Histology Basics Quiz

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Questions and Answers

What is the primary purpose of histology?

To study the behaviors of living organisms

To analyze the chemical composition of cells

To determine the genetic makeup of tissues

To examine the microscopic structure of normal tissues (correct)

Which component is essential for light-transmission microscopy?

Visible light (correct)

Electron beams

Fluorescent dyes

Ultraviolet radiation

What magnification is achieved using objective lenses with X40 and eyepiece lenses X10?

X400 (correct)

X40

X100

X60

What is the first step in preparing tissue for microscopic examination?

Fixation Signup and view all the answers

What is the purpose of the dehydration step in tissue preparation?

To remove all water from the tissue Signup and view all the answers

Why is clearing important in the tissue preparation process?

It removes alcohol to increase transparency Signup and view all the answers

During which step is the tissue placed in a small mold with melted paraffin?

Embedding Signup and view all the answers

What is the typical size range of a cell examined in histology?

10-30 micrometres Signup and view all the answers

What is the main function of epithelial tissue?

Lining surfaces and glandular secretion Signup and view all the answers

Which domain of epithelial cells is exposed to the lumen or external environment?

Apical domain Signup and view all the answers

What type of connective tissue features fixed and wandering cells within an abundant matrix?

Connective tissue proper Signup and view all the answers

Which type of epithelial tissue forms glands that secrete substances?

Secretory/glandular epithelia Signup and view all the answers

What is the main function of the basement membrane?

Anchor the epithelia to connective tissue Signup and view all the answers

Which of the following components is NOT part of the basement membrane?

Fibroblasts Signup and view all the answers

What characteristic differentiates muscle tissue from other types of tissue?

Ability to contract for body movements Signup and view all the answers

Which statement correctly describes the differences between epithelial and connective tissues?

Epithelial tissues have distinct cell orientations, while connective tissues do not and have a matrix. Signup and view all the answers

What is the primary purpose of staining sections in microscopy?

To enhance the visibility of specific structures Signup and view all the answers

Which stain is most commonly used for examining biological material?

H&E stain Signup and view all the answers

Why does water freeze quickly when using liquid nitrogen for tissue preparation?

It prevents the formation of large ice crystals Signup and view all the answers

What characteristic makes cytoplasm eosinophilic?

Presence of carbohydrates Signup and view all the answers

What type of microscopy is used when observing untainted samples?

Phase-contrast microscopy Signup and view all the answers

Which method is confined to the examination of blood and bone marrow cells?

May-Grünwald-Giemsa method Signup and view all the answers

In the context of immunochemistry, what does an epitope refer to?

The binding site for antibodies on an antigen Signup and view all the answers

What phenomenon occurs in phase-contrast microscopy when light waves are out of phase?

They completely cancel each other out Signup and view all the answers

What type of proteins transport vesicles along the cytoskeleton?

Myosin and kinesin Signup and view all the answers

Which shape of cells is more likely to differentiate into osteoblasts?

Star-shaped cells Signup and view all the answers

What is the main difference between prokaryotic and eukaryotic ribosomes?

Eukaryotic ribosomes are larger and more complex. Signup and view all the answers

Which component is crucial for integrins to function effectively?

Substrate binding Signup and view all the answers

What effect does blebbistatin have on cells?

Blocks cell contraction Signup and view all the answers

How does the stiffness of the matrix influence cell differentiation?

It triggers specific gene expression patterns. Signup and view all the answers

What is the primary function of intermediate filaments in a cell?

Providing structural support Signup and view all the answers

Which approach is NOT considered a method of tissue engineering?

Extracting DNA from tissues Signup and view all the answers

What is the main function of importins in the cell?

To transport cargo from the cytoplasm into the nucleus Signup and view all the answers

Which of the following statements is true about euchromatin?

Euchromatin is lighter and represents the active form of chromatin. Signup and view all the answers

What role does the H1 histone play in relation to nucleosomes?

It holds the DNA tightly wrapped around the histone proteins. Signup and view all the answers

How do histone acetylation and methylation differ in their effects on gene expression?

