Pathophysiology 1 Cell Biology - Objectives

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chapter 1 - cellular biology - chapter objectives

Understand what activities cells use to survive.

Functions: Movement, Conductivity, Metabolic Absorption, Secretion, Excretion, Respiration, Reproduction, Communication

Cellular Function - Movement

muscle cells can generate forces that fprduce motion; muscles attatched to bones produce limb movments, whereas those muscles that enclose hollow tupes or cavities move or empty contents when they contract

Cellular Function - Conductivity

conduction as a response to a stimulus is manifested by a wave ef excitation, an electrical potential that passes along the surface of the cell to reach its other parts. Conductivity is the chief function of the nerve cell

Cellular Function - Metabolic Absorption

all cells can take in and use nutrients and other substances from their surroundings

Cellular Function - Secretion

certain cells, such as mucous gland cells, can synthesize new substances from substances they absorb and then secrete the new substances to serve as needed elsewhere

Cellular Function - Excretion

all cells can rid themselves of waste products resulting from metabolic breakdown of nutrients. Membrane-bound sacs (lysosomes) within cells contain enzymes that break down, or digest, large molecules, turing them into waste products that are released from cell

Cellular Function - Respiration

cells absorb oxygen, which is used to transform nutrients into energy in the form of ATP; cellular respiration, or oxidation, occurs in mitochondria

Cellular Function - Reproduction

tissue growth occurs as cells enlarge and rproduce themselves; even w/o growth, tissue maintenance requires that new cells be produced to replace cells that are lost normally through cell death; not all cells are capable of continuous division

Cellular Function - Communication

vital for cells to survive as a society of cells; appropriate communication allows the maintenance of a dynamic steady state

Eukaryotic Cell

has a nucleus w/nuclear envelope, nucleous, DNA (replication, repair, transcription), histone (DNA binding proteins)

DNA and DNA folding

in nucleus and the "chain" is so long that is is easily broken. therefore histones that bind to DNA cause DNA to fold into chromosomes, which decreases the risk of breakage and is essential for cell division in eukaryotes

Cellular Components - Plasma Membrane

outer membrane of eukaryotic cell and is said to be fluid; basic component is a lipid bilayer with proteins for recogintion or channels; it can include or exclude various molecules, and by controlling movment of substances from one compartment to another, membranes exert a powerful influence on metabolic pathways; also has important role in cell-to-cell recognition as well as cellular mobility and maintance of cellular shape

Celluar Components - Cytoplasm

an aqueous solution that fills the cytoplasmic matrix (space between nuclear envelope and plasma membrane); represents about 1/2 of volume; contains thousands of enzymes and organells (ribosomes for proteins, mitochondria for ATP, ect)

Cellular Function - Plasma Membrane Proteins

made from chain of amino acids (20); act as recoginition and binding units (receptors) for substnaces moving into and out of cell; pores or trasport channels for various electrically charged particles (ions/electrolytes) and specific carriers for amino acids and monosacharrides; specific enzymes that drive active pumps to promote concentration of certain ions (K+/Na pump) within cell while keeping concentrations lower of other ions in extracellular matrix; cell surface markers (ex-glycoproteins) that identify cell to neighbor; cell adhesion molecules (allow cells to attach to eachother); catalysts of chemical reactions

Cellular Function - Cell to Cell Adhesion

once cells are arranged, they are held together by 1) cell adhesion molecules in plasma membrane, 2) extracellular matrix and 3) specialized cell junctions

Cellular Function - Cell to Cell Adhesion - Extracellular Matrix

cells can be united by or through the matrix (including basement membrane) which cells secrete around themselves; it is intricate meshwork of fibrous proteins embedded in a watery, gel-like substance compsed of complex carbohydrates; Collagen, Elastin and Fibronectin are interwoven in matrix

Cellular Function - Metabolism (ATP production)

chemical tasks of maintaing essential cellular functions; uses Anabolism (making molecules - energy using) and Catabolism (breaking molecules - energy releasing)

Cellular Function - ATP

created from the chemical energy contained within organic molecules; used in synthesis of organic molecules, muscle contraction and active transport; stores and tansfers energy

What are the different modes of cellular communications?

