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Cells image (Pathology Connections (How microorganisms cause disease…

- - - - Since the late 1800s cell research has been going on and has provided us with the cell theory:
        
        A cell is the basic structural and functional unit of living organism. So when we define cell prosperities we are in fact defining the properties of life
        
        The activity of an organism depends on the collective activities of its cells
        
        According to the principle of complementarity , the biochemical activities of cells are dictated by the relative number of their specific subcellular structures
        
        Continuity of life has cellular basis
  - - - Problem is the reactions tht are needed are reactions that take time (it is a slow process)
        
        To solve the slowness problem, cells have special proteins
        
        Enzymes (speed up the rate of a chemical reaction)
        
        Facilitate important chemical reactions in body
        
        One way is by speeding up reactions ( I did just say that so it must be important!!)
        
        Not used up by reactions that they facilitate; instead, act like carrier molecules
        
        Very specific; each only facilitates (catalyzes) certain reactions
  - - - When cell needs to reproduce, enters mitotic phase (actual cell division)
        
        Mitotic phase divided into two major portions: mitosis and cytokinesis
        
        Mitosis
        
        Sorting and division of genetic material; has 4 phases
        
        Cellular reproduction: process of making new cell; also called cell division
        
        Asexual reproduction: cells make identical copies of themselves without involvement of another cell
        
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        One cell divides into two cells
        
        Prophase
        
        Nucleus disappears, chromosomes become visible, set of chromosomal anchor lines or guide wires, spindle, forms
        
        Metaphase
        
        Chromosomes line up in center of cells
        
        Anaphase
        
        Chromosomes split and spindles pull them apart
        
        Telophase
        
        Chromosomes go to far ends of cell, spindle disappears, and nuclei reappear
        
        Cytokinesis: division of cytoplasm
        
        During or directly after telophase, cytokinesis happens and cell divides in half
        
        Original cell was mother cell that has now formed into two new identical daughter cells
        
        Thus mitosis (asexual reproduction), results in two new daughter cells identical to original mother cell
        
        The cell cycle is tightly controlled to avoid overproduction of cells (which can sometimes lead to cancer)
        
        To avoid this, the cell has check points
        
        Several places in cell cycle are checkpoints where cells must wait for signal to tell them to keep dividing
        
        If something is wrong with cell or there is some reason cell should not reproduce, cell will not get signal and will stop dividing
        
        If timing is good, cell will get go ahead signal and divide without interruption
        
        Purpose of mitosis
        
        Provides the “new” cells fo body growth in the youth and is necessary to repair body tissues all through life. For example
        
        Growth; example: bone (lengthening)
        
        Muscles (increase in size with exercise)
        
        Tissue replacement; example: red blood cells
        
        Say you cut your hand, the skin is replaced, first by collagen, but then the skin is replaced
      - Most of the time the cell cycle is in interphase where it is NOT dividing and is performing its normal function
  - - - Used to make sperm and egg cells for sexual reproduction
      - Each parent cell produces four new cells that are not identical to parent cell and has only half normal number of chromosomes; other half of chromosomes contributed when sperm fuses with egg in sexual reproduction
  - - - Bacteria
        
        Bacteria can be harmful, as in case of pathogens, or can be harmless and essential for life
        
        FYI bacteria grows rapidly and reproduces by splitting in half, doubling as fast as every 30 minutes!
        
