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How are some people immune to HIV?

Inherited mutation blocks production of certain proteins that function as receptors on specific humans - the virus is essentially kept out

Basic organizational structure of the human body

the cell

How many cells are in the human body?

50-100 trillion

What is differentiation?

When cells specialize. As a result they vary in size and shape due to their unique function

Parts of a composite cell (also called a "typical" cell)

nucleaus
cytoplasm
cell membrane (aka plasma membrane)

Cell Membrane

outer limit of the celll; controls what moves in and out of the cell; selectively permeable; composed mostly of lipids and proteins embedded and freely movable;phospholipid bilayer; proteins

Phospholipid Bilayer of a cell

-water soluble "heads" form surfaces (hydrophilic)
-water insoluble "tails" form interior (hydrophobic)
-permeable to lipid soluble substances/insoluble to water

What stabilizes the cell membrane?

cholesterol

Proteins and the cell membrane

intergral proteins span the membrane; peripheral proteins project from the membranes outer surface; transmembrane proteins extend outside the cell membranes at one end and dips into the cytoplasm interior

Proteins functions in the membrane

Receptors (transmembrane proteins)
Pores, channels and carriers
Enzymes
CAMs (cell adhesion modules) -peripheral proteins
Self-markers - glycoproteins

What do faulty ion channels do?

cause disease

Cystic Fibrosis

-abnormal chloride channels in the cells lining the lung passageways & ducts of the pancrease cause the symptoms
-salt is trapped in the cells

CAMs (cell adhesion modules)

-Guide cells on the move
-Selectin - allows the cells to "anchor"
-Integrin - guids EBCs thru capillary walls
-Important for growth of embryonic tissue
-Important for grown of nerve cells

Cytoplasm

-Cytosol = water
-Organelles = solids
(kinda like a fruit salad where the jello is the cytosol & the fruits are the organelles)

Organelles

-Ribosomes -Cetrosome
-Endoplasmic Reticulum (ER) -Cilia
-Golgi Apparatus -Flagellum
-Vesicles -Microfilaments & microtubules
-Mitochondria -Intermediate Filaments
-Lysosomes -Inclusions
-Peroxisomes

Ribosomes (in organelles)

-Free floating or connected to ER
-Provide structural support and enzyme activity to amino acids to form protein

Endoplasmic Reticulum (ER) (organelle)

-Connected, network of interconnected membrane-bound sacs, canals and vesicles
-Transport system
-Rough ER: studded with ribosomes; participates in the synthesis of protein
-Smooth ER: lipid synthesis (added to proteins arriving from rough ER); Breakdown of drugs

Golgi Aparatus (organelle)

-Stack of flattened, membranous sacs
-Modifies/refines, packages and delivers proteins syntheaized on Rough ER

Vesicles

-Membranous sacs
-Store substances
-They form when a portion of the cell membrane folds inward and pinches off

Mitochondria

-Membranous sacs with inner partitions
-2 membranes (inner membrane forms cristae - increases the surface area where the chemical reactions occur)
-Generate energy-capture and xfer newly released energy into specific chemical bonds of ATP

Lysosomes

-Enzyme containing sacs
-Digest worn out cell parts or unwanted substances/debris

Peroxisomes

-Enzyme containing sacs
-Break down organic molocules

Centrosome

Two rod-like centriles
-Used to produce cilia and flagella
-Distributes chromosomes during cell division

Cilia

-Short hair-like projection
-Propel substances on cell surface

Flaglellum

-Long tail-like projection
-Provides motility to sperm

Microfilaments & Microtubules

-Thin rods and tubules
-Support cytoplasm
- Allows for movement of organelles
-Found in all cells

Intermediate Filaments

-Found in specialized cells
-Form a strong inner scaffolding that helps cells attach and form a barrier

Inclusions

-Temporary nutrients (glycogen & lipids) and pigments (melanin)

Disease at the Organelle Level

ALD (adrenoleukodystrophy)
-Peroxisomes lack the 2nd most abdumdant protein in the outer membrane of this organelle which usually tansports an enzyme into the peroxisome
-The enzyme controls breakdown of a type of ver long chain fatty acids
-W/o the enzyme, the fatty acids build up in cells in the brain and spinal chord stripping them of myelin

Cell Nucleaus

-Control center of the cell
-Directs activities of the cell
-Nuclear envelope (porous dbl membrane; separates nucleoplasm from cytoplasm)
-Nucleolus (dense collection fo RNA & proteins; site of ribosome production)
-Chromatin (fibers of DNA & proteins; stores info for synthesis of proteins)

Types of movements inside the cell

-Passive
-Active

Passive (physical) Processes

Require no cellular energy and include:
-Simple diffusion
-Facilitated diffusion
-Osmosis
-Filtration

Active (physiological) Processes

Require cell energy and include:
-Active transport
-Endocytosis
-Exycytosis
-Transcytosis

Simple Diffusion (passive process)

-Movement of substances from regions of hight concentration to those of lower concentration
-Oxygen, carbon dioxide and lipid soluble substances
-Factors the affect rate of diffusion: distance, concentration gradient, temp, molecular weight

Facilitated Diffusion (passive process)

-Diffusion across a membrane with the helop of a channel of carrier molecule
-Follows the concentration gradient
-Glucose and amino acids

Osmosis (passive process)

-Movement of water thru a selectively permeable membrane from regions of hight to lower concentrations
-Water moves toward higher concentration of solutes

Osmosis & Osmotic Pressure

-OP: the ability of osmosis to generate enough pressure to move a volume of water
-OP increases as concentration of nonpermeable solutes increases
See Isotonic, Hypertonic & Hypertonic cards

Isotonic Solutions

-same osmostic pressure as cells in solution
-0/9% NaCl (saline)

