Emergency Care In The Streets - Ch. 6

Front 1

Biology

Back 1

- study of living organisms with regard to their origin, growth, structure, behavior, and reproduction

Front 2

the human body is made up of:

Back 2

- cells, tissues, and organs
- function in a constantly changing microenvironment

Front 3

Pathophysiology

Back 3

- refers to the study of the function of the organism (physiology) in the presence of suffering/disease (pathos)
- when the normal conditions of functioning of the cellular systems break down in response to stressors, and the systems can no longer maintain homeostasis, disease may result

Front 4

Etiology

Back 4

- the cause of the disease process

Front 5

The Cell

Back 5

- the basic self-sustaining unit of the human body
- can be specialized (ex. kidney cells) through the process of differentiation
- groups of cells form tissues, various types of tissues form organs, and groups of organs make up organ systems

Front 6

Components of a cell

Back 6

- the cell membrane, the cytoplasm (containing the internal components or organelles), and a nucleus
- the exception is mature red blood cells and platelets

Front 7

cell membrane

Back 7

- consists of fat and protein
- surrounds the cell and protects the internal components within the cytoplasm

Front 8

organelles

Back 8

- found within the cell's cytoplasm (fluid)
- operate in a cooperative and organized fashion to maintain life of the cell
- consists of: ribosomes, endoplasmic reticulum, Golgi complex, lysosomes, mitochondria, and nucleus

Front 9

ribosomes

Back 9

- contain RNA and protein
- interact with RNA from other parts of the cell
- join amino acid chains together to form proteins
- when they are attached to the endoplasmic reticulum, they create the rough endoplasmic reticulum

Front 10

chemically fatty compounds

Back 10

- found in the cell membrane
- neutral
- soluble in oil but not in water

Front 11

electrolytes

Back 11

- sodium, potassium, calcium, and chloride
- charged
- water-based
- charged molecules enter through a cell by transport channels (ion channels) - protein lined pores that are specifically sized for each substance (calcium and potassium)
- local anesthetics and antiarrhythmic drugs exert their effects by blocking ion channels
- plays an important role in the cell signaling
- plays an important role in generating the nervous system's action potential

Front 12

endoplasmic reticulum

Back 12

- a network of tubules, vesicles, and sacs
- rough - involved in building proteins
- smooth - involved in building lipids (fats) - like those found in the cell membranes and carbohydrates

Front 13

Golgi complex

Back 13

- located near the nucleus of the cell
- involved in the synthesis and packaging of various carbohydrates (sugar) and complex protein molecules such as enzymes

Front 14

Lysosomes

Back 14

- membrane-bound vesicles that contain digestive enzymes
- enzymes function as an intracellular digestive system, breaking down bacteria and organic debris that have been taken into the cell

Front 15

Peroxisomes

Back 15

- similar to lysosomes
- found in high concentrations in the liver and neutralizes toxins such as alcohol

Front 16

Mitochondria

Back 16

- small, rod-like organelles that function as the metabolic center of the cell
- produce adenosine triphosphate (ATP) - major energy source for the body

Front 17

Nucleus

Back 17

- contains the genetic material (chromatin) and the nucleoli
- surrounded by a membrane (nuclear envelope)
- embedded in the cytoplasm

Front 18

Nucleoli

Back 18

- round, dense structures that contain ribonucleic acid (RNA)

Front 19

RNA

Back 19

- ribonucleic acid
- responsible for controlling the cellular activities

Front 20

Tissues are composed of:

Back 20

- groups of similar cells that work together for a common function

Front 21

4 types of tissues

Back 21

- epithelial
- connective
- muscle
- nerve

Front 22

epithelium

Back 22

- covers the external surfaces of the body
- lines hollow organs within the body, sucha s the intestines, blood vessels, and bronchial tubes
- play a role in the absorption of nutrients in the intestines and the secretion of various body substances
- example - sweat gland's (in the dermis layer) stratified squamous epithelium produce a solution containing urea and salt
- example - small intestine's simple columnar epithelium absorbs nutrients from the food we eat

Front 23

endothelial cells

Back 23

- epithelial cells that line the inside of blood vessels
- regulate the flow of blood through the vessel as well as clotting of the blood (coagulation)

Front 24

connective tissue

Back 24

- binds other types of tissues together
- extracellular matrix is a nonliving substance consisting of protein fibers, nonfibrous protein, and fluid that separates connective tissue cells from one another

Front 25

Collagen

Back 25

- major protein within the extracellular matrix
- at least 12 types of collagen exist, with types I, II, III being the most abundant
- alterations in collagen sturcture resulting from abnormal genes or abnormal processing of collagen proteins result in numerous diseases

Front 26

subtypes of connective tissue

Back 26

- bone
- cartilage
- adipose tissue

Front 27

adipose tissue

Back 27

- a special type of connective tissue that contains large amounts of lipids (fat)

Front 28

Muscle tissue

Back 28

- characterized by its ability to contract
- is enclosed by fascia
- overlie the framework of the skeleton
- classified by their structure and function
- either striated (microscopic bands) or nonstriated (smooth)
- either voluntary (consciously controlled) or involuntary (not normally under conscious control)

Front 29

fascia

Back 29

- the layer of fibrous connective tissue that separates individual muscles

Front 30

3 types of muscle tissue

Back 30

- skeletal (striated voluntary)
- cardiac (striated involuntary)
- smooth (nonstriated involuntary)

Front 31

skeletal muscles

Back 31

- most used muscles in voluntary day-to-day activities

Front 32

cardiac muscle

Back 32

- hearts muscles that have the ability to both contract and generate impulses

Front 33

smooth muscle

Back 33

- lies most glands, digestive organs, lower airways, and vessels
- example - when a patient's brain senses the need to respond to an environmental stimulus by vasoconstriction, the vessels in the periphery react
- example - smooth muscle in the bronchioles may vasoconstrict during an asthma attack, leading to wheezing and difficulty moving air out of the lungs
- example - responsible for constriction and dilation of the pupil of the eye when it is exposed to changes in light levels

