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Histology/Embryology > Lesson 6 - Part 1 > Flashcards

Lesson 6 - Part 1 Flashcards

1
Q

Define histology

A
  1. Histio - relating to tissue; Logia(ology) - the study of
  2. 18th century Histology became a separate branch of science :establishing the normal structure of tissues and cells in relationships to their function
  3. Based upon the examination of samples of cells and tissue
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2
Q

Human eye has resolution of about _________. _________ is the only cell structure we discuss that is visible with human eye.

A
  1. 100 um
  2. Plant cell
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3
Q

Describe the use of a light microscope for histological examination

A
  1. cells observed under a light microscope can be alive or fixed and stained
  2. Light microscope can magnify up to 1000 times the size of an object
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4
Q

How are tissues prepared for histological examination?

A
  1. Histological sections: thin sections
  2. Study by transmitted light through the prepared slide
  3. compound lenses in sequential magnification
  4. Staining tissues: most tissues are colorless and indistinguishable under the LM - Staining is based on the pH of cellular constituents; Chemically preserved tissues reveal the biochemical composition of tissue
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5
Q

Describe H&E stain

A
  1. Acid containing structures :nuclei - Hematoxylin = blue stain (purple)
  2. Alkaline substances: cytoplasm - Eosin = red stain
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6
Q

Describe electron microscopes

A
  1. Invented in the first half of the 20th century
  2. distinguish individual molecules of biological importance. In effect, it can magnify objects up to 1 million times.
  3. Nm= 1 billionth of a meter
  4. Angstrom=.1 nanometer
  5. Electrons are transmitted through a thin specimen in a vacuum
  6. Images are projected onto a fluorescent screen
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7
Q

What is the major limitation of the transmission electron microscope?

A

Since no living specimen can survive under their high vacuum, they cannot show the ever-changing movements that characterize a living cell.

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8
Q

Describe the scanning electron microscope

A
  1. Specimen must be fixed, dried and coated with a thin layer of heavy metal (gold or platinum)
  2. Electron beam is reflected from the surface of the coated specimen
  3. As tissue is scanned by a focused beam of electrons, the electrons are converted into a image onto a screen
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9
Q

There are about __________ known distinct human cell types, body is composed of __________ cells.

A
  1. 210
  2. 100 trillion
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10
Q

Describe the Nucleus of a cell

A
  1. In all human cells except RBC
  2. Double layered nuclear membrane with pores
  3. Contains 1 or more nucleoli: DNA< RNA and protein, ribosomal RNA: protein synthesis
  4. 46 chromosomes: DNA + protein
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11
Q

Describe Plasmalemma

A
  1. Thin, flexible, dynamic barrier between the organized, living particles within the cell and the outside the cell
  2. Selective barrier: responsible for maintaining the difference between the external and internal environment of the cell(homeostasis)
  3. Visible with Electron microscope
  4. It is the site of transport of molecules and particles in and out of the living cell (Exchange of information between adjacent cells) - For example: hormone receptors
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12
Q

Describe the 3 layers of the Plasmalemma (trilaminar)

A
  1. Outer surface - glycoproteins: receptors for hormones & neurotransmitters
  2. Inner surface - proteins: 60-70% of total mass, structural reinforcement
  3. Central layer - phospholipids: barrier for diffusion
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13
Q

Describe Rough Endoplasmic reticulum

A
  1. Series of interlocking membrane-bound canals in a pattern of flattened long, branching tubules with ribosomes on their cytoplasmic face
  2. Function: synthesis & distribution of proteins for export (dependent on the number of ribosomes) ie: Collagen from fibroblasts; Digestive enzymes from pancreas
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14
Q

Describe Smooth Endoplasmic reticulum

A
  1. Structure - Is a tubular network free of ribosomes
  2. Function - synthesis of steroids; Degradation of hormones and drugs
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15
Q

Describe Mitochondria

A
  1. Trilaminar/Membranous
  2. Function - Obtains energy by enzymatic action and then converts it into ATP for cellular use
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16
Q

