2.1 Epithelial tissue

• What attaches cells to connective tissue?

  A non-cellular basement membrane
• What is the composition of the basement membrane?

  A mixture of carbohydrates and proteins
• What is the primary function of the basement membrane?

  It anchors the epithelium to adjacent tissue
• Is epithelial tissue vascular or non-vascular?

  Non-vascular
• How does epithelial tissue obtain nutrients?

  By transport from underlying connective tissue
• What are the functions of epithelial tissue?

  • Protection from environmental conditions
  • Transport of substances (e.g., renal tubules)
  • Absorption (e.g., intestine)
  • Secretion (e.g., glands)
  • Stimulus reception (e.g., olfactory epithelium)

  
• What role does keratin play in epithelial protection?

  It strengthens epithelial cells against mechanical stress
• How does melanin protect epithelial cells?

  It protects against UV-induced photodamage
• What is the function of mucus in the stomach?

  It protects the stomach wall from acid
• How does mucus in airway epithelium protect against pathogens?

  It forms a barrier preventing microorganisms' entry
• What types of transport do epithelial cells use?

  • Active transport
  • Passive transport

  
• What is the role of enterocytes in absorption?

  They absorb nutrients like glucose from the lumen
• What percentage of glucose is reabsorbed in the proximal convoluted tubules?

  100%
• How does fluid secretion occur in the small intestine?

  Solutes draw water into the lumen by osmosis
• What type of epithelium is involved in sensing smell?

  Pseudostratified columnar epithelium
• What are the main cell types in the olfactory epithelium?

  Basal cells, supporting cells, olfactory cells

  
• What are the characteristics of simple epithelium?

  • One layer of cells
  • Functions in diffusion, absorption, or secretion
  • Not found in areas with mechanical stress
• What is the function of simple squamous epithelium?

  Passive transport (diffusion)
• What is the structure of simple cuboidal epithelium?

  Single layer of cuboidal cells
• Where is simple cuboidal epithelium located?

  In collecting tubules and thyroid follicles
• What are the characteristics of simple columnar epithelium?

  Single layer of tall, thin cells
• What are the functions of cilia and microvilli in columnar epithelium?

  They aid in absorption and secretion

  
• Why is pseudostratified epithelium named so?

  It appears multilayered but is actually simple
• Where is pseudostratified epithelium located?

  In respiratory epithelia and epididymis
• What is the function of stratified epithelium?

  • Provides protection against physical stress
  • Related to the degree of physical stress exposure
• What is the role of non-keratinized stratified squamous epithelium?

  Protects against abrasion and reduces water loss

  
• Where is non-keratinized stratified squamous epithelium found?

  In the vagina, esophagus, and mouth

  
• What characterizes keratinized stratified squamous epithelium?

  Upper layers are dead and filled with keratin

  
• What is the structure of the epidermis?

  Stratum basale, spinosum, granulosum, corneum

  
• Where is cuboidal stratified epithelium found?

  In exocrine glands like salivary glands
• What is the function of transitional epithelium?

  Allows distensibility in the urinary tract
• Where is transitional epithelium located?

  In the renal calyces, ureters, and bladder
• What are the four basic types of tissue in the body?

  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue

  
• What are the general characteristics of epithelial tissues?

  • Widespread throughout the body
  • Cover body surfaces and line cavities
  • Avascular and aneural
  • Perform various functions (protection, secretion, absorption, etc.)

  
• What are the embryonic origins of epithelial tissues?

  • Ectoderm: epidermis, nervous system
  • Endoderm: lining of digestive and respiratory tracts
  • Mesoderm: urinary epithelium, circulatory system