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BIOL131 - Tissue Level of Organization > Epithelial Tissues > Flashcards

Epithelial Tissues Flashcards

1
Q

What are the two fundamental types of cells in the body?

A

Sex cells (gametes)

-consists of eggs and sperm
-produced through meiosis

Somatic cells

-200 different types of cells in the human body
-produced through mitosis

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2
Q

What are body tissues?

A

Cells of similar function and/or structure can be grouped together to form tissues

Different combinations of body tissues assemble to form organs

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3
Q

What are the 4 different types of body tissues? (4)

A

Epithelial tissue: forms the linings, covers, and glands (skin, tube linings)

Connective tissue: connects and supports other tissues transports materials and store energy reserves (connects epithelial tissue to deeper tissues)

Nervous tissue: specialized to convey electrical impulses: control

Muscle tissue: specialized contractile tissue: movement, heart contraction, and muscular walls of organs

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4
Q

What are the epithelia tissue forms? (3)

A

1) the covering on a body surface (ex. skin)
2) the lining of body cavities or tubes (ex. serous and mucous membranes)
3) the glandular tissue of the body (ex. most endocrine glands)

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5
Q

What are the functions of epithelial tissues?

A

Epithelial tissue can function to protect, absorb, filter, and secrete, but usually is specialized to one or two functions

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6
Q

How are epithelial tissue classified?

A

The tissue is classified by its cellular shape and the number of layers

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7
Q

What are the characteristics of epithelia?

A

-have one exposed or apical surface

-basal surface is attached to a basement membrane (basal lamina) = a gel-like, sticky, non-cellular membrane made of glycoproteins and polysaccharides; anchors epithelia to connective tissue

-avascular, and depend on underlying connective tissue for nutrients; are innervated

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8
Q

What does it mean to be avascular?

A

Without blood vessels; relies on diffusion from underlying structures for nutrition

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9
Q

What are the epithelial tissue types/functions (3)

A

Epithelia cover exposed surfaces and line internal cavities and passageways; they often contain secretory cells, or gland cells, scattered among the other cell types

Glands are derived from epithelia, but secretory cells predominate; there are two types

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10
Q

What are the two types of secretory glands?

A

Exocrine glands: secrete onto external surfaces or onto internal passageways (ducts) that connect to the exterior

Endocrine glands: glands secrete hormones or precursors into the interstitial fluid, usually for distribution by the bloodstream

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11
Q

What are the functions of epithelial tissue? (4)

A

1) Physical protection - from abrasion, dehydration, and chemical or biological agents

2) Control permeability - epithelial cells differ in the degree that ions, protein hormones, nutrients can cross

3) Provide sensation - most have large sensory nerve supplies; neuroepithelia tissue contain cells that sense smell, taste, sight, equilibrium, and hearing

4) Produce specialized secretions - gland cells; epithelia that secrete

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12
Q

What are the specializations of epithelial cells (2)

A

Microvilli - absorption, increase surface area of the cell by 20x

Cilia - 250 cilia/cell coordinated beating moves mucus, injured by smoke, abrasion, and disease

Specialized epithelial will always only have one and not the other

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13
Q

How do epithelial tissues maintain integrity? (3)

A

1) Intercellular connections
2) Attachment to the basal lamina
3) Maintenance and repair - stem cells, epithelia germinative cells located near basal lamina

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14
Q

What is the difference between inter/intracellular?

not directly content related; important to be able to differentiate ^0^

A

Intercellular - between 2 cells

Intracellular - within 1 cell

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15
Q

What are intercellular connections?

A

Epithelial cells attach to one another and extracellular fibres of the basal lamina

  • Plasma membranes attach through transmembrane proteins called cell adhesion molecules; cadherin, integrin (CAMs)
  • Intercellular cement - made of proteoglycans
  • Cell junctions:

1) Adhesion belt
2) Tight/occluding junctions (interlocking proteins and lipids)
3) Gap junctions (interlocking channel proteins “connexons” that allow ion transport; necessary for muscle contraction and cilia synchronization
4) Desmosomes (spot desmosomes and hemidesmosomes) (aka macula adherens) - consist of CAMs to link plasma membranes

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16
Q

What is an occluding/tight junction?

A

The lipid portions of the two plasma membranes are tightly bound together by interlocking transmembrane proteins

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17
Q

What is an adhesion belt?

