a&p cytology

What type of cells are human body cells?

Human body cells are animal cells.

What type of cells are animal cells?

Eukaryotic cells that lack a cell wall and have a plasma membrane.

What are the three main components of a human cell?

1. Plasma membrane 2. Cytoplasm 3. Nucleus

What is the plasma membrane?

A thin membrane that covers the outside of the cell.

What molecules make up the plasma membrane?

Lipids, proteins, and carbohydrates.

What is the Fluid Mosaic Model?

A model describing the plasma membrane as a fluid phospholipid bilayer with proteins, lipids, and carbohydrates embedded like a mosaic.

What is a phospholipid bilayer?

A double layer of phospholipids that forms the basic structure of the plasma membrane.

What are the four major lipid components of the plasma membrane?

Phospholipids, glycolipids, cholesterol, and lipid rafts.

What are phospholipids?

The primary lipids that form the phospholipid bilayer.

What are glycolipids?

Lipids with attached carbohydrates important for cell recognition.

What is cholesterol's role in the membrane?

Helps maintain membrane stability and fluidity.

What are lipid rafts?

Specialized clusters of lipids within the plasma membrane.

How are membrane proteins classified?

By position and by function.

What are the two classifications of membrane proteins by position?

Integral proteins and peripheral proteins.

What are integral proteins?

Proteins embedded within or spanning the phospholipid bilayer.

What are peripheral proteins?

Proteins attached to the inner or outer surface of the phospholipid bilayer.

What are the functions of membrane proteins?

Anchoring, recognition, enzymes, receptors, carrier proteins, and channels.

What do anchoring proteins do?

Attach the cell to neighboring cells or the cytoskeleton.

What do recognition proteins do?

Allow cells to identify one another.

What do membrane enzymes do?

Catalyze chemical reactions on the membrane.

What do receptor proteins do?

Receive and respond to chemical signals.

What do carrier proteins do?

Transport specific substances across the membrane.

What do channel proteins do?

Provide passageways for ions or molecules across the membrane.

Where are most carbohydrates found on the plasma membrane?

Extending from the outer surface in the glycocalyx.

What is the glycocalyx?

A carbohydrate-rich layer on the cell surface involved in protection and cell recognition.

What are proteoglycans?

Carbohydrates that help tissues retain water and resist compression.

What are glycoproteins?

Proteins with attached carbohydrates that help cells recognize each other, communicate, and function as receptors.

What are glycolipids important for?

Cell recognition and membrane stability.

What are the functions of membrane carbohydrates?

Lubrication, protection, anchoring, locomotion, specificity in binding, and recognition.

How do carbohydrates provide lubrication and protection?

They form a protective coating around cells.

How do carbohydrates aid anchoring and locomotion?

They help cells attach and move.

What is specificity in binding?

The ability of carbohydrates to bind only certain molecules.

Why is cell recognition important?

It allows the immune system and cells to distinguish self from non-self.

What are the three main types of cell junctions?

Tight junctions, desmosomes, and gap junctions.

What is a tight junction?

A junction where adjacent proteins tightly seal neighboring cells together.

Where are tight junctions commonly found?

The superficial layers of the skin and tissues requiring tight seals.

What is a desmosome?

A strong spot attachment that holds cells together while allowing flexibility.

Why are desmosomes important?

They prevent tissues from pulling apart during stress.

What is a gap junction?

A junction containing protein channels connecting adjacent cells.

What is the function of gap junctions?

Allow substances and electrical signals to pass directly between cells.

Where are gap junctions commonly found?

Cardiac muscle and other specialized tissues.

What is selective permeability?

The ability of the plasma membrane to allow some substances to pass while restricting others.

What is passive transport?

Movement across the membrane without the use of cellular energy (ATP).

What is active transport?

Movement across the membrane that requires ATP.

What is diffusion?

The movement of molecules from an area of higher concentration to lower concentration.

What is simple diffusion?

Movement directly through the plasma membrane without transport proteins.

What is facilitated diffusion?

Diffusion requiring carrier or channel proteins.

Which substances can freely diffuse through the membrane?

Lipid-soluble molecules and relatively small molecules.

What is filtration?

