Part 1 Topics The Cell Types of Tissue Organ Systems Disease Causes Disease Pathophysiology
The Normal Cell The cell is the fundamental unit of the human body. Cells contain all the necessary components for life functions.
Cell Structure The cell membrane is the outer covering that encircles and protects the cell. Cytoplasm is the thick, viscous fluid that fills and gives shape to the cell. Organelles are structures that perform specific functions within a cell.
Epithelial Tissue Lines internal and external body surfaces and protects the body. Some forms perform specialized functions: Secretion Absorption Diffusion Filtration Skin, mucous membranes, lining of intestinal tract.
Muscle Tissue Has the capability of contraction when stimulated. Cardiac tissue is found only within the heart. Has the unique capability of spontaneous contraction without external stimulation. Smooth muscle is found within the intestines and encircling blood vessels. Generally under control of the autonomic nervous system. Skeletal muscle allows movement and is generally under voluntary control. Most abundant type.
The Three Types of Muscle:Skeletal muscle, also calledvoluntary muscle, is foundthroughout the body.Cardiac muscle is limited tothe heart.Smooth muscle, occasionallycalled involuntary muscle, isfound within the intestinesand surrounding bloodvessels.
Connective Tissue Most abundant tissue in the body. Provides support, connection, and insulation. Examples include bone, cartilage, and fat. Blood is classified as connective tissue.
Nerve Tissue Specialized tissue that transmits electrical impulses throughout the body. Examples include the brain, spinal cord, and peripheral nerves.
Organs, Organ Systems, and the Organism An organ is a group of tissues functioning together. A group of organs working together is an organ system. The sum of all cells, tissues, organs, and organ systems makes up an organism.
System Integration Homeostasis The natural tendancy of the body to maintain a steady and normal internal environment Metabolism Building up (anabolism) and breaking down (catabolism) of nutrients to create energy
System Integration Chemical Signaling Endocrine Parachrine Synaptic Negative Feedback
Integumentary System Epidermis Dermis Subcutaneous Hair Nails
Hematopoietic System Blood Bone Marrow Liver Spleen Kidneys
Endocrine System Secrete hormones directly into the circulatory system. Some endocrine glands include: pituitary, thyroid, parathyroid, adrenal glands, Islets of Langerhans in the pancreas, testes, and ovaries.
The body’s cells interactand intercommunicate with substances secreted by various body glands.
Signaling Endocrine signaling—hormones distributed throughout the body. Paracrine signaling—secretion of chemical mediators by certain cells that act only upon nearby cells. Autocrine signaling—cells secrete substances that act upon themselves. Synaptic signaling—cells secrete neurotransmitters that transmit signals across synapses.
Cellular Adaptation Cells, tissues, organs, and organ systems can adapt to both normal and injurious conditions. Adaptation to external stressors results in alteration of structure and function. Examples: Growth of the uterus during pregnancy, dilation of the left ventricle after an MI.
Types of Cellular Adaptations (1 of 2) Atrophy—decreased size resulting from a decreased workload. Hypertrophy—an increase in cell size resulting from an increased workload.
Types of Cellular Adaptations (2 of 2) Hyperplasia—An increase in the number of cells resulting from an increased workload. Metaplasia—Replacement of one type of cell by another type of cell that is not normal for that tissue. Dysplasia—A change in cell size, shape, or appearance caused by an external stressor.
Manifestation of Cellular Injury When cells are injured metabolism is changed, causing substances to infiltrate or accumulate to an abnormal degree in cells.
Cellular Swelling Results from a permeable or damaged cellular membrane. Caused by an inability to maintain stable intra- and extracellular fluid and electrolyte levels.
Fatty Change Lipids invade the area of injury. Occurs most commonly in vascular organs, most frequently the liver. Causes a disruption of the cellular membrane and metabolism and interferes with the vital functions of the organ.
Signs and Symptoms of Cellular Change Fatigue and malaise Altered appetite Fever Increased heart rate associated with fever Pain
Cell Death (1 of 3) Apoptosis Injured cell releases enzymes that engulf and destroy the cell. Cells shrink. Eliminating damaged and dead cells allows tissues to repair and possibly regenerate.
Cell Death (2 of 3) Necrosis A pathological process Cells swell and rupture Coagulative Liquefactive Caseous Fatty
Cell Death (3 of 3) Gangrenous necrosis Cell death over a wide area Dry Wet Gas
The Cellular Environment:Fluid and Electrolytes
Water is the most abundantsubstance in the human body.
Where the Water is Found Intracellular fluid—fluid inside the cells. Extracellular fluid—all the fluid outside the body cells. Intravascular fluid—fluid within the circulatory system. Interstitial fluid—fluid outside of the cell membranes but not within the circulatory system.
