diversity of cells Flashcards
what are the 4 basic tissue types?
- epithelium
- connective tissue
- muscle
-nervous tissue
where are epithelia?
cover surfaces of body and line surface, cavities and tubes and hollow organs (also form many solid organs & glands like liver)
why are epithelia perfect to cover space and line body cavities?
because of strong adhesion between cells which makes sheet with minimum intra-cellular space
what is basal lamina?
layer of extracellular matric component at basal surface of epithelia (attached to the cells)
are epithelial cells polarized?
yes - apical = top and basal = bottom
what are the functions of epithelia?
Mechanical barrier (e.g. skin)
Chemical barrier (e.g. lining of stomach)
Absorption (e.g. lining of intestine)
Secretion (e.g. salivary gland)
Containment (e.g. lining of urinary bladder)
Locomotion (by cilia) (e.g. oviduct)
Minor functions include: sensation (neuroepithelium, e.g. taste buds) and contractility (myoepithelial cells)
what are the 3 types of epithelia cell shape?
- squamous (squashed - flattened)
- cuboidal (cube)
- columnar (column- tall & thin)
nuclei in squamous = bulge out in distinct way
nuclei in columnar = elongated
what are different layers of epithelia cells?
- simple = 1 layer
- stratified = multiple layers
- pseudostratified = looks like multiple layers but actually just nuclei sporadically placed as when look closely, all cells have contact with basal lamina)
what can be on surface of epithelia?
- cilia
- microvilli (smaller than cilia)
- presence of layers of keratin proteins = keratinized (helps support skin, heal wounds & keep nails/hair healthy)
what specialised cell types can be in epithelia?
goblet cells = single cell mucous glands that secrete mucous
what is function of glandular epithelia?
produce secretory products like sweat, milk, oil, hormones, mucous, enzymes etc
what are endocrine glands?
product secreted towards basal end of cell and then product distributed by vascular system throughout body
- termed “ductless” (secretions are released directly into the blood, not to any tubes or ducts)
- have lots of capillaries to disperse around body
what are exocrine glands?
product secreted towards apical end of cell either into lumen of internal space, a duct or body surface
- termed “ducted glands” (tube or passageway that helps transfer secretiona)
what is connective tissue?
forms the framework and support of the body
- has a dynamic role in development, growth & homeostasis of tissues and via fat, energy store
- protects against disease, transports substances and helps repair damage
what are the types of connective tissue and examples?
soft = tendons. ligaments, mesentary (stomach membrane), stroma (like cytoplasm but for organelles) of organs
hard = bone & cartillage
- type determined by relative amounts of extracellular matrix & cells
what is extracellular matrix of connective tissue made up of?
- fibres = collagen, reticular & elastic fibres
- ground substance
- tissue fluid
what is ground substance in extracellular matrix of connective tissue?
an amorphous (shapeless) space occupying material made of huge unbranched polysaccharide molecules called gylcosaminoglycans (GAG’s) most of which are bound to protein cores to form glycoproteins (important for cell interactions)
proteoglycan - class of glycoprotein that especially found in extracellular matrix of connective tissue
what cells are found in extracellular matrix of connective tissue?
- fibroblasts (widely distributed cells that produce & maintain extracellular matrix)
- adipose cells (fat cells
- osteocytes (bone cells)
-chondrocytes (cartilage cells)
what are some key characteristics of soft connective tissue?
- elastic fibres, thin & spread out
- collagen fibres stretch around with gaps in between but meet and form bundles
- fibroblast nuclei
general - loosely packed fibres seperated by ground substance with cells relatively plentiful
what are 2 types of soft connective tissue?
dense regular connective tissue
= when collagen fibres aligned (regularly present) e.g. tendon
dense irregular connective tissue
= when collagen fibre bundles run in many directions (irregularly present) e.g. dermis of skin
what are some key characteristics of hard connective tissue?
- strong, flexible, compressible, semi-rigid tissue (due to highly hydrated nature of ground substance - GAG’s and proteoglycans)
- cartilage is avascular so receives nutrients from adjacent tissue by diffusion through matrix
what are the 3 types of hard connective tissue
- hyaline = most common, has chondrocytes clumped together and found in epiphyseal growth plate, tracheal rings, costal cartilage & articular surfaces (thin layer of connective tissue at joints)
- elastic
- fibrocartilage
how do bones get blood supply?
by haversian canals = which penetrate for blood vessels and nerves
- contain living cells called osteocytes
what are 3 major kinds of muscle in body?
- smooth
- skeletal
- cardiac
how does muscle produce force?
produced by movement of actin fibres over myosin fibres, with the aid of a number of accesory proteins
(muscle cells cytoplasm is packed with fibres and cells highly specialised for production of contractile forces)
what are some key characteristics of smooth muscle?
also called “involuntary” or “visceral”
= structurally simplest
- smooth as no visable straitions
- not under conscious control hence involuntary
- visceral as predominantly in organs
what are 2 types if smooth muscle?
longitudinal
transverse
- indiv fibres are elongated, spindle shaped cells with great range in length with cigar shaped nuclues
what are some key characteristics of skeletal muscles?
also called “voluntary” or “straited”
- muscles that respond to conscious control
1 muscle fibre = many straitions & many nuclei that are elongated and located at periphery of cell just internal to cell membrane, sarcolemma
*not all straited muscles are skelatal and some skeletal muscles aren’t under control of will
what are some key characteristics of cardiac muscle?
forms major part of wall of heart chambers
- has straitions but less prominent than skeletal
- fibres much shorter and branch to form complex network
- single nucleus near centre of cell
- intercalated discs can be seen passing across fibres at irregular intervals = they’re sites of end-end attachements of adjacent cells and contain mutiple intercellular junctions to maintain mechanical integrity
what does nervous tissue consist of?
neurons and support cells (glia)
- glia outnumber neurons in CNS
surrounded by connective tissue “coat” = meninges for CNS and epineurium for PNS
what are 3 types of nervous tissue?
- multipolar = most common = 1 cell has many dendrites and 1 axon
- bipolar = 1 cell has 1 dendrite & 1 axon
- pseodounipolar = 1 cell has only 1 short process that gives rise to axon in both direction
what are glia cells and what are types?
support cells
1. astrocytes = support CNS, induce blood brain barrier
2. oligodenrocytes = produce myelin in brain & spinal cord
3. microglia = provide immune surveillance
principle glia of PNS = schwann cells which produce myelin sheath and support axons