        Harmless bacteria sometimes called normal flora
        
        Certain bacteria in intestines help to digest food
        
        Some help to synthesize vitamin K, needed for blood clotting
      - Viruses
        
        Infectious particles that have core containing genetic material surrounded by protective protein coat called a capsid
        
        Cannot grow, eat, or reproduce by themselves; must enter another cell and use that cell for energy to grow and reproduce
        
        Do not respond to antibiotics; can stay dormant in body and become active later in life
      - Fungi
        
        Plural form of fungus; can be one-celled or multi-celled organism; plant-like organisms with tiny filaments, called mycelia, that travel out from cell to find and then absorb nutrients
        
        Good fungi, like edible mushrooms, are harmless; others can cause disease
        
        Fungi spread through release of spores
        
        Examples of fungal infections include athlete’s foot, thrush, or candidiasis
      - Protozoa
        
        One-celled, animal-like organisms that can be found in water and soil
        
        Diseases caused by these microorganisms can result from swallowing them or from being bitten by insects that carry them in their bodies
- - - - Often referred to as the building blocks of our bodies
  - - - Nucleus
        
        "Brains” of cell (book describes it as city hall)
        
        Dictates activities of other organelles in cell
        
        Much like City Hall dictates the activity of the city departments
        
        Has double walled nuclear membrane with large pores allowing certain materials to pass in and out, while preventing other materials from entering ( metal detectors at city hall)
        
        Chromatin (bumpy loose threads)
        
        Material found in nucleus that contains deoxyribonucleic acid (DNA); DNA contains blueprints, or specifications, for creation of new cells
        
        Will eventually form chromosomes, which contain genes
        
        Genes determine our inherited characteristics
      - Organelles
        
        Organelles are made of even smaller substances called atoms
        
        Atoms are tiny building blocks of all matter
        
        Atoms combine to form molecules like water, sugar and proteins
        
        These molecules build the cellular structures and facilitate the cell functions
        
        There are four basic types of molecules found in cells:
        
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      - Cytoplasm
        
        Gel-like substance composed of water, nutrients, and electrolytes, which looks a lot like white of raw egg
        
        Required by cells for their internal environment in order for parts of cell, known as organelles, to thrive and function
        
        Centrosomes
        
        Act as building contractor, building new structures as need arises
        
        Specialized regions that contain centrioles that are involved in division of cell
        
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        Mitochondria
        
        Tiny bean-shaped organelles, act as power plant to provide up to 95% of bodies’ energy needs for cellular repair, movement, and reproduction
        
        If cell needs more power, it increases number of mitochondria in cell
        
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        Contain special enzymes that help to take in oxygen for use in producing energy
        
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        Endoplasmic reticulum
        
        Series of channels set up in cytoplasm that are formed from folded membranes
        
        Has two distinct forms:
        
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        Golgi apparatus
        
        Looks like a bunch of flattened membranous sacs
        
        Once protein from the endoplasmic reticulum is received, it further processes and stores it
        
        Takes processed protein to cell membrane where it is released Salivary glands and pancreatic glands have higher numbers of Golgi apparati because they have higher level of secretion or storage
        
        Lysosomes
        
        Organelles containing powerful enzymes that take care of cleaning up intercellular debris and other waste
        
        Lysosomes help keep us healthy; they destroy unwanted bacteria by participating in process of phagocytosis
        
        Vesicles: can be thought of as little vans; they can be loaded up with substances and travel to other sites within cell
        
        Cytoskeleton: network of microtubules and interconnected filaments that provide shape to cell and allow cell and its contents to be mobile
        
        Flagella: whip-shaped tails that move some cells, like sperm, to other locations
        
        Cilia: short, microscopic, hair-like projections located on outer surface of some cells; move particles using wavelike motion
      - Cell membrane
        
        Defined boundary that possesses a definite shape but flexible and actually holds cell contents together, acting as protective covering
        
        Allows material in and out of cell
        
        Selectively permeable or semi permeable because they choose what gets in or out
        
        Selective permeability is only promising on a healthy, unharmed cell. When a cell dies or is badly damaged, its plasma membrane can no longer be selective and becomes permeable to nearly everything.
        
