Mamm. pays cells (1)

• epithelial
• connective 
• muscle
• nervous

characteristics = 1 or more layers of densely arranged cells with very little ECM

• Functions
• 1. conversand protects body
• 2. lines body cavities
• 3. movement substances, glandular activity (secretory)

Where found = skin, lining got respiratory tract, digestive tract, glands of body

characteristics = few cells surrounded by lots   of ECM 

• Functions =
• anchor
• supports body functions
• structure
• transport
• metabollic support

where its found = bone, tendon, blood, fat

ECM = made of fibres in a protein and polysaccharide matrix, secreted and organized by the cells in the ECM (fibroblast)


Except for blood cells, all connective tissue cells (fibroblasts) secrete ECM molecules like collagen to give support and structure

If the ECM is calcified = makes teeth or bone

• Specialized forms of ECM
• tendons
• cartillage

• general connective tissue = loose or dense

• the cells sit in a matrix made of:
• glycoproteins
• fibrous proteins 
• glycosaminoglycans

characteristics = long fibrelike cells

• Functions
• can contract and generate force

• Where its found:
• heart
• skeletal muscle
• surrounding hollow organs like bladder and uterus

• 3 types of muscle cells:
• 1. skeletal
• 2. cardiac
• 3. smooth

Characteristics = cell specialized for sending nerve impulses

• Function
• initiate and transmit electrical impulses

• Where is it found?
• brain
• spinal cord
• nerves

body adjusts variable to maintain a "set point" in an acceptable or normal range

• Examples=
• temperature regulation
• regulation of blood CO2 levels
• regulation of blood glucose levels

If YOU HAVE ↓ GLUCOSE:

• body will make an adjustment to slow glucose uptake and keep more in the blood stream
• more glucose = released by liver

sensor - detects and reacts to any changes from normal set point

intergrating or control - information is analysed and if needed, a specific action is initiated

effector mechanism - brings about the change to return to the set point

feedback - process of information about a variable constantly flowing back from the sensor to the investigator

• are inhibitory
• act to reset physiological variables
• are responsible for maintaining homeostasis
• MORE COMMON THAN POSITIVE FEEDBACK

• are stimulatory
• amplify or reinforce the change that is occurring
• tend to produce destabilizing effects and disrupt homeostasis 
• bring specific body functions to swift completion

• 1. Intracellular control
• operates within cells
• genes or enzymes often regulate cell process

• 2. Intrinsic control (autoregulation)
• regulation within tissues or organs
• may involve chemical signals 
• ex. growth factors in ovaries

• 3. Extrinsic control
• regulation from organ to organ
• may involve nerve signals
• may involve endocrine organs (hormones / glands)

• tendons
• ligaments

main cell type: fibroblast

• cell types:
• white = single droplet lipid
• brown = multiple droplet lipid

where found = depends on age and sex

• plasma matrix
• free blood cells

where? = in blood and lymph vessels

• Cartillage
• light an flexible

found in = trachea, ear, spine, nose

• Bone
• calcified
• rigid

• blood cells:
• red blood cells = transport O2 and CO2
• white blood cells = fight invaders

macrophages = fight invaders

• macrophages = fught invaders
• adipocytes = store energy in fat
• fibroblasts = most common connective tissue
•                    synthesize the matrix

• contractile = force  and movement
• signal conduction
• 3 types = cardiac, smooth, skeletal

• nucleus
• muscle fibre (cell)
• striations

• striations
• muscle fiber
• intercalated disks
• nucleus

• muscle fiber 
• nucleus

• neurons send signals
• excitable
• electrical
• chemical

glial cell support

by cell differentiation

by the control of gene expression

• as cells mature, they differentiate
• embryo cells (blastocyst) are not yet differentiated = totipotent
• totipotent cells = can form any cell type in the org. of the embryo
• In adults, the stem cells = pluripotent cells 
• pluripotent cells = true embryonic cells since they've gone through growth

• in the gut
• bone marrow

1. undifferentiated cells = give rise to all cell types

• 2.highly proliferative = self renewing 
•                                   large quantities can be produced for medical reasons like repairing damaged tissue

