Histology and Cell Membrane Overview

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Questions and Answers

Which body system is primarily responsible for transporting oxygen and nutrients throughout the body?

Respiratory system

Nervous system

Digestive system

Cardiovascular system (correct)

What is the significance of using anatomical terminology in the study of human anatomy?

It provides a standardized way to communicate about body structures and their locations. (correct)

It allows for informal and subjective descriptions of body parts.

It is only necessary for advanced medical professionals.

It simplifies the complexity of anatomical structures.

Which organ system is responsible for the elimination of waste products from the body?

Endocrine system

Muscular system

Urinary system (correct)

Reproductive system

What characteristic is commonly compared across different types of tissues in anatomy?

Structural properties and function Signup and view all the answers

Which of the following organs is part of the muscular system?

Biceps brachii Signup and view all the answers

What is histology primarily concerned with studying?

The microscopic anatomy of biological tissues Signup and view all the answers

Which type of microscope offers the highest magnification capability?

Electron microscope Signup and view all the answers

Histology is most similar to which of the following fields?

Gross anatomy Signup and view all the answers

What are the typical dimensions of tissue sections examined in histology?

Several cm2 in area Signup and view all the answers

Which statement correctly describes the use of various microscopes in histology?

Light microscopes can magnify tissues up to approximately 1000 X. Signup and view all the answers

What topic is covered on the date 1 Nov?

Respiratory system Signup and view all the answers

Which two topics are covered in relation to the nervous system?

Nervous system 1 and Nervous system 2 Signup and view all the answers

What is the scheduled time for assessments?

2pm to 2:30pm Signup and view all the answers

How many attempts are allowed for each assessment?

One attempt Signup and view all the answers

What is the pass mark required to succeed in assessments?

40% Signup and view all the answers

What format will the questions in assessments primarily take?

MCQ and fill-in-the-blanks Signup and view all the answers

On which date is the second lecture about the cardiovascular system scheduled?

25 Oct Signup and view all the answers

What is the frequency of online assignments throughout the course?

Five assignments total Signup and view all the answers

What comprises the cytoplasm of a cell?

Cytosol and organelles Signup and view all the answers

Which component is primarily responsible for the stability of the cell membrane?

Cholesterol Signup and view all the answers

Which function is NOT associated with membrane proteins?

Generating ATP Signup and view all the answers

What structural feature allows phospholipids to form a bilayer in aqueous environments?

Hydrophobic tails and hydrophilic heads Signup and view all the answers

Which of the following accurately describes integral membrane proteins (IMPs)?

Permanently attached to the membrane Signup and view all the answers

What is the primary role of glycolipids in the cell membrane?

Intercellular communication Signup and view all the answers

Which statement is true about the cell membrane functions?

It regulates exchange and provides structural support. Signup and view all the answers

What is the role of membrane proteins in relation to the extracellular matrix?

To attach cells to the extracellular matrix Signup and view all the answers

What is the primary function of membrane carbohydrates?

Lubrication and protection Signup and view all the answers

Which type of endocytosis involves the engulfing of large particles?

Phagocytosis Signup and view all the answers

What process is primarily responsible for the movement of small lipid-soluble molecules across cell membranes?

Diffusion Signup and view all the answers

Which cellular component is primarily packaged with DNA in eukaryotic cells?

Chromatin Signup and view all the answers

Exocytosis is best described as which of the following?

Transport of materials out of the cell Signup and view all the answers

What structure is formed when the cell membrane engulfs material during endocytosis?

Vesicle Signup and view all the answers

Which of the following statements is true regarding nuclear pores?

They facilitate communication between the nucleus and cytoplasm. Signup and view all the answers

What type of transport requires energy and can move ions against their gradient?

Active transport Signup and view all the answers

What distinguishes Haematoxylin from Eosin in the staining process?

Haematoxylin specifically stains nucleic acids. Signup and view all the answers

Which of the following statements about the electron microscope is accurate?

It operates using a beam of accelerated electrons. Signup and view all the answers

Which stain would be most appropriate for identifying carbohydrates in a tissue sample?

Periodic acid-Schiff (PAS) Signup and view all the answers

What is the characteristic color produced by Eosin when applied to cytoplasm?

Red/Pink Signup and view all the answers

Which of the following statements about the commonly used H&E stain is incorrect?

Eosin targets reticular fibres. Signup and view all the answers

What distinguishes histology from gross anatomy?