A

An adhesion belt encircles cells and binds them to their neighbours through bands of dense transmembrane glycoproteins (cadherin) attached to microfilaments (actin)

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18
Q

What are connexons?

A

Connexons are channel proteins that form a narrow passageway and let small molecules and ions pass from cell to cell

6 connexin proteins make up each connexon channel

(found in cardiac tissue and smooth muscle tissue)

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19
Q

What type of tissues are connexons found in?

A

Cardiac tissue and smooth muscle tissue

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20
Q

What is a gap junction? *? :3

A

Gap junctions are membrane channels between adjacent cells that allow the direct exchange of cytoplasmic substances. Substances exchanged include small molecules and ions.

*

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21
Q

What is cadherin?

A

A cell adhesion molecule (CAMs) that are transmembrane proteins that bind to each other and to extracellular materials

(looks like the little paddleboards, connecting the membranes)

22
Q

What can membranes of adjacent cells also be bonded by? *

A

Intercellular cement, a thin layer of proteoglycans *

23
Q

What is a spot desmosome?

A

A spot desmosome increases the resistance of the tissue to mechanical stress

24
Q

Why are desmosomes only in spots?

A

To allow for stretching and twisting without damage

25
Q

Where in the body do we have an abundance of spot desmosomes?

A

In the skin :3

26
Q

What are hemidesmosomes?

A

Attaches the deepest epithelial cells to the basal lamina

27
Q

Yo if u look on the diagrams of a spot desmosome and hemidesmosome, what are the little noodles coming out??

A

Intermediate filaments (keratin) of the cytoskeleton >.<

28
Q

What is the basement membrane?

A

The basement membrane, is a complex structure produced by the basal surface of the epithelium and the underlying connective tissue

Consists of 2 layers; basal lamina/lamina lucida and reticular lamina/lamina densa

lamina lucida: clear layer with glycoproteins
reticular lamina: coarse reticular fibres, restricts diffusion, gives the basal lamina its strength

29
Q

What is the basal lamina? What is the reticular lamina?

A

Basal lamina (clear layer; lamina lucida) : the upper clear layer of the basement membrane, containing glycoproteins and a network of fine protein filaments

Reticular lamina (dense layer; lamina densa) : contains bundles of coarse reticular fibres, giving the basal lamina its strength and acts as a filter that restricts diffusion between the adjacent tissues and the epithelium

30
Q

What does it mean for epithelia to be simple? What does it mean for epithelia to be stratified?

A

Simple - single layer of cells

Stratified - multiple layers of cells

31
Q

What are simple squamous epithelia?

appearance; purpose; location; functions

A

Single layer of flattened, squashed cells >.< that are specialized for diffusion and filtration (i.e. exchange of substances)

  • forms the lining of blood vessels (diffusion of gas)
  • forms the alveoli in the lungs, capillary walls, and endocardium
  • lines body cavities that are not open to the outside, where they are part of serous membranes

functions: reduces friction, regulate fluid composition - controls permeability, performs absorption and secretion
locations: mesothelia lining ventral body cavities; endothelia lining heart and blood vessels, portions of kidney tubules (thin sections of nephron loops); inner lining of corneal alveoli of lungs

32
Q

How does transport occur across simple epithelia? What are the (2) modes of transport and the (1/3) steps?

A

Paracellular transport: substance passes through the narrow space between cells (1 step)

Transcellular transport: substance first enters the cell via active or passive means, then substance diffuses through the cytosol, substance then exits the other surface of the cell via active or passive means (3 step!)

33
Q

What are stratified squamous epithelia?

appearance; purpose; location; functions

A

Multiple layers of flattened, squashed cells that are specialized for protection, and is found in high use areas where abrasion can occur (i.e. lines the mouth, esophagus, outer layer of skin (keratinized))

-the apical surface contains squamous shaped cells, whereas deeper cells may be columnar or cuboidal
-packed with keratin protein that prevents dehydration and keeps cells strong and durable
-as cells on the surface are rubbed away, they are replaced by the mitotic division of basal cells (they are stem cells ^0^)

functions: provides physical protection against abrasion, pathogens, and chemical attack
locations: surface of skin; lining of mouth; throat; esophagus; rectum; anus; vagina

34
Q

What are simple cuboidal epithelia?

appearance; purpose; location; function

A

Single layer of square shaped cells that specialize in absorption and secretion through glands and ducts

functions: provides limited protection, secretion, absorption
locations: kidney tubule, thyroid gland!!! <- important

also glands and ducts i guess lol..