Front 34

nerve tissue

Back 34

- characterized by its ability to transmit nerve impulses
- CNS - consists of brain and spinal cord
- peripheral nerves

Front 35

peripheral nerves

Back 35

- extend from the brain and spinal cord
- exiting from between the vertebrae to various parts of the body

Front 36

neurons

Back 36

- main conducting cells of nerve tissue and the cell body of the neuron is the site of most cellular functions
- has one axon, but may have several dendrites

Front 37

dendrites

Back 37

- receive electrical impulses from the axons of other nerve cells and conduct them toward the cell body

Front 38

axons

Back 38

- conduct electrical impulses away from the cell body

Front 39

synapse

Back 39

- the gap that separates nerve cells

Front 40

neurotransmitter

Back 40

- carry the impulse from axon to dendrite
- electrical impulses travel down the nerve and trigger the release of neurotransmitters
- proteins that affect signals between cells of the nervous system
- example - acetylcholine - aids in the movement of nerve impulses from neuron to neuron

Front 41

Homeostasis

Back 41

- adaptive responses to various stimuli allow the cells and tissues to respond and function in stressful environments
- in a constant effect to preserve a degree of stability or equilibrium
- dynamic steady state "same steady"
- normal regulatory systems are counterbalanced by counter-regulatory systems
- for every cell, tissue, or organ that performs a function, there is always at least one component that performs the opposing function
- example - autonomic nervous systems consists of sympathetic and parasympathetic components (to speed up and slow down activity)
- internal temperature
- regulation of pH and acid-base balance
- balance of water or hydration

Front 42

cell signaling

Back 42

- when cells communicate electrochemically
- they release molecules (such as hormones) that bind to proteins (receptors - located on the surface of receiving cells)
- signaling triggers chemical reactions in the receiving cells that lead to a biological action
- regulatory systems communicate within the body mainly at the cellular level

Front 43

feedback inhibition

Back 43

- "negative feedback"
- when action is completed and the opposing system "turns off" the action

Front 44

thermostat mechanism

Back 44

- an example of a feedback mechanism
- a thermostat detects a decrease in temp and signals to the furnace to produce heat
- when the temperature rises the thermostat gives a negative feedback to the furnace to shut down

Front 45

5 primary mechanisms to eliminate excess temp:

Back 45

- convection
- conduction
- radiation
- evaporation
- respiration

Front 46

ways the body maintains homeostasis

Back 46

- body balances what it takes in with what it puts out
- example - the body takes in chemicals and electrolytes, food and water
- utilizes the nutrients, proteins, sugars, and oxygen and the eliminates the unnecessary chemicals and byproducts through respiration (CO2), urine and sweat (excess liquids) and feces (soilds)

Front 47

Disease occurs when:

Back 47

- normal cell signaling is interrupted
- normal counterbalances within the body are rendered inefficient - the normal regulatory systems begin to operate autonomously
- the system stops providing critical negative feedback and give an opposing positive feedbackq

Front 48

excessive output

Back 48

- can rapidly upset homeostasis
- diarrhea
- dehydration

Front 49

Degree of fluid imbalance is affected by:

Back 49

- patient's size
- age
- underlying medical conditions

Front 50

amount of fluid loss to show symptoms:

Back 50

Adults
- loss of 30% of total body fluid
Children
- loss of only 10-15% of total body fluid

Front 51

ligands

Back 51

- molecules that are either produced by the body (endogenous) or given as a drug (exogenous)
- bind any receptor, anywhere, and lead to any reaction

Front 52

common ligands include:

Back 52

- medications
- hormones
- neurotransmitters
- electrolytes

Front 53

hormones

Back 53

- substances that are formed in very small amounts in one specialized organ or group of cells and then carried to another organ or group of cells in the same organism to perform regulatory functions

Front 54

endocrine hormones

Back 54

- carried to their target organ or cell group in the blood
- example - thyroid hormones and adrenal steroids

Front 55

exocrine hormones

Back 55

- reach their target via a specific duct that opens into an organ
- example - stomach acid and perspiration

Front 56

paracrine hormones

Back 56

- diffuse through intracellular spaces to reach their target
- example - histamine - the hormone released during allergic and inflammatory reactions

Front 57

autocrine hormone

Back 57

- the hormone that acts on the cell that secreted it

Front 58

cell adaptation

Back 58

- when cells try to protect themselves from injury when exposed to adverse effects
- exposure can change cell's structure and function permanently or just temporarily

Front 59

atrophy

Back 59

- a decrease in cell size due to a loss of subcellular components
- leads to a decrease in size of the tissue and organ
- actual number of cells stays the same
- the decreased size represents an attempt to cope with a new steady state with less-than-favorable conditions or lack of use
- example - casted, immobilized limb will shrink in size due to disuse atrophy

Front 60

hypertrophy

Back 60

- an increase in the size of the cells due to synthesis of more subcellular components
- leads to an increase in tissue and organ size
- example - the left ventricle of the heart may hypertrophy owing to chronic high resistance pressures from hypertension (high BP)

Front 61

hyperplasia

Back 61

- an increase in the actual number of cells in an organ or tissue
- usually results in an increase in the size of the organ or tissue
- example - a callous represents hyperplasia of the keratinized layer of the epidermis of the foot in response to increased friction or trauma

Front 62

dysplasia

Back 62

- an alteration in the size, shape, and organization of cells
- most often found in epithelial cells that have undergone irregular, atypical changes in response to chronicirritation or inflammation
- example - dysplasia is strongly associated with the development of cancer in the cervix of women (HPV) and in the respiratory tracts of smokers

