Epithelia Flashcards
What is the shape of Squamous Epithelial Cells
Flat and thin
What is the function of Squamous Epithelial Cells
Squamous epithelial cells are involved in diffusion, filtration, and secretion. They line the air sacs of the lungs, blood vessels, and form the outermost layer of the skin (epidermis).
What is the shape of Cuboidal Epithelial Cells
Cube-shaped with a central nucleus.
What is the function of Cuboidal Epithelial Cells
Cuboidal epithelial cells are involved in secretion and absorption. They are found in kidney tubules, various glands (e.g., thyroid gland), and the lining of the small ducts in the pancreas.
what is the function of Columnar Epithelial Cells
Columnar epithelial cells are involved in absorption and secretion. They line the digestive tract (from stomach to intestines), respiratory tract (e.g., bronchi), and parts of the reproductive system
What is the function and importance of tight junctions
Function: Create a watertight seal between adjacent cells.
Importance: Prevent the leakage of substances between cells, ensuring selective transport across epithelial tissues.
What is the function and importance of Adherens Junctions
Function: Provide mechanical strength and stability to tissues.
Importance: Help cells resist separation during mechanical stress, maintaining tissue integrity.
What is the function and importance of Desmosomes
Function: Anchor cells together and distribute mechanical stress.
Importance: Enable tissues to withstand stretching and contraction, particularly in tissues subjected to mechanical forces (e.g., skin, heart muscles).
What is the function and importance of Gap Junctions
Function: Allow direct cell-to-cell communication.
Importance: Enable the rapid exchange of ions, small molecules, and electrical signals between adjacent cells, facilitating coordinated cellular activities.
What is the function and importance of Hemidesmosomes
Function: Attach epithelial cells to the underlying basement membrane.
Importance: Provide structural support, preventing the detachment of epithelial cells from the underlying connective tissue.
What is the function and importance of Basement Membrane
Function: Support and separate epithelial tissues from underlying connective tissues.
Importance: Acts as a selective filter, regulates the exchange of molecules, and provides structural support for epithelial cells.
What is Simple Diffusion
Passive movement of ions across a membrane down their concentration gradient.
No energy input required.
Small, non-polar ions can diffuse directly through the lipid bilayer.
What is Facilitated Diffusion
Passive movement of ions across a membrane through specific transport proteins.
No energy input required.
Larger or charged ions rely on transporters or channels to cross the membrane.
What is Active Transport
Movement of ions across a membrane against their concentration gradient.
Energy input, usually in the form of ATP, is required.
Ion pumps or carriers actively transport ions across the membrane.
what is Endocytosis
Process by which cells engulf substances from the extracellular environment.
Involves the formation of a vesicle around the material to be transported.
Allows for the uptake of large particles or bulk amounts of ions.
what is Exocytosis
Process by which cells release substances into the extracellular environment.
Involves the fusion of vesicles with the plasma membrane.
Allows for the secretion of large molecules or bulk amounts of ions.
what are ion channels
Protein-based pores in the cell membrane.
Allow selective passage of specific ions.
Can be gated (open or closed) based on various stimuli, such as voltage or ligand binding.
What is the Electrochemical Gradient
Combined effect of the concentration gradient and membrane potential on ion movement across a membrane.
Determines the direction and magnitude of ion flux
What is the Membrane Potential
Difference in electrical potential across a cell membrane.
Generated by the unequal distribution of ions across the membrane.
Plays a crucial role in various cellular processes, including ion transport.
What is the Concentration Gradient
Difference in ion concentration between the inside and outside of a cell.
Forms the chemical component of the electrochemical gradient.
Drives passive ion movement down the gradient from an area of higher concentration to an area of lower concentration
What is the Voltage Gradient
Difference in electrical charge across a cell membrane.
Forms the electrical component of the electrochemical gradient.
Results from the separation of positive and negative charges across the membrane, often maintained by ion pumps or channels.
