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202: Histology I > 2.2: Epithelia and Glands ✅ > Flashcards

2.2: Epithelia and Glands ✅ Flashcards

1
Q

Basic tissue types

A

Epithelial

Muscle

Nervous

Connective

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2
Q

Epithelial tissues

A

Cover external and internal surfaces of the body

Form secretory glands

Eg lining of GI tract, skin surface

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3
Q

Muscle tissues

A

Create the force that allows movement

Generate body heat

Eg cardiac muscles, smooth muscles, skeletal muscles

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4
Q

Nervous tissues

A

Collect and analyze info

Signal muscles and glands to take appropriate actions

Eg brain, spinal cord, nerves

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5
Q

Connective tissues

A

Protect and support other tissues and various organs

Blood is considered a connective tissue

Eg fat, bone, tendon

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6
Q

What is tissue classification primarily based on?

A

Morphology
-epithelial tissue
-connective tissue

Function
-muscle
-nervous

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7
Q

Where do you find Epithelium

A

Lines and covers all body surfaces
-except articular cartilage, tooth enamel and anterior of iris

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8
Q

Functions of epithelium

A

Protection
-skin, bladder, vagina

Absorption
-intestines

Transport
-of material to surface (cilia)

Gas exchange
-lungs’ alveolas

Excretion
-kidneys’ tubules

Secretion
-glands

Receptor function
-olfactory epithelium, retina

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9
Q

Epithelium

A
  1. Characterized by closely packed cells
    -joined by specialized cell-to-cell junctions
  2. Have a free surface as they cover body surfaces and cavities
  3. Supported by a Basement Membrane = basal lamina + connective tissue
    -basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits
  4. Most epithelial cells renew constantly by mitosis
  5. Lack a direct blood/lymphatic supply.
    -nutrients are delivered by diffusion
  6. Avascular (no blood vessels).
  7. All epithelia are directional:
    have an:
    - apical (free) surface
    - basal surface
    - lateral surface
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10
Q

Structural classification of epithelial tissue

A

Simple squamous
Stratified squamous

Simple cuboidal
Stratified cuboidal

Simple columnar
Stratified columnar

*Pseudostratified columnar

*Transitional (urothelium)

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11
Q

Pseudostratified

A

Appear to be stratified but consists of a single layer of irregularly shaped and differently sized columnar cells

The neighboring cells’ nuclei appear to be on different levels instead of being clustered in the basal end

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12
Q

Transitional epithelium

A

Urothelium

Stratified

Multiple layers which can contract and expand to the degree of distension needed

Lines organs of urinary system

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13
Q

What occurs to epithelial cells in special situations?

A

They lack a free surface

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14
Q

Discuss the polarity of epithelial cells

A

All are polarized

-apical surface faces lumen/externally
-basal surface faces basement membrane

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15
Q

Function of each surface of epithelial cells is based on..

A

Based on different sets of proteins

-achieved by DIFFERENTIAL sorting

Proteins targeted to the plasma membrane are sorted in the trans-Golgi network- based on signal sequences

A. Basal surface signal sequences primarily reside in the protein sequence

B. Apical surface proteins’ signal sequences are more diverse, and found in protein or carbs attached to proteins

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16
Q

Microvilli

A

Finger-like membrane protrusions of the apical plasma membrane

Supported by the actin cytoskeleton

Increase surface area

Functions:
-absorption
-secretion
-adhesion
-mechanotransduction

17
Q

Cilia

A

Hair-like extensions of apical plasma membrane

Supported by microtubules

In nearly all cells in body

Classified into
-motile cilia (can move)
-primary cilia (immotile, in nearly every cell)
-nodal cilia (in embryo)

18
Q

What are cell junctions?

A

Multiprotein complexes between
-neighboring cells or
-between a cell and the extracellular

19
Q

Cell junction functions

A

Adhesion

Paracellular transport control

Communication between cells

20
Q

Types of cell junctions

A

Tight junctions

Adherens junctions

Desmosomes

Gap junctions

Hemidesmosomes

21
Q

Tight junctions

A

Intercellular

Form an impermeable barrier to most molecules, between 2 sides of epithelium

Claudin and occludin proteins are major components

Regulate paracellular pathway of ions and molecules

22
Q

Gap junctions

A

Specialized intercellular connections

Connect cytoplasm of 2 cells
-allow molecules, ions, electrical impulses from cell to cell

Made of 2 connexons (hemichannels)

Found in most tissues in body
-exception: adult skeletal muscle and mobile cell types

23
Q

Anchoring junctions

A

Multiprotein complexes

Found at
-cell-cell junctions
-cell-extracellular matrix junctions

Help keep cells together
-structural cohesion of tissues

Allow substances through

Commonly found in tissues prone to mechanical stress constantly
-eg skin and heart

24
Q

Adherens junctions

A

Multiprotein complexes

Found in epithelial and endothelial tissue
-at cell-cell junctions

Linked to actin cytoskeleton

Made of cadherins and catenins

25
Q

Basement membrane overview

A

Part of ECM

Cell and tissue support
-underlines epithelia, mesothelia and endothelia
-surrounds muscle, fat and Schwann cells

26
Q

What is the basement membrane composed of?

A

Basal lamina and reticular lamina

Entirely extracellular tissue

Underlying connective tissue attaches to basal lamina with collagen 7
-anchoring fibrils and fibrillin microfibrils

27
Q

Functions of basement membrane

A

Structural attachment

Compartmentalization

Filtration (kidneys)

Tissue scaffolding
-during regeneration

28
Q

Basal lamina

A

Covers surface of muscle cells

Helps maintain integrity of skeletal muscle fiber during contraction

-disruption of basal lamina-muscle connection-> muscular dystrophies

29
Q

Glands

A

Make and release substances that affect functions of specific organs

Formed by ingrowth of epithelial surface

Types
-exocrine: secrete products onto surface, through duct
-> eg of products =sweat and mucus

-endocrine: secrete products into bloodstream, through basal lamina
-> products are hormones

30
Q

Exocrine glands types of secretion

A

Merocrine secretion
-product delivered by exocytosis
-eg mucus and serous glands

Apocrine
-product secreted from apical site, portion of cell is lost
-eg apocrine cell glands

Holocrin
-product secreted through lysis of cell
-eg sebaceous glands

202: Histology I (16 decks)

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