Front 63

metaplasia

Back 63

- refers to the reversible, cellular adaptations
- one adult cell is replaced by another type of adult cell
- example - the ciliated and secretory epithelium in the ariways of smokers may be replaced by squamous metaplasia

Front 64

cellular environment

Back 64

- refers to the distribution of cells, molecules and fluids throughout the body

Front 65

reasons for changes in cellular environment

Back 65

- aging
- exercise
- pregnancy
- medications
- disease
- injury

Front 66

body fluids contain:

Back 66

- water
- sodium
- chloride
- potassium
- calcium
- phosphorus
- magnesium

Front 67

fluid vs. total body weight

Back 67

- 50-70% of the total body weight (total body water) is fluid
- average male is 60% of BW
- average female is 50% of BW
- intracellular fluid is 45% of BW
- extracellular fluid is 15% of BW
- interstitial fluid (part of extracellular) is 10.5% of BW
- intravascular fluid is 4.5% of BW

Total body volume
- intracellular 75%
- extracellular 25%

Front 68

interstitial fluid

Back 68

- surrounds tissue cells and includes cerebrospinal fluid and synovial fluid

Front 69

intravascular fluid

Back 69

- found within the blood vessels but outside the cells themselves

Front 70

passive transport diffusion

Back 70

- movement of a substance from an area of higher concentration to an area of lower concentration

Front 71

facilitated diffusion

Back 71

- a transport molecule ("helper" molecule) within the membrane helps the movement of a substance from areas of higher concentration to areas of lower concentration

Front 72

osmosis

Back 72

- the movement of a solvent, such as water, from an area of low solute concentration to one of high concentration through a selectively permeable membrane to equalize concentrations of a solute on both sides of the membrane
- moves water between intracellular and extracellular fluid
- the movement of water down its concentration gradient and across a membrane

Front 73

filtration

Back 73

- the movement of water and a dissolved substance from an area of high pressure to an area of low pressure

Front 74

active transport

Back 74

- movement via "pumps" or transport molecules that require energy and move substances from an area of low concentration to an area of high concentration

Front 75

total body water throughout life

Back 75

- at birth, a healthy, full-term infant is 80% water
- older people may only be 45% (dehydration can be serious in the elderly)

Front 76

plasma

Back 76

- makes up about 55% of the blood
- is composed of 91% water or 9% plasma proteins

Front 77

plasma proteins

Back 77

- includes albumin, globulin, fibrinogen, and prothrombin

Front 78

albumin

Back 78

- maintains osmotic pressure

Front 79

prothrombin

Back 79

- assists with clotting

Front 80

Starling's forces

Back 80

- conditions with effect water movement between plasma and interstitial fluid
- under normal conditions - the amount of fluid filtering outward through the arterial ends of the capillaries equals the amount of fluid that is returned to the circulation by reabsorption at the venous ends of the capillaries

Front 81

the equilibrium between the capillary and interstitial space is controlled by:

Back 81

- capillary hydrostatic pressure
- capillary colloidal osmotic pressure
- tissue hydrostatic pressure
- tissue colloidal osmotic pressure

Front 82

capillary hydrostatic pressure

Back 82

- pushes water out of the capillary into the interstitial space
- because the pressure is higher on ther arterial end than the venous end, so more water is pushed out of the capillary on the arterial end and more water is reabsorbed on the venous end

Front 83

capillary colloidal osmotic pressure

Back 83

- generated by dissolved proteins in the plasma that are too large to penetrate the capillary membrane

Front 84

tissue hydrostatic pressure

Back 84

- opposes the pushing of fluids from the capillary into the interstitial space

Front 85

tissue colloidal osmotic pressure

Back 85

- pulls fluid into the interstitial space

Front 86

capillary and membrane permeability

Back 86

- plays an important role in the movement of fluid and the emergence of edema in the surrounding tissue
- if permeability increases, capillaries and membranes are more likely to leak
- if permeability decreases, capillaries and membranes are less likely to leak

Front 87

edema

Back 87

- occurs when excess fluid builds up in the interstitial space

Front 88

peripheral edema

Back 88

- ankles and feet are the most common form

Front 89

severe edema

Back 89

- caused by long-standing lymphatic obstruction
- if a patient is bedridden, edema can occur in the saccral area (sacral edema)

Front 90

Ascites

Back 90

- the abnormal accumulation of fluid in the peritoneal cavity

Front 91

increased capillary pressure

Back 91

- arteriolar dilation
(allergic reaction, inflammation)
- venous obstruction (hepatic obstruction, heart failure, thrombophlebitis)
- increased levels of adrenocortical hormones
- premenstrual sodium retention
- pregnancy
- environmental heat stress
- effects of gravity from prolonged standing

Front 92

decreased colloidal osmotic pressure in the capillaries

Back 92

- decreased production of plasma proteins (liver disease, starvation, severe protein deficiency)
- increased loss of plasma proteins (protein-losing kidney diseses, extensive burns)

Front 93

cardinal sign of overhydration

Back 93

edema

Front 94

fluid and water balance

Back 94

- average adult takes in about 2500ml of water per day
- 60% of fluid intake is drinking
- 30% is intake of water in foods
- 10% is a biproduct of cellular metabolism
- 60% of water is lost in urine
- 28% is lost through the skin and lungs
- 6% lost in feces
- 6% lost in sweat - variable by environment or exercise

Front 95

passive transport and active transport

Back 95

- water (solvent) and dissolved particles (solutes) move between cells as well as between blood vessels and connective tissues

Front 96

osmotic pressure

Back 96

- develops when two solutions of different concentrations are separated by a semipermeable membrane
- water moves from the region of low osmotic pressure to the region of higher osmotic pressure