Percentage of total body weight due to water distributed into various fluid compartments.
Sodium (Na ) + Most prevalent cation in extracellular fluid. “Water follows sodium.” Important in transmission of nervous impulses. Hypernatremia is an abnormal increase in sodium. Hyponatremia is an abnormal decrease in sodium.
Potassium (K ) + Most prevalent cation in the intracellular fluid. Important in transmission of electrical impulses. Hyperkalemia is an abnormally high potassium level. Hypokalemia is an abnormally low potassium level.
Calcium (Ca ) ++ Plays a major role in muscle contraction as well as nervous impulse transmission. Hypercalcemia is an abnormally increased calcium level. Hypocalcemia is an abnormally low calcium level.
Magnesium (Mg ) ++ Necessary for several biochemical processes. Closely associated with phosphate. Hypermagnesemia is an abnormally increased level of magnesium. Hypomagnesemia is an abnormally decreased level of magnesium.
Diffusion is the movement of a substancefrom an area of greater concentration to an area of lesser concentration.
Types of Solutions Isotonic—solutions on opposite sides of a membrane are equal in concentration. Hypertonic—the concentration of a given solute is greater on one side of a membrane than the other. Hypotonic—the concentration of a given solute is less on one side of a membrane than the other.
OSMOSIS VS. SOLUTES (1 of 2) Osmosis is the movement of water from an area of higher WATER concentration to an area of lesser WATER concentration. Because water is a solvent, it moves from an area of lower SOLUTE concentration to an area of higher SOLUTE concentration.
Active Transport The movement of a substance across the cell membrane against the osmotic gradient (toward the side that already has more of the substance). Faster than diffusion. Requires energy.
Facilitated Diffusion Certain molecules can move across the cell membrane with the assistance of “helper proteins.” Glucose is one example. Depending on the substance, this movement may or may not require energy.
OSMOTIC VS. ONCOTIC Osmotic pressure—pressure exerted by the concentration of solutes on one side of a semipermeable membrane. Oncotic force (colloid osmotic pressure)—osmotic pressure exerted by large protein particles.
Starling’s Hypothesis Net Filtration = (Forces favoring filtration) MINUS (–) (Forces opposing filtration)
Edema Accumulation of water in the interstitial space due to disruption in the forces and mechanisms that normally keep net filtration at zero.
Mechanisms that Cause Edema A decrease in plasma oncotic force. An increase in hydrostatic pressure. Increased capillary permeability. Lymphatic channel obstruction.
Edema (1 of 2) Can be local or within a certain organ system. For example: Sprained ankle vs. pulmonary edema.
Edema (2 of 2) Water in interstitial spaces is not available for metabolic processes. Edema, therefore, can cause a relative condition of dehydration.
Acid-Base Balance Acid-base balance is a dynamic relationship that reflects the relative concentration of hydrogen ions in the body. Hydrogen ions are acidic and the concentration of those in the body must be maintained within fairly strict limits.
Acidosis — pH below 7.35 Alkalosis — pH above 7.45 A variation of only 0.4 of a pHunit in either direction of normal can be fatal in humans.
Mechanisms to Remove Hydrogen Ions From the Body
Buffer System (Bicarbonate Buffer System) The fastest mechanism. Two components of this system are bicarbonate ion (HCO3-) and carbonic acid (H2CO3) and are normally in equilibrium with hydrogen (H+).
H + HCO3 + - H2CO3 Hydrogen may combine with bicarbonate to produce carbonic acid. In other circumstances carbonic acid will dissociate into bicarbonate and hydrogen.
Respiratory and Kidney Mechanisms Increased respirations cause increased elimination of CO2 which causes a decrease in hydrogen ions and an increase in pH. The kidneys regulate the pH by altering the concentration of bicarbonate ions in the blood.
The Respiratory Component of Acid-Base Balance
Respiratory Acidosis Caused by abnormal retention of CO2 from impaired ventilation due to problems occurring in the lungs or respiratory center of the brain.Respiration = CO2 + H2O H2CO3 H+ + HCO3-
Respiratory AlkalosisCaused by increased respirationand excessive elimination of CO2.The CO2 level is decreased and thepH is increased.Respiration = CO2 + H2O H2CO3 H+ + HCO3-
Metabolic AcidosisResults from the production ofmetabolic acids such as lactic acid.These acids consume bicarbonateions.Can be the result of dehydration,diabetes, or medication usage. H+ + HCO3- H2CO3 H 2O + CO2
Compensation for metabolicacidosis begins with an increase in respirations.
Metabolic Alkalosis The pH is increased and the CO2 level is normal. It is usually caused by administration of diuretics, loss of chloride ions associated with prolonged vomiting, and overzealous administration of sodium bicarbonate. H + HCO3 + - H2CO3 H 2O + CO2