Notes March 15-17
Notes March 15-17 BIO 151
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This 5 page Class Notes was uploaded by Chelsea Notetaker on Wednesday March 23, 2016. The Class Notes belongs to BIO 151 at Central Michigan University taught by Professor Learman in Winter 2016. Since its upload, it has received 16 views. For similar materials see Human Biology in Biology at Central Michigan University.
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Date Created: 03/23/16
15 March >Tissues – groups of similar cells working together toward a specific function >Organ – made up of two or more tissues that work together toward a specific task >Organ system – multiple organs working together toward a vital body function Epithelial tissue – closely packed cells forming sheets that cover surfaces (like the cavities of internal organs) -Are frequently replaced (think of skin) -Functions: gas transport (lungs); absorption/secretion; protection against wear/water loss Connective tissue – most abundant and widely distributed tissue; composed of a variable protein matrix with few living cells -cells – tissue repair, secrete proteins -proteins – structure of tissue, proteins determine function ->loose – more cells to protein ratio; holds tissues/organs in; exists in a layer beneath skin; surrounds muscles; energy storage; insulation; absorbs shock ->dense – more proteins to cells ratio; connects muscles and skeleton -tendons – connect muscle to bone -ligaments – connect bone to bone Blood – liquid plasma with protein and many cells -transport and immune systems Cartilage – gelatinous proteins with few cells; tough and flexible -provides cushioning and absorbs shock -has no blood supply or nerves ->heals slowly because of having no blood supply Bone – solid protein matrix (with calcium and phosphorus) and few living cells -provides protection, support, movement, bloody synthesis, cells Skeletal muscle - attached to bones; voluntary movement Cardiac muscle – heart; pumps blood; involuntary movement Smooth muscle – moves the walls of internal organs for passage of materials; involuntary movement Nervous tissue – communication network that controls body activities; found in brain, spinal cord, nerves -neurons – nerve cells, impulses, conduction -neuroglia – support, insulate, protect neurons >Most organs are suspended in internal body cavities which protect the organs and allow them to move against each other and change shape. >Ventral cavity – divided by the diaphragm: thoracic cavity (lungs) and abdominal (duh) >Dorsal cavity – cranial (brain) and spinal (spinal cord) >Membranes – sheets of epithelium, supported by connective tissues; line passageways that open to exterior of the body; lines the body cavities and organs; lines cavities of freely moveable joints; skin >All organ systems work to maintain homeostasis – balance of cellular/internal body conditions (think of the sixth characteristic of life) Process: 1—change in internal or external environment (stimulus) is sensed by the body 2—imbalance is communicated to the brain (cell interactions) 3—brain sends signal for adjustment (change in cell function) to the body 4—cell function is altered (response) based on the stimulus to affect change (change in gene expression) -negative feedback: response turns stimulus off -positive feedback: response enhances the original stimulus >The cells that compose tissues are held together by varying junctions -leak-proof – prevents passage of materials -flexible/strong – connect but maintain structure for moving tissues -direct communication – small gaps between cells, allow them to communicate ->with ions, proteins, hormones, etc ->sent from the signal cell and received by the target cell >Target cells have specific receptors for specific signals -target cell then generates a response, which triggers a command, changing gene expression and active proteins >Signals often sent through the bloodstream, and therefore have access to virtually all body cells -cell must have the right receptor to respond to signals >Our cells have specialized epithelial cells to exchange materials (Oxygen, nutrients, carbon dioxide, water) with the environment >Disrupted homeostasis leads to health problems >Concentration – the amount of something in a given area >Osmosis – diffusion of water across cells; moves from areas of high water-concentration to low water-concentration -cells don’t easily control water movement, so imbalances can be detrimental to cell structure/function >Aging is disrupted homeostasis; progressive decline in structure/function -body processes lose efficiency, proteins for structure change >Main causes: decrease in growth hormone and less efficient mitosis—divisions become less frequent, with more errors -smoking, stress, UV rays, certain chemicals, poor diet, etc, can accelerate aging 17 March >Proto-oncogenes – genes/proteins that function to turn cell division on >Tumor-suppressor genes – proteins that turn cell division off >some cells lose ability to divide (most neurons/nerve cells don’t divide) >some stop dividing until the need arises (liver cells) >some divide throughout their life (skin cells) >Cell cycle can be ‘paused’at specific places to make sure everything is going as it should: G1, G2, M -G1: ready for DNAsynthesis? Enough food/water? -G2: was DNAsynthesis successful? Not too many mutations? -M: is the cytoskeleton assembled correctly? >If the cell doesn’t pass a checkpoint it’ll evaluate the problem and either fix it or die >to pass a checkpoint it needs to: monitor internal and external environments; check/fix problems; >Healthy cell cycle rules: -regulated growth – dividing only with a signal from the environment; stopping at the checkpoints; respond to apoptosis signals -density dependent – won’t divide if too crowded (contact inhibition) -anchorage dependence – won’t divide unless it’s attached to something -resources – it’ll make sure there are enough resources (nucleotides, ATP,sugar) -limited lifetime – normal cells will have a limited number of divisions before dying (depends on the cell type) >There are at least fifty DNAdamage response proteins (DNAdamage repair enzymes) >Sources of mutations: spontaneous, induced (exposure to a mutagen) -chemicals – remove/add a nucleotide -UV radiation – link two nucleotides together -virus – inserts DNAinto a nucleus >Sometimes happens in a cell cycle regulatory gene – impacts how the cell divides (oncogenes): can overstimulate cell division or halt it altogether >Cancer is characterized by a loss of cell cycle control >Cancer cells can spread into surrounding tissue, take space and nutrients from healthy cells (killing them) and making cancer cells live -cancer cells don’t follow the ‘rules’ -cells can pile up into a tumor – may or may not impact the neighboring tissue >Benign tumor – cluster of cells that have no effect on the neighboring tissue, cells don’t spread, not considered cancerous (yet) >Malignant tumor – causing healthy cells to die, can spread, is called cancer >Metatastis – process by which a cancer cell breaks off from the primary malignant tumor and travels through the bloodstream to a different site in the body to form other tumors/colonies >Angiogenesis – the tumors can develop their own blood supply by signaling the need to the body, then developing their own vascular system >Cancer generation/progressions are caused by accumulated mutations/errors across multiple levels of regulation -usually takes six or more affected genes -all controls must be inactivated for cancer to initiate -usually happens in older people (who have undergone more divisions, have had more time for errors) >The exact grouping of mutations is different for each case of cancer -is an individual combination of mutations for each individual -mutations in cell regulation AND failure of body’s other control mechanisms Treatments: >Surgery – for solid, easily located tumors that are localized >Chemotherapy/radiation therapy – cancers of the blood, metastases, inaccessible tumors -Chemo – medications that kill dividing cells (and healthy ones) -Radiation – causes DNAdamage to prevent mitosis progress (shooting Z-rays at cancer cells) -very hard for either to ensure death to all cancer cells Newer Therapies: >Target proteins critical to cancer cells (unfortunately they’re also critical to healthy cells) >’Designer’treatment using analysis of the individual’s DNAto locate the mutations and target them >Gene therapy – stimulate the immune system, regulate gene expression proteins Assessing the Risk: >Predisposition – individuals already born with some mutations in cell cycle control (breast and ovarian cancer) >Environmental factors – exposure to mutagens/carcinogens >The rest is up to your cells’ability to divide accurately and repair mistakes
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