Front 97

hypertonic solution

Back 97

- when the solution with a higher solute concentration has a higher osmotic pressure
- when a cell is placed into a hypertonic solution, water is pulled out of the cells and they shrink

Front 98

hypotonic solution

Back 98

- when the solution with a lower solute concentration has a lower osmotic pressure
- when cells are placed in a hypotonic solution it will swell

Front 99

isotonic solution

Back 99

- solutions with equal solute concentrations (0.9% NaCl or lactated Ringer's solution)
- when cells are placed in an isotonic solution they will neither shrink nor swell

Front 100

intracellular fluid volume is controlled by two ways:

Back 100

- by the proteins and organic compounds that cannot escape through the cell membrane
- by the sodium-potassium membrane pump

Front 101

intracellular substances

Back 101

- most are negatively charged and so attract postively charged ions (potassium)
- all are osmotically active - so they can pull water into the cell (even it ruptures)

Front 102

Sodium/Potassium Pump

Back 102

- responsible for keeping the substances osmotically active
- maintains the cell's electrical potential by continuously removing three sodium ions from the cell for every two potassium ion that are moved back into the cell
- if it is impaired due to insufficient potassium in the body, the sodium accumulates and causes the cells to swell

Front 103

lymphatic vessel obstruction due to infection:

Back 103

- disease of the lymphatic structures or their removal (mastectomy and removal of lymph nodes may lead to edema in the upper extremity)
- the amount of fluid leaving the arterial end of capillaries does not equal the amount of fluid that returns in the venous side of the capillaries
- more fluid leaves the arterial sides where the mean forces favoring outward movement are slightly higher and the additional fluid is picked up by the lymphatic system

Front 104

clinical manifestations of edema

Back 104

- local or generalized
- patients may have pulmonary edema for cardiac reasons
- may present following near-drowning (submersion) or a narcotic overdose
- excess fluid in the lungs (acute pulmonary edema) impairs the diffusion of oxygen into pulmonary capillaries - causes hypoxia
- patients can drown in their own fluids if they do not receive proper care

Front 105

water balance in the body

Back 105

- maintained through a variety of factors
- most important are the thirst mechanism and the release of antidiuretic hormone (ADH)
- renin-angiotensin-aldosterone system also plays a role in water homeostasis

Front 106

3 types of receptors that continuously monitor hydration

Back 106

- osmoreceptors
- volume-sensitive receptors
- baroreceptors

Front 107

osmoreceptors

Back 107

- monitor extracellular fluid osmolarity
- sensors for these receptors are located primarily in the hypothalamus
- when the extracellular fluid osmolarity is too high, they stimulate the production of ADH

Front 108

volume-sensitive receptors

Back 108

- located in the atria
- when the intravascular fluid increases, the atria are stretched - leads to the release of natriuretic proteins

Front 109

baroreceptors

Back 109

- found primarily in the carotid artery, aorta, and kidneys

Front 110

release of ADH

Back 110

- an increase in blood osmolarity, stimulates the release of ADH (vasopressin) from the pituitary gland

Front 111

ADH stimulates:

Back 111

- the kidneys to resorb water
- decreases the blood's osmolarity

Front 112

sodium

Back 112

- most common cation (positively charged ion)
- average adult has 60 mEq of sodium for each kg of body weight
- most of body's sodium is in the extracellular fluid, with a small amount in intracellular fluid
- plays an important role in the regulation of the body's acid-base balance (sodium bicarbonate buffer system)
- it is taken in with foods (only 500mg/day is needed)
- average US adult ingests between 6-15g of sodium/day

Front 113

intracellular sodium

Back 113

- transported out of the cell by the sodium-potassium pump because a resting cell membrane is relatively impermeable to sodium

Front 114

renin-angiotensin-aldosterone system (RAAS)

Back 114

- sodium is regulated by this and by natriuretic proteins
- it is a complex feedback mechanism responsible for the kidney's regulation of sodium in the body
- when sodium levels are in excess, it is excreted into the urine
- when sodium levels are low, the kidneys reabsorb sodium
- activation through RAAS leads to retention of sodium and water, and the production of natriuretic proteins increases

Front 115

renin

Back 115

- a protein that is released by the kidneys into the bloodstream in response to changes in blood pressure, blood flow, the amount of sodium in the tubular fluid, and the glomerular filitration rate
- when renin is released, it converts the plasma protein angiotensinogen to angiotensin I

Front 116

angiotensin I

Back 116

- in the lungs it is rapidly converted to angiotensin II by angiotensin-converting enzyme (ACE)

Front 117

angiotensin II

Back 117

- stimulates sodium resorption by the renal tubules
- constricts the renal blood vessels (slows the kidney blood flow) and decreases the glomerular filtration rate
- results in less sodium is filtered into the urine and more sodium is resorb into the blood
- also responsible for stimulating the secretion of the adrenal hormone aldosterone

Front 118

aldosterone

Back 118

- acts on the kidneys to increase the reabsorption of sodium into the blood and enhance the elimination of potassium in the urine
- release of aldosterone is also stimulated by the increased extracellular potassium levels, decreased extracellular sodium levels, and release of adrenocorticotropic hormone (ACTH) from the pituitary gland

Front 119

Natriuretic proteins

Back 119

- inhibit ADH and promote excretion of sodium and water by the kidneys

Front 120

chloride

Back 120

- an important anion (negatively charged ion)
- when combined with sodium makes table salt
- when placed in water, the compound will separate into its original ionic form
- it assists in regulating the acid-base balance - especially the stomach pH
- is involved in the osmotic pressure of the extracellular fluid
- where sodium goes, chloride follows

Front 121

tonicity

Back 121

- refers to the tension exerted on a cell due to water movement across the cell membrane

Front 122

isotonic fluid deficit

Back 122

- is a decrease in extracellular fluid with proportionate losses of sodium and water

