A&P 1 Chapter 3: Cellular Form and Function

What is cytology?

The scientific study of cells.

What are the four main principles of cell theory?

1. All organisms are composed of cells and cell products. 2. The cell is the simplest unit of life. 3. Cell activities determine an organism's structure and function. 4. Cells arise only from preexisting cells.

About how many cell types are in the human body?

About 200.

What does squamous mean?

Thin flat scaly.

What does cuboidal mean?

Cube-shaped or squarish-looking.

What does columnar mean?

Taller than it is wide.

What does polygonal mean?

Irregularly angular shape with multiple sides.

What does stellate mean?

Star-shaped.

What does spheroid mean?

Round to oval.

What does discoidal mean?

Disc-shaped.

What does fusiform mean?

Thick in the middle and tapered at the ends.

What does fibrous mean?

Threadlike.

Most human cells are about what size?

10 to 15 μm in diameter.

What is 1 micrometer (μm)?

One-millionth of a meter or one-thousandth of a millimeter.

How large is an egg cell?

About 100 μm in diameter.

How long can some nerve cells be?

More than 1 meter long.

Why can't cells become extremely large?

Volume increases faster than surface area making it difficult to support the cell.

What does TEM stand for?

Transmission Electron Microscope.

What does SEM stand for?

Scanning Electron Microscope.

What is resolution?

The ability to reveal detail.

What is SEM best used for?

Viewing 3D surface features.

What surrounds the cell?

The plasma membrane.

What is cytoplasm?

Material between the nucleus and cell membrane.

What is cytosol?

The intracellular fluid inside the cell.

What is extracellular fluid (ECF)?

Fluid located outside cells.

What is the plasma membrane mainly made of?

Lipids and proteins.

What percentage of membrane lipids are phospholipids?

About 75%.

What percentage of membrane lipids is cholesterol?

About 20%.

What percentage of membrane lipids is glycolipid?

About 5%.

amphipathic

Having both hydrophilic and hydrophobic regions.

Which part of a phospholipid is hydrophilic?

The phosphate head.

Which part of a phospholipid is hydrophobic?

The fatty acid tails.

What is the function of cholesterol in the membrane?

Stabilizes and stiffens the membrane.

glycolipids

Lipids with carbohydrate chains attached.

What is the glycocalyx?

A carbohydrate coating on the cell surface.

Why is the glycocalyx important?

Protection immunity defense against cancer transplant compatibility cell adhesion fertilization and embryonic development.

What are cell-identity markers?

Glycoproteins that act as identification tags.

What are CAMs?

Cell-adhesion molecules that mechanically