Explain how the Sodium/Potassium ATPase works and its action in ion transport mechanisms
The Sodium/Potassium ATPase is a protein that uses ATP energy to transport sodium (Na+) and potassium (K+) ions across the cell membrane. It actively pumps three sodium ions out of the cell for every two potassium ions it brings into the cell. This process helps maintain the concentration gradients of these ions, which is essential for nerve impulse transmission, muscle contraction, and other cellular functions.
What is the structure and cell types of Nasal Epithelium
Structure: Pseudostratified columnar epithelium.
Cell Types:
Goblet cells: Secrete mucus to trap particles and pathogens.
Ciliated cells: Beat their cilia to move mucus and trapped particles towards the throat for removal.
Basal cells: Stem cells for epithelial cell regeneration.
What is the structure and cell types of Tracheal Epithelium
Structure: Pseudostratified columnar epithelium.
Cell Types:
Goblet cells: Secrete mucus to trap debris and pathogens.
Ciliated cells: Move mucus towards the throat for clearance.
Basal cells: Responsible for epithelial cell renewal.
What is the structure and cell types of Alveolar Epithelium
Structure: Simple squamous epithelium.
Cell Types:
Type I alveolar cells: Thin, flat cells that make up the majority of the alveolar surface for efficient gas exchange.
Type II alveolar cells: Secrete pulmonary surfactant, a substance that reduces surface tension and prevents alveolar collapse.
Alveolar macrophages: Phagocytic cells that engulf and remove debris and pathogens.
What is the function of cilia
Function: Beat in coordinated movements to move mucus and trapped particles out of the respiratory tract.
Helps in the clearance of debris, pathogens, and mucus from the airways.
what is the function of goblet cells
Function: Secrete mucus, a sticky substance that traps particles and pathogens in the respiratory tract.
Aids in the filtration and removal of foreign substances from the airways
What is the function of microvilli
Function: Increase the surface area of respiratory epithelial cells for enhanced absorption and secretion.
Facilitates efficient gas exchange and absorption of nutrients.
What are the functions of Type 1 alveolar cells
Function: Form a thin, flat barrier for efficient diffusion of gases (oxygen and carbon dioxide) between the lungs and bloodstream.
Maximizes the surface area available for gas exchange and minimizes the diffusion distance.
What are the functions of Type 2 alveolar cells
Function: Secrete pulmonary surfactant, a substance that reduces surface tension in the alveoli and prevents their collapse.
Maintains alveolar stability and prevents alveolar collapse during
what is the functions of Alveolar Macrophages
Function: Engulf and remove debris, pathogens, and foreign particles present in the alveoli.
Helps maintain lung health by defending against infections and removing harmful substances.
What is Asthma
Disorder characterized by inflammation and narrowing of the airways.
Epithelial cells in the airways may undergo hyperreactivity, leading to increased mucus production and bronchoconstriction.
Symptoms include wheezing, shortness of breath, coughing, and chest tightness.
What is COPD
Group of progressive lung diseases, such as chronic bronchitis and emphysema.
Epithelial cells in the airways may be damaged due to chronic exposure to irritants like tobacco smoke or pollutants.
Results in persistent airflow limitation, difficulty breathing, coughing, and excess mucus production.
What is Cystic Fibrosis
Genetic disorder that affects the function of epithelial cells, particularly in the respiratory and digestive systems.
Defective chloride ion channels lead to thickened mucus production, which clogs the airways and makes breathing difficult.
Results in recurrent lung infections, persistent coughing, wheezing, and progressive lung damage.
What is Pneumonia
Infection of the lungs caused by bacteria, viruses, or fungi.
Epithelial cells lining the alveoli may become inflamed and damaged.
Results in symptoms such as fever, cough with phlegm, chest pain, and difficulty breathing.
What is intestinal Epithelial Regeneration
Intestinal epithelial regeneration is the restoration of intestinal epithelial cells after damage.
What is differentiation
Differentiation is the process of immature cells maturing into specialized cell types.