• to treat diseases and injuries
• ex.spinal cord injury, CVD, Alzheimer's

by therapeutic cloning

• cells could not be reprogrammed easily
• DNA could have mutation

• Dr. Douglas Kerr used a rat model to show that stem cell therapy is a viable treatment to restore function to damaged nerve cells
• ESC were injected into rat spinal cord fluid who model nerve disease
• stem cells did not regard but restored the environment to prevent further damage

• all eukaryotic cells have 4 major structures:
• 1. plasma membrane
• 2. cytoplasm
• 3. nucleus
• 4. organelles

• plasma membrane = encloses the cell
• organelle membranes = sacs and canals made of the same material as plasma membrane that encloses organelles such as the ER and the Golgi
• lipid bilayer of phospholipids

• control transport in and out of cell urinary system
• ex. water channels
• allow secretive receptivity and signalling via transmembrane receptor endocrine
• surface glycoproteins - immune system
• anchor for cytoskeleton or ECM = imp. fr movement and tissue structure
• cell signalling provides sites for binding and catalysis of enzymes
• provides a passageway across the membrane for certain molecules like gap junctions
• cell to cell communication

• self markers (MHC)
• identifying cells for the immune 

• self tolerance
• ability for our immune system to attack foreign cells but spare our own 

• non self markers
• molecules on the surface of foreign cell or particles act as flags to the immune system

ex. unrinary system

structure = protein channel

• function 
• controlled transport of water soluble molecules
• ex. Na and K
• specificity
• can open or close gated channels

initial response = release of ADH

ADH acts on the distal tubule of the kidneys to increase water permeability by inserting aquaporin channels into cell membranes

water moves out of the distal tubes of the kidneys by osmosis through these channels thus ↓ osmolarity

overall affect is an ↑ water reabsorption by the kidney and a ↓ in urine flow

structure = membrane receptor

• function = when bound by a ligand triggers intracellular signalling cascade that will alter intracellular activities
• ex. FSH receptor 

• 1. first messenger = an extracellular chemical messenger
• 2. binding of an extracellular messenger to receptor activates a G protein, the alpha subunit of which shuttles to and activates adenylyl cyclase
• 3. cycle AMP (the 2nd messenger) will activate PKA, which will phosphorylate a particular protein
• 4. phosphorylation changes the shape and function of proteins
• 5. there will be a cellular response

structure = intergral membrane proteins

• functions:
• binds other integral proteins to form cell-cell concentrations
• binds ECM to give structure to tissues

• an example of structural adhesion proteins
• join cell to cell or cell to ECM
• heterodimer made of alpha and beta units
• integral proteins
• involved in wound healing, angiogenesis, embryo attachment, cancer invasion

integrin alpha6

gel like substance of cells that includes many organelles suspended in water materials fluid called cytosol

• 1. membranous organelles
• specialized sacs or canals made of cell membrane
• ex. Golgi, ER, plasma membrane, lysosome, proteosome

• 2. Non membranous organelles
• made of microscopic filaments or other non membranous materials
• ex. cytoskeleton, ribosomes, cilia, flagella, nucleolus (imp. for formation of ribososmes)

• structure 
• made of canals with membranous walls present through out the cytoplasm
• extend from the nucleus to the plasma membrane 

• Functions
• proteins move through canals
• make proteins
• transport proteins

• Rough
• ribosomes are found on the outside of the membrane walls
• ribosomes make proteins
• functions in cell synthesis and intracellular transportation
• transports porteins to the Golgi

• Smooth
• does not have ribosomes on membrane walls
• makes certain lipids and carbs
• makes membrane for use through out the cell
• removes Ca++ from cells interior for muscle contraction and hormone production

• ribosomes on the Er make proteins
• these proteins move through the canals of the ER
• they're then folded and assembled into macromolecular groups

proteins = designed for cell export and cell membrane (RER)

the proteins then go to the Golgi complex to be modified

• protein factories
• many are attached to the RER and are just in the cytoplasm
• ribosome = non membranous structure made of 2 pieces
• a large subunit + a small subunit
• each subunit is composed of RNA (ribosomal RNA)
• free ribosomes make proteins for domestic use
• attached ribosomes make proteins for export
• working ribosomes form groups know as polyribosomes