        We see this problem when someone is badly burned
        
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        Has identification markers that identify it as coming from a certain person
        
        Like a certain person come from PA (identification marker) that tells us Pittsburg PA is in Pennsylvania
        
        3/10,000,000 of an inch thick
      - Nucleolus
        
        Spherical body made up of dense fibers found within cell nucleus
        
        Major function is to synthesize/create ribonucleic acid (RNA) that forms ribosomes
        
        Ribosomes
        
        Made of ribonucleic acid (RNA) and assist in production of enzymes and other protein substances needed for cell repair and reproduction. It is the actual site for protein synthesis in the cell
        
        Can be considered “remodeler” of cell, taking existing structure and maintaining and repairing
        
        Organelles found on endoplasmic reticulum or found floating around in cytoplasm
- - - - Like a yo-yo simply falling as it unwinds from a string
      - Passive transport can be divided into four types:
        
        Diffusion
        
        Most common form of passive transport in which substance of higher concentration travels to area of lesser concentration
        
        The difference between these two concentrations is called the concentration gradient
        
        Examples:
        
        Adding packet of powdered drink mix to pitcher of water
        
        Water gradually assumes the color and flavor of the powder
        
        Smell of classmate’s perfume filling room
        
        The smell diffuses from high concentration on the individual to low concentration throughout the room
        
        Necessary to move oxygen from lungs to blood stream, or carbon dioxide from blood stream to lungs
        
        Osmosis
        
        Another form of diffusion in which water travels through selectively permeable membrane to equalize concentrations of a substance
        
        Dissolved substance called a solute
        
        Water tends to travel across a membrane to equalize concentrations of a solute; ability of substance to pull water toward area of higher concentration called osmotic pressure
        
        The greater concentration of solute, the greater osmotic pressure, or pull, it exerts to bring in water
        
        Filtration
        
        Differs from osmosis in that pressure is applied to force water and its dissolved materials (solutes) across or through a membrane(capillary wall) by fluid or hydrostatic pressure
        
        Similar to a crowd of people being pushed through the turnstiles during rush hour
        
        Effect you get when you squeeze the trigger on a squirt gun.
        
        Major supplier for forces in body is pumping of heart, which forces blood flow into kidneys, where filtration takes place
        
        Like diffusion, filtration is a passive process and a gradient is involved. The gradient is called a pressure gradient (actually pushes filtrate from high pressure to low pressure area
        
        Facilitated diffusion
        
        Facilitated diffusion (carrier mediated passive transport)is a variation of diffusion in which a substance is helped in moving across the membrane, similar to an usher helping you to your seat
        
        Glucose is the substance that is often helped across a cell this way.
        
        These carriers are very specific meaning only glucose can be carried by its special carrier
        
        How is this passive transport then?
        
        Think of it as a situation that glucose was already moving in an attempt to get across the cell and it has encountered an already revolving door
        
        once it steps into the door it is pushed along
    - - Can be broken down further to three different types:
        
        Active transport pumps
        
        Require addition of energy in form of ATP (adenosine triphosphate) to move substance
        
        Energy needed because cell is trying to move substance into area that already has high concentration of substance
        
        Example: need to transport potassium into our cells, where high concentration already exists; it must be “pushed” in
        
        Endocytosis
        
        Used by cells for intake of liquid and food when substance too large to diffuse across membrane
        
        The cell membrane will actually surround the substances with a small portion of its membrane, forming a chamber or vesicle, which will then separated from the membrane and move into the cell (phagocytosis).
        
        This is what a WBC will do to bacteria to prevent infection
        
        When done to a liquid it is called pinocytosis.
        
