Histology Cell Structure & Function

nucleus

organelle that synthesizes all types of RNA and replicates its DNA, stores genetic material, and regulates cell activities

plasma membrane

a double layer of phospholipids and membrane proteins

cytoplasm

contains cytosol, cellular organelles, inclusions, and cytoskeleton

microvillus

One of many fine, finger-like projections of the epithelial cells in the lumen of the small intestine that increase its surface area

cilium

a hairlike cell surface structure arranged in tightly packed rows that projects from the surface of some cells

stereocilium

any of the hairlike extensions on the tips of hair cells in the cochlea that, when flexed, initiate the release of neurotransmitters

basolateral fold (basal fold)

cell surface structure found in the nasal cavity epithelium

basal lamina

thin extracellular layer that lies underneath epithelial cells and separates them from other tissues

cytoskeleton

A network of fibers that holds the cell together (structural support), helps the cell to keep its shape, and aids in movement

actin filament (microfilament), myosin filament, intermediate filament, microtubule

name 4 major cytoskeleton elements

phosphilipids, cholesterols, glycolipids

name 3 membrane lipids

phospholipids

membrane lipids with hydrophilic heads and hydrophobic tails

cholesterols

membrane lipids that connect phospholipids together and prevent them from drifting apart

glycolipids

membrane lipids with an attached carbohydrate, located on the outer membrane

integral proteins and peripheral proteins

2 types of membrane proteins

integral proteins

membrane proteins embedded in the lipid bilayer (i.e. transmembrane proteins)

transmembrane proteins

membrane proteins that cross the plasma membrane, such as sodium ion channels, gap junction proteins, glycoproteins, integrins, cadherins, and selectins

peripheral proteins

membrane proteins attached to the inner or outer surface that function as carriers and act as electron carriers

peripheral proteins

The following are examples of what kind of protein: cytochrome c, annexins, synapsin I, spectrin?

transmembrane proteins (and, therefore, integral proteins)

The following are examples of what kind of protein: sodium ion channels, gap junction proteins, glycoproteins, integrins, cadherins, selectins?

cell membrane (plasmalemma)

The function of the _________ is to protect intracellular elements, give shape to cells, and allow transport of materials between the intracellular and extracellular environments via endocytosis and exocytosis.

nucleus and mitochondria

What 2 organelles have a double membrane?

smooth ER

What organelle has a branching tubular form, with Y-shaped profiles of the membrane and NO ribosomes on its outer surface?

true

T/F: The smooth ER does NOT relate to protein synthesis.

hepatocytes (liver cells)

What cells contain abundant SER?

smooth ER

The main functions of what organelle include detoxification and the synthesis and transport of lipids and steroids?

rough ER

The membrane of what organelle encloses a cisternal space in disk or tubule shapes and has ribosomes on the outer surface of the membrane?

passive transport

a process in which the substances transfer across a cell membrane through a concentration gradient

simple diffusion

a passive transport process that transports small, uncharged molecules directly through the cell membrane without assistance

exchange of oxygen and CO2 between blood and body tissue

give an example of simple diffusion

facilitated diffusion

a passive transport process that transfers large polar molecules through the membrane with assistance from transmembrane proteins

osmosis

a passive transport process that involves the transfer of water from an area of lower concentration to an area of high concentration via a semipermeable membrane

filtrations

the passive transport process of separating a solid substance from a fluid (during the process, a medium stops the substance from passing. fluid flows from high to low pressure areas)

glomerular filtration during urine production

give an example of passive transport by filtrations

active transport

an energy-dependent process that utilizes cellular energy and requires the assistance of carrier proteins to transfer molecules across the cell membrane against an electrochemical gradient from low to high concentration

vesicle transport

a special type of active transport that includes exocytosis and endocytosis

exocytosis

process in which vesicles transfer their contents from inside to outside the cell (substances leave the cell)

endocytosis

process in which vesicles transfer materials from the outside of the cell to the inside

both passive and active transport

What kind(s) of transport can small molecules/ions use to cross the cell membrane?

transport of glucose and amino acids

give an example of facilitated diffusion

facilitated

What's faster, simple diffusion or facilitated?

low to high

Water moves from ______ to ______ solute concentration by osmosis.

primary active transport

movement of ions, in which energy is derived directly from ATP hydrolysis

secondary active transport

transportation of glucose and amino acids, which is indirectly linked to ATP hydrolysis

receptor-mediated endocytosis

endocytosis with the aid of a receptor for a specific molecule outside of the cell. the molecule (ligand) binds to the receptor on the external membrane and the protein clathrin forms a coat under the receptor on the internal side of the membrane, causing the coated area to form a vesicle that carries the ligand and receptor into the cell interior

symport

an active transportation system that carries 2 molecules in the same direction across cell membrane

antiport

active transportation of 1 molecule in one direction while another molecule is transported in another direction

sodium-glucose transport protein

give an example of symport

sodium-potassium pump

give an example of antiport

exocytosis (vesicle transport, which is active)

If secretory vesicles (enzymes and hormones) are moved from the cytoplasm to the outside environment, what type of transport is this an example of?

pinocytosis, phagocytosis, and receptor-mediated endocytosis

3 types of endocytosis

phagocytosis

movement of solid particles via vesicles from outside to inside the cell to be digested in the cytoplasm

pinocytosis

a process of moving fluid within vesicles from the extracellular space across the membrane into the cell

clathrin

In receptor-mediated endocytosis, the molecule (ligand) binds to the receptor on the external membrane and the protein _________ forms a coat under the receptor on the internal side of the membrane.