Histology examines tissues under a microscope. Signup and view all the answers

Which type of microscope can achieve subcellular resolution?

Transmission electron microscope Signup and view all the answers

What date is the first lecture about muscle tissue scheduled?

17 Oct Signup and view all the answers

What is the primary focus of histology in biological tissues?

To study the microscopic structure of tissues. Signup and view all the answers

Which lecture focuses on the topic of the urinary system?

1 Nov Signup and view all the answers

Why is the use of various stains important in histology?

To differentiate between various cellular components. Signup and view all the answers

How many continuous assessments are there in the course?

5 Signup and view all the answers

What limits the areas that can be examined using a light microscope compared to an electron microscope?

Light microscopes are limited by lower magnification powers. Signup and view all the answers

What is the scheduled time for assessments unless otherwise indicated?

2pm to 2:30pm Signup and view all the answers

Which of these dates does not pertain to a lecture on the cardiovascular system?

22 Nov Signup and view all the answers

What is the minimum percentage needed to pass the assessments?

40% Signup and view all the answers

Which lecture is the second on the topic of joints?

11 Oct Signup and view all the answers

On which date is the first lecture on the reproductive system scheduled?

21 Nov Signup and view all the answers

What is the main component that stabilizes the cell membrane?

Cholesterol Signup and view all the answers

Which function is primarily associated with glycolipids in the cell membrane?

Intercellular communication Signup and view all the answers

Which statement correctly describes the nature of integral membrane proteins (IMPs)?

They are permanently attached to the membrane. Signup and view all the answers

How do membrane proteins assist in the process of chemical signaling between cells?

By acting as receptors Signup and view all the answers

What structural property of phospholipids allows them to form bilayers in aqueous environments?

Hydrophobic and hydrophilic regions Signup and view all the answers

What role do peripheral membrane proteins play in relation to the cell membrane?

They interact temporarily with membrane components. Signup and view all the answers

Which lipid type surrounds and anchors proteins in the cell membrane?

Phosphoglycerides Signup and view all the answers

What is the primary role of membrane carbohydrates in the cell membrane?

Serving as receptors for signaling Signup and view all the answers

What are the primary roles of membrane carbohydrates in cells?

Lubrication, protection, and recognition Signup and view all the answers

Which process involves the internalization of extracellular fluid along with dissolved particles?

Pinocytosis Signup and view all the answers

How does the nucleus communicate with the cytoplasm?

Via nuclear pores Signup and view all the answers

What is the purpose of the glycocalyx coating on the extracellular surface of the membrane?

To provide a protective and lubricating layer Signup and view all the answers

In which structural form does chromatin exist within eukaryotic cells?

A complex of DNA and proteins Signup and view all the answers

During exocytosis, which of the following statements is true regarding the energy requirements?

Exocytosis is an energy-dependent process. Signup and view all the answers

What type of membrane protein can penetrate the lipid bilayer and is involved in transport across it?

Integral membrane proteins Signup and view all the answers

Which of the following accurately describes the process of active transport?

It requires energy to transport substances against their gradient. Signup and view all the answers

Which of the following organ systems is not comprised of muscles and bones?

Respiratory system Signup and view all the answers

What is primarily emphasized when discussing the structure-function relationship of organs?

The correlation between the shape of an organ and its role in the body Signup and view all the answers

Which of these textbooks is not recommended for the study of human anatomy?

Human Physiology by Guyton & Hall Signup and view all the answers

Which body system would be least involved in the process of waste elimination?

Nervous system Signup and view all the answers

In the study of anatomical terminology, which aspect is considered least important?

Understanding historical perspectives of terminology Signup and view all the answers

What is the primary role of an electron microscope in biological studies?

To provide subcellular resolution using a beam of accelerated electrons Signup and view all the answers

How does the resolution of an electron microscope compare to that of a light microscope?

It provides subcellular resolution. Signup and view all the answers

Which stain is typically used to highlight nucleic acids within a cell?

Haematoxylin Signup and view all the answers

How does Eosin function in histological staining?

It stains cytoplasmic structures in shades of pink or red Signup and view all the answers

What is a primary advantage of using stains in histology?

They enhance visibility of specific structures in tissues. Signup and view all the answers

Which of the following statements accurately describes the H&E staining system?

