Histology Flashcards
what is cytology?
- study of cells
what is histology?
- study of the microscopic structures of tissues
levels of cellular organisation
- specialised cell types
- tissues
- organ
- organ system
preparation tissues for histology study
- cutting the tissue
- fixation and processing
- tissue embedding in paraffin
- block cut to make slices
- slide staining
- microscopic evaultion
why do specimens to be studied have to be thin for light microscope?
- to allow light to pass through
why is it important to put tissue through a complex process before microscopy?
- as when thinly sliced it is transparent/translucent so needs to be stained to be seen
parenchyma vs stroma
- parenchyma is the functional tissue of an organ as distinguished from the stroma (connective and supporting tissue)
what are artifacts?
- foreign substances or tissue alterations due to preparation process
define tissues
- organised aggregations of cells that function in collective manner
what is epithelial tissue?
- covers body surfaces and lines body cavities
- forms glands
what is connective tissue?
- underlies or supports the other three basic tissues, both structuralaly or functionally
what is muscle tissue?
- comprimises contractile cells and is responsible for movement
what are nerve tissues?
- recieves, transmits, and integrates both external and internal information to control activities of the body
epithelia characteristics
- covering/lining membranes- free surface
free surfaces are characteristics of the structure lined - cells always contiguous - usually joined by specialised cell-to-cell junctions (barrier between free surface and deeper tissue)
- minimal intercellular space
- ‘simple’ or multiple ‘stratified’ layers of cells
- shape of surface cells (apical) may be flat, square/short rectangular, rectangular or globular
epithelia cell shape characteristics
- generally avascular
- cells separated from underlying tissue by a basement membrane or ‘basal lamina’
- cells exhibit ‘polarity’ with distinct apical, lateral and basal aspects
- classification based on cell shape and number of layers (not function)
epithelia functions
- protection/seperation- areas within the body/underlying tissue from the outside world e.g. from dehydration or pathogens
- help hold tissues together
- thermoregulation
- hormone release or transformation
absoption
synthesis
excretion
control of permeability
sensory
ummuneresponse
simple epithelia types, locations and major functions
- stratified squamous - epidermis, barrier and protection
- stratified cuboidal - sweat gland ducts, barrier and conduct
- stratified columnar - exocrine glands, barrier and conduct
- traditional - renal, uterus, bladder, barrier, disposable property
skeletal muscle key points
- long cylindrical myocytes - muscle fibres
- syncytium- mutlinucleated
- microscopically stained
- each muscle composed of muscle fibres held together by connective tissue
- endomysium around individual fibres
- perimysium around a group of fibres (‘fascicle’)
- epimysium around the entire muscle
smooth muscle key facts
- involuntary and normally unconscious
- in hollow organs - vasculature, eyes, skin etc
- bundles or layers of elongated, spindle-shaped (fusiform) cells
- small diameter - non-striated cells with central muscle
- possess a contractile apparatus of thin and thick filaments
- cytoskeleton of desmin and vimentin intermediate filaments
- specialised for slow, prolongated contraction
- capable of mitotic division to maintain or increase number
cardiac muscle key features
- involuntary and unconscious heart
- minimal ability to regenerate (mature cardiac muscle cells are able to divide)
- medium diameter, striated, branching fibres with central nuclei (occasionally binucleate)
- intercalated discs represent junctions between cardiac muscle cells
what is the nervous system?
- the system of cells, tissues and organs that regulates the body’s responses to internal and external stimuli
nervous system: anatomically & functionally allows…
- anatomically: central (CNS) and peripheral (PNS) nervous system
- functionally: somatic, autonomic (sympathetic, parasympathetic, enteric)
- multiple central functions e.g.; neural integration, attention, perception, memory, language, consciousness, etc
- allows rapid response to external stimuli
nervous system key facts:
2 cells types and subtypes examples
- 2 principal cell types: neurons and supporting cells
- neuron-> structural and functional unit
- peripheral neuroglia - schwann cells, satellite cells
- central neuroglia - astrocytes, oligodendrocytes, microglia, and ependymal cells
- cell bodies for interpretation & generation
- axons for signal transmission
grey and white matter location and function
- grey- cortex and nuclei. signal interpretation and generation
- white-tracts (a.k.a fasciculus, funiculus, lemniscus, peduncle)
- signal and transmission
functions of connective tissue
- structural/mechanical support - forms structural framework of many body tissues
- loose CT - packing material, fills spaces, determines shape of organ
- dense CT - tough physical support, Demis, ligaments, tendons
- specialised support - cartilage and bone metabolic eg. adipose tissue
- effect repair transport or mediation of exchange
- repair
what is connective tissue?
forms continuous compartment throughout the body that connects, supports, protects and gives structure to other tissue/organs
what is connective tissue embryologically?
- mesodermal
what is the % composition of connective tissue?
- 5% cells
- 95% extracellular martrix
what is the ECM?
- extracellular matrix
what cells compose of connective tissue?
- fixed (intrinsic, resident cells) - product and maintain ECM
- free (extrinsic, immigrant cells) - tissue react to injury or invasion of organisms
3 different connective tissue fibres?
- fibroblasts
- collagen - tensile strength & structural support
- elastic - elasticity
- reticular
what does collagen disorders result in?
- reduced tensile strength
- causes tissue laxity, joint hyper mobility
- susceptibility to injury
types of loose (areolar) connective tissue
- eubperitoneal tissue
- endomysium
- lamina propria
characteristics of loose (areolar) connective tissue
- loosely arranged fibres
- increased cells of various types
- ground substance
what is loose areolar connective tissue surrounded by?
- typically surrounding glands
- tubular organs
- blood vessels
cells found in loose areolar connective tissue
- fibroblasts
- mesothelial cells
- mast cells
- elastic
- collagen fibres
characteristics of dense irregular connective tissue?
- decreased cells (primary fibroblasts)
- randomly distributed
- bundles of collagen fibres in 3 dimensions
- provides significant strength
- allows organs to resist
characteristics of dense regular connective tissue?
- low cells
- densely packed
- fibres arranged in parallel unidriectional resistance to stress
- little ground substance
where are dense regular connective tissue?
- tendons
- aponeuroses
- ligaments
what tissue types of organs made from?
- parenchyma = function cells
- stroma - support cells
