Histology and Cytology Flashcards Preview

Anatomy 6511 Exam One Material > Histology and Cytology > Flashcards

Flashcards in Histology and Cytology Deck (58):
1

What is histology?

microscopic division of Anatomy

the study of the TISSUEs of the body
-now used to encompass cytology and organology as well

2

What is cytology?

study of the cells of the body

3

What are the four types of tissue studied in histology?

epithelial tissue (epithelium)
muscle tissue
connective tissue
nervous tissue

4

define a tissue

group of similar cells with common function, also ECM

5

list the levels of structural organization

chemical > cellular > tissue > organ > organ system > organismal

6

epithelial tissue

covers body surfaces, lines hollow organs, body cavities and ducts and glands

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connective tissue

diverse, protect and support body

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muscle tissue

contractile, makes force

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nervous tissue

detect stimuli and generate action potentials and nerve impulses

10

Light Microscopy

Specimens examined via transillumination (i.e., passing light through the specimen to facilitate observation)

Steps:
1. Acquisition of Cells or Tissues
2. Fixation
3. Processing
Dehydration – using a graded series of alcohol
Clearing – using a miscible substance
Infiltration – using a liquid embedding medium
4. Embedding
5. Sectioning
6. Staining

-pink images

takes a lot of time, can lose components
or get contaminants in slide prep, has to be incredibly thin (7-10 micrometers)

fixative: stop metabolism and bacteria/viruses/fungi, harden tissue (12 hours in fixative)

11

Electron Microscopy

Provides:
Greater Resolution
Higher Magnification

Two Types:
Transmission Electron Microscopy (TEM)

Scanning Electron Microscopy (SEM)

12

Transmission Electron Microscopy (TEM)

uses a beam of electrons that passes through the specimen

higher magnification
greater resolution

black and white on images

13

Scanning Electron Microscopy (SEM)

beam of electrons scans the surface of the specimen

14

Atomic Force Microscopy

AFM

15

How is resolving power (resolution) defined? How does it compare between the three microscope types and the human eye?

Defined as how far two objects must be separated from one another so that they can be distinguished as two distinct objects:

Human Eye – 0.2 mm
Light Microscope – 0.2 μm
SEM – 2.5 nm
TEM – 0.05 nm (theoretical) / 1.0 nm (tissue section)
Atomic Force Microscopy – 50.0 pm

16

What 5 factors is resolution dependent on?

1. Optical System
2. Wavelength of Light Source
3. Specimen Thickness
4. Quality of fixation
5. Staining Intensity

17

What does fixative do?

stop metabolism and bacteria/viruses/fungi, harden tissue (12 hours in fixative)

for light microscopy

18

Processing
Dehydration

using a graded series of alcohol

19

Clearing

using a miscible substance

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Infiltration

using a liquid embedding medium

21

What are the common problems with the typical histological technique used to prepare tissues to be observed with a light microscopic examination (i.e. with paraffin)?

1. Time - takes awhile (days)
*Use of Cryostat (tissue into liquid N, back in few min.)

2. Solvent Dissolves Lipids (interested in them often, don't want to lose)
*Double Fixation – First fixation with glutaraldehyde and a second fixation with osmium tetroxide
*great for preservation of membranes and TEM looks great

3. Shrinkage of Tissues
*Embedding in Resin

22

Acidic dyes

-carry a net negative charge; bind with cationic cell/tissue components (i.e. those that carry a net positive charge)

-ex. eosin (pink or red hue), orange G, and acid fuchsin

-stain acidophilic (or eosinophilic) tissues (i.e. those tissues with a high affinity for acid dyes; these tissues exhibit acidophilia)

-mitochondria, secretory granules, collagen fibers (as well as other extracellular fibers), general cytoplasm, basement membrane; staining with acidic dyes is less specific; more substances within cells and the extracellular matrix exhibit acidophilia than basophilia

23

Basic Dyes

-carry a net positive charge; bind with anionic cell/tissue components (i.e. those that carry a net negative charge)

