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Questions and Answers
What is the primary focus of histology?
What is the primary focus of histology?
What is the correct order of organization from cells to body systems?
What is the correct order of organization from cells to body systems?
What do groups of cells form?
What do groups of cells form?
Which of the following is NOT a level of biological organization mentioned in histology?
Which of the following is NOT a level of biological organization mentioned in histology?
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Which of the following pairs are considered body systems?
Which of the following pairs are considered body systems?
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What is the thickness of the outer electron-dense lamina in a trilaminar structure?
What is the thickness of the outer electron-dense lamina in a trilaminar structure?
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Which layer of the trilaminar structure is electron-lucent?
Which layer of the trilaminar structure is electron-lucent?
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What is the combined thickness of the outer and inner electron-dense laminae in the trilaminar structure?
What is the combined thickness of the outer and inner electron-dense laminae in the trilaminar structure?
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Which of the following correctly lists the layers of the trilaminar structure from outermost to innermost?
Which of the following correctly lists the layers of the trilaminar structure from outermost to innermost?
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How many layers are present in the trilaminar structure observed at the electron microscope level?
How many layers are present in the trilaminar structure observed at the electron microscope level?
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What does it mean when a protein is described as a peripheral or extrinsic protein?
What does it mean when a protein is described as a peripheral or extrinsic protein?
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Which of the following statements is true about peripheral proteins?
Which of the following statements is true about peripheral proteins?
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How do peripheral proteins primarily interact with the membrane?
How do peripheral proteins primarily interact with the membrane?
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What is a characteristic of extrinsic proteins in relation to the phospholipid layer?
What is a characteristic of extrinsic proteins in relation to the phospholipid layer?
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In what way do peripheral proteins differ from integral proteins?
In what way do peripheral proteins differ from integral proteins?
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Which function of the cell membrane involves protecting the cell from external dangers?
Which function of the cell membrane involves protecting the cell from external dangers?
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What is the primary role of the cell membrane regarding substances?
What is the primary role of the cell membrane regarding substances?
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Which modification of the cell membrane is primarily responsible for cell-cell attachment?
Which modification of the cell membrane is primarily responsible for cell-cell attachment?
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In what way does the cell membrane aid in cellular recognition?
In what way does the cell membrane aid in cellular recognition?
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Which of the following is NOT a function of the cell membrane?
Which of the following is NOT a function of the cell membrane?
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What surrounds the engulfed material during phagocytosis?
What surrounds the engulfed material during phagocytosis?
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What is the name of the vesicle formed after the plasma membrane fuses around engulfed particles?
What is the name of the vesicle formed after the plasma membrane fuses around engulfed particles?
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What happens to the phagosome after it is formed?
What happens to the phagosome after it is formed?
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What is the role of pseudopodia in the process of phagocytosis?
What is the role of pseudopodia in the process of phagocytosis?
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Which statement best describes the initial step of phagocytosis?
Which statement best describes the initial step of phagocytosis?
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How does the Golgi apparatus appear when stained with silver salts or osmium in light microscopy?
How does the Golgi apparatus appear when stained with silver salts or osmium in light microscopy?
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In the context of electron microscopy, which component is NOT part of the Golgi apparatus structure?
In the context of electron microscopy, which component is NOT part of the Golgi apparatus structure?
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What term describes the lighter-stained region corresponding to the Golgi apparatus in H&E sections?
What term describes the lighter-stained region corresponding to the Golgi apparatus in H&E sections?
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How many distinct smooth membrane-limited compartments compose the Golgi apparatus?
How many distinct smooth membrane-limited compartments compose the Golgi apparatus?
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What is characteristic of the cis face of the Golgi apparatus?
What is characteristic of the cis face of the Golgi apparatus?
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Study Notes
Histology and Cytology
- Cytology is the study of cells, including their structure, function, and division.
- Histology is the study of tissues and organs, including their structure and function.
- Cells form tissues, tissues form organs, and organs form systems, which make up the body.
Tools of Studying Histology
- Microscopes are used to study cells and tissues at different levels of magnification.
The Cell
- Cells are the smallest structural and functional units of living organisms.
