissue of destroyed area

4. New blood vessels carry nutrients, oxygen, amino acids, and fibroblasts into the wound

5. Fibroblasts must synthesize collagen fibers to “criss-cross” the wound, binding different areas together (scar tissue)

6. Myofibroblasts and endothelial cells can develop into myofibroblasts, which have contractile abilities

What is granulation tissue?

• Name for the visible, characterstics stage of wound healing that looks like hundreds of tiny red granules

• Not actually granules, but it is the appearance of:

  • “Spouting” new blood vessels

  • Delicate new connective tissue matrix (which is gel-like and wet)

  • Newly made collagen fibers (fibroblasts, gel-like matrix, collagen fibers, and sprouting blood vessels)

When can granulation tissue be seen?

Seen immediately within 1-10 days

What might be a cause of poor wound healing?

If an infection is present → makes it difficult to heal due to the toxins produced by the bacteria that begin to take over

What are first and second intentions?

• 1st Intention:

  • Often surgical wounds

  • Opposite sides brought closer together

  • Faster healing

• 2nd Intention:

  • Often wounds caused by trauma (car accidents, blasts)

  • Leg ulcers

  • Burns

  • Opposite sides are far away with gap due to loss of tissue

  • Slower healing

What is a diabetic foot ulcer?

• Crater on the foot that heals slowly (and sometimes not at all)

• Because diabetics have high blood glucose, it damages blood vessels and nerves causing a loss of sensation on feet → lead to damage that is not recognized

Why is a diabetic foot ulcer a big issue?

• Neuropathy

• Lack of sufficient blood flow

• WBC and other components of immune system are impaired by hyperglycemia

• Wound infections are common

• Often many concurrent medical problems that can impede healing or adversely affect treatment

• Amputation may be required

What is pus?

• “Battlefield of microbes and bacteria”

• Living and dead bacteria

• Living and dead white blood cells

• Resultant material from immune response to infection

What factors can cause cell injury?

• Oxygen deprivation (ischemia, hypoxia, severe anemia)

• Physical agents (mechanical/physical trauma, temperature extremes, radiation/electrical shock)

• Chemical agents and drugs (arsenic, cyanide, mercury, CO, pollutants, tobacco smoke, alcohol)

• Infectious agents

• Genetic mutations

• Immunological reactions (allergy, autoimmune)

• Nutritional imbalances (protein calorie malnutrition, obesity)

What are the different response of cells to factors that can cause cell injury?

• Adapt

• Injury

• Death

What are some cellular adaptations?

• Hypertrophy (cells get bigger)

• Hyperplasia (cells replicate)

• Atrophy (cells get smaller)

• Metaplasia (cell morphs or converts to another cell type)

What is necrosis?

• Always bad, unregulated cell death

• Many cells, entire tissues, or part/all of an organ dies at once

• Triggers inflammation, neighboring tissue involvement and injury, and infection

What are the two types of necrosis?

• Coagulative Necrosis

  • Remains solid, replaced by firm scar tissue (happens in heart attacks)

• Liquefactive Necrosis

  • Becomes liquid (not replaced by scar tissue)

  • Happens in stroke, damages to the spinal cord

What is apoptosis?

• Organized/controlled cell death (causes cells to “self-destruct” harmlessly when they are no longer needed)

  • e.g., lymphocytes in lymph nodes in neck replicate (hyperplasia) to fight off strep through → then cells self-destruct

• “Clean” cell death

Can apoptosis be negative?

• Yes, apoptosis is negative when needed cells mistakenly self-destruct

  • e.g., Neurodegenerative disorders like Parkinson’s, Alzheimer’s, and ALS

  • (Abnormal protein deposits in neurons appear to trigger apoptosis in Parkinson’s and Alzheimer’s)

What is gangrene?

Dead tissue in extremities or skin and underlying soft tissue

What is the cause of gangrene?

Ischemia (loss of blood supply) and frostbite

What is the difference between “dry” and “wet” gangrene?

• Gangrene of the extremities is “dry” (eventually becomes infected by bacteria)

• Visibly infected gangrene is called “wet” gangrene

What is ischemia?

Loss of blood supply to an area

What is infarction?

Complete blockage of blood supply (often thrombus or emboli) causing necrosis of tissue

What are the different causes/types of trauma?

• Motor Vehicle Accidents (can be penetrating or blunt trauma)

• Falls (usually a blunt trauma)

• Violence (penetration or blunt)

• Sports Injuries (usually blunt)

• Burns (heat trauma)

What is the differences between first, second, and third-degree burns?

