LC 4

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Questions and Answers

Which germ layer is responsible for giving rise to the epidermis of the skin?

Ectoderm (correct)

Endoderm

Mesoderm

All of the above

What is NOT an exocrine gland function?

Discharge of saliva

Secretion of hormones (correct)

Production of perspiration

Release of enzymes

Which type of epithelial tissue is most likely to be involved in absorption?

Simple columnar epithelium (correct)

Simple cuboidal epithelium

Stratified squamous epithelium

Pseudostratified epithelium

Which characteristic feature of epithelial cells is primarily involved in cell-to-cell adhesion?

Desmosome Signup and view all the answers

Which epithelial layer is responsible for filtering waste from blood plasma?

Simple squamous epithelium Signup and view all the answers

Which type of epithelial tissue is NOT considered to be specialized for secretion?

Stratified squamous epithelium Signup and view all the answers

Which structure is critical for communication between epithelial cells?

Gap junctions Signup and view all the answers

What is the primary function of the basal lamina in epithelial tissue?

Support and filtration Signup and view all the answers

What defines the apical surface of epithelial cells?

It borders an open space known as lumen. Signup and view all the answers

Which characteristic of epithelial tissues contributes to their rapid regeneration?

Nourishment provided from adjacent connective tissues. Signup and view all the answers

Which of the following is NOT a function of the basal lamina in epithelial tissues?

Generating new epithelial cells. Signup and view all the answers

What is the significance of the highly specialized junctions between lateral surfaces of epithelial cells?

They help in adhering cells together, achieving barrier function. Signup and view all the answers

What shape do cuboidal epithelial cells resemble?

Cube-like. Signup and view all the answers

Which statement about the vascularity of epithelial tissues is correct?

Epithelial tissues lack blood vessels and are avascular. Signup and view all the answers

Which of the following accurately describes a function of epithelial tissue?

It serves as a boundary controlling substance movement. Signup and view all the answers

What is the role of connective tissue in relation to epithelial tissue?

Nourishing the epithelial cells and supporting them. Signup and view all the answers

What is the primary function of simple columnar epithelium?

Absorption and filtration Signup and view all the answers

Which characteristic helps simple columnar epithelium increase its absorption efficiency?

Microvilli on the apical surface Signup and view all the answers

Where is simple squamous epithelium primarily located?

Walls of capillaries and air sacs in lungs Signup and view all the answers

What is the function of goblet cells found in epithelial tissue?

Protection through secretion of mucus Signup and view all the answers

Which term describes membranes that are open to body cavities, producing mucus?

Mucous membranes Signup and view all the answers

What structural feature is common in simple columnar epithelium that supports its function?

Apical microvilli Signup and view all the answers

What is the main limitation of simple epithelium regarding its protective capability?

Single layer of cells Signup and view all the answers

Which type of epithelial cells are typically elongated with nuclei at the same level?

Columnar cells Signup and view all the answers

Which junction types are classified as impermeable?

Zonulae occludentes Signup and view all the answers

What distinguishes stereocilia from microvilli?

Stereocilia are longer and non-motile. Signup and view all the answers

What is the main function of gap junctions?

Facilitate communication between adjacent cells. Signup and view all the answers

How are microplicae characterized in epithelial tissues?

Folds that are 1 µm high and 0.8 µm wide. Signup and view all the answers

Which statement about flagella is accurate?

They have an undulating movement. Signup and view all the answers

What is the primary structure of desmosomes?

Offer mechanical support by linking adjacent cells. Signup and view all the answers

What unique feature does cilia possess compared to other cell projections?

They have a wave-like motion. Signup and view all the answers

Which of the following epithelial surface specializations is primarily associated with absorption?

Microvilli Signup and view all the answers

What distinguishes the effective stroke from the recovery stroke in kinocilia?

The effective stroke is rapid and stiffens forward, while the recovery stroke is slower. Signup and view all the answers

Which of the following best describes the structure of the axoneme in kinocilia?

