Cellular Regulation Flashcards
Water percentages
Adult bodies: 50-65% water
Child bodies: 75%
*Children are most susceptible to dehydration
Cell membrane
Protects, serves as a boundary, regulates material coming in and out of the cell
Ribosomes
Made of RNA and assist in the production of enzymes and other proteins needed for cell repair and reproduction
Cytoplasm
The internal environment of the cell that is a watery soup of proteins, nucleic acids, gasses, salts, etc.; surrounds and protects the cell
Nucleus
The control center or “brain” of the cell; contains the DNA of the cell
Nucleolus
Found within the nucleus; synthesizes RNA that forms ribosomes
Endoplasmic Reticulum
“Transport system”: series of channels in the cytoplasm
Rough ER: has ribosomes; responsible for synthesis of proteins
Smooth ER: no ribosomes, synthesizes lipids and steroids
Mitochondria
Creates energy from food into ATP molecules; supplies 95% of the body’s energy needed for cell repair, movement, and reproduction
Golgi Apparatus
Sorts and correctly ships the proteins produced in the ER; “packaging and sorting system”
Lysosomes
“Digestive system” of the cell: breaks down large molecules into smaller pieces that the cell can use, clean up intracellular waste, and destroy unwanted bacteria through phagocytosis
Atrophy
Reduction in the size of the cell
Hypertrophy
Enlargement of the cell to an increased workload
Hyperplasia
Increase in cell number due to an increased rate of cellular division
Metaplasia
Replacement of one mature cell with another less mature cell type
Ex causes of atrophy
Happens from disuse, nutritional deprivation, decreased hormonal stimulation, aging, denervation pressure
Ex causes of hypertrophy
Mechanical signals: stretch
Trophic signals: growth factors, hormones, and vasoactive agents (eg uterine growth)
Ex causes of hyperplasia
Hormonal: occurs in estrogen-dependent organs (eg uterus and breast)
Compensatory: mechanism that allows certain organs to regenerate (eg liver hepatocytes)
Dysplasia
Deranged cell growth of specific tissue results in abnormal size, shape, and appearance (eg cervical precancer and cancer r/t HPV)
When does cellular injury occur?
When the cell is unable to maintain homeostasis
How do all forms of disease begin?
With alterations to cell
Cellular injury causes
Physical injury: trauma, UV radiation
Toxic injury: external (eg smog) or internal
Infectious injury: bacteria, fungi, viruses, parasites
Hypoxic Injury: anemia, decreased perfusion, hypoxia, ischemia
Deficiency injury: nutrition and hydration
How long can skeletal muscles vs the heart tolerate ischemia?
Skeletal muscles: 2-3 hrs
Heart: 20 mins
What are liver cells susceptible to?
Chemical injury (eg tylenol and OTC cold meds)
Free Radicals
AKA Reactive Oxygen Species
Unpaired electron; highly unstable and reactive; will try to steal an electron from another molecule, thereby causing a chain reaction (another molecule becomes a free radical)
Initiation of free radicals
1) Absorption of extreme energy sources (eg UV light)
2) Endogenous reactions when oxygen is reduced to water (eg cell growth and proliferation)
3) Enzymatic metabolism (eg cigarette smoke and alcohol)
Ex of free radical damage
Lipid peroxidation: destruction of polyunsaturated lipids leading to membrane damage and increased permeability
Protein alterations: causing fragmentation of poly peptide chains
DNA fragmentation: causing decreased protein synthesis
Mitochondrial damage: causing liberation of calcium into the cytosol
Ways of terminating free radicals
Antioxidant enzymes: block synthesis of free radicals
Endogenous: Catalaste, superoxide dismutase (SOD)
Exogenous: vitamin E
Necrosis
Sum of cellular changes after local cell death and the process of cellular self-digestion
Fat necrosis
Cellular dissolution caused by powerful enzymes (called lipases) that occur in the breast, pancreas, and other abdominal structures
Coagulative necrosis
Occurs primarily in the kidneys, heart, and adrenal glands; commonly results from hypoxia caused by severe ischemia or hypoxia from chemical injury; Coagulation is caused by protein denaturation, which causes the protein albumin to change from a gelatinous, transparent state to a firm, opaque state
Liquefactive necrosis
Commonly results from ischemic injury to neurons and glial cells in the brain; cells are digested by their own hydrolases, so the tissue becomes soft, liquefies, and segregates from healthy tissue, forming cysts
Caseous necrosis
Usually results from tuberculous pulmonary infection; tissue resemble clumped cheese in that they are soft and granular; a granulomatous inflammatory wall encloses areas of caseous necrosis
Necrosis: gangrene
Results from severe hypoxic injury, commonly occurring because of arteriosclerosis, or blockage, of major arteries, in particular those of the lower extremities (PVD)
Gaseous gangrene
Caused by infection of injured tissue by one of many species of Clostridium; produces hydrolytic enzymes and toxins that destroy connective tissue and cellular membranes; leads to gas bubbles to form in muscles cells
Wet gangrene
Develops when neutrophils invade the site, causing liquefactive necrosis (diabetic ulcer)
Dry gangrene
Usually the result of coagulative necrosis; the skin becomes very dry and shrinks, resulting in wrinkles, and its color changes to dark brown or black
Apoptosis
Programmed cell death and is implicated in both normal and pathologic tissue changes (cells need to die in order for people not to became huge; the avg adult creates 10 billion new cells every day—and destroy the same number)
Final step of apoptosis
WBC eats apoptic bodies (phagocytosis)