Acetylation increases gene expression while methylation represses it. Signup and view all the answers

What is true about chromosomes during cellular division?

Chromosomes are condensed to allow them to split from the mother cell to the daughter cells. Signup and view all the answers

Which component of the nucleosome serves as the core around which DNA is wrapped?

Octameric core complex of histones Signup and view all the answers

What structure is responsible for the initial organization of DNA into chromatin?

Nucleosome Signup and view all the answers

What are the two arms of a chromosome called?

Chromatids Signup and view all the answers

What primarily increases the surface area of the inner mitochondrial membrane?

Folds called cristae Signup and view all the answers

What does the endosymbiotic theory suggest about the origin of mitochondria?

They were once free-living bacteria that formed a symbiotic relationship. Signup and view all the answers

How do metabolites like pyruvate and fatty acids enter the mitochondria?

Via membrane porins. Signup and view all the answers

What is a result of the movement of electrons through the inner membrane's electron-transport system?

Protons ($H^+$) are pumped into the intermembranous space. Signup and view all the answers

What role does ATP synthase play in ATP production?

It allows protons to flow back into the matrix, generating ATP. Signup and view all the answers

What do peroxisomes primarily function in?

Catabolism of long-chained fatty acids and oxidation reactions. Signup and view all the answers

What byproduct is formed in peroxisomes during the oxidation of fatty acids?

Hydrogen peroxide ($H_2O_2$) Signup and view all the answers

What type of DNA do mitochondria possess that supports the endosymbiotic theory?

Circular DNA similar to that of bacteria Signup and view all the answers

Study Notes

Histology

Histology is the study of the microscopic structure of normal tissues. It helps understand how tissues are built to perform their functions.
Tissues are collections of cells with similar characteristics.
Cell size ranges from 10-30 micrometers.
Microscopes are used to study cells.

Light Transmission Microscopy

Uses visible light to examine a sample.
Objective lenses enlarge and project the image to the eyepiece.
Common magnifications are X4, X10, and X40.
The sample needs to be transparent.

Tissue Preparation

Fixation: Preserves tissue structure using chemicals that cross-link proteins and inactivate enzymes.
Dehydration: Removes water from the tissue using alcohol solutions (e.g., moving from 65% to 100% alcohol).
Clearing: Tissue is transferred to organic solvents that are miscible with both alcohol and paraffin to make it transparent.
Infiltration: Tissue is immersed in melted paraffin until fully infiltrated (absorbed by paraffin).
Embedding: The tissue is placed in molds filled with melted paraffin. Once solidified the specimen forms paraffin block.
Trimming: The block is trimmed to expose the tissue for sectioning. Freezing with liquid nitrogen is an alternative to paraffin embedding for tissue sectioning.
Staining: Highlights specific tissue structures and components. H&E staining is common (nuclei stain blue, cytoplasm stains pink/red). PAS stain is used for carbohydrates.

Microscopy Techniques

Phase-contrast microscopy: Used to observe unstained samples, useful for live cells that would be killed under staining.
Confocal microscopy: Allows observation of a single plane of a sample, useful for 3D-imaging.
Stereomicroscopy: A microscope that magnifies an object without thin-sectioning the specimen.
Electron microscopy: Uses electrons, in two kinds of configurations, Transmission electron microscope (TEM) or Scanning electron microscope (SEM). TEM can give a 3D picture (in a 2D arrangement) while SEM gives a 3D surface rendering.

Immunochemistry

Uses antibodies (produced by B-lymphocytes) to identify specific proteins/molecules.
Antibodies have a variable domain (paratope) that attaches to the specific protein/molecule (antigen).
The epitope is the part of the antigen that the antibody recognizes.

The Cell

The basic unit of life, and composed of plasma membrane, the encircling membrane surrounding the cell.
Phospholipids create a bi-layer with hydrophobic tails facing inward and hydrophilic heads facing outward.
Cholesterol is found between the phospholipids affecting membrane fluidity and flexibility.
Proteins perform various functions, some face outward, some inward, and others span the membrane.
Glycocalyx: a sugar layer surrounding the membrane, bonded with proteins and phospholipids. It plays a role in recognition and cell-cell interactions.
Hyaluronic acid: creates a jelly-like layer around cells, which retains water.