- Cells are made of protoplasm, which is divided into cytoplasm and nucleus.
- Cytoplasm includes cytoplasmic organelles, cytoplasmic inclusions, and the cytoplasmic matrix.
Cytoplasmic Organelles
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Membranous Organelles
- Cell membrane (plasma membrane, plasmalemma): The outer membrane of a cell, acting as a barrier between the internal and external environments. It is too thin to be seen with light microscopes (8-10 nm), but can be stained. At the electron microscope level, it has a trilaminar structure (3 layers).
- Mitochondria: Involved in cell respiration and energy production. Contain ATP synthase and cristae. The matrix has enzymes, ribosomes, DNA, and RNA. The number varies depending on cell type (e.g., absent in red blood cells, hundreds in muscle and liver cells).
- Rough Endoplasmic Reticulum (RER): Associated with ribosomes, involved in protein synthesis (secretory proteins, lysosomal proteins, and membrane proteins) and glycosylation (adding carbohydrates to proteins to form glycoproteins). Appears basophilic in light microscopes; tubules, vesicles and flattened cisternae under electron microscope.
- Smooth Endoplasmic Reticulum (SER): Devoid of ribosomes. Involved in steroid hormone synthesis, drug detoxification (liver cells), lipid synthesis (intestinal cells), calcium ion release/storage (muscle cells), and HCl production (stomach cells). Appears acidophilic in light microscopes, with tubules and vesicles under electron microscope.
- Golgi apparatus (Golgi complex): Involved in packaging, concentrating, and modifying secretory products, as well as producing primary lysosomes. Composed of flattened cisternae, Golgi vesicles, and a forming and maturing face.
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Non-membranous Organelles
- Ribosomes: Involved in protein synthesis.
- Centrioles: Involved in cell division.
- Cilia and Flagella: Involved in motility.
- Microfilaments and Microtubules: Contribute to cell structure and function.
Cell Membrane Molecular Structure
- Fluid Mosaic Model: Describes the arrangement of components in the cell membrane.
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Lipids (30%):
- Phospholipids form a bilayer. Polar heads face outwards; nonpolar tails face inwards.
- Glycolipids and Cholesterol are also present.
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Proteins (60%):
- Extrinsic (peripheral) proteins are only partially embedded.
- Intrinsic (integral) proteins are firmly attached to the lipid bilayer – some are transmembrane proteins (include cell receptors).
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Carbohydrates (10%):
- Glycocalyx: Carbohydrates are attached to proteins (glycoproteins) and lipids (glycolipids) on the cell surface.
- Functions: Cell recognition, adhesion, protection from chemical and mechanical damage, and hormone binding.
Cell Membrane Modifications
- Cell junctions (for cell-cell attachment).
- Microvilli and cilia (for motility or surface area increase).
Cell Transportation (Endocytosis and Exocytosis)
- Endocytosis: Engulfing of solid particles (phagocytosis) or fluid droplets (pinocytosis) by forming vesicles.
- Exocytosis: Release of substances from vesicles to the outside of the cell.
Mitochondria
- Involved in cell respiration and energy production.
Endoplasmic Reticulum (ER)
- An irregular network of branching and anastomosing tubules, cisternae, and vesicles within the cytoplasm.
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Rough ER: Associated with ribosomes; protein synthesis and glycosylation.
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Smooth ER: Involved in steroid hormone synthesis, drug detoxification, and lipid synthesis.
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Golgi Apparatus (Golgi Complex)
- A membranous organelle involved in packaging, concentration, and modification of secretory products, and production of primary lysosomes.
Lysosomes
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Membrane-bounded vesicles containing hydrolytic enzymes that break down macromolecules.
- Primary lysosomes: Newly formed, containing hydrolytic enzymes.
- Secondary lysosomes: Formed by fusion with other vesicles; breakdown of material within.
- Residual bodies: Terminal stage of lysosomal activity; may contain indigestible material.
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These structures are involved in breaking down materials.
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Description
This quiz covers the fundamental concepts of histology and cytology, including the structure and function of cells, tissues, and organs. It also explores the tools used in histological studies, such as microscopes, and delves into the components of cells and organelles.