It contains two single microtubules in the center with nine doublet microtubules uniformly spaced. Signup and view all the answers

What type of stroke occurs when kinocilia beat in a coordinated fashion across multiple rows?

Metachronal stroke Signup and view all the answers

What is the primary function of kinocilia?

To transport mucus or fluid over a surface. Signup and view all the answers

How are the protofilaments arranged in the central microtubules of kinocilia?

Central microtubules feature 13 protofilaments, similar to cytoplasm. Signup and view all the answers

What structural feature do vestibular hair cells possess?

A single motile hair and multiple non-motile hairs. Signup and view all the answers

Which description accurately reflects the relationship between the mitochondria and spermatozoa?

Mitochondria in the midpiece are crucial for generating energy for motility. Signup and view all the answers

Which component of kinocilia is responsible for the beating motion?

The core complex (axoneme) that includes microtubules. Signup and view all the answers

Study Notes

Primary Germ Layers and Their Derivatives

Ectoderm develops into corneal epithelium and skin epidermis, also forms glandular skin appendages like sudoriferous, sebaceous, and mammary glands.
Endoderm gives rise to intestinal glands, liver, pancreas, and produces endocrine and exocrine glands.
Mesoderm generates kidneys, reproductive organs, and linings of blood and lymph vessels, as well as peritoneal and serous cavities.

Overview of Epithelial Tissue

Consists of continuous cells covering surfaces and lining cavities.
Avascular; relies on underlying connective tissues for nourishment.
Regenerative, repairs quickly due to cellular turnover.
Basal lamina forms a boundary controlling substance movement between environments.

Classification of Epithelial Tissue

Based on cell shape:
- Squamous (flattened)
- Cuboidal (cube-shaped)
- Columnar (tall, column-like)
Layers can be simple (single layer) or stratified (multiple layers).

Functions of Epithelial Tissue

Protection: Skin as a barrier against UV light, pathogens, and physical damage.
Absorption: Intestinal lining absorbs nutrients into the bloodstream.
Filtration: Kidney tubules filter waste from blood plasma.
Secretion: Glands produce substances such as sweat, oils, enzymes, and mucus.

Special Features of Epithelial Cells

Apical surfaces have specialized structures:
- Microvilli increase absorbent surface area.
- Stereocilia are long projections for increased surface area and sensory functions.
- Kinocilia facilitate fluid movement across epithelial surfaces.
- Flagella are long, whip-like structures primarily in sperm for locomotion.

Junctions in Epithelial Tissue

Zonula occludens (tight junctions) create impermeable barriers.
Zonula adherens (adhesion junctions) provide structural integrity.
Gap junctions facilitate intercellular communication through small pores.

Examples of Epithelial Tissue Types

Simple Squamous Epithelium: Thin and permeable, found in capillaries and alveoli, ideal for diffusion and filtration.
Simple Cuboidal Epithelium: Often involved in secretion and absorption, seen in ducts of glands and kidney tubules.
Simple Columnar Epithelium: Absorption and secretion functions, contains goblet cells for mucus production, found in digestive tract linings.
Pseudostratified Epithelium: Appears layered due to cell height variations; often ciliated, found in respiratory tract.
Stratified Squamous Epithelium: Provides protection, can be keratinized (dry areas like skin) or non-keratinized (moist areas like the esophagus).
Transitional Epithelium: Specialized for stretching, capable of changing shape, lining the urinary bladder.

Key Specializations of Apical Surfaces

Microvilli: Increase epithelial surface area; seen in intestinal and renal epithelia.
Stereocilia: Non-motile, found in the epididymis and inner ear hair cells.
Kinocilia: Motile, involved in moving mucus or fluid.
Flagella: Rare, primarily in sperm cells for propulsion.

Miscellaneous

Adhering junctions enhance cell-cell adhesion, crucial for maintaining tissue integrity.
Mitochondria in sperm provide energy necessary for motility during fertilization processes.

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