diversity of cells

Question 1

what are the 4 basic tissue types?

Answer 1

• epithelium
• connective tissue
• muscle
  -nervous tissue

Question 2

where are epithelia?

Answer 2

cover surfaces of body and line surface, cavities and tubes and hollow organs (also form many solid organs & glands like liver)

Question 3

why are epithelia perfect to cover space and line body cavities?

Answer 3

because of strong adhesion between cells which makes sheet with minimum intra-cellular space

Question 4

what is basal lamina?

Answer 4

layer of extracellular matric component at basal surface of epithelia (attached to the cells)

Question 5

are epithelial cells polarized?

Answer 5

yes - apical = top and basal = bottom

Question 6

what are the functions of epithelia?

Answer 6

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)

Question 7

what are the 3 types of epithelia cell shape?

Answer 7

1. squamous (squashed - flattened)
2. cuboidal (cube)
3. columnar (column- tall & thin)

nuclei in squamous = bulge out in distinct way
nuclei in columnar = elongated

Question 8

what are different layers of epithelia cells?

Answer 8

1. simple = 1 layer
2. stratified = multiple layers
3. pseudostratified = looks like multiple layers but actually just nuclei sporadically placed as when look closely, all cells have contact with basal lamina)

Question 9

what can be on surface of epithelia?

Answer 9

• cilia
• microvilli (smaller than cilia)
• presence of layers of keratin proteins = keratinized (helps support skin, heal wounds & keep nails/hair healthy)

Question 10

what specialised cell types can be in epithelia?

Answer 10

goblet cells = single cell mucous glands that secrete mucous

Question 11

what is function of glandular epithelia?

Answer 11

produce secretory products like sweat, milk, oil, hormones, mucous, enzymes etc

Question 12

what are endocrine glands?

Answer 12

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

Question 13

what are exocrine glands?

Answer 13

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)

Question 14

what is connective tissue?

Answer 14

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

Question 15

what are the types of connective tissue and examples?

Answer 15

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

Question 16

what is extracellular matrix of connective tissue made up of?

Answer 16

• fibres = collagen, reticular & elastic fibres
• ground substance
• tissue fluid

Question 17

what is ground substance in extracellular matrix of connective tissue?

Answer 17

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

Question 18

what cells are found in extracellular matrix of connective tissue?

Answer 18

• fibroblasts (widely distributed cells that produce & maintain extracellular matrix)
• adipose cells (fat cells
• osteocytes (bone cells)
  -chondrocytes (cartilage cells)

Question 19

what are some key characteristics of soft connective tissue?

Answer 19

• 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

Question 20

what are 2 types of soft connective tissue?

Answer 20

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

Question 21

what are some key characteristics of hard connective tissue?

Answer 21

• 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

Question 22

what are the 3 types of hard connective tissue

Answer 22

• 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

Question 23

how do bones get blood supply?

Answer 23

by haversian canals = which penetrate for blood vessels and nerves
- contain living cells called osteocytes

Question 24

what are 3 major kinds of muscle in body?

Answer 24

• smooth
• skeletal
• cardiac

Question 25

how does muscle produce force?

Answer 25

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)

Question 26

what are some key characteristics of smooth muscle?

Answer 26

also called "involuntary" or "visceral" = structurally simplest - smooth as no visable straitions - not under conscious control hence involuntary - visceral as predominantly in organs

Question 27

what are 2 types if smooth muscle?

Answer 27

longitudinal transverse - indiv fibres are elongated, spindle shaped cells with great range in length with cigar shaped nuclues

Question 28

what are some key characteristics of skeletal muscles?

Answer 28

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

Question 29

what are some key characteristics of cardiac muscle?

Answer 29

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

Question 30

what does nervous tissue consist of?

Answer 30

neurons and support cells (glia) - glia outnumber neurons in CNS surrounded by connective tissue "coat" = meninges for CNS and epineurium for PNS

Question 31

what are 3 types of nervous tissue?

Answer 31

1. multipolar = most common = 1 cell has many dendrites and 1 axon 2. bipolar = 1 cell has 1 dendrite & 1 axon 3. pseodounipolar = 1 cell has only 1 short process that gives rise to axon in both direction

Question 32

what are glia cells and what are types?

Answer 32

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