The combination allows for differentiation between nucleus and cytoplasm in tissue sections Signup and view all the answers

Which anatomical feature can histology not effectively study?

Organ systems visible to the naked eye. Signup and view all the answers

Which of these stains is specifically identified for staining acidic epithelial mucins in the extracellular matrix?

Alcian blue Signup and view all the answers

In what way does gross anatomy differ from histology?

Histology requires special stains to visualize structures. Signup and view all the answers

Which feature limits the light microscope's ability to examine structures compared to electron microscopy?

Limited magnification capabilities. Signup and view all the answers

What is the main function of the glycocalyx?

Lubrication and protection Signup and view all the answers

Which cellular process is specifically responsible for the engulfing of small particles suspended in extracellular fluid?

Pinocytosis Signup and view all the answers

What is a primary role of nuclear pores in the cell?

Transport of substances between the nucleus and cytoplasm Signup and view all the answers

Which statement accurately describes the role of chromatin in eukaryotic cells?

It packages DNA into a denser structure. Signup and view all the answers

In terms of transport mechanisms, which process requires energy to occur?

Active transport of ions Signup and view all the answers

What is the process called when a cell expels materials through vesicular transport?

Exocytosis Signup and view all the answers

What type of membrane protein can penetrate the lipid bilayer and is involved in ion transport?

Integral membrane proteins Signup and view all the answers

Which of the following statements about phagocytosis is true?

It can be used for the removal of pathogens. Signup and view all the answers

What is the main function of somatic cells in the human body?

To carry out specialized functions forming tissues and organs Signup and view all the answers

Which of the following statements correctly defines morphology?

Study of the form and shape of structures Signup and view all the answers

Which of these best describes the nucleus of the cell when stained?

Stained purple indicating presence of DNA Signup and view all the answers

What is the primary focus of cytology?

Study of cellular structure and function Signup and view all the answers

Which of the following accurately describes gametes?

They are specialized sex cells involved in sexual reproduction Signup and view all the answers

What distinguishes morphometry from morphology?

Morphometry deals with the measurement of shapes and sizes Signup and view all the answers

How many different types of somatic cells are generally found in the human body?

Approximately 220 types Signup and view all the answers

Which of the following is NOT a function associated with somatic cells?

Participate in genetic recombination Signup and view all the answers

What are the primary advantages of using an electron microscope over a light microscope in histology?

An electron microscope offers higher magnification up to ~ 100,000 X and provides subcellular resolution, allowing for detailed examination of small areas. Signup and view all the answers

Why is histology considered essential for understanding tissue function in the context of gross anatomy?

Histology provides insights into the microscopic structure of tissues, which is vital for understanding their function and relationships within larger anatomical contexts. Signup and view all the answers

How do the staining techniques differ in their applications for light and electron microscopy?

Light microscopy uses a wide range of stains for visualizing larger structures, while electron microscopy typically requires heavy metal stains to enhance contrast at a subcellular level. Signup and view all the answers

In what ways do the dimensions of tissue sections prepared for histological examination affect the quality of observation?

Thin tissue sections are essential for allowing light or electrons to pass through, which enhances clarity and resolution during microscopic examination. Signup and view all the answers

What limitations do the physical characteristics of light microscopes impose on histological studies compared to electron microscopes?

Light microscopes are limited by a maximum magnification of ~ 1000 X and cannot provide subcellular resolution, restricting the level of detail observed in tissues. Signup and view all the answers

What is the main source of illumination used in an electron microscope?

A beam of accelerated electrons. Signup and view all the answers

How does Eosin stain structures in a tissue sample?

Eosin stains structures red or pink, particularly cytoplasm. Signup and view all the answers

What specific cell components does Haematoxylin primarily stain?

It primarily stains nucleic acids in the nucleus. Signup and view all the answers

Which stain would you use to identify nerve and reticular fibers in a tissue sample?

Silver stain. Signup and view all the answers

What is the significance of using the H&E stain in histology?

H&E stain provides a contrast between nuclear and cytoplasmic components. Signup and view all the answers

What color does the nucleus stain with the appropriate dye?

Purple Signup and view all the answers

Define cytology in the context of cell biology.

Cytology is the study of cellular structure and function. Signup and view all the answers

What are the two major divisions of cells in the human body?

Sex cells (gametes) and somatic cells. Signup and view all the answers

How many different cell types are there approximately in the human body?

Over 200 different cell types. Signup and view all the answers

What is the significance of homeostasis at the cellular level?