Describe functional differentiation of intestinal epithelial cells
Functional differentiation of intestinal epithelial cells refers to the process by which immature or undifferentiated cells in the intestinal epithelium acquire distinct characteristics and functions to perform specialized roles in the digestive process and maintenance of intestinal homeostasis.
What are enterocytes responsible for
nutrient absorption
What do goblet cells secrete and why
mucus to protect the intestinal lining.
What do enteroendocrine cells produce and why
hormones and peptides that regulate digestion
What do Paneth cells secrete and why
antimicrobial peptides for gut barrier integrity
What are tuft cells
Tuft cells are chemosensory cells involved in immune responses
What is absorptive transport
Nutrient Absorption: Absorptive cells (enterocytes), Transport Mechanisms, Sodium-Glucose Cotransport: Sodium-glucose cotransporters (SGLTs), Amino Acid Transport: Amino acids are transported into enterocytes through SNAT or PAT
What is secretory transport
Electrolyte Secretion, Chloride Secretion,
What is Paracellular transport
Paracellular Pathway and Tight Junction Regulation
Examples of intestinal epithelial disorders
Inflammatory Bowel Disease, Crohn’s Disease, Celiac Disease and Intestinal Epithelial Dysplasia
Explain reabsorption in the Proximal convoluted tubule
Reabsorption: PCT epithelial cells have numerous microvilli on their apical surface, increasing the surface area for reabsorption. They reabsorb the majority of filtered nutrients, such as glucose, amino acids, and ions like sodium (Na+), potassium (K+), and chloride (Cl-).
Explain secretion in the Proximal convoluted tubule
PCT cells also secrete waste products, toxins, and drugs into the tubular fluid, helping to eliminate them from the body.
what is the difference between the descending and ascending limp of the loop of Henle
Descending Limb: Permeable to water, allowing water reabsorption.
Ascending Limb: Permeable to ions, facilitating passive diffusion.
What is the function of the thick ascending limb
Active transport of ions (sodium, potassium, chloride) out of the tubular fluid.
Impermeable to water.
What is the functions of the distal convoluted tubule
Regulation of ion reabsorption and secretion.
Hormonal control (aldosterone, PTH) influences ion transport.
What is the function of the collecting duct
Water reabsorption, regulated by antidiuretic hormone (ADH).
Acid-base balance through bicarbonate reabsorption or hydrogen ion secretion.
What is passive diffusion
Movement of substances from an area of higher concentration to an area of lower concentration without the use of energy.
Example: Passive diffusion is involved in the resorption of lipid-soluble substances, such as oxygen and carbon dioxide, across the renal tubules
What is facilitated diffusion
Movement of substances across the cell membrane with the help of specific carrier proteins, without the expenditure of energy.
Example: Glucose reabsorption in the proximal convoluted tubule involves facilitated diffusion through glucose transporters (GLUTs).
What is active transport
Movement of substances against their concentration gradient with the expenditure of energy, typically provided by ATP.
Example: Sodium reabsorption in various segments of the nephron, particularly the proximal tubule, involves active transport via sodium-potassium pumps.
What is Sodium-Glucose Cotransport
Simultaneous transport of sodium ions and glucose molecules across the cell membrane.
Example: The proximal convoluted tubule uses sodium-glucose cotransporters (SGLTs) to resorb glucose against its concentration gradient, utilizing the sodium gradient established by active transport.
What is endocytosis
Process by which cells engulf substances from the extracellular fluid into intracellular vesicles.
What is Polycystic Kidney Disease (PKD)
PKD is a genetic disorder characterized by the formation of fluid-filled cysts in the kidneys, leading to kidney enlargement and progressive loss of renal function, mostly caused by Autosomal Dominant PKD, rarely caused by Recessive PKD
What is Renal Cell Carcinoma
Renal cell carcinoma is the most common type of kidney cancer, originating from the epithelial cells of the renal tubules