        Exocytosis
        
        Transport of things out of cell
        
        Some cells produce substance needed outside cell
        
        Once substance is made, it is surrounded by membrane, forming a vesicle,(sac or bladder) and moves to cell membrane
        
        Vesicle becomes part of cell membrane and expels its load out of cell
        
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      - Cell energy and ATP: energy molecule
        
        Digestion breaks food down, releasing energy
        
        In order for cells to use energy, nutrients must be converted to ATP, an energy transfer molecule
        
        ATP made up of base, sugar, and three phosphate groups
        
        Phosphate groups held together by high-energy bonds
        
        Energy released each time bond is broken, turning ATP to ADP (two phosphate groups)
        
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        Cells produce ATP through process called cellular respiration
        
        In cellular respiration, glucose (from food) is combined with oxygen
        
        Chemical reaction results in production of ATP in mitochondria
        
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        Breathing (exchange of oxygen and carbon dioxide) provides necessary materials for cellular respiration
        
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- - - - Caused by malformation in membrane channels for chloride and sodium ions
        
        Sodium and chloride do not diffuse across cell membrane as they normally would because these channels are not normal.
        
        Fluid around cells becomes extremely salty due to excess sodium and chloride which then ….
        
        Results in excessively thick mucus in respiratory, digestive, pancreas especially) and reproductive systems; mucus can cause clogging in organs
        
        Symptoms may include
        
        Difficulty breathing (lungs appear normal at birth, but soon after birth obstruction of the airways with viscid mucus that leads to infection and a chronic inflammatory process)
        
        Nutritional deficits due to decreased absorption of nutrients (failure of the pancreas to secrete enzymes ) will have excessive fat and protein in the stool) Missing lipase amylase, and trypsin (necessary for the breakdown and digestion of fat.
        
        Increased risk of respiratory infection
        
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        Diabetes failure of the pancreas working correctly
        
        Infertility (especially in males)- the epididymis, vas deferens, and seminal vesicles are usually poorly developed or absent . Female fertility is low owing to plugging of the cervix with a thick mucus that is abnormal in physical and chemical properties that blocks the entrance of sperm
        
        Diagnosis
        
        Prenatal genetic testing
        
        Postnatal genetic testing
        
        Testing pulmonary function
        
        Testing amount of sodium in sweat- this is called the pilocarpine test. Usually done after at least one month of age.
        
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        Treatment
        
        No cure; treatments help extend and improve quality of life (want the patient living an independent life
        
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  - - - Glucose transported into cells via facilitated diffusion with diabetes glucose cannot get into the cells
        
        Hormone insulin must be present in order for transport of glucose to occur
        
        Insulin is either absent, or cells insensitive to insulin (Insulin usually refereed to as the key to the door)
        
        How does the body become insensitive to insulin?
        
        Results in glucose not getting to cells like it should
        
        Lack of glucose transport into cells causes several problems
        
        Lots of glucose hangs around in bloodstream, causing big osmotic problems for cells
        
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    - - Type 1 diabetes (formerly IDDM - insulin dependent diabetes mellitus); auto-immune disorder
        
        Immune system attacks and destroys cells in pancreas that make insulin resulting in cessation of insulin production
      - Type 2 diabetes (formerly NIDDM - non-insulin dependent diabetes mellitus)
        
        Develops when cells stop responding (insulin resistance); insulin still produced by pancreas, but tissues don’t respond
        
        Usually related to obesity; associated with high cholesterol, high lipids and high blood pressure
      - Treatment depends on type of diabetes
        
        Type-1 diabetes: not curable
        
        Can be treated with daily insulin injections
        
        Patients must adhere to strict diet
        
        Type-2 diabetes: can sometimes be reversible
        
        First step of treatment includes adoption of healthy diet & exercise habits and weight loss
        
        Medications affecting pancreas or tissues can improve blood sugars
        
        Some patients eventually require supplemental insulin
  - - - Normally low density lipoprotein (LDL or “bad cholesterol”) binds to cholesterol, and allows it to be carried into cells via endocytosis; once inside, cholesterol used to make other lipids
        
        In familial hypercholesterolemia, LDL doesn’t move into cells, and stays in blood; causes two problems
        
        Too little cholesterol gets into cells, and cells must make more cholesterol
        
        LDL that cannot get into cells hangs around in blood; causes plaques in blood vessels which can lead to blood clots, strokes, and heart attacks
      - Severe form of familial hypercholestrerolemia
        