• Structure
• membranous organelle consisting of cristernae stacked on one another  and located near the nucleus

• Function
• processes and packages protein molecules from the endoplasmic reticulum
• proteins are modified by enzymes in the Golgi
• processed proteins leave in a vehicle
• contents may be secreted outside of the cell

• they travel through the ER
• leave the ER in vesicle that fuse with the Golgi
• proteins are modified in the Golgi
• vesicle fuses with Plasma Membrane for the release of the protein outside the cell

• Structure
• made of microscopic sacs that have "pinched off" from the Golgi apparatus

• Functions
• cell digestive/recycling system performed by enzymes
• breaks down proteins, food particles,foreign particles (neutrophils) like bacteria, old organelle
• Amino acids = recycled

its caused by a failure to produce enzyme needed to break down lipids-ganglioside (FA derivative found in all cell membranes)

• break down protein molecules 1 at a time by tagging each one with a  chain of ubiquitin molecules and unfolding it as it enters the proteasome, the breaking apart peptide bonds
• short peptide chains exit the other end of the proteasome

in Parkinsons disease, the proteasome system fails and improperly folded proteins kill nerve cells in the brain that regulate muscle tension

• Structure
• composed of inner and outer membranes separated by fluid (matrix)

• Function
• powerhouse of the cell
• catalyses seri A of oxidation reactions that provide 95% of cells energy supply
• each mitochondrion has 1 DNA molecule, allowing it to produce its own enzymes and replicate itself

• you can get mitochondrial diseases from the mother ONLY
• ex. Parkinson, Alzeihmers and Diabetes inheritance

muscle cells have a lot of mitochondria

• Structure
• nuclear envelop made of 2 membranes each with the same molecular structure as plasma membrane
• sourrounding nucleoplasm
• nuclear enveloppe has holes called NUCLEAR PORES
• this allows protein like transcription factors in and out of the nucleus
• majority of cells has 1 nucleus
• multinucleate cells = often associated with cancerous cells

• Nucleus contains DNA which appear as the following:
• 1. heterochromatin (genes off) = silent genes, tightly compacted
• 2. euchromatin (genes on)= active sites of gene expression/transcription
• 3. gene transcription = determines phenotype

• Structure
• internal supporting framework made up of rigid, rodlike pieces

• Functions
• provides support
• allows movement of cells and of proteins and organelles within the cell

the cytoskeleton at mitosis and meiosis serves critical functions in chromatin movement and mechanisms

• smallest cell filament = microfilaments
• made of thin, twisted strands
• that lie parallel to long axis of cell

microfilaments can slide past each other, causing shortening of the cell muscular contraction

• the myosin heads bend with a strong force e when the bind the actin filaments
• this pulls the thin filaments past them
• each head releases and then pulls again
• the pulling by the myosin heads and the sliding of the actin filaments is the essential movement of muscle contraction

this is known as SLIDING FILAMENT MODEL

• Intermediate filaments
• are twisted protein strands slightly thicker than microfilaments
• they form much of the supporting framework in many types of cells
• ex. prtective layer of skin

• Microtubules
• are tiny
• hollow tubes that are the thickest of the cell fibres
• they are made of protein subunits arranged in spiral fashion

Function = move things around in the cell

• an area of the cytoplasm near the nucleus that coordinates the binding and breaking of microtubules in the cell
• plays an important role in cell division

• cytoskeletons form projections that extend the plasma membrane outward to form tiny, finger like processes
• ex. microvilli formed from microfilaments
• cilia and flagella formed by microtubules

• Microvilli
• found in epithelial cells that line the intestine and other areas of absorption
• helps ↑ surface area

• Cilia and flagella
• CELL PROCESSES THAT HAVE CYLINDER MICROTUBULES AT THEIR CORE
• cilia = shorter and more numerous than flagella
• flagella = only found on human sperm cells

gap junctions hold cells together to form tissues

3 categories:

1. gap junctions = create communication bridges

• 2. tight junctions = prevent movement of materials between cells
• cells partly fuse
• ex. intestinal tract
• regulate when cels enter and exit

• 3. anchoring junctions = cells attach to each other or to the ECM
• ex. belt desmosome or spot desmosome

skin cells are held together this way