Hypertonic Solutions

-Have higher osmotic pressure (water loss) than cells in solution
-Lose water by osmosis
-Cells shrink (crenate)

Hypotonic Solutions

-Has lower osmotic pressure (fewer solute particles - water gain) than cells in solution
-Cells swell/hemolyze

Filtration (passive)

-Is the movement of molecules thru a membrane by hydrostatic pressure that is > on one side of the membrane than the other
-Smaller molecules are forced thru porous membranes
-Hydrostatic pressure important in the body (Heartbeart)
-Molecules leaving blood capillaries

What is the definition of hydrostatic pressure in A&P?

created by the weight of water due to gravity
-forces water molecules thru to the other side

Active Transport

Carries substances across a membrane from regions of lower concentration to higher concentration (requires energy)

Primary Active Transport

-ATP is used directly
-Energy to drive solutes across membranes is from and electrochemical gradient that is created by pumping ions out of cells
-Two main forms: counter-transport (antiport)
co-transport (symport)

Counter-transport

-2 species of ions or other solutes are pumped in opposite directions across a membrane
-One of these is allowed to flow from high to low concentration which drives the transport of the other solute from low to to high concentration

Co-transport

-Uses the flow of one solute to from and area of high to low concentration to move another molecule against its preferred direction of flow
-Both solutes move in the same direction across the membrane
-Ex: glucose symporter cotransports 2 sodiums from every molecule of glucose that it imports into the cell

Active Transport: Sodium Potassium Pump

-Active transport mechanism
-Creates balance by "pumpiong" 3 sodium and 2 potassium INTO a cell
-2:1 ratio

Endocytosis (active transport)

-Cell engulfs a substance by forming a vesicle around the substane. 3 types:
Pinocytosis: substance is mostly water
Phagocytosis: substance is solid
Receptor-mediated endocytosis: needs the substance to bind to a membrane-bound receptor and are enclosed in vesicles

Transcytosis (active transport)

-Encocytosis followed by exocytosis (=transcytosis)
-Transports a substance rapidly thri a cell
-HIV crossing a cell layer

The Cell Cycle

-Series of changes a cell undergoes from the time it forms until the time it divides
-Stages:
Interphase
Mitosis
Cytokinesis (sytoplasmic division)
Differentiation

Interphase

-Very active period;cell grows (surface area increases to a lesser degree than its volume)
-Cell maintains routine functions
-Cells replicate genetic material to prep for nuclear division
-Cell synthsizes new organelles to prep for cytoplasmic division
2 phases

Phases of Interphase

-G phases: cell grows and synthsize structures other than DNA
-S phase - cell replicates D"NA (chromosomes duplicate)

Mitosis

-Produces 2 daughter cells from and original somatic cell
- Nucleus divides: karyokineses
- Cytoplasm divides: cytokinesis
...see next card: 4 phases of nuclear division

4 phases of nuclear division

-Prophase: chromosomes form; nuclear envelope disappears
-Metaphase: chromosomes alighn midway between centioles
-Anaphase: Centromeres of the chromatids separate, chromosomes spearate and move to centrioles
Telophase: chromatin forms; nucliear envelope forms

Cytoplasmic Division

-Also known as cytokinesis
-Begins during anaphase
-Continues thru anaphase
-Contractile ring pinches cytoplasm in half

Cell Division Capacities (cntrl of cell div)

-Varies greatly among cell types
-Skin and blood cells divide often and continually
Most types of human cells divide 40-60 X, when grown
in a lab

Chromosome Tips (cntrl of cell div)

(telomeres-physical basis) shorten with each mitosis and provide a mitotic clock

Why do cells divide?

To provide a more favorable surface area to volume relationship

Growth factors and hormones (cntrl of cell div)

-Stimulate cell division
-Hormones stimulate mitosis of smooth muscle cells in
uterus
-Epidermal growth factor stimulates growth of new skin

Contact (density depenent inhibition)
(cntrl of cell div)

-

Tumors (cntrl of cell div)

-Abnormal growth/neoplasm
-Disorganized mass
-Too frequent mitosis or thise that continue unabated
TWO TYPES / TWO MAJOR CAUSE OF GENE CS (next)

Two types of tumors

Benign: usually remain localized
Malignant: invasive and can metastasize; cancerous

Two major types of genes that cause cancer

Oncogenes: acrivate other genes that cause cell divisionm
Tumor suppressor genes: normally regulate mitosis; if inactivated they can't regulate mitosis

Stem Cells

-Can divide to form 2 new stem cells (self renewel and characteristic of a stem cells)
-Can divide to forma stem call and a progenitor cell
-Totipotent: can give rise to every cell type
Pluripotent: can give rise to a restriced # of cell types

Progenitor Cells

-Comminuted cell
-Can divide to become an of a restriced number of cells
-Pluripotent

What is common about all cells in the human body

all cells (EXCEPT RBCs) have the same set of genetic instructions, but as cells specialize - they use some genes and ignore others
Bone cells and muscle cells differ in structure & function
b/c each expresses a different subset

Theraputic Stem Cell Sources

-Donor umbelical cord stem cells
-Dervied from patient: natural sites, cultured from "reprogrammed" differenctiated cells

Cell Death

Apoptosis
Caspases

Apoptosis (cell death)

-Programmed cell death
-Acts as a protective mechanism
- A continuos process'
-Caspases are activated inside the cell

Caspases (cell death)

-Destroy enzymes that replicate & repair DNA
-Activate enzymes that cut DNA intoo similar sized pcs
-Dismantle cytoskeletal threads
-Fracture mitichondria
-Abolish cells ability to adhere to other products
-Transport certain phospholipids outside the cell to
attract phagocytes

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