        Patients often have heart attacks or strokes as children
        
        Often fatal in children or teenagers
        
        Has no effective treatment
      - Moderate form of familial hypercholestrerolemia
        
        Leads to heart attacks and strokes, but usually not until mid-life
        
        Can be treated with diet modifications and cholesterol lowering drugs
        
        Estimated that 1/500 Americans have moderate form
  - - - Lysosomal storage disorder
        
        Occur when lysosomes missing one of their enzymes. When an enzyme is missing or broken
        
        Results in some molecules not breaking down and accumulating in cells
        
        Many kinds of lysosomal storage disorders (40 )
        
        All are genetic
        
        Most lack effective therapies
        
        Tay Sachs
        
        Most common in Jews of central and eastern Europe descent
        
        Enzyme missing in lysosomes of nervous system cells
        
        As result, glycoproteins accumulate in cells in nervous system
        
        Build up causes inflammation and eventual cellular destruction
        
        Symptoms include mental regression, dementia and paralysis appearing within first year of patient’s life
        
        Diagnosis: appearance of cherry red spot on back of patient’s eyes; abnormalities in startle reflex
        
        No treatment; disease generally fatal within two or three years of onset
        
        Availability of genetic test has decreased incidence in recent years
      - Cigarettes and paralyzed cilia
        
        Smoking causes cilia in respiratory tract to become paralyzed
        
        As a result, cannot keep lungs clean
        
        Over time, can lead to chronic obstructive pulmonary disease (COPD) and other smoking-related lung problems
        
        Passive smoking (second hand smoke exposure) also increases risk of lung problems
  - - - Most common in Caucasians of Irish, Scottish, or Scandinavian descent
      - Patients missing enzyme: phenylalanine hydroxylase (FENAL AL LA NEENE)
        
        Without enzyme, amino acid phenylalanine builds up in cells
        
        Build up affects nervous system; causes progressive mental retardation if not treated
        
        Other signs include
        
        Light pigmentation of skin, hair and eyes (inability to produce melanin)
        
        Abnormalities of posture and gait
        
        Epilepsy
        
        Musty odor created by the excretion of phenylalanine metabolites in the urine and sweat
        
        Behavioral problems can occur (hyperactive, agitated, aggressive)
        
        Treatment: is aimed to balance the amino acids needed for growth and development against the dangers of amino acid accumulation
        
        low phenylalanine diet includes avoidance of high protein foods and products sweetened with aspartame (NutraSweet™)
        
        Consequences of going “off diet”
        
        Children: cognitive defects
        
        Adults: depression, anxiety, or other neurological changes
        
        Diagnosis
        
        Blood tests & genetic tests
        
        Guthrie test (few drops of blood required) 72 hours to 7 days after birth
        
        Every newborn in US routinely screened
  - - - Sometimes conditions are altered that trigger changes in way cells reproduce; this wild, uncontrolled reproduction can lead to too many cells being produced, creating a lump, or tumor/neoplasm (new growth)
        
        Not all tumors or neoplasms are cancerous
        
        Tumors can generally be either benign or malignant
        
        Benign tumors- a local affair
        
        Tend to be surrounded by a capsule
        
        Slow growth
        
        Tend to push healthy cells out of the way. If they are removed before they compress vital organs they will seldom kill their host (person)
        
        Generally non-life threatening
        
        Malignant tumors -(bad neoplasms)
        
        Rapid growth
        
        Noncapsulated
        
        Cells tend to be immature cells that tend to invade healthy tissues (like a crab- spread out into healthy tissue like the legs and pincers of a crab)
        
        Can enter blood or lymphatic system and start new tumors in other parts of body; this kind of spread called metastasis
        
        Reason lung cancer so deadly (more woman die from lung then breast) It metastasize for a long time before lung cancer is dx and it spread to the liver, and brain.
        