Homeostasis maintains optimal conditions for cellular functions. Signup and view all the answers

What does stereology contribute to cell biology?

Stereology examines 2D images to infer information about 3D structures. Signup and view all the answers

What roles do somatic cells play in the human body?

Somatic cells comprise all body cells except gametes and are responsible for forming tissues and organs. Signup and view all the answers

What is the primary function of morphometry in cell biology?

Morphometry involves the measurement of the shape of structures. Signup and view all the answers

What is the primary function of glycocalyx in cell membranes?

The glycocalyx mainly provides lubrication, protection, and specificity in binding. Signup and view all the answers

How do phagocytosis and pinocytosis differ in their processes?

Phagocytosis involves engulfing large particles, while pinocytosis is the intake of small particles suspended in fluid. Signup and view all the answers

Describe the role of nuclear pores in the nucleus.

Nuclear pores facilitate communication between the nucleus and the cytoplasm, allowing the transport of molecules. Signup and view all the answers

What is exocytosis and when is it typically employed by the cell?

Exocytosis is a process where cells expel molecules through energy-dependent secretion, commonly used for releasing hormones and neurotransmitters. Signup and view all the answers

Explain the concept of active transport and give an example.

Active transport is the movement of molecules against their concentration gradient using energy, such as the transport of Na$^+$ ions. Signup and view all the answers

What is chromatin, and why is it important in eukaryotic cells?

Chromatin is a complex of DNA and proteins that packages DNA into dense structures, essential for DNA organization and regulation. Signup and view all the answers

List two primary functions of membrane proteins.

Membrane proteins are involved in transport across the membrane and act as receptors for signaling. Signup and view all the answers

What distinguishes peripheral membrane proteins from integral membrane proteins?

Peripheral membrane proteins are loosely attached to the membrane's surface, while integral membrane proteins are embedded within the lipid bilayer. Signup and view all the answers

What is the optimal pH range for the enzymes in lysosomes, and why is this pH significant?

The optimal pH range for lysosomal enzymes is about 4.5–5.0, which is significant as it enhances the hydrolytic processes necessary for biomolecule breakdown. Signup and view all the answers

Describe the structure of mitochondria and its significance in energy production.

Mitochondria have an outer membrane, an inner membrane, and an intermembranous space, which are significant for ATP production through processes like the electron transport chain. Signup and view all the answers

What are the three main components of the cytoskeleton, and what functions do they serve?

The three main components are microfilaments, intermediate filaments, and microtubules, serving functions like cell shape maintenance, motility, and intracellular transport. Signup and view all the answers

Explain one role of lysosomes in cellular processes beyond digestion.

Lysosomes are involved in plasma membrane repair by fusing with damaged areas to help restore cellular integrity. Signup and view all the answers

How do microtubules contribute to intracellular transport?

Microtubules provide tracks along which motor proteins can transport organelles and vesicles within the cell. Signup and view all the answers

What are some examples of intermediate filaments and their importance?

Examples of intermediate filaments include keratin, desmin, and vimentin, which provide mechanical strength and structural support to cells and tissues. Signup and view all the answers

What is the role of mitochondrial DNA, and why is it important?

Mitochondrial DNA encodes some of the proteins essential for mitochondrial function, which is important for ATP production and cellular metabolism. Signup and view all the answers

Identify one mechanism through which lysosomes can protect cells from damage.

Lysosomes can engulf and digest damaged organelles through a process called autophagy, protecting cells from accumulated debris. Signup and view all the answers

Study Notes

Histology

Histology, the microscopic study of tissues, examines thin tissue slices using a microscope.
Light microscopes allow for viewing wide areas, multiple stains, and magnifications up to 1000x.
Electron microscopes allow for detailed examination of smaller areas with magnifications up to 100,000x.

Cell Membrane

Separates the cell's internal environment (cytoplasm) from the external fluid (interstitial fluid).
Consists of a phospholipid bilayer with embedded proteins and surface carbohydrates.
Functions:
- Physical isolation.
- Regulates exchange of substances with the environment.
- Sensitivity to external stimuli.
- Provides structural support.

Structure of the Cell Membrane

Composed of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
Proteins are embedded within the membrane framework.

Membrane Lipids

Three main types:
- Phosphoglycerides: Form 50% of the membrane, anchor and surround proteins.
- Cholesterol: Stabilizes the membrane.
- Glycolipids: Involved in intercellular communication.