Front 123

isotonic fluid excess

Back 123

- is a proportionate increase in both sodium and water in the extracellular fluid compartment
- common causes include kidney, heart and liver failure
- manifestation depend on the serum sodium level
- when dehydration exists, orthostatic hypotension and decreased urine output (oliguria) are common
- hyperthermia, delirium, and coma may be seen with very high sodium levels (>160mEq/L)

Front 124

hypertonic fluid deficit

Back 124

- caused by excess body water loss without a proportionate sodium loss (a relative water loss exists)
- results in hypernatremia which is clinically defined as a serum sodium level greater than 148 mEq/L and serum osomolarity greater than 295 mOsm/kg

Front 125

oliguria

Back 125

dd

Front 126

hypernatremia

Back 126

- causes may include excess sweating from hot environmental conditions or exercise as well as gastrointestinal losses through vomiting, diarrhea, inappropriate intravenous fluids, or diuretics
- some patients have nausea and headaches, and others go on to develop seizures and coma

Front 127

hypotonic fluid deficit

Back 127

- caused by excessive sodium loss with less water loss (a relative water excess exists)
- results in hyponatremia which is characterized by a serum sodium level less than 135 mEq/L and serum osmolarity less than 280 mOsm/kg

Front 128

hyponatremia

Back 128

- causes may include excess sweating from hot environmental conditions or exercise as well as gastrointestinal losses through vomiting, diarrhea, inappropriate intravenous fluids, or diuretics
- some patients have nausea and headaches, and others go on to develop seizures and coma
- hyponatremia over a matter of days have fewer symptoms than when an abnormality is developed acutely

Front 129

potassium

Back 129

- major intracellular cation
- is critical to many function of the cell
- is necessary for neuromuscular control, regulation of the three types of muscles, acid-base balance, intracellular enzyme reactions, and maintenance of intracellular osmolarity
- the normal serum level of potassium is in the range of 3.5 to 5.0 mEq/L

Front 130

hypokalemia

Back 130

- defined as a decreased serum potassium level
common causes include:
- decreased potassium intake
- potassium shifts into the cells (insulin, alkalosis, beta-adrenergic stimulation such as with epinephrine)
- renal potassium losses (increased aldosterone activity, diuretics)
- extrarenal postassium losses (vomiting, diarrhea, laxatives)
- in mild and moderate forms the most frequent complaints are muscular weakness, fatigue, and muscle cramps
- flaccid paralysis, hyporeflexia, and tetany may occur with very low levels of potassium (>2.5 mEq/L)
- ECG shows decreased amplitude and broadening of T waves, prominent U waves, premature ventricular contractions and other arrhythmias, and depressed ST segments
- acute hypokalemia can be treated with IV potassium supplementation but isn't usually in a prehospital setting

Front 131

hyperkalemia

Back 131

- an elevated serum potassium level, excessive potassium intake
- common causes include spurious causes (repeated fist-clenching during phlebotomy, with release of potassium from forearm muscles; specimen drawn from an arm with a potassium infusion)
- decreased excretion ((renal failure, drugs that inhibit potassium excretion (spironolactone, ACE inhibitors, nonsteroidal anti-inflammatory drugs (NSAIDS))
- shifts of potassium from within the cell (burns, metabolic acidosis, insulin deficiency)
- elevated potassium levels interfere with normal neuromuscular function - leads to muscle weakness and rarely flaccid paralysis
- ECG changes occur in fewer than half of patients with a serum potassium level greater than 6.5 mEq/L and included peaked T waves, widening of the QRS complex, and arrythmias
- can be life-threatening due to its cardiac manifestations
- it should be treated in the prehospital setting
- calcium administered IV immediately antagonizes cardiac conduction abnormalities
- bicarbonate, insulin, and albuterol shift potassium into the cells during a 15 to 30 min period

Front 132

calcium

Back 132

- majority (98%) of the body's calcium is in the bones and teeth
- provides strength and stability for the collagen and ground substance that forms the matrix of the skeletal system
- calcium enters the body through the gastrointestinal tract and is absorbed from the intestine in a process that depends on the presence of vitamin D
- vitamin D is largely obtained through exposure to sunlight, stored in the bone, and ultimately excreted by the kidney
- the normal serum calcium level is 8.5 to 10.5 mg/100ml

Front 133

hypocalcemia

Back 133

- defined as a decreased serum calcium level
- causes include decreased intake or absorption (malabsorption, vitamin D deficit)
- increased loss (alcoholism, diuretic therapy)
- endocrine disease (hypoparathyroidism, sepsis)
- symptoms reflect the increased excitation of the neuromuscular and cardiovascular systems
- spasm of skeletal muscle causes cramps and tetany
- laryngospasm with stridor can obstruct the airway
- convulsions can occur as well as abnormal sensations (paresthesias) of the lips and extremities
- prolongation of the QT interval predisposes to the development of ventricular arrhythmias

Front 134

hypercalcemia

Back 134

- an increased intake or absorption (excess antacid ingestion)
- endocrine disorders (primary hyperparathyroidism, adrenal insufficiency)
- neoplasms (cancers)
- miscellaneous causes (diuretics, sarcoidosis)
- symptoms include constipation and frequent urination (polyuria)
- stupor, coma, and renal failure may develop in severe cases
- treatment of the cause is the mainstay for treating hypercalcemia
- an acute basis, volume replacement with boluses of 0.45% or 0.9% normal saline may be helpful