        Cancer cells consume an exceptional amount of the body’s nutrients, leading to weight loss, and tissue wasting that contributes or gives way to death.
        
        What causes this transformation in cells?
        
        It is well known that radiation, mechanical trauma, viral infections, and many chemicals ( tobacco, tars, saccharine) can act as a carcinogen
        
        All of these have one thing in common and that is the mutation that they cause.
        
        Prognosis often determined by stage at diagnosis; two basic strategies for staging cancers
        
        Staging based on amount of metastasis
        
        Stage I: no cancer spread
        
        Stage II: spread to nearby tissues
        
        Stage III: spread to the lymphatic system
        
        Stage IV: spread to distant organs
        
        TNM classification of stages
        
        Tumor characteristic or extent (T)
        
        Number of lymph nodes invaded (N)
        
        Any tumor metastasis (M)
        
        Diagnosis of cancer
        
        Imaging techniques (MRI, CAT, X-ray, etc.)
        
        Blood tests
        
        Biopsy (surgical examination of abnormal tissue)
        
        Treatment of cancer; four main types; typically more than one type used to attack cancer
        
        Chemotherapy: uses chemicals to kill rapidly dividing cells
        
        Radiation therapy: uses energy to target cancer cells
        
        Surgery: removes cancer cells from body
        
        Biological or immunotherapy: trains body’s natural defenses to fight cancer cells
        
        Typically, more than one treatment will be used
        
        Success depends on stage at diagnosis and specific characteristics of the cancer itself
  - - - Destroy body tissues
      - Destroy blood cells
      - Inhibit ribosomes
      - Cause fluid loss
      - Cause high fever
      - Cause decreased blood pressure
      - Increase blood clotting
      - Cause fluid in the lungs
      - Cause paralysis
      - Signs and symptoms of bacterial infection
        
        High fever
        
        Rapid pulse
        
        Rapid breathing
        
        Abnormal, often foul-smelling discharge from infected area
        
        Pain at infection site
        
        Swelling at infection site
      - Antibiotics used to treat bacterial infections
        
        Chemicals kill prokaryotic bacteria without harming eukaryotic cells
        
        Most antibiotics produced naturally by other microorganisms
    - - Viruses cause disease by
        
        Causing cell to rupture and release viruses
        
        Making good environment for secondary bacterial infection
        
        Example: influenza can result in secondary bacterial pneumonia
        
        Shutting down cell
      - Signs and symptoms of viral infection
        
        Low grade fever (although sometimes can be high)
        
        Muscle aches
        
        General fatigue
        
        Some have no symptoms
        
        Some may be latent (hidden without symptoms) for many years, only to activate and cause symptoms later
        
        Some may become chronic, causing low level symptoms for weeks, months, or even years
      - Few treatments for viral infections
        
        Antibiotics do not kill viruses
        
        Treatment for most is rest, fluids, and treatment of symptoms to keep patient comfortable
        
        Some antiviral drugs, but because viruses use host cell’s machinery, drugs commonly affect host cell as well, causing side effects
    - - Symptoms vary depending on type of protozoan
        
        Many are serious disease causing long term debilitating illness; example: malaria, which is transmitted by mosquitoes
        
        Some are relatively mild illnesses; example: “beaver fever” caused by Giardia, protozoan that lives in streams and water supplies contaminated by fecal matt
    - - Fungal infections
        
        Spores: tiny bodies resistant to environmental changes (able to stay dormant until conditions are just right)
        
        Spores enter body through open wounds
        
        Spores are inhaled
        
        Most fungal spores do not cause disease in otherwise healthy individuals; exception is fungal infections of skin (such as athlete’s foot and jock itch
        
        Many fungal infections opportunistic (only infect people with compromised immune systems or other underlying disease)
        
        Symptoms of fungal infection vary depending on location of infection
        
        Treatment of fungal infections is difficult
        
        Most anti-fungal drugs are highly toxic
        
        Many fungal infections are resistant to treatment