Histology Flashcards
(54 cards)
Plasma Membrane
Structure: Lipid bilayer composed of phospholipids and cholsesterol with proteinsthat extend across or are buried in surface. Hydrophilic heads and hydrophobic tales. Function: controls entry and exit of substances
Nucleus
Structure:largest organelle, double membeane, the outer of we which is continuos with the ER. Contains nucleotides which is one to four dense bodies consisting of rRNA and proteins. Function: command centre of the cell and repository of its archives. Sire of ribonucleic acid synthesis (mRNA, tRNA,rRNA)
Cytoskeleton
Structure: composed of micotubles ( hollow cylinders made of protein tublin), actin filaments (small fibrils of protein actin) intermediate filaments (protein fibres), and cell extensions (projections of plasma membrane important for movement. Function:overall shape and movement. microfillaments provide structural support and allow connections. microtubles are larger and involved in movement. centrosome directs organisation of microtubles and is made of a pair of centrioles which are important in cell division.
mitochondria
structure: spherical or rod shaped, or threadlike structures enclosed by double membrane, inner membrane forms projections called cristae. function: major site of ATP synthesis when oxygen is available aka produce energy through aerobic respiration
endoplasmic reticulum
structure: smooth (membranous tublues and flattened sacs with no ribosomes) rough ( membranous tubules and flattened sacs with ribosomes. Function: smooth ( site of lipid and carbohydrate synthesis, detoxifies harmful chemicals. Rough (protein synthesis and transport to GA)
Golgi Apparatus
Structure: flattened membrane saces stacked on each other. function: produces lysosomes, newly synthesised proteins from ER are further processed, sorted, and packaged for transport to their final destinations in the cell
lysosomes
Structure: membrane bounded vesicle pinched of GA conatining hydrolytic enzymes at acidic pH. Function: decompose substances taken into cell and dispose of damaged oganelles fragments can be removed or recycled
how do cells communicate with each other?
junctions: communicting, occluding, anchoring
anchoring junctions
main role is to mechanically attach cells and their cytoskeleton to adjacent cells or the extracellular matrix, they can either be actin filament or intermediate filament
Types of anchoring junctions
cell-cell actin= adherens, cell-cell intermediate = desmosomes. cell-matrix actin = focal, cell-matrix intermediate = hemidesmosomes
communicating junctions
can be gap or chemical synapses. main role is to control the passage of signals, either chemical or electrical, from one cell to another, most cells are linked to neighbours via gap cells e.g cardiac smooth muscle
connexins
channel forming proteins
occluding junctions
main role is to seal cells together to prevent molecules from leaking, either to another cell or across a boundary (tight junctions)
how are cells seen
stains. h&e; nucleus = purple, rest = pink masson;'s trichome nuclei= black, connective tissue = green van kossa: mineral = black alizarin: mineral = red oil red o : fat globule = red
Types of tissues
epithelial, connective, muscle, nervous. They are classified by size, shapes, and function. They are composed of cells and extracellular matrix,
ECM
Ecm is made by cells and exported to fill extracellular space
Role of the ECM
forming junctions with cells, regulating migration, influencing development and growth,
changing cell morphology (function). connectove tissue has lots of ecm skin doesnt
Epithelial tissue function
covers the body, lines body cavities, found in glands, can be simple or stratified. part of the integumentary system
Types of simple epithelial tissue
squamous, cuboidal, columnar, pseudostratified
squamous simple epithelial tissue
flattened cells attached to a basement membrane lines heart, blood vessels, lymph vessels, lung aveoli, and collecting ducts of nephrons
cubiodal simple epithelial tissue
cube shaped cells attached to a basement membrane forms kindey tubules and some glands, important in secretion, absorbtion, and excretion
colunmnar simple epithelial tissue
rectangle shaped cells attached to a basement membrane found in stomach, small intestine, trachea, and fallopian tubes. it can be ciliated having hair like fingers)
pseudostratified epithelium
gives impresion of multiple cells but it is in fact only one cell thick . psuedostratfied columnar ciliated epithelium is only found in the respiratoty tract and forms mucocilary escalator where goblet cells excrete mucus
Stratified epithelial tissue
consists of several layers of cells with continual cell division from basal layer. its main function is to protect from wear and tear