Membrane Transport

Simple diffusion: Lipophilic molecules and small, uncharged molecules pass through easily.
Channel/facilitated diffusion: Membrane proteins act as channels to allow passage of specific molecules(usually charged).
Carrier/pump: Larger molecules/charged molecules transported against their concentration gradient, requiring energy., often using ATP as energy source.

Cytoskeleton

Microfilaments: Composed of actin.
Microtubules: Composed of tubulin required for mitosis and other cellular needs.
Intermediate filaments: Provide structural support.

Organelles

Ribosome: Synthesize proteins based on instructions from mRNA. They have three sites (A, P, and E) to perform protein synthesis.
Endoplasmic Reticulum (ER): Rough ER (RER) has ribosomes and synthesizes proteins for transport/secretion. Smooth ER (SER) synthesizes lipids and other molecules.
Golgi Apparatus: Modifies and packages proteins and lipids for secretion or use within the cell.
Lysosomes: Contain digestive enzymes to break down waste and molecules.
Mitochondria: Produce ATP through cellular respiration.
Peroxisomes: Contain enzymes to break down fatty acids into smaller molecules.
Cellular inclusion: Accumulation of substances like lipids or glycogen, storing energy in some cells.
Nucleus: Contains DNA, controls cellular activities, including protein production, and contains the nucleolus where ribosomes assemble.

Cell Cycle

Interphase: period of cell growth and DNA replication. Divided in G1, S, and G2 phases.

Mitochondria

Produce ATP
Metabolism of amino acids and lipids
Act as a sensor for the health of the cell
Cells can undergo apoptosis (programmed cell death)

Cell Division

Mitosis: Process of cell division, resulting in two identical daughter cells.
Cytokinesis: Division of the cytoplasm.
Stem cells: Undifferentiated cells that can divide indefinitely and differentiate into specialized cell types.
Types of stem cells include embryonic and adult stem cells.

Types of tissues

Epithelial: Covers body surfaces, lines cavities, forms glands responsible for secretions.
Connective: Supports, connects, and separates different tissues and cells. Forms extracellular matrix.
Muscular: Responsible for movement, contracts.
Nervous: Transmits information via nerve impulses.

Bone

Compact bone: Dense bone tissue organized into osteons. Each osteon is around a central canal.
Spongy bone: A framework of trabeculae.
Epiphysis: Ends of the long bone.
Diaphysis: Shaft of the bone.
Osteoblasts: Bone-forming cells.
Osteocytes: Mature bone cells.
Osteoclasts: Bone-resorbing cells. -Periosteum: Membrane covering bone. Contains cells that produce new bone tissue, which has a key role in bone growth and fracture healing. -Endosteum: Membrane lining the internal surfaces of the bone. Contains cells that produce new bone tissue, which has a key role in bone growth and bone remodeling.

Blood

Consists of a suspension of cells (red blood cells, white blood cells, platelets) within a fluid matrix called plasma.
Function is to transport substances throughout the body.

Connective Tissue

Connective tissue is characterized by an abundance of extracellular matrix that is largely composed of protein fibers (collagen, elastic) embedded in a ground substance.
Types include loose (areolar) connective tissues, dense regular connective tissue, dense irregular connective tissue, reticular connective tissue.
Specialized connective tissues include cartilage, bone, and blood.

Glands

Glands are epithelial tissue; they produce and secrete substances. Glands can be exocrine (secrete through ducts) or endocrine (secrete into the bloodstream).

Special epithelia structures

Cilia: hair-like extensions of the cell membrane that can beat, move substances.
Stereocilia: (also called static cilia), extensions of the cell membrane that do not beat or move.
Microvilli: finger-like projections that increase surface area for absorption.

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Description

Test your knowledge on the fundamental concepts of histology, including tissue preparation, microscopy techniques, and the types of tissues. This quiz covers essential questions about epithelial and connective tissues as well as the processes involved in microscopic examination.