Membrane Proteins

Function:
- Connect cytoskeletal filaments to the cell membrane.
- Attach cells to the extracellular matrix.
- Transport molecules in and out of cells.
- Act as receptors for intercellular communication.
- Possess specific enzymatic activity.

Membrane Carbohydrates

Located on the cell's outer surface as a coating called the glycocalyx.
Functions:
- Lubrication and protection.
- Anchoring and locomotion.
- Binding specificity.
- Recognition.

Transport Across Cell Membranes

Diffusion: Movement of gases, lipophilic or small molecules across the membrane.
Active Transport: Requires energy to move substances against concentration gradients, like Na+ ions.
Bulk Transport:
- Endocytosis: Brings substances into the cell.
  - Pinocytosis: Ingests small particles suspended in fluid.
  - Phagocytosis: Engulfs large particles, like pathogens and cell debris.
- Exocytosis: Transports molecules out of the cell by secretion.

The Nucleus

Enclosed by the nuclear envelope, which communicates with the cytoplasm through nuclear pores.
Contains:
- Cellular DNA.
- Nucleoli: sites of rRNA, mRNA, and tRNA synthesis.
- Nucleoproteins.
Chromatin: complex of DNA and protein responsible for packaging DNA.

Chromatin

DNA wraps around histone proteins, forming nucleosomes and the "beads on a string" structure (euchromatin).

Histology

The study of microscopic anatomy of biological tissues
Examined by looking at thin slices of tissue under a microscope
Uses a light microscope for larger areas and wide range of stains
Uses an electron microscope for smaller areas with subcellular resolution

Electron Micrograph

A micrograph prepared using an electron microscope
An electron microscope is a microscope that uses a beam of accelerated electrons to illuminate the specimen

Stains

Stains are used to identify specific structures in the cell or tissues
Haematoxylin stains nucleic acids purple/blue
Eosin stains elastic and reticular fibers red/pink
Toluidine blue stains nucleus and cytoplasm blue
Silver stains nerve and reticular fibers black/brown
Periodic acid-Schiff reacts with carbohydrates to stain them purple/blue
Alcian blue stains acidic epithelial mucins blue
Cyanin stains myelin purple

Haemotoxylin & Eosin Stain

The most commonly used staining system is called H&E
Eosin is an acidic dye that stains structures red or pink
Haematoxylin is a basic dye that stains structures blue or purple

Cell Membrane

Separates the cell contents (cytoplasm) from the extracellular fluid
Cytoplasm consists of cytosol and organelles
Functions are physical isolation, regulation of exchange with the environment, sensitivity to the environment and structural support

### Structure of the Cell Membrane

Formed by a lipid bilayer with specialised proteins and surface carbohydrates
Lipid molecules are amphipathic with a hydrophilic end (phosphate) and hydrophobic end (lipid)
Forms a bilayer in water

Membrane Lipids

Phosphoglycerides (phospholipids)
- Make up 50% of membrane lipid
- Surround and anchor proteins
- Include phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine
Cholesterol
- Stabilizes the membrane
Glycolipids
- Involved in intercellular communication
- Include sphingolipids and gangliosides

Membrane Proteins

Attach cytoskeletal filaments to the cell membrane
Attach cells to the extracellular matrix
Transport molecules into and out of cells
Act as receptors for chemical signalling
Possess specific enzymatic activity

Membrane Carbohydrates

Located on the extracellular surface as a coating called the glycocalyx
Functions include lubrication and protection, anchoring and locomotion, specificity in binding and recognition

Transport across cell membranes

Diffusion for gases, lipophilic or small molecules
Active transport for Na2+ ions
Bulk transport for endocytosis, pinocytosis, phagocytosis and exocytosis

Endocytosis

Cellular process in which substances are brought into the cell
The material to be internalized is surrounded by an area of cell membrane which buds off inside the cell to form a vesicle containing the ingested material

Pinocytosis

Also known as fluid endocytosis and bulk-phase pinocytosis
Small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in suspension of the particles within a small vesicle inside the cell
These pinocytotic vesicles subsequently fuse with endosomes to hydrolyze the particles

Phagocytosis

Process by which a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
It is one type of endocytosis
In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris

Exocytosis

Form of active transport and bulk transport by which a cell transports molecules out of the cell by secreting them through an energy-dependent process

The Nucleus

Bounded by nuclear envelope
Communicates with cytoplasm through nuclear pores
Contains cellular DNA, nucleoli (rRNA, mRNA, tRNA) and nucleoproteins

Chromatin

A complex of DNA and protein found in eukaryotic cells
Its primary function is packaging long DNA molecules into more compact, denser structures: DNA wraps around histone proteins, forming nucleosomes and the so-called "beads on a string" structure.

