Histology Flashcards
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
types of stratified epithelial tissue
squamous.( keratinised. non-keratinised)
keratinsed startifeid squamous epithelium
found on dry surfaces, skin,hair, and nails. the top layer of cells have no nuclei
non-keratinised stratified squamous epithelium
found on moist surfaces as it protects them from drying out, mouth, pharynx, oesophogus, vagina
transitional epithelium
pear shaped and only found in the urinary tracts as it protects fromchemicals ine unrine
types of epithelium
simple, stratified, transitional
connective tissue funcrtions
is the most abundant tissue in the body and consists of cells imbedded in the ecm, it’s main functions are binding, structural support, protection, transport, insulation
types of connective tissue
loose (areolar), adipose, reticular, dense, cartilage, bone, or blood
loose (areolar) connective tissue
most abundant connective tissue, consists of semi-solid matrix of collagen and elastin fibres conating fibroblasts, adipocytes, mast cells, and macrophages. it connects and supports other tissues eg under skin or between muscles
adipose tissue
areolar tissue matrix containing adipoctytes which contain large fat globules, there are two types of adipose tissue white 20-25% average bmi acts as a therma linsulator and energy store, brown found in newborns and is highly vascularised
reticular tissue
found in lymph nodes and organs of the lymphatic system. matrix conisits of reticular fibres and the cells present are reticular and white blood
dense connective tissue
low cell number but high fibre count and can be eithert fibrous or elastic tissue
fibrous dense connective tissue
contains collagen fibres that are in closely packed bundles. fibroblast cells sit between fibres e.g tendon, ligament, peristeium
elastic dense connective tissue
contains elastin fibres that are separated by fibroblast cells, the tissue has a high degree of recoil and is found in organs where shape change is common e.g blood vessels and lungs
cartilage tissue aka chondocytes
embedded in a collagen and proteoglycen matrix. three types ;hyaline, fibrocartilage, articulating fibrocartilage
osteoblasts
make bone matrix
osteocytes
break down bone matrix
osteocytes
mature bone cells
bone cells aka osteocytes
embedded within a mineralised collagen matrix, 3 types
hyaline
found at the ends of long bones (articulating cartilage)
fibrocartilage
found inbetween invertebral discs
articulating fibrocartilage
found in outer ear
tendons and ligaments
bone to muscle, muscle to bone. both usually white due to avascular nature
muscle tissue function
provides movement as it can contract and relax, looks dark brown/ red as its highly vascularised, shortens when contracted. there are 3 types of muscle tissue: skeletal, smooth, cardiac
skeletal muscle tissue
striated ( striped) multinucleated, muscle fibres are under voluntary control, moves bones of the skeleton
smooth muscle tissue
non-striated, muscle fibres are under involuntary control, useful in propelling contents along tubes by peristalsis in gut and ureter
cardiac muscle tissue
striated, mononucleated, muscle fibres under involuntary control, makes up walls of the heart. intercalated discs between cells help propagate wave of contraction
nervous tissue function
interconnected network that allows communication from brain and spinal cord to other body parts. two types: neurons and glial cells
neurons
excitable and initiate, recieve, transmit, and perfrom information. the axons are found in PNS. and cell bodies in CNS. dendrite - ax0n - muscle
glial cells
non- excitable, support neurons, more glial cells than neurons, glial cells can be astrocytes, olgiodendrocytes,epedeymal, microglyal
Types of skin
thick (no hair soles of feet etc) , and thin ( three layers, epidermis, dermis, hypodermis)
