Tissues & ECM Basics
What is the definition of tissue?
→ A collection of cells and their extracellular matrix (ECM). (Slide 3)
What is epithelium?
→ Thin tissue layers that cover/protect body surfaces and line structures. (Slide 10)
What two criteria are used to classify epithelial tissue?
→ By number of layers and cell shape. (Slides 13–14)
Where is simple squamous epithelium commonly found?
→ Alveoli, blood vessels, serous membranes. (Slide 15)
What makes pseudostratified columnar epithelium appear stratified?
→ Different cell heights. (Slide 19)
What is a gland?
→ Epithelial structure that secretes substances. (Slide 25)
What is a simple gland?
→ Single, unbranched duct. (Slide 27)
Name the two main components that make up the extracellular matrix (ECM).
→ Ground substance and protein fibers. (Slide 4)
List two general functions of epithelial tissue.
→ Protection, secretion, absorption, filtration, diffusion, sensory relay. (Slide 10)
What does “simple” mean in epithelial classification?
→ One layer of cells. (Slide 13)
What is the function of simple cuboidal epithelium?
→ Absorption/secretion in glands, ducts, kidney tubules, ovaries. (Slide 16)
Where is ciliated pseudostratified columnar epithelium typically located?
→ Respiratory tract (nasal cavity, pharynx, larynx, trachea, bronchi). (Slide 19)
How do endocrine glands release their products?
→ Directly into the bloodstream. (Slide 25)
What is a compound gland?
→ Branched ducts. (Slide 27)
What are the four major tissue types?
→ Epithelial, connective, muscle, nervous. (Slides 5–9)
What are the apical and basal surfaces of epithelial tissue?
→ Apical = external/top surface; Basal = attached to basement membrane. (Slide 12)
What does “stratified” mean in epithelial classification?
→ 2 or more layers of cells. (Slide 13)
Which epithelium lines most of the gastrointestinal tract?
→ Nonciliated simple columnar. (Slide 17)
What is the main function of stratified squamous epithelium?
→ Protection from abrasion. (Slide 21)
Why are epithelial tissues well-suited for forming glands?
→ Continuous layers ideal for secretion. (Slide 25 + Supplemental)
What is merocrine secretion?
→ Secretion via vesicles; cell intact. (Slide 28)
Which protein fiber in the ECM provides tensile strength?
→ Collagen fibers. (Slide 4)
Why is epithelial tissue avascular but highly innervated?
→ Avascular to reduce bulk; highly innervated for sensory functions. (Slide 12)
Which cell shape is best for diffusion, and why?
→ Squamous; thinness allows easy diffusion. (Slide 15)
How do goblet cells aid nonciliated columnar epithelia?
→ Secrete mucus for protection/lubrication. (Slide 17)
Why doesn’t nonciliated pseudostratified columnar epithelium contain goblet cells?
→ No mucus production/movement needed. (Slide 20)
Where is transitional epithelium found in the body?
→ Bladder, ureters, part of urethra. (Slide 24)
How do exocrine glands release their products?
→ Onto epithelial surface via ducts. (Slide 26)
Compare connective tissue and epithelial tissue in terms of cells and ECM.
→ Connective = few cells, abundant ECM; Epithelial = many cells, little ECM. (Slides 5–7)
How does epithelial tissue regenerate quickly compared to other tissues?
→ High turnover and stem cell activity at basement membrane. (Slide 12 + Supplemental)
How does the presence of cilia or microvilli modify epithelial function?
→ Cilia move substances; microvilli increase absorption surface. (Slides 17–18)
Why is ciliated simple columnar epithelium important in the uterine tubes?
→ Cilia move oocytes/embryos along. (Slide 18)
How do stratified cuboidal and stratified columnar epithelia differ in location?
→ Cuboidal = ducts/ovaries; Columnar = salivary glands, conjunctiva, urethra. (Slides 22–23)
Compare endocrine and exocrine glands in structure and function.