Histology

The study of microscopic anatomy of biological tissues
Examines thin slices of tissue under a microscope
Light microscopy provides a wide range of stains for larger areas, up to ~ 1000 X magnification
Electron microscopy offers high magnification (up to ~ 100,000 X) for small areas, providing subcellular resolution
Electron micrograph is a micrograph prepared using an Electron Microscope

Stains

Used to identify specific structures or molecules in the cell / tissue
Haematoxylin stains nucleic acids purple/blue
Eosin stains cytoplasm red/pink, elastic and reticular fibers
Toluidine blue is a general cell stain, staining nucleus and cytoplasm blue
Silver stains nerve and reticular fibers black/brown
Periodic acid-Schiff (PAS) stains carbohydrates purple/blue
Alcian blue stains acidic epithelial mucins and extracellular matrix of support cells blue
Cyanin stains myelin purple

H&E Staining

Haemotoxylin and Eosin (H&E) is the most commonly used staining system.
Eosin, an acidic dye, stains structures red or pink, highlighting cytoplasm
Haematoxylin, a basic dye, stains structures purplish blue, highlighting the nucleus

Definitions

Morphology is the study of the form and shape of structures.
Morphometry is the measurement of the shape of structures.
Stereology examines 2D images to gain information about 3D structures.

The Cell

The fundamental building blocks of all animals and plants.
All cells arise from the division of pre-existing cells.
Perform all vital physiological functions.
Maintain homeostasis at the cellular level.
Cytology is the study of cellular structure and function.

Types of Cells

Over 200 different cell types in the human body.
Each type is specialized for a specific function, often forming a particular tissue.
Tissues combine to form organs, where each cell type contributes to the organ's functionality.
- Sex cells/gametes fuse during sexual reproduction (e.g., sperm, oocytes).
- Somatic cells are all other cells in the body, including internal organs, skin, bones, blood and connective tissue.

Membrane Proteins

Peripheral membrane proteins attach to integral membrane proteins or the peripheral regions of the lipid bilayer.
These proteins can function as regulatory subunits of ion channels or transmembrane receptors.

Membrane Carbohydrates

Located mainly on the extracellular surface, forming a coating called the glycocalyx.
Functions include: lubrication and protection, anchoring and locomotion, specificity in binding, and recognition.

Transport Across Cell Membranes

Diffusion: For gases, lipophilic or small molecules.
Active transport: For molecules like Na²⁺ ions.
Bulk transport:
- Endocytosis: Substances taken into the cell.
  - Pinocytosis: Takes small particles suspended in extracellular fluid into the cell.
  - Phagocytosis: Engulfs large particles, forming a phagosome.
- Exocytosis: Molecules are transported out of the cell by secretion.

The Nucleus

Bounded by the nuclear envelope.
Communicates with the cytoplasm through nuclear pores.
Contains:
- Cellular DNA
- Nucleoli (rRNA, mRNA, tRNA)
- Nucleoproteins

Chromatin

Complex of DNA and protein found in eukaryotic cells.
Packages long DNA molecules into compact structures like nucleosomes (the "beads on a string" structure, also known as euchromatin).

Histology

Histology is the study of the microscopic anatomy of biological tissues
It is performed by examining thin slices (sections) of tissue under a microscope
Light microscopes are used for examining large areas and offer a wide range of stains with up to 1000x magnification
Electron microscopes are used for examining small areas and offer subcellular resolution with up to 100,000x magnification

Stains

Stains can be used to identify specific structures or molecules in the cell and tissue
Haematoxylin stains the nucleus purple/blue and specifically stains nucleic acids
Eosin stains the cytoplasm red/pink and specifically stains elastic and reticular fibers
Toluidine blue stains the nucleus and cytoplasm blue and is a general cell stain
Silver stains nerve and reticular fibers black/brown
Periodic acid-Schiff (PAS) stains carbohydrates purple/blue
Alcian blue stains acidic epithelial mucins and the extracellular matrix of support cells blue
Cyanin stains myelin purple

