Lecture Quiz 2 Flashcards
What is sphingosine
polar/hydrophillic phospholipid
Describe phospholipids
water solubule heads and water insoluble tails
separate the cytoplasm of a cell from the outside world
Describe the plasma membrane
double layer of phospholipids
cholesterol and protein embedded in it
What does cholesterol do in the plasma membrane?
decreases membrane fluidity
What do proteins do in the plasma membrane?
serve as recognition, receptor, and transport proteins
What are the functions of the plasma membrane?
isolate the cell from the external environment
regulate the exchange of essential compounds
communicate with the environment
Define gradient
a difference of concentrations between two regions in space
What is passive transport?
the movement of molecules from high concentration to low concentration
down the gradient
What is active transport?
the movement of molecules from low to high concentration
against the gradient
this process requires energy
What is diffusion?
movement of molecules down the concentration gradient - from high concentration to low concentration
Define simple diffusion
small water-soluble molecules and fat-soluble molecules can directly diffuse through the phospholipid bilayer down the concentration gradient, from high to low
Define facilitated diffusion
Ions and bigger water-soluble molecules, such as amino acids and monosaccharides, can diffuse through the membrane with the help of transport proteins
What do channel proteins do?
pores
form permanent hydrophilic opening
ions go through pores down the concentration gradient
Permeability of channels is often regulated by what two things?
Chemicals (ligands) or voltage
What do carrier proteins do?
bind to specific molecule
changes the shape of the carrier in such a way that the molecule is passed through the other side of the plasmamembrane
What are aquaporins?
special channels for water molecules to pass through the plasma membrane directly
What is osmosis?
The movement of water down the concentration gradient into a cell
Define isotonic
when water concentration in the solution is the same as inside the cell, and the movement of water into the cell and out of the cell is the same
Define hypotonic
when the concentration of water in the solution is higher than in the cell
concentration of other substances (ions) is lower than in the cell
water enters the cell, increasing its volume
Define hypertonic
when the concentration of water in the solution is lower than in the cell
concentration of other substances (ions) higher than in the cell
Water leaves the cell and the cell shrinks
Describe active transport
substances are moved against their concentration gradient which requires energy input
primary active transport - pumps, energy comes from ATP
secondary active transport - symport or antiport, energy comes from diffusion of another substance
What is endocytosis?
the cell engulfs materials and forms vesicles that separate the from the cell membrane and float in the cytoplasm
What are the three types of endocytosis?
pinocytosis
phagocytosis
receptor-mediated endocytosis
What cellular processes involve exocytosis?
secretion of proteins like enzymes, peptide hormones, and antibodies from cells
turnover of plasma membrane
release of neurotransmitter from presynaptic neurons
placement of membrane proteins
antigen presentation during the immune response
recycling of plasma membrane-bound receptors
What is vesicular trafficking?
moves substances within the cell from one membrane-enclosed area of the cell or organelle to another
What is transcytosis?
moves vesicles into the cell, through, then out of it
endothelialiocytes lining the capillary
enterocytes lining the gut
What are the four types of tissue?
Epithelial
connective
muscle
nervous
What is a tight junction?
a type of cell junction
a fluid that seal that prevents fluid from leaving a cavity
What is an anchoring junction?
cell junction
adhesion
found in tissues that stretch, such as a heart muscle
What is a gap junction?
cell junction
allows a passage of chemical and electrical signals
What are the properties of epithelial tissue?
cells bound tightly together in sheets
apical and basal surfaces
cells rest on basement membrane
capable of rapid cell division
What can epithelial tissues be subdivided into?
glandular (secretory) and surface epithelium
All epithelia are named according to:
number of cell layers
cell shapes
surface modifications
What are the two names for different number of cell layers in epithelia?
simple - single layer of cells resting on basal membrane
stratified - multiple layers of cells
What are the three different cell types in epithelia?
squamous - flattened or scale-like
cuboidal - resembles a cube
columnar - cylindrical in shape
Describe simple squamous epithelia
form the thinnest membranes in the body
it is found in the sacs in lungs and lining of blood vessels
Describe simple cuboidal epithelia
found lining ducts and other tubular structures
often adapted for secretion and absorption
kidney tubules and pancreatic ducts are made of this tissue
Describe simple columnar epithelia
cells are taller than they are wide
most commonly found lining the digestive tract and some exocrine glands
functions to absorb nutrients and secrete mucous
may be equipped with cilia or microvilli
Describe pseudostratified columnar epithelium
found lining the trachea and bronchi, as well as certain areas of the naval cavity
often ciliated to facilitate mucus removal from the airway
Describe stratified squamous epithelium
designed for abrasion and other abuse
protects against absorption, drying out, and infection
keratinized stratified squamous epithelium is found in the epidermis of the skin
upper layers formed by dead cells filled with waterproof keratin
nonkeratinized stratified squamous epithelium is the mucous membrane which lines most body orifices
Describe stratified cuboidal and columnar epithelia
found in mammary glands and salivary glands
adapted for secretion and absorption of water
Describe transitional epithelium
capable of a great deal of distension
when stretched it appears as stratified squamous
found in the lining of the urinary bladder, urethra, and ureters
Define glands
one or more cells that makes and secretes an aqueous fluid: mucus, hormones, enzymes, etc
formed by modified epithelial tissue
classified by site of product release
Describe endocrine glands
have no ducts
release their secretory products into the interstitial spaces around the cells
hormones diffuse into nearby capillaries and are then carried to all parts of the body
Describe exocrine glands
more numerous than endocrine glands
secrete their products onto body surfaces or into body cavities
have a secretory part and a duct
ex: mucous, sweat, oil, or salivary glands
classified according to shape and structure of the duct or mode of the secretion
What is the merocrine mode of secretion?
secretory vesicles are moved to the apical surface where the vesicles coalesce with the membrane on the apical surface to release the product
What is the apocrine mode of secretion?
apical portions of cells are pinched off and lost during the secretory process
mammary glands release their products in this manner
What is the holocrine mode of secretion?
involves death of the cell
sebaceous glands release their product in this manner