signaling molecules

_______ are secreted by signaling cells and can bind with membrane receptor proteins to promote cell-to-cell interactions.

direct cell-to-cell signaling

cell signaling that occurs from direct interaction between 2 neighboring cells

endocrine signaling

cell signaling that occurs through secreted and released molecules that act on distant target cells

paracrine signaling

cell signaling in which signaling molecules or hormones are released into the intercellular space and act on nearby cells

autocrine signaling

cell signaling in which the signaling molecules are secreted into the extracellular space and then bind to receptors on the signaling cell itself

T cells

example of cells that perform autocrine signaling

hydrophobic (lipid-soluble) signaling molecules

type of signaling molecules that cross the cell membrane and bind to receptors inside the cell in the cytoplasm or nucleus

steroid and thyroid hormones

Which groups of signaling molecules are are hydrophobic/lipid-soluble?

hydrophilic signaling molecules

type of signaling molecules that bind to and activate cell surface receptors

neurotransmitters and most hormones

Which groups of signaling molecules are hydrophilic (bind to surface receptors)?

synaptic signaling between 2 neurons

What is the prime example of direct cell-to-cell signaling?

hormones released by endocrine cells are carried through the bloodstream to act on distant target cells

Give an example of endocrine signaling

paracrine

The following are all examples of what kind of cell signaling: allergic response, tissue repair, scar formation, blood clotting?

autocrine

What type of cell signaling is closely associated with the human immune response?

It binds to and inactivates acetylcholine receptors, which prevents the opening of Na+ channels.

How does snake venom cause muscular weakness and paralysis?

muscular weakness and paralysis

What are the 2 main symptoms of snake venom, caused by inactivated Ach receptors?

neurotoxic effect

What kind of effect is it when venom acts on the neuromuscular junction?

vasculotoxic effect

What kind of effect is it when venom destroys endothelial cell membranes, leading to coagulation disorders and the lysis of red blood cells?

myotoxins effect

What kind of effect is it when venom causes muscle weakness that can lead to heart damage?

intravenous administration of antivenom

What is the only specific treatment to counteract snake venom?

nuclear envelope

double-layered structure constituting an inner and outer nuclear membrane

heterochromatin

an inactive form of DNA that appears dark and electron dense

euchromatin

an active DNA that appears light and electron lucent

nucleolus

spherical structure inside the nucleus that is the site of ribosome and rRNA production and plays an important role in assisting protein synthesis

when a cell is actively synthesizing proteins

When can more than one nucleolus be found within one nucleus?

nuclear pores complex

The ________ __________ _________ provides transport pathways and selectively controls bidirectional movement of proteins between the nucleus and cytoplasm, permitting their passage via receptor-mediated transport.

receptor-mediated transport

The nuclear pore complex provides transport pathways and selectively controls movement of proteins between the nucleus and cytoplasm, permitting their passage via __________ -___________ __________.

perinuclear cisternae

What part of the nuclear envelope is located between 2 nuclear membranes?

nuclear pores

In the cell that is actively synthesizing proteins, the nuclear envelope has numerous __________.

diaphragm

Nuclear pores are not simply openings, but rather each has a __________.

outer

In some cells, the ________ nuclear membrane is studded with ribosomes.

rough ER

In some cells, the perinuclear cisternae are continuous with the cisternae of the ____________.

cytosol

gel-like cellular fluid that provides support and maintains organelles in suspension within the cytoplasm

mitochondria, RER, SER, golgi complex, ribosomes, lysosomes, vesicles

List the 7 main organelles.

cytoplasmic inclusions

___________ are temporarily present in the cytosol and are NOT able to carry out metabolic activities. (ex: stored nutrients, secretory products, granules)

mitochondria

elongated organelles with a double-layer membrane whose main function is the production of energy for cellular use through ATP generation, and they also contribute to the synthesis of some molecules

a) outer membrane

b) inner membrane

c) cristae

d) matrix

Fill in the parts of the mitochondria:

a) ________ is smooth

b) ________ shows winding folds

c) The winding folds are called ___________

d) ________ is fluid within the inner membrane

ribosomes

small granular particles where all protein synthesis occurs

attached to the surface of the RER and floating freely in the cytosol

Where are ribosomes found in the cell?

polyribosome

a group of ribosomes aggregated to form a cluster structure, which is attached to a single mRNA molecule and is commonly found in the cytosol

mRNA; cytosol

The polyribosome is a group of ribosomes aggregated to form a cluster structure, which is attached to a single _______ molecule and is commonly found in the _______.

rough ER

an organelle with a series of membranous folds with an inner lumen and an outer surface, to which numerous mature ribosomes are attached; the primary site of protein synthesis, whose main functions are modifying, sorting, and TRANSPORTING proteins made by the ribosomes

nucleus and golgi complex

With which 2 organelles is the rough ER closely associated?

RER

Proteins synthesized by the ___________ have specific final destinations, such as the cell membrane, cell exterior, or the ER itself.

golgi apparatus

an organelle resembling a flattened stack of membranes, composed of multiple cisternae (saccules) with 3 regions, and whose main functions are sorting, modifying, and PACKAGING proteins and lipids

the trans golgi network (TGN), the medial golgi network, and the cis golgi network (CGN)

Name the 3 regions of the golgi complex: the __________ (shipping side), the _________, and the ___________ (receiving side)