-ex. toluidine blue, alcian, and methylene blue; hematoxylin(doesnt actually have neg charge or pos charge but acts like it does), although not a basic dye, acts like one

-stain basophilic tissue (i.e. those tissues with a high affinity for basic dyes; these tissues exhibit basophilia)

-these dyes will bind to the negative phosphate group on DNA and RNA (cell nucleus, nucleoli, RNA-rich portions of the cytoplasm); the carboxyl groups of proteins; sulfate groups of cartilage matrix (GAGs)

24

Hematoxylin

(+: no charge actually, but acts as if its basic): basophilic tissue, blue hue

stains: nuclei, DNA/RNA phosphate groups, protein carboxyl group, GAGs (sulfate group) in cartilage matrix

25

Eosin

(-): bind with cationic/ acidophilic/eosinophilic tissue, pink hue

stains: "EVERYTHING BUT THE NUCLEUS" mitochondria, secretory granules, collagen fibers, cytoplasm, basement membrane

-less specific
MORE substances in cells and ECM take to acidic dyes**

26

Histochemistry and Cytochemistry

"Don't wanna use a lot of fixation with these, use cryostat so proteins are functional, enzymes working"
Steps:
1. Section immersed in solution of enzyme’s substrate
2. Enzyme acts on substrate
3. Section put in contact with a marker compound
4. Marker compound reacts w/ molecule produced by enzymatic action on substrate
5. Final product (insoluble and visible by light or electron microscopy) precipitates over site

27

artifact

dust, hair, particles that can be an issue when studying tissue sections

28

vesicular transport

exocytosis
endocytosis

29

The plasma membrane (plasmalemma) is composed of what? What is its function?

phospholipids, cholesterol, proteins, and chains of oligosaccharides

Site where materials are exchanged between the cell and its environment; regulates the ion concentration of the cytoplasm; also recognition, regulatory, and interaction functions.

30

Humans have approximately ____ different cell types

200

31

How thick is the plasma membrane?

7.5-10 nm in thickness, EM

32

Describe the structure of the plasma membrane

Trilaminar
EM: fluid mosaic model

33

Which process is responsible for the bulk uptake of material across plasma membrane and into the cell?

Endocytosis

34

Endocytosis

bulk uptake of material across plasma membrane into cell;
folding and fusion of membrane to form vesicles

Phagocytosis
Pinocytosis (Fluid-Phase Endocytosis)
Receptor-Mediated Endocytosis

35

Phagocytosis

"cell-eating"; phagosome; then fuses with lysosomes

36

Pinocytosis

Fluid-Phase Endocytosis

binding of the ligand to a receptor causes coated pits made of clathrin to form
-pinches off to form a coated vesicle
-fuses with endosomal compartment to form endosomes

37

Exocytosis

release of materials across plasma membrane into the EC space

-involves vesicle fusing with plasma membrane and releasing its contents

38

Describe the role of lysosomes as well as their structure

Function: intracellular digestion and turnover of cellular components

Size: 0.05-0.5 micrometers

Structure: membrane bound vesicles that contain about 40 different HYDROLYTIC ENZYMES

-abundant in neutrophils, macrophages

39

Ribosomes

Function: Protein synthesis

Size: 20nm x 30nm

Structure: Composed of two different-sized subunits; the subunits are composed of rRNA and proteins; can be found free within the cytoplasm or attached to membrane of the endoplasmic reticulum.

phosphate on rRNA makes them MORE BASOPHILIC

40

Rough ER

Network of intercommunicating channels and sacs of membranes which enclose a space called a cisterna.

Ribosomes on the cytosolic side of the membrane; produces proteins for secretion.

41

Smooth ER

Network of intercommunicating channels and sacs of membranes which enclose a space called a cisterna.

Regions of ER without ribosomes; cisternae are much more tubular; important in the production of phospholipids; abundant in cells that synthesize steroid hormones (i.e. steroid synthesis - aka in adrenal cortex

42

Golgi Apparatus

Golgi Complex

Function: Completes post-translational modifications, packages, and sorts proteins synthesized in the RER.