35
Q

What are stratified cuboidal epithelia?

appearance; purpose; location; function

A

Multiple layers of square shaped cells

functions: protection, secretion, absorption
locations: sweat glands!!!!, lining of some ducts (rare)

36
Q

What are transitional epithelia?

appearance; purpose; location; function

A

Shape of cells change. These cells tolerate repeated compression and stretching

functions: permits expansion and recoil after stretching
locations: bladder; renal pelvis; ureters

37
Q

What state are the transitional epithelial cells in inside an empty vs full bladder?

A

Empty bladder: cells are relaxed; appear almost columnar

Full bladder: cells are stretched horizontally; appear almost squamous

38
Q

What are simple columnar epithelia?

appearance; purpose; location; function

A

Single layer of column shaped cells that are hexagonal at the top, that specialize in absorption and secretion, lining the digestive tract from the stomach to the anus.

Contains glandular cells called goblet cells that produce a lubricant called mucous, giving epithelial lined cavities that are open to the outside the name mucous membranes

function: protection, secretion, absorption
location: Intestinal lining!!!, stomach lining, gallbladder, uterine tubes, collecting ducts in kidneys

39
Q

What are stratified columnar epithelia?

appearance; purpose; location; function

A

Multiple layers of column shaped cells

location: salivary glands, pancreas ducts!!!

40
Q

What are ciliated pseudostratified columnar epithelia?

appearance; purpose; location; function

A

Appears to be multi-layered column cells but is actually composted of only one layer as all epithelia are connected to the basement membrane but only appear to be different layers due to the variation in cell heights. They have cilia :3

Secreted mucous collects debris and cilia propel it upwards to swallow or be swept to be thrown up

functions: protection, secretion
location: lines more of the respiratory tract; nasal cavity lining, trachea, bronchi; portions of the male reproductive tract

41
Q

What are exocrine glands?

A

Exocrine glands: secretory glands that secrete onto external surfaces or onto internal passageways (ducts) that connect to the exterior

42
Q

What are the types of exocrine glands? (3)

A

Merocrine, Apocrine, Holocrine

these glands differ from one another based on their ways of secretion

43
Q

What are merocrine glands?

A

Secretion of mucous and saliva

nucleus transcribe into proteins necessary in the composition of saliva and mucous, which are then packaged with other materials into secretory vesicles at the golgi body, which are then exocytosed.

44
Q

What are apocrine glands?

A

Secretion of breast milk

nucleus transcribe into proteins necessary in the composition of milk, which are then packaged with other materials (carbohydrates, fats, etc), which move towards the apical surface of the exocrine gland cell, which then breaks off of the cell and is secreted from the body (becomes milk with all the carbohydrates and fats)

plasma membrane seals over where the surface was broken off and the process is repeated

mammary glands (breasts) use both apocrine and merocrine

45
Q

What are holocrine glands

A

Sebaceous glands that produce oil and sebum (located at hair follicles)

cells at the lower layer go through mitosis and matured daughter cells begin producing oil product

as cells become more full of oil product, cells burst and die, releasing their contents (lubricate hair and moisturizes the skin)

46
Q

What are the types of simple glands?

*refer to images on pg. 32

A

Simple tubular: intestinal glands; gland cells; kinda looks like a grape

Simple coiled tubular: merocrine sweat glands; tubular gland that is coiled; duct

Simple branched tubular: gastric glands; mucous glands; tongue; duodenum; 3 branches of tubular glands

Simple alveolar: not found in adults; a stage in development of branched glands; little bulb

Simple branched alveolar: sebaceous glands; 3 sacs/bulbs

47
Q

What method of secretion does a mucous cell use?

A

Merocrine :3

48
Q

What mode of secretion do eccrine sweat glands use?

A

Merocrine

49
Q

What are eccrine sweat glands?

A

Sweat glands that cover most of the body that secrete a clear, odorless substance (mostly water and NaCl)

armpits do not use this

50
Q

What sweat glands do armpits use? (different from the rest of the body)

A

Armpits have apocrine sweat glands

51
Q

How does armpit sweat differ from the sweat from the rest of your body?

A

armpit sweat is protein rich, contains water, NaCl, and waste product which produces its smell

regular sweat is mostly water and NaCl

BIOL131 - Tissue Level of Organization (5 decks)

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