Cells and Tissues ( epithelium) Flashcards
What is Anatomy
Describes the structures of the body
What is Physiology
The study of the functions of anatomical structures
What is Histology
The study of body tissues
What is the name of the watery medium that surrounds a cell
Extracellular fluid
What can the cytoplasm also be known as
Intracellular fluid
Where are integral proteins located
within the plasma membrane
where are peripheral proteins located
Bound to inner or outer
surface of the membrane
what is the function of plasma membrane proteins
Control ion and fluid movement
and for communications (e.g.
binding to hormones)
what is the plasma membrane function
- Physical isolation
- Barrier separating inside of cell from the surrounding extracellular fluid
- Regulates exchange with environment
- Controls entry of ions and nutrients
- Wastes eliminated and cellular products released
- Monitors the environment
- Receptors allow cell to recognize and respond to specific molecules
- Chemical signals (hormones) from other cells
- Affected by changes in composition, concentration, or pH of extracellular fluid
composition - Structural support
- Anchors cells and tissues (cell to cell attachments)
describe the role of the plasma membrane in diffusion
Plasma membrane acts as barrier that
selectively restricts diffusion
* Ion or molecule can diffuse across a
plasma membrane only by:
* Crossing the lipid portion of the
membrane (simple diffusion)
* Passing through a membrane channel
(channel-mediated diffusion)
what does the nucleus contain
genetic material
name the 4 body tissues
epithelial, connective, muscular, nervous
what does epithelial cells cover
Protective coverings of surfaces both
inside and outside of the body
What does epithelial tissue include
Includes the skin surface and the
linings of the heart, blood vessels,
digestive tract, respiratory tract,
urinary tract and body cavities
* Includes secretary cells and glands
what are the functions of epithelium
1) physical protection - from abrasion, dehydration, destruction
2) controls permeability- allow water, gases and nutrients to cross in and out
3) provide sensation
4) produce specialized secretions - hormones, sweat, mucous and joint fluid
Give an example of simple squamous epithelium
capillary and alveoli
give an example of columnar epithelium
intestine
Give an example of cuboidial epithelium
sweat duct
Describe the role of simple squamous
Role in secretion and
absorption
describe the role of stratified squamous
Provides physical
protection
describe the role of simple cuboidial epithelium
secretion (glands eg thyroid gland) and absorption
describe the role of stratified cuboidal epithelium
secretion and absorption
describe the role of simple columnar epithelium
- Secretion,
absorption,
protection - Lining of intestine
describe the role of pseudostratified columnar epithelium
Secretion,
movement of
mucas with cilia
describe the role of stratified columnar epithelium
protection
explain transitional epithelium
- Allows repeated
expansion and
recoiling after
stretching - Returns to
previous shape
without damage - Urinary bladder
what is a goblet cell
Goblet cell - secretions by a single cell
what is a gland
Gland - secretions by a group of cells
describe endocrine glands
Ductless Glands
* Release secretions into the blood
* E.g. Insulin hormone
What are exocrine glands
Single cells called goblet cells that
are specialised for secretion
* Goblet cells secrete mucin – mixes
with water to form a sticky lubricant
called mucus
what are multicellular exocrine glands
Gland cells form an epithelium that
releases secretions into an inner
compartment e.g., salivary glands
produce mucins and digestive
enzymes
what is MEROCRINE secretion
Product is released from an
exocrine cell by secretory
vesicles through exocytosis
* Most common method of
exocrine secretion
* E.g., mucin is a merocrine
secretion: mucous secretions of
the salivary glands coat food and
reduce friction during
swallowing; merocrine sweat
glands in the skin produce
perspiration that cools body on
hot day
what is apocrine secretion
involves the loss of cytoplasm as
well as the secretory product
* Apical portion of cytoplasm is
packed with secretory vesicles
and then shed
* E.g. milk production in the
mammary glands involves
merocrine and apocrine
secretions
what is holocrine secretion
Superficial cell in a stratified
glandular epithelium becomes
packed with secretory vesicles
and then burst – releasing
secretion but also killing the cell
* Further secretion dependent on
replacing destroyed gland cells
by division of underlying stem
cells
* E.g., sebaceous glands of hair
follicles produce oily hair coating
by holocrine secretion
name at least 3 endocrine glands
thyroid gland- thyroxine
pancreatic islets- insulin and glucagon
parathyroid gland- parathyroid hormone
hypothalamus- ADH
what are hormones
- Chemical messengers released from endocrine glands
- Transported in the bloodstream
- Reach target cell/organ(s)
- Alter metabolism of target cell
name 3 apical surface specializations
keratin, cilia, microvilli
function of cilia ?
Cilia move substances (fluids or secretions)
over epithelial surface
function of microvilli
Microvilli increase the surface area of the epithelial cells
explain tight (occluding )cell junctions
BETWEEN 2 PLASMA MEMBRANES
* Adhesion belt forms and attaches to terminal web
* Prevents passage of water and solutes
* Isolates wastes in the lumen
explain gap junctions
ALLOW RAPID COMMUNICATION
Held together by channel proteins (junctional proteins, connexons)
* Allow ions to pass so cells can communicate
* Allow the coordination of cilia beating or coordinating muscle cell contractions
Explain desmosomes
SPOT DESMOSOMES
* Small disks connected to bands of intermediate filaments
* Tie cells together
* Allow bending and twisting
HEMIDESMOSOMES
*attach cells to the basal lamina
* Helps stabilize position of epithelial cells