Contact signaling by plasma membrane-bound molecules (contact-dependent signaling), Remote signaling by secreted molecules (paracrine signaling, autocrine signaling, hormonal signaling), Contact signaling via gap junctions (neurotransmitters)

Contact dependend signaling

requires cells to be in close membrane-membrane contact

Remote Signaling (Chemical Signaling)

Hormones, pancrines, autocrine, neurotransmitters, and neurohormones are all intercellular messengers that accomplish communication between cells; Important differences lie in the speed and selectivity with which the signals are delivered to their targets

Contact Signaling via Gap Junctions

neurotransmitters

Paracrine signaling

cells secrete local chemical mediators that are quickly taken up, destroyed, or immobilized; paracrine signaling usually involves different cell types

Autocrine Signaling

cells that produce signals to which they alone respond; autocrines bind to receptors on the same cell; cell is both signaling cell and target cell; ex - cancer cells

Hormonal Signaling

involves specialized endocrine cells that secrete chemicals (hormones); hormones are released by one set of calls that travel through the bloodstream to produce a response in other sets of cells; Neurohormonal signaling: hormones are released into blood by neurosecretory neurons

Neurotransmitter

neurons communicate directly with the cells they innervate by releasing chemicals or neurotransmitters at specialized junctions called chemical synapses; neurotransmitter diffuses across synaptic cleft and acts on postsynnaptic target cell; some act in contact-dependent mode as local chemical mediators that influence multiple target cells in the area

What are the 2 main types of diffusion and which one needs ATP?

passive transport (no ATP) and active transport (ATP needed)

Passive Transport

water and small, electrical uncharged molecules move easily through pores n the plasma membrane's lipid bilayer; process occurs naturally through any semipermiable barrier; driven by osmosis, hydrostatic pressure, and diffusion, all of which depend on the laws of physics and do not requre ATP

Passive Transport - Diffusion

the movement of a solute molecule from any area of greater solute concentration to an area of lesser solute concentration; uses concentrated gradient; although particles move randomly in any direction, the particles distribute themseles evenly throughout the solution

Passive Transport - Filration

the movement of water and solutes through a membrane because of a greater pushing pressure (force) on one side of the membrane than on the other side; Hydrostatic pressure is the mechanical force of wather pushing against cellular membranes; in vascular system, hydrostatic pressure is blood pressure

Passive Transport - Osmosis (water)

the movement of water "down" a concenration gradient (across semipermiable membrane); For osmosis to occur the membrane must be more permeable to water than to solutes and the concentration of solutes on one side of membrane must be greater than that on the other side so that water moves more easily; directly related to both hydrostatic pressure and solute concentration but NOT to particle size or weight

Passive Transport - Tonicity (cells)

describes the effective osmolality of a solution; solutions have a relative degree of tonicity; Isotonic - has same osmolality or concentration of particles; Hypotonic - has lower concentration and is more dilute than body fluids; Hypertonic - has concentration of more than body fluids; Tonicity is important when correcting water and solute imbalances by admistering different types of replacement solutions

Passive Transport - Passive Mediated Transport

involves integral or transmembrane proteins with receptors that are highly specific for the substance being transported; uses proteins passively to move particles across membrane, not necessarily based on concentration or water

Active Transport

an energy-requiring process in which transport proteins bind with particles and move them through a cell membrane; some molecules are too large to pass through pores or are ligand bound to receptors on the cell's plasma membrane; Both Endocytosis and Exocytosis

Active Transport - Endocytosis

a section of the plasma membrane enfolds substances from outside the cell, invaginates (folds inward), and separates from the plasma membrane, forming a vesicle that moves into the cell

Active Transport - Endocytosis - Pinocytosis

(cell drinking) involves the ingestion of fluids and solute molecules through formation of small vesicles; vesicle contating fluids, solutes or both fuses with a lysosome, and lysosomal enzymes digest the vesicle's contents for use by the cell

Active Transport - Endocytosis - Phagocytosis

(cell eating) a type of endocytosis sometimes referred to as cell eating in which substances such as bacteria and cell particulates are incorporated into large vesicles or vacuoles and digested; ingestion of large particles, such as bacteria, through formation of large vesicles (vacuoles); the large molecular substances are engulfed by the plasma membrane and enter the cell so that they can be isolated and destroyed by lysosomal enzymes; substances not degrated are isolated in residual bodies and rleased by exocytosis

Active Transport - Endocytosis - Receptor Mediated

(ligand internalization); rapid and enables the cell to ingest large amounts of specific ligands without ingesting large volumes of extracellular fluid

Active Transport - Endocytosis - Potocytosis

;

Active Transport - Exocytosis

has 2 main functions, 1) replacement of protions of the plasma membrane that have been removed by endocytosis 2) release of molecules synthesized by the cells into the extracellular matrix

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