Front 135

phosphate

Back 135

- primarily an intracellular anion and is essential to many body functions

Front 136

hypophosphatemia

Back 136

- characterized by a decrease in serum phosphate levels
- causes include decreased supply or absorption ((starvation, malabsorption, blocked absorption (aluminum-containing antacids))
- excessive loss of phosphate ion (diuretics, hyperparathyroidism, hyperthyroidism, alcoholism)
- intracellular shift of phosphorous (administration of glucose, anabolic steroids, oral contraceptives, respiratory alkalosis, salicylate poisoning)
- electrolyte abnormalities (hypercalcemia, hypomagnesemia, metabolic acidosis)
- abnormal losses folled by inadequate repletion (diabetic ketoacidosis, chronic alcoholism)
- symptoms include muscle weakness, decreased deep tendon reflexes, mental obtundation, and confusion
- weakness is common
- acute, severe cases can lead to acute hemolytic anemia and increased susceptibility to infection
- muscle death (rhabdomyolysis) may occur
- treatment involves oral replenishment in mild to moderate cases
- severe cases and symptomatic patients require IV phosphate treatment

Front 137

hyperphosphatemia

Back 137

- defined as an increased serum phosphate level
- causes include massive loading of phosphate into the extracellular fluid (excess vitamin D, laxatives or enemas containing phosphate, IV phosphate supplements, chemotherapy, metabolic acidosis)
- decreased excretion into the urine (renal failure, hypoparathyroidism, excessive growth hormone (acromegaly)
- symptoms vary widely, but include tremor, paresthesia, hyporeflexia, confusion, seizures, muscle weakness, stupor, coma, hypotension, heart failure, and prolonged QT interval
- treatment of the underlying casue and of any accompanying hypocalcemia is the most common therapeutic approach
- saline boluses (forced diuresis) are often helpful

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magnesium

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- the second most abundant intracellular cation, after potassium
- about 50% of the body's magnesium is stored in the bones
- 49% in the body cells
- 1% in the extracellular fluid
- normal serum levels are 1.5 to 2.0 mEq/L

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hypomagnesemia

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- defined as a decreased serum magnesium level
- causes include diminished absorption or intake (malabsorption, chronic diarrhea, laxative abuse, malnutrition)
- increased renal loss (diuretics, hyperaldosteronism, hypercalcemia, volume expansion)
- miscellaneous causes (diabetes, respiratory alkalosis, pregnancy)
- common symptoms are weakness, muscle cramps, and tremor
- patients develop marked neuromuscular and central nervous system hyperirritability with tremors and jerking
- there may be hypertension, tachycardia, and ventricular arrhythmias
- in some patients, confusion and disorientation
- treatment consists of IV fluids containing magnesium

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hypermagnesemia

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- an increased serum magnesium level
- it is almost always the result of kidney insufficiency and the inability to excrete the amount of magnesium taken in from food or drugs, especially antacids and laxatives
- symptoms include muscle weakness, decreased deep tendon reflexes, mental obtundation, and confusion
- weakness is common and respiratory muscle paralysis or cardiac arrest is possible

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Acidosis vs. Alkalosis

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- when the buffering capacity of the body is exceeded, acid-base imbalances occur
- disturbances of acid-base balance are associated with potassium balance (because the kidney transport system moves hydrogen and potassium in opposite directions)

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alkalosis

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- a blood pH greater than 7.45
- pH is too high
- neurons become hyperexcitable, firing action potentials at the slightest signal
- condition first manifests as sensory changes, such as numbness or tingling, then muscle twitches
- if it is severe, muscle twitches turn into sustained contractions (tetanus) that paralyze respiratory muscles
- the kidneys resorb hydrogen and excrete potassium

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acidosis

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- a blood pH less than 7.35
- pH is too low
- neurons become less excitable and CNS depression results
- patients become confused and disoriented
- if CNS depression progresses, the respiratory centers cease to function
- the kidneys excrete hydrogen and resorb potassium

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pH

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- the measurement of hydrogen ion concentration of a solution
- normal physiologic pH range is 7.35 to 7.45

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buffers

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- maintains the acid-base balance
- molecules that modulate changes in the pH
- in the absence of buffers, the addition of acid to a solution will cause a sharp change in pH
- in the presence of buffers the pH change will be moderated or may even be unnoticable in the same situation
- most buffers combine with hydrogen because acid production is a challenge to pH homeostasis

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buffer systems

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- include proteins, phosphate ions, and bicarbonate
- large amounts of bicarbonate produced from the carbon dioxide made during metabolism create the body's most important extracellular buffer system
- hydrogen and bicarbonate ions combine to form carbonic acids - which readily dissociates in water and carbon dioxide

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bicarbonate buffer system

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- excess acid combines with bicarbonate and forms hydrogen bicarbonate
- rapidly dissociates in water and carbon dioxide (exhaled)
- the acid is eliminated as water and carbon dioxide (the pH doesn't change significantly)
- similar process occurs with the production of metabolic base (bicarbonate)

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metabolic acidosis

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- an accumulation of abnormal acids in the blood
- several reasons (sepsis, diabetic ketoacidosis, salicylate poisoning)
- Pa CO2 (partial pressure of carbon dioxide) is not affected, but the pH is decreased
- the body compensates for the metabolic abnormality by hyperventilating, leads to excretion of CO2 and compensatory respiratory alkalosis
- example - diabetic ketoacidosis - can cause Kussmaul respirations

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Kussmaul respirations

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- deep, rapid, sighing ventilations
- hyperventilate to "blow off" CO2 and decrease the acidosis

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Acid-Base Disturbances

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two types:
- metabolic
- respiratory

- both are broken down into acidosis and alkalosis

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metabolic alkalosis

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- rarely seen in an acute condition, but is very common in chronically ill patients (especially those undergoing nasogastric suction)
- involves either a buildup of excess metabolic base (chronic antacid ingestion)
- loss of normal acid (through vomiting or nasogastric suctioning)
- the pH is high and the Pa CO2 unchanged initially
- chronically, the body compensates by slowing ventilations and increasing the Pa CO2, thereby creating compensatory respiratory acidosis