Describe Golgi complex

A
  1. Structure - electron microscope 6-8 smooth surface membranes; Cavities filled with fluid and expand during secretory activity
  2. Function - protein formation and secretion
17
Q

Describe Lysosomes

A
  1. Structure is related to Function
  2. Shape & density vary greatly
  3. Budding vesicle on the maturing face of the Golgi body
  4. Contains digestive enzymes
  5. Digestion of worn out cells (autophagocytic)
18
Q

Describe Microvilli

A
  1. Specialized structures that appear on the free surface of some epithelial cells, extensions of the plasmalemma
  2. Microscopic,fingerlike projections increase the absorptive surface area up to 30X
  3. Part of a tastebud: taste hairs
  4. Modification to increase surface area of the intestines
19
Q

Describe Cellular Transport Mechanisms

A
  1. Exocytosis: active transport from a vesicle within the cell to the extracellular environment, fusion of the vesicle membrane with the cell membrane
  2. Endocytosis: uptake of material from the extracellular environment
  3. Phagocytosis: moving cell engulfs/digests material from EE - Ie: WBC engulf bacteria
  4. Pinocytosis: stationary cell engulfs/digests material from EE - Ie:kidney tubules reabsorb proteins
20
Q

Describe Microtubules

A
  1. Structure - Formed from proteins; Slender, hollow, cylindrical structures; Diameter about 25nm; Nonmembranous cellular organelles
  2. Function - Act as scaffold to determine cell shape, building block of the cell; Guidance system in intracellular transport: Provides a set of “tracks” for cell organelles and vesicles to move on
  3. cytoskeleton to maintain shape of cell
  4. Framework of centrioles (mitosis)
  5. Mitotic spindle fibers for separating chromosomes in mitosis
  6. Support of cilia
  7. Geometric patterns inside flagella and cilia, they are used for locomotion/support movement
21
Q

What medical problems are defects in the cilia and flagella of human cells are associated with?

A
  1. Kartagener’s syndrome: portions of the microtubules are not connected properly, this is characterized by recurrent respiratory infections related to the inability of cilia in the respiratory tract to clear away bacterial and other materials.
  2. Damage to respiratory cilia may also be acquired rather than inherited and is most commonly linked to smoking cigarettes. Bronchitis, for instance, is often triggered by a build-up of mucus and tar in the lungs that cannot be properly removed due to smoking-related impairment of cilia.
22
Q

Describe the specialized microtubles related to mitosis

A
  1. Framework of centrioles - 9 sets of triplets
  2. Mitotic spindle fibers - spindle fibers for separating chromosomes during mitosis
23
Q

Describe Microfilaments

A
  1. Thin threadlike proteins: filamentous cytoplasmic structures; diameters vary from 5 – 7nm
  2. Predominantly composed of contractile protein: actin
  3. most abundant cellular protein
  4. carry out cellular movements including gliding and contraction
  5. Contraction & support all cells except RBC
  6. Cellular movements including gliding and contraction
  7. E.g. Actin & myosin filaments: most highly organized and concentrated in skeletal muscle - involved in muscle contraction
  8. E.g. Tonofilaments of hemidesmosomes and desmosomes, mechanical and structural function (attachment apparatus)
  9. E.g. Neurofilaments
24
Q

Describe CYTOPLASMIC INCLUSIONS

A
  1. In addition to organelles, there is a wide variety of cellular inclusions (endogenous or exogenous)
  2. Not present in all cells, maybe present in specific cells during certain physiological activities
25
Q

Describe Endogenous inclusions

A
  1. Generally essential to life, arise from within the cell
  2. E.g. Lipid droplets (fat storage); some pigments
26
Q

Describe melanin

A
  1. Most abundant and important pigment
  2. Origin: neural crest cells produced by melanocytes
  3. Pigment transferred to basal epidermal cells to screen out harmful overexposure to ultraviolet light
27
Q

Describe Exogenous inclusions

A
  1. transitory and often harmful, arise outside the cell
  2. Incorporated by phagocytosis, pinocytosis, absorption: heavy metals, lead poisoning, asbestos, carbon

Histology/Embryology (14 decks)

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