• 1st Degree:

  • Epidermis only

• 2nd Degree:

  • Inflammation and fluid leaking out, blisters as epidermis is pushed up

  • “Sun poisoning”

• 3rd Degree:

  • Can lead to damage to nerves

  • Can go as deep as the bone

What is “burn shock”?

Blood volume drops (liquid from blood vessels is secreted)

CO (carbon monoxide) attaches to _________ on red blood cells meaning that ________ cannot bind

CO attaches to hemoglobin on red blood cells meaning that oxygen cannot bind

Scalds account for __% of all burns

Scalds account for 33% of all burns

Most scalds are ______-based

Most scalds are water-based

What is Immune Thrombocytopenic Purpura (ITP)?

• Immune system attacks platelets (essentially, it thinks the platelets are bacteria and creates antibodies)

• Two few platelets in the blood → inhibits blood clotting

• Cause of Thrombocytopenia (low blood platelet counts)

• Bleeds into skin (petechiae, purpura, ecchymosis/bruising)

• Type II hypersensitivity

What is Hemophilia A?

• Deficiency of coagulation Factor 8

• X-linked recessive inheritance

• 1 per 5,000 male births

What is Hemophilia B?

• Deficiency of coagulation Factor 9

• X-linked recessive inheritance

• 1 per 30,000 male births

An individual with Hemophilia cannot form a _____ clot to complete the _____plug

Cannot form a fibrin clot to complete the platelet plug

What is petechia?

Bleed from the blood vessels into the skin (small red dots)

What is purpura?

Blood collections in the skin in larger, flat areas

What is hemarthroses?

• Bleeding into joint cavity

• Can be caused by a traumatic event or be hereditary (e.g., hemophilia)

• Can lead to osteoarthritis in teens

What is a thrombosis?

Blood clots that occur when and where they aren’t supposed to

Where are some locations that thromboses can occur?

• Coronary arteries (myocardial infarction)

• Carotid or cerebral arteries (stroke)

• Left atrium (in atrial fibrillation)

• Deep veins (especially of leg; DVT)

What is a mural thromboses?

Overlying myocardial infarctions

How and where can an emboli arise?

• Can arise from a mural thromboses, vegetations, and left atrium and embolize to the brain or anywhere in the body (other than the lungs

• Can arise from deep veins of the legs and embolize to lungs

  • Massive pulmonary emboli decreases flow of blood to and from the lungs back to the heart

Thromboses (or blood clots) form due to…

• Stasis of blood flow (or turbulence)

• Endothelial damage (from inflammation due to fractures or infection)

• Hyper-coagulability (metastatic cancer, estrogens, antiphospholipid syndrome, factor V Leiden)

What are some predispositions for a DVT?

• Bed ridden for a long time

• Turbulent flow (stasis)

• Damage to endothelial lining

• Hypercoagulable state (genetic causes: Favtor V)

• Changes in hormones (birth control, pregnancy)

What is shock?

Circulatory failure → failure to deliver sufficient oxygen

What are the three main types of shock?

• Cardiogenic

• Hypovolemic

• Distributive

Hemorrhagic stroke is a common form of _______ shock.

Hemorrhagic shock is a common form of Hypovolemic Shock

What is sepsis?

Infection, systemic inflammatory response syndrome (SIRS), and widespread damage to blood vessels

Fluid balance in capillaries has to do with __________ pressure pushing fluid _____ and _____ (or osmotic) pressure due to albumin pushing fluid ____

Fluid balance in capillaries has to do with hydrostatic pressure pushing fluid out and oncotic (or osmotic) pressure due to albumin pulling fluid in

When the hydrostatic pressure forces are “out of balance”, what occurs?

• Too much fluid is being pushed out

• This causes edema or total body swelling (anasarca)

When albumin is low, thus decreasing the oncotic pressure, what occurs?

• Less fluid being pulled in

• Cirrhosis and nephrosis lower albumin

What three disease can cause bilateral leg edema?

• Heart failure

• Cirrhosis (live damage)

• Nephrosis (kidney disease)

How does unilateral leg swelling occur?

• Occurs with deep vein thrombosis (DVT)

• Can also be caused by issues with lymphatic drainage

Accumulation of fluid in the soft tissues is called…

• Edema

• Anasarca (if total body swelling)

What is ascites?

Accumulation of fluid around the abdominal cavity

What is pericardial effusion?

Accumulation of fluid around the heart

What is pleural effusion?

Accumulation of fluid around the lungs