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respiratory acidosis

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- occurs when CO2 retention leads to increased PaCO2 levels
- also occurs in situations of hypoventilation (heroin overdose) or intrinsic lung diseases (asthma or COPD)

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respiratory alkalosis

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- excessive blowing off of CO2 with a resulting decrease in PaC02
- many potentially serious diseases can occur
- pulmonary embolism, acute myocardial infarction, severe infection, diabetic ketoacidosis - all can increase ventilatory levels

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Cell Injury

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- may result from various causes:
- hypoxia (lack of oxygen), ischemia (hypoxia due to lack of blood supply), chemical injury, infectious injury, immunocologic(hypersensitivity) injury, physical damage (mechanical injury), and inflammatory injury
- manifestations of cell injury and death depend on how many and which types of cells are damaged
- they are on the microscopic (structural) and the functional levels

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microscopic abnormalities of a cell

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- those observed in the cardiac cell undergoing necrosis from hyposemia for an extended period of time
- includeds cell swelling, rupture of the cell membrane or nuclear membrane, and breakdown of nuclear material (chromosomes)
- often results in a change in cell shape and function

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functional changes due to cell injury

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- include an ability to use oxygen appropriately, development of intracellular acidosis, accumulation of toxic waste products, inability to metabolize nutrients
- functional changes often have an impact on the entire organism
- some cases only minor systemic abnormalities occur, like a fever
- other cases entire systems fail and the patient becomes critical (kidney failure)
- disfunction of one system, inevitably affects another
- affects the homeostatic balance

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Cell injury repair

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- cells may be repaired up to a point with proper treatment
- irreversible injury
- cell death
- necrosis

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irreversible injury

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- once cells have passed the "point of no return"
- no treatment will help

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necrosis

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- a process where the cell breaks down
- the cell membrane becomes abnormally permeable
- leads to the influx of electrolytes and fluids
- the cell and its organelles swell
- lysosomes also release enzymes that destroy intracellular components
- these processes occur both during and after actual cell death

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hypoxic injury causes

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- may result from decreased amounts of oxygen in the air or loss of hemoglobin function (CO poisoning)
- a decreased number of red blood cells (bleeding)
- disease of the respiratory or cardiovascular system (COPD)
- loss of cytochromes (mitochondrial proteins that convert oxygen to ATP - cyanide poisoning)

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process of hypoxic injury

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- cells that are hypoxic for more than a few seconds produce mediators
- results in a positive feedback cycle where mediators lead to more cell damage
- leads to more hypoxia
- leads to further mediator production
- and so on

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hypoxic injury

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- common and often deadly
- cause of cellular injury
- deleterious effects on the cell

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mediators

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- substances that may damage other local or distant body locations

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free radical

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- earliest and most dangerous mediators
- produced by cells in response to hypoxia
- they are missing one electron in their outer shell
- the unpaired electron results in chemical unstability
- randomly attack cells and membranes in attempt to steal the missing electron
- widespread and potentially deadly tissue damage

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chemical injury

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- a variety of chemicals can injure and destroy cells

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causes of chemical injury

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- includes poisons, lead, CO, ethanol, pharmacologic agents
- common posions: cyanides and pesticides

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cyanide

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- induces cell hypoxia by blocking oxidation phosphorylation in the mitochondria and preventing the metabolism of oxygen

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pesticides

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- block acetylcholinesterase (an enzyme) prevents proper transmission of nerve impulses

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lead

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- chronic ingestion leads to brain injury and neurologic dysfunction
- can be caused by ingesting lead-based paint
- it has the ability to substitute for calcium (molecules of calcium and lead are similar in size) - a common factor in it's toxic actions
- lead is mistaken for calcium in vital biochemical reactions leading to abnormal results and dysfunction

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carbon monoxide

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- (CO)
- binds to hemoglobin and prevents adequate oxygenation of the tissues

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symptoms of CO

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low levels - nausea, vomitign and headache
high levels - death

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symptoms of ethanol poisoning

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low doses - ethanol causes well-known effects of inebriation
higher doses - results in severe CNS depression, hypoventilation, and cardiovascular collapse

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pharmacologic agents

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- produce toxic products when they are metabolized in the body, especially in "overdose conditions"
- Acetaminophen (Tylenol) - in doses of more than 140mg/kg in an adult results in acute overdose - causes accumulation of toxic intermediates that poison the liver and can lead to death

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infectious injury

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- occurs as a result of an invasion of either bacteria or viruses

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bacteria

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- all have a circular strand of DNA, cytoplasm, and a plasma membrane
- many have a cell membrane
- may cause injury either by direct action on cells or by the production of toxins
- the growth and survival of bacteria in the body depend on the effectiveness of the body's own defense mechanisms adn the bacteria's ability to resist those mechanisms

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viruses

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- intracellular parasites that take over the metabolic processes of the host cell and then use the cell to help them replicate
- consists of a nucleic acid core of either RNA or DNA
- have a capsid and some have an envelope
- often initiate an inflammatory response that leads to cell damage and patient symptoms

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virulence

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- measures the disease-causing ability of a microorganism

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pathogenicity

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- a function of a microorganism's ability to reproduce and cause disease within the human body

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depressed immune system

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- less able to fight off microorganisms that the body perceives as harmful
- populations with weaker immune systems may include:
- newborn infants, elderly patients, diabetics, and people with cancer or other chronic diseases

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phagocytes

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- cells that engulf and consume foreign material such as microorganisms and cellular debris
- white blood cells

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capsule

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- protects some bacteria from ingestion and destruction by phagocytes

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Mycobacterium tuberculosis

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- lacks a capsule
- stills stubbornly resists destruction
- can be transported by phagocytes throughout the body

