Chapter 2: Cytology

Cells have the same basic chemical composition….

proteins, carbohydrates, lipids, DNA

cells

tiny packages of biochemically active molecules enclosed in membranes of protein and lipid

components of cell

Plasma membrane, cytoplasm, nucleus

cytoplasm:

cytoskeleton, organelles, inclusions, cytosol

squamous cells

thin and flat; line the esophagus and alveoli, epidermis of skin

cuboidal cells

equal; liver cells

Columnar

taller than wide; inner lining of stomatch & intestines

polygonal

irreg shapes; secretory cells of glandsSt

Stellate

starlike; nerve cells

Spherooidal to ovoid

round to oval; WBCs, egg,

Discoidal

disc shaped;RBC

Fusiform

elongated w thick middle and tapered ends; smooth muscle cells

Fibrous

long slender threadlike: skeletal muscle cells, axons of nerve cells

plasma membrane

forms cells boundry

plasma membrane is composed of…..

lipids and proteins

Plasma membrane: Surfaces

Basal surface: lower part, anchored to deeper tissues

Apical surface: upper part, faces interior cavity. serves such functions like absorption and secretion. EX: Intestinal lumen

Lateral surface: side, adheres to neighboring cells

Cytoplasm includes….

cytosol: clear fluid

Cytoskeleton: scaffold of filaments and tubules

Organelles: structures that carry out functions of cell

Inclusions: foreign matter, stored cells products

Examples of Extracellular fluid

blood plasma, lymph, cerebrospinal fluid

Membrane lipids: Phospholipids (75%)

3 carbon glycerol backbone; 2 carbons fatty acid, 3rd is phosphate head`

Membrane lipids: Cholesterol (20%)

stiffin membrane (making it less fluid)

higher concentrations can increase membrane fluidity

Membrane lipids: Glycolipds (5%)

• Phospholipids with short carbohydrate chains bound to them

• On extracellular face of membrane

• Contribute to the glycocalyx—sugary cell coating

Glycocalyx define

fuzzy surface coat of sugars belonging to glycolipids and glycoproteins

Glycocalyx Functions

cushions membrane and protects

cell identity; distinguish its own healthy cells from diseased or foreign cells

determines human blood types & compatibility

cell adhesion molecules-sperm-egg binding at fertilization

Membrane Transport: Active transport

carrier transport of solute up concentration gradient; requires ATP.

Ac

Membrane Transport: Active Transport example

Sodium potassium pump: ejects 3 sodium ions and transports 2 potassium ions

Membrane Transport: Vesicular transport

large particles or droplets of fluid passes through membrane in bubble like vesicles; ATP req.

what are the 3 forms of endocytosis

Pinocytosis, receptor-mediated endocytosis, phagocytosis

Pinocytosis

• pinch off, droplets of ECF “cell drinking”;

• ex: kidney reclaim proteins so we dont lose in unrine

Receptor mediated endocytosis

selective process; molecules bind receptors on mmebrane surface, snks in and pinches off to form internal vesicle

Hepatitis, polio & AIDs viruses trick our cells into admitting them by this process

Form of Endocytosis: Phagocytosis

pseudopods surround a particle and engulf it to form internal vesicle “cell eating“

• Ex: WBC and macrophages

Extensions of cell surface

aid in absorption, movement, and sensory processes

(microvilli, cilia, flagella, pseudopods)

Extensions of cell surface: Microvili

increase surface area

max absorption

fuzzy brush border

ex: epithelial cells of intestines and kidney tubules

taste buds and inner ear, serve sensory

Extensions of cell surface: Cilia

hairlike

Motile cilia (respiratory tract, uterus, & uterine (fallopian) tubes) beat move substances across epithelium

contain axoneme core of microtubules; nasal body anchors cilium to cell

dynein: movement/bending of cilium

Action of cilia

Kartangener syndrome

hereditary disease where dynein is lacking from cilia and flagella

male sterility; sperm has defectve flagella

congestion cause of inability of cilia to clear mucus from respiratory tract

cellular Junctions

link cells together and attach them to extracellular material

(Tight, desmosomes, gap)