Haemotoxylin & Eosin Stain (H&E)

Most commonly used staining system
Eosin is an acidic dye that stains structures red or pink, so the cytoplasm is stained pink in the picture
Haematoxylin is considered a basic dye and is used to stain structures a purplish blue, so the nucleus is stained purple

Definitions

Morphology: study of the form and shape of structures
Morphometry: measurement of the shape of structures
Stereology: examination of 2D images to gain information about 3D structures

The Cell

Cells are the building blocks of all animals and plants
All cells come from the division of pre-existing cells
Cells are the smallest units that perform all vital physiological functions
Each cell maintains homeostasis at the cellular level
Cytology: the study of cellular structure and function

Types of Cells

There are over 200 different cell types in the human body
Each cell type is specialized to carry out a particular function
Cells form tissue which combine to form organs
Two major divisions of cells: Sex cells/gametes and somatic cells

Sex Cells/Gametes

Cells that fuse during sexual reproduction
Examples: sperm and oocytes

Somatic Cells

All other cells in the human body
Make up all the internal organs, skin, bones, blood and connective tissue
There are approximately 220 types of somatic cell in the human body

Membrane carbohydrates

Mainly found on the extracellular surface as a coating called the glycocalyx
Functions include lubrication and protection, anchoring and locomotion, specificity in binding, and recognition

Transport across cell membranes

Diffusion (gases, lipophilic or small molecules)
Active transport (Na2+ ions)
Bulk transport:
- endocytosis
- pinocytosis
- phagocytosis
- exocytosis

Endocytosis

A cellular process in which substances are brought into the cell
The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material

Pinocytosis

Also known as fluid endocytosis and bulk-phase pinocytosis
Involves small particles suspended in extracellular fluid being brought into the cell through an invagination of the cell membrane, resulting in a suspension of the particles within a small vesicle inside the cell
These pinocytotic vesicles subsequently fuse with endosomes to hydrolyze the particles.

Phagocytosis

Process where a cell uses its plasma membrane to engulf a large particle, giving rise to an internal compartment called the phagosome
It is one type of endocytosis
In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris

Exocytosis

A form of active transport and bulk transport in which a cell transports molecules out of the cell by secreting them through an energy-dependent process

The Nucleus

Bounded by a nuclear envelope
Communicates with cytoplasm through nuclear pores
Contains:
- cellular DNA
- nucleoli (rRNA, mRNA, tRNA)
- nucleoproteins

Chromatin

A complex of DNA and protein found in eukaryotic cells
Its primary function is packaging long DNA molecules into more compact, denser structures:
- DNA wraps around histone proteins, forming nucleosomes and the so-called "beads on a string" structure (euchromatin)

Lysosomes

Membrane-bound spherical organelle containing hydrolytic enzymes -break down many kinds of biomolecules engulfed by cell
Has a specific composition, of its membrane proteins, and luminal proteins
The lumen's pH (~4.5–5.0) is optimal for the enzymes involved in hydrolysis, analogous to the activity of the stomach
Involved in various cell processes-plasma membrane repair, cell signalling, and energy metabolism

Mitochondria

Membrane-bound organelle
- outer and inner membranes, separated by intermembranous space
Responsible for energy (ATP) production
Matrix contains many enzymes and small amounts of mitochondrial DNA

Cytoskeleton

In eukaryotes the cytoskeleton is composed of three main components-all capable of rapid growth or disassembly dependent on the cell's requirements:
- Microfilaments
- Intermediate filaments
- Microtubules

Microfilaments

Long, thin filaments of actin (5nm diameter)
Functions include cytokinesis, amoeboid movement, cell motility, and changes in cell shape

Intermediate filaments

Desmin, glial fibrillary acidic protein, keratin, lamin, neurofilaments, vimentin (10nm diameter)
Most stable component of the cytoskeleton-found in particularly durable structures such as hair, scales, fingernails.

Microtubules

 and  tubulin (25nm diameter)
Provide platforms for intracellular transport and are involved in a variety of cellular processes, including the movement of secretory vesicles, organelles

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Description

This quiz explores the essential concepts of histology and the structure and function of cell membranes. It covers the microscopic examination of tissues and the characteristics of the phospholipid bilayer. Test your understanding of membrane functions, types, and the technology used in histological studies.