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gram-postive bacteria

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- distinguished by very thick cell walls composed of many layers of peptidoglycan (amino acids and sugar)

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gram-negative bacteria

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- consists largely of lipids
- pathogenic qualities include the microorganism that causes bubonic plague (makes them especially problematic for humans)

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exotoxins

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- produced by bacteria
- substances such as enzymes or toxins that can injure or destroy cells
- staphylococci, streptococci, and Clostridium tetani secrete exotoxins into the medium surrounding the cell

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endotoxins

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- produced by bacteria
- substances such as enzymes or toxins that can injure or destroy cells
- lipopolysaccharides that are part of the cell walls of grame-negative bacteria
- when large amounts are present in the the body, a person may develop septic shock

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pyrogens

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- released by white blood cells
- cause a fever to develop
- the body's most common reaction to the presence of bacteria is inflammation
- some bacteria have the ability to produce hypersensitivity reactions
- when cells are injured, circulating white blood cells are attracted to the site of injury

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bacteremia

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- (sepsis)
- the proliferation of microorganisms in the blood

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capsid

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- layer of protein surrounding the viral core
- protects the virus from phagocytosis

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viral envelope

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- an additional protective coating

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replication of a virus

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- occurs inside the host cell (viruses do not contain their own organelles)
- viral infection leads to decreased synthesis of macromolecules that are vital to the host cell
- viruses do not produce exotoxins or endotoxins

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symbiotic relationships between viruses and normal cells

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- results in a persistent unapparent infection
- viruses have been known to evoke a strong immune response and can rapidly produce irreversible, lethal injury in highly susceptible cells
- example - AIDS

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Inflammation

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- a protective response that can occur even without bacterial invasion
- infection is characterized by and invasion of microorganisms that cause cell or tissue injury which leads to the inflammatory response

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immune system

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- protects the body by providing defenses to attack and remove foreign organisms such as bacteria or viruses

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cellular membrane injury due to immune or inflammatory process

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- cells may become injured when the come in direct contact with the cellular or chemical components of immune/inflammatory process
- chemical/cellular components include:
- phagocytes (neutrophils and macrophages), histamine, antibodies, and lymphokines

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reaction of cell membrane during immune or inflammtory process

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- potassium leaks out of a damaged cell and water flowes inward
- causes the cell to swell
- the nuclear envelope, organelle membranes, and cell membrane may all rupture
- leads to cell death
- degree of swelling and chance of membrane rupture depends on the severity of the responses

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Other Injurious Factors

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- genetic factors
- nutrition
- physical agents

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genetic injurious factors

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- genetic factors that may damage cells
- include chromosomal disorders, premature development of artherosclerosis, and obesity
- two ways an abnormal gene may develop:
- by mutation of the gene during meiosis (affects a newly formed fetus)
- by heredity
- example - trisomy 21 (Down syndrome) - a child is born with an extra chromosome

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good nutrition injurious factors

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- good nutrition is required to maintain good health and assist the cells in fighting off disease
- nutritional disorders can injure cells and the organism as a whole
- includes: obesity, malnutrition, vitamin excess or deficiency, mineral excess or deficiency
- these conditions can lead to alterations in mental growth, mental and intellectual retardation, and death in some circumstances

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physical agent injurious factors

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- heat, cold, and radiation that can cause cell injury
- examples - burns, frostbite, radiation sickness and tumors
- the degree of cell injury that results is determined by the strength of the agent and the length of the exposure

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apoptosis

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- normal cell death
- a unique genetically programmed part of the normal development of a cell, menses, lactating breast tissue, thymus involution, and red blood cell turnover
- cells exhibit characteristics nuclear changes and typically die in well-defined clusters, rather than randomly

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process of apoptosis

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- apoptosis can be activated prematurely by pathologic factors such as cell injury
- results in early cell death (occurs in some forms of heart failure)
- molecular mechanism underlying apoptosis involves the activation of genes that code for caspases
- proteins and DNA undergo controlled degradation that allows their remnants to be taken up and reused by neighboring cells (different from disease process)
- allows the body to eliminate a cell but still recycle many of its components
- areas of apoptosis do show any inflammation (typically only seen in cells undergoing necrosis from hypoxia or cellular toxins)

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death of hepatocytes

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- (liver cells)
- affects patient with viral hepatitis
- dying cells form lumps of chromatin (Councilman's bodies)

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factors that inhibit normal course of apoptosis

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- result in unwanted cellular proliferation, as in cancer and rheumatoid arthritis (uncontrolled synovial tissue proliferation)

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caspases

Back 205

- proteins that are essential cellular "cyanide"
- production leads to cell suicide

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abnormal cell death

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- if the injury that leads to cell degeneration is of sufficient intensity and duration, irreversible cell injury will lead to death
- necrosis is the result of the morphological changes that occur following cell death in living tissues
- can be either simple (coagulation) or derived necrosis

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simple necrosis

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- refers to areas of necrosis where the gross and microscopic tissue and some of the cells are recognizable
- may be caused by acute ischemia, acute toxicity (from heavy metals), or direct physical injury (caustic chemicals and burns)

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derived necrosis

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- includes caseation necrosis, dry gangrene, fat necrosis, a nd liquefaction necrosis

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caseation necrosis

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- manifested by the loss of all features of the tissue and cells
- they come to resemble cheese when viewed through a microscope

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dry gangrene

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- results from the invasion and putrefaction of necrotic tissue after the blood supply is compromised to the tissue and the tissue undergoes coagulation necrosis

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fat necrosis

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- results from the destruction of fat cells, usually by enzymes (pancreatic proteases and lipases)

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liquefaction necrosis

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- results from coagulation necrosis
- followed by liquefaction necrosis of tissues and invasion by putrefying bacteria that grow rapidly in a warm moist environment
- the bacteria lytic enzymes and gas