Tight (zipper) junctions

bind neighboring cells of many epithelia

encircle cell near apical surface

protens project and interlock like zipper

seal off intercellular space and influence ability of substance to pass between cells

Useful in: digestive tract (stomach and intestines) enzymes and bacteria kept from leaking into blood stream

Desmosomes (snap on a pr of jeans)

• patches that hold cells at specific point

• keep cells from pulling apart

• dense patches (plaque) of protein near plasma membrane; transmembrane protens anchor plaque of one cell to another

• half desmosomes: anchor cells to basement

• Useful in: stress areas (skin, cardiac muscle) epidermis, uterine cervix

Clincal App 2.1: When desmosomes fail

name: pemphigus vulgaris

autoantibodies attack desmosome proteins;

breakdown of desmosomes leads to widespread blistering of skin and oral mucosa, loss of tissue fluid, death

Cytoskeleton Filaments: Microfilaments

• thin filaments

• made of actin protein

• forming the terminal web

  • involved in contraction process

Cytoskeleton Filaments: Intermediate filaments

• cell shape, resist stress, cell junctions

• in epidermal cells, they are made of keratin protein

Cytoskeleton Filaments: Microtubules

• hollow cylinder of protofilaments, each

• made of tubulin proteins

• Act like railroad tracks

• involved in mitosis

• appear and disappear

Nucleus

• cell chromosomes

• nuclear envelope—two parallel unit membranes; lined by the nuclear lamina, a web of intermediate filaments

• nucleoplasm: material w thing nucleous

• chromatin: complex of protein and DNA

• nucleolus—where subunits of ribosomes are made and assembled

Endoplasmic reticulum

• little network within cytoplasm

• interconnected channels (cisterns) enclosed by membrane

Rough ER

• produces lipids and proteins of PM, synthesizes proteins to be secreted or packaged into lysosomes

• abundant in antibody producing cells and cells of digestive glands

• abundant in cells synthesizing large amounts of protein (ribosomes)

Smooth ER

• steroids and other lipids, detoxifies alcohol and drugs, manufactures membrane of cell

• abundant n cells that engage in detoxification, liver and kidney cells.

Ribosomes

• granules of protein and ribonucleic acid (RNA),

• “reading’’ genetic messages

• assemble amino acid to proteins

Golgi complex

• cisterns part of endomembrane system

• synthesizes carbohydrates, lipids; modifies proteins synthase in ER

• 
  

golgi

• sorts, edits, packages into golgi vesicles,

• some become lysosomes or secretory vesicles

Relationships of endomembrane system

• ribosomes make proteins

• modified protein transported in a transport vesicle to golgi

• golgi sorts, edits, packages into golgi vesicles; some become lysosomes other become secretory vesicles

Lysosomes

• membrane bound organelles; has 50 diff enzymes

• participate autophagy: breakdown of extra/aged organelles

• immune cells digest internalized microbes w lysosomes

• participate in apoptosis (programmed cell death)

Peroxisomes

• arise by division of old existing peroxisomes & colab btwn ER and mitochondria

• oxidize organic molecules, fatty acids

• hydrogen peroxide produced

• detoxify alcohol

• present in nearly all cells.

• abundant in liver and kidneys

mitosis

cell division

PMAT

Prohase

• chromosomes condense

• two sister chromatids attached at a centromere

• nuclear envelope degenerates

  • centrioles sprout microtube spindle fibers that attach to each chromosome at a kinetochore

metaphase

• chromosomes align on cell equator

  • spindle fibers form array, mitotic spindle

anaphase

sister chromatids pulled to opposite poles of cell

telophase

new nuclear envelope forms

chromosomes uncoil

mitotic spindle breaks up

cytokinesis

overlaps w end of mitosis

cytoplasm divides into two cells

stem cells

immature cells w ability to develop into one or more types of mature specialized cells (developmental plasticity)

adult stem

• replace lost cells

• unipotent: develop into only one mature cell type, cells that develop into sperm or epidermal cells

• multipotent: develop into multiple mature cell types, certain bone marrow cells that give rise to 5 types of WBC

Embryonic stem

• 150 cells

• pluripotent- developed into any cell type. Growth & differentiation

• replace cells lost/damaged in some disease 9injured spinal cord, heart attack, Parkison and Alzheimer disease