→ Endocrine = ductless, hormones → blood; Exocrine = ducts, secretions → surface. (Slides 25–26)
How does apocrine secretion differ from merocrine secretion?
→ Apocrine pinches off apical portion, unlike merocrine. (Slide 29)
Why does the ECM composition differ between tissues?
→ Different tissues need unique strength, flexibility, or support functions. (Slide 3 + Supplemental)
Provide two examples of locations where epithelium is found in the human body.
→ Skin, inside mouth, gut, lungs, blood vessels. (Slide 11)
Compare cuboidal vs. columnar epithelial cells in terms of shape and function.
→ Cuboidal = cube-like, absorption/secretion; Columnar = tall, absorption/secretion + mucus. (Slides 16–18)
Compare ciliated vs. nonciliated simple columnar epithelium in terms of structure and function.
→ Ciliated = secretion + movement; Nonciliated = absorption + mucus. (Slides 17–18)
Explain why stratified squamous is well-suited for the skin.
→ Many layers resist abrasion. (Slide 21)
Predict the consequences of replacing transitional epithelium with stratified cuboidal in the bladder.
→ Bladder couldn’t expand properly, causing damage. Transitional prevents rupture while storing urine. (Slide 24)
Explain the holocrine mode of secretion and give an example.
→ Cell disintegrates, releasing contents; Sebaceous glands. (Slide 30)
Predict what would happen to tissue structure if elastic fibers were absent from the ECM.
→ Tissues would lack resilience and not return to shape. (Slide 4)
Explain why the basement membrane is critical for epithelial tissue survival.
→ Anchors epithelium and supplies nutrients from connective tissue. (Slide 12)
Predict what might occur if the urinary bladder were lined by simple squamous epithelium instead of transitional.
→ Bladder would tear and leak since squamous cannot stretch. (Slide 24)
Predict the outcome if alveoli were lined with cuboidal epithelium instead of squamous.
→ Gas exchange impaired, diffusion slowed. (Slide 15)
Predict how replacing stratified squamous epithelium with simple squamous in the esophagus would affect function.
→ Esophagus would be vulnerable to damage, ulceration, tearing. (Slide 21)
Predict the effect on homeostasis if endocrine glands secreted hormones onto epithelial surfaces instead of the bloodstream.
→ Hormones wouldn’t reach circulation; systemic effects would fail. (Supplemental)
Predict what would happen to sebaceous gland function if epithelial replacement did not occur after holocrine secretion.
→ Sebaceous glands would stop functioning. (Slide 30)
Explain how the balance of collagen, elastic, and reticular fibers determines a tissue’s function.
→ Collagen = strength, Elastic = flexibility, Reticular = supportive nets. (Slide 4)
Evaluate how epithelial tissue structure supports both absorption and protection simultaneously.
→ Tight packing + polarity allows protection; thin layers + microvilli/cilia allow absorption/filtration. (Slides 10, 12)
Design a classification chart for an unknown epithelial sample that has two layers of tall, narrow cells.
→ Stratified columnar. (Slide 23)
Analyze how epithelial type determines efficiency of absorption, secretion, or diffusion in different organs.
→ Squamous = diffusion, Cuboidal = secretion/absorption, Columnar = absorption/movement. (Slides 15–18)
Analyze how layering contributes to the function of stratified epithelia compared to pseudostratified.
→ Stratified = multiple layers for abrasion; Pseudostratified = single layer but protective with mucus/cilia. (Slides 19–23)
Evaluate how disruption of both endocrine and exocrine gland functions could impact multiple organ systems.
→ Endocrine failure = hormonal imbalance; Exocrine failure = digestion/lubrication issues. (Slides 25–26 + Supplemental)
Compare merocrine, apocrine, and holocrine glands in secretion method, cell survival, and energy cost.
→ Merocrine = vesicles, Apocrine = pinched apical, Holocrine = whole-cell destruction. (Slides 28–30)