2) Overview of Cells and Specializations of Epithelium Flashcards
Cell membrane aka plasma membrane
Regulates what enters and exits the cell
Nucleus Vs Nucleolus
Specialized organelle that controls the cell
Ribosomal production and initial assembly of ribosomes
Cytoplasm
Jelly-like fluid in the cell membrane
Houses organelles and inclusions
Mitochondria
ATP
Ribosomes
Made of protein and RNA. Free ones roam in cytoplasm, attached ones are on the RER
Endoplasmic reticulum
Membranous tubules and sacs
Endoplasmic reticulum: Rough (RER)
Has ribosomes attached to its surface (that’s why it’s rough) and specializes in protein synthesis and modification and to be exported into the cell membrane
Endoplasmic reticulum: Smooth (SER)
Lacks ribosomes (that’s why it’s smooth) and is involved in lipid synthesis, detoxification (breakdown of toxic substances), and calcium storage
Golgi apparatus
Receives newly synthesizes proteins from RER via transport vesicles, their proteins are post translationally modified, glycosylated or phosphorylated and packaged for transport through the cell.
Lysosomes
Contains digestive enzymes and breaks down worn out cell parts or invaders. Apoptosis happens there as well
Secretory granules
Vesicles that contain specific substances synthesized by cells from the golgi apparatus and get release from the cell membrane by exocytosis
Vacuoles
Stores nutrients, water, enzymes, pigments and wastes.
What is Cytology?
It’s the study of the structure and function of cells.
Cell division: INTERPHASE
Cell division: PROPHASE
“Prepare”: The chromosomes condense (get thick and visible), and the nuclear membrane starts breaking down. Spindle fibers begin to form.
Cell division: METAPHASE
“Middle”: Chromosomes line up in the middle of the cell, and spindle fibers attach to their centers (centromeres).
Cell division: ANAPHASE
“Apart”: The spindle fibers pull the sister chromatids (identical halves) apart to opposite sides of the cell.
Cell division: TELOPHASE
“Two”: Two new nuclei form as the chromosomes are now at opposite ends, and the cell starts to split. The chromosomes also begin to uncoil.
What are the 4 basic tissues?
Epithelium
Connective
Muscle
Nervous
Which tissue has the following functions: Covering, Lining, Glandular
Epithelium
Which tissue has the following functions: Connecting & Supporting
Connective
Which tissue has the following functions: Movement
Muscle
Which tissue has the following functions: Transmission of impulses
Nervous
T or F: Cells in the epithelium DO NOT have a regular shape and arrangement
False
Where are the apical surface and basemental surface on the epithelium?
Apical is the surface facing outside the lumen (surface of the skin)
The basemental surface is adjacent to the underlying tissue
T or F: Epithelium is Avascular?
True
What are some functions of the epithelium?
Protection
Reduces friction
Absorption
Cleaning
Excretion
Sensation
Secretion
Diffusion
Explain SIMPLE SQUAMOUS epithelium
Single layer of flat cells; thin and smooth; allows for easy diffusion.
Gas exchange, filtration, and diffusion.
Explain SIMPLE CUBOIDAL epithelium
Single layer of cube-shaped cells; may have microvilli or cilia.
Absorption, secretion, excretion.
Explain SIMPLE COLUMNAR epithelium
Single layer of tall, column-like cells; may have goblet cells and microvilli or cilia.
Absorption of nutrients, secretion of digestive enzymes.
Explain PSEUDOSTRATIFIED COLUMNAR epithelium
Appears stratified, but all cells touch the basement membrane; often has goblet cells and cilia.
Secretion and movement of mucus via cilia.
Explain STRATIFIED SQUAMOUS KERATINIZED epithelium
Multiple layers of cells; surface cells are flat and dead; contain keratin.
Protection against abrasion, water loss, and pathogens.
Explain STRATIFIED SQUAMOUS NON-KERATINIZED epithelium
Multiple layers; surface cells are flat but alive; no keratin.
Protection against abrasion and pathogen entry.
Explain STRATIFIED CUBOIDAL epithelium
Two or more layers of cube-shaped cells.
Protection and secretion.
Explain STRATIFIED COLUMNAR epithelium
Multiple layers of cells; surface cells are columnar.
Protection and secretion.
Explain TRANSITIONAL epithelium
Several layers of cells; surface cells are dome-shaped and can stretch.
Allows for stretching as bladder fills.
What is MICROVILLI?
Tiny Fingerlike projections of the cell membrane
increases surface area for absorption.
What is CILIA?
Hairlike projections that extend from the cell surface
capable of movement.
(only one that moves out of microvilli and stereocilia)
Moves fluids/particles
What is STEREOCILIA?
Long, thin, finger-like
Sensation, absorption
What are Goblet cells?
Goblet-shaped, no projections
No movement (mucus secretion only)
Cytoplasm (mucus-filled)
What is the difference between Keratinized and non-keratinized epithelium?
keratinized epithelium is better suited for dry, high-friction areas, while non-keratinized epithelium serves moist surfaces where absorption and protection are both necessary.
State some facts about Keratinized epithelium.
Dead, keratin-filled, no nuclei
Presence of Keratin: Present
Moisture: Dry
Protection: High (against friction, drying)
Locations: Skin, palms, soles
State some facts about non-Keratinized epithelium.
Alive, moist, retain nuclei
Presence of Keratin: Absent
Moisture: Moist
Protection: Moderate
Locations: Esophagus, oral cavity, vagina
What are Cell junctions?
Intercellular junctions are structures which provide adhesion and communication between cells
Present in epithelial cells but can be in other cells (cardiac muscle) that are characterized by their strong attachment to each other and to the extracellular matrix
Provides stability to epithelial tissue
3 types –>
- tight junctions
- adherent (includes desmosomes and hemidesmosomes)
- gap junctions
What are Tight Junctions?
seal adjacent cells in a narrow band beneath their apical surface
Molecules pass between cell through diffusion or active transport
Tight belt prevents other molecules from passing
What are Gap Junctions?
Gap junctions: intercellular channels that permits free transfer and exchange of nutrients, ions and signal molecules
What are Adherent Junctions?
Subunits: Desmosomes and Hemidesmosomes
provide strong mechanical attachment between cells
hold epithelial cells and cardiac muscle together
Desmosomes: localized patches that hold 2 cells together
(in simple terms: Strong cell adhesion) Ex: Skin, heart
Hemidesmosomes: link cells to underlying basement membrane
(in simple terms: Anchor to basement membrane)
Ex: Skin (epidermis-dermis)
Glandular epithelium: Exocrine and Endocrine
Exocrine: products are excreted to the surface
via. a duct
(i.e epi or lining surface)
Mucous or serous
Endocrine: products are secreted into blood
no ducts are involved
(i.e thyroid hormones)
Exocrine glands
Secrete substances through the
duct onto body surfaces
Mucous or serous
Simple: 1 duct (sweat glands in
skin)
Compound: more than 1 duct
(salivary glands)
Exocrine glands
Substances are released and go directly
to the bloodstream (hormones)
* Goes further into the body
2 types
* Follicles (thyroid) hormones are
stored in follicles, epi is simple cuboidal
- Clump and cord (pancreas) pituitary
gland, secretory glands are surrounded
by a rich network of blood supply - Going directly into blood stream