Movement of water and small solutes driven by pressure differences.

What is osmosis?

The movement of water across a selectively permeable membrane.

What determines the direction of osmosis?

Tonicity (solute concentration).

What is an isotonic solution?

A solution with equal solute concentration on both sides of the membrane; there is no net movement of water.

What is a hypertonic solution?

A solution with a higher solute concentration than the cell; water moves out of the cell.

What is a hypotonic solution?

A solution with a lower solute concentration than

What is the normal resting membrane potential of most cells?

Between -10 mV and -100 mV.

What happens when there is a greater difference in charge across the membrane?

The membrane potential increases.

How is the resting membrane potential maintained?

By active and passive forces, especially the Na+/K+ pump.

What does the sodium-potassium pump do?

Moves 3 Na+ out of the cell and 2 K+ into the cell using ATP to help maintain the resting membrane potential.

What are the three major components found in the cytoplasm?

Cytosol, inclusions, and organelles.

What is cytosol?

The intracellular fluid in which organelles are suspended.

What are inclusions?

Stored materials within the cell that are not enclosed by membranes.

What are organelles?

Specialized structures ("little organs") that perform specific cellular functions.

How are organelles grouped?

Membranous and non-membranous.

What are non-membranous organelles?

Organelles not enclosed by a membrane and in direct contact with the cytosol.

Which organelles are non-membranous?

Cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes.

What are membranous organelles?

Organelles completely enclosed by membranes with no direct contact with the cytosol.

Which organelles are membranous?

Endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria, and nucleus.

What are the three components of the cytoskeleton?

Microfilaments, intermediate filaments, and microtubules.

What protein makes up microfilaments?

Actin.

What are the functions of the cytoskeleton?

Support, maintain cell shape, movement, and intracellular transport.

Do any two cells have the exact same cytoskeleton?

No. Each cell's cytoskeleton is unique.

What are microvilli?

Non-motile projections supported by microfilaments that increase surface area.

What is the function of microvilli?

Increase surface area for absorption.

Are microvilli motile?

No.

What are cilia?

Motile projections supported by microtubules that move substances across the cell surface.

What is the arrangement of microtubules in cilia?

A 9+2 arrangement (nine outer doublets surrounding two central microtubules).

What is the basal body?

The structure at the base of a cilium containing a 9+0 microtubule arrangement.

Where are flagella found in humans?

Only on sperm cells.

What is the function of a flagellum?

Propels the entire cell.

How is a flagellum structured?

Like cilia with a 9+2 microtubule arrangement.

What are centrioles?

Cylindrical structures arranged at right angles with a 9+0 microtubule pattern.

What is the function of centrioles?

Direct chromosome movement during mitosis.

What is the centrosome?

The region containing the pair of centrioles and surrounding material.

What are proteasomes?

Hollow cylindrical protein complexes that destroy proteins.

Which proteins are degraded by proteasomes?

Only proteins tagged with ubiquitin.

What are ribosomes?

The site of protein synthesis where translation occurs.

What process occurs at ribosomes?

Translation.

What are lysosomes?

Membrane-bound organelles containing digestive enzymes.

What is the function of lysosomes?

Digest macromolecules and worn-out organelles.

What is autophagy?

The process in which lysosomes digest damaged cell parts.

Where do lysosomes originate?

They bud from the Golgi apparatus.

What additional role do lysosomes play?

Important in immune defense.

What are peroxisomes?

Membrane-bound organelles that detoxify harmful substances.

Where do peroxisomes originate?

They bud from the smooth endoplasmic reticulum.

What do peroxisomes break down?

Oxidizing substances such as hydrogen peroxide (H₂O₂).

How do lysosomes differ from peroxisomes?

Lysosomes digest macromolecules, while peroxisomes detoxify harmful chemicals.

What is the rough endoplasmic reticulum (RER)?

ER covered with ribosomes that synthesizes and modifies proteins.

Why is the rough ER called "rough"?

Because ribosomes are attached to its surface.

What is the function of the smooth endoplasmic reticulum (SER)?

Synthesizes lipids, detoxifies drugs and toxins, and contains many enzymes.

Which organ is especially rich in smooth ER?

The liver.