Structure: Composed of smooth membranous saccules
-has a cis (i.e., entry) face and a trans (i.e., exit) face.

43

Mitochondria

POWERHOUSE Function: Membrane-enclosed organelles with enzymes arrays specialized for aerobic respiration and production of adenosine triphosphate (ATP).

Size: 0.5μm-1.0μm in diameter and 5μm-10μm in length.

Structure: Two membranes (i.e., inner and outer) and two compartments (i.e., matrix and intermembrane space); inner membrane folded to form cristae which project into matrix.


EOSINOPHILIC

common in muscle, liver, kidney

stain pink with eosin
eosinophilic

44

Secretory Vesicles (Granules)

STORAGE

Function: Formed at the Golgi apparatus; store product until it is released via exocytosis.

Structure: Secretory product surrounded by membrane.

45

Proteasomes

Function: Degrade denatured and nonfunctional polypeptides.

Structure: Cytoplasmic protein (i.e. no membrane); cylindrical structure made of four stacked rings.

46

Peroxisomes

Function: Oxidizes various potentially toxic molecules as well as prescription drugs.

Size: 0.5μm in diameter

Structure: Spherical membrane-limited organelles.

liver, kidney

47

Microtubules

Fine tubular structures found in cytoplasmic matrix, centrioles, basal bodies, cilia, and flagella. Hollow lumen.

Function: Formation and maintenance of cell shape; cellular transport of organelles and vesicles; create repeated beating motion

Size: outer diameter of 24nm and a dense wall 5nm thick; hollow lumen

Length: variable; can be many μm in length

Structure: composed of α and β tubulin molecules; organize to form 13 parallel protofilaments

cilia, flagella: 9+2

48

microtubule pattern

In cilia and flagella, the same core structure is present – axoneme.
Assembly of microtubules in a 9+2 pattern.
Nine peripheral doublets have an outer arm of dynein which connects to next doublet; ATP-dependant interaction cause conformational changes – get repeated beating movement.

49

Microfilaments
(Actin Filaments)

Function: Allow for contractile activity within cells, including cell shape changes for endocytosis, exocytosis, and cell locomotion, moving cytoplasmic components, and cleavage during mitosis.

Size: 5-9nm

Structure: Composed of globular subunits organized into a double-stranded helix.

50

Intermediate Filaments

Very stable; provide mechanical strength and stability.

Size: 10-12nm in diameter

Structure: Protein subunits different in different cell types; rod-like subunit that organize into a cable-like structure.

51

Inclusions

Are NOT considered organelles

Cytoplasmic structures or deposits composed mainly of accumulated metabolites or other substances

-liquid droplets ( cells appear empty in staining cause of organic solvents in processing)
-glycogen granuels
-pigment deposits

52

Nucleus

Main Components:
1. Nuclear Envelope – two parallel unit membranes separated by a narrow space; at sites where inner and outer membranes of the nuclear envelope fuse, nuclear pore complexes form; where regulation of the transport between the nucleus and cytoplasm takes place.

2. Chromatin – the chromosomal material in a largely uncoiled state.
Heterochromatin – course granules in EM and basophilic clumps in light microscopy.
Euchromatin – less coiled; fine granules in EM and lightly basophilic areas in light microscopy.

3.Nucleolus – spherical, highly basophilic structure present in nuclei of cells active in protein synthesis; lots of rRNA in this location.

euchromatin lightly basophilic sdoesnt stain well

53

Nucleus main components

1. Nuclear Envelope
2. Chromatin
Heterochromatin
Euchromatin
3. Nucleolus

54

Apoptosis

The process of cell suicide or programmed cell death; leads to the production of small membrane-enclosed apoptotic bodies which undergo phagocytosis by neighboring cells.

55

necrosis vs apoptosis

PROGRAMMED cell death = apoptosis

56

Autophagosome

lysosomes that get rid of nonfunctional cellular components

57

cisterna

space enclosed by ER

58

The basal lamina is observed in TEM by using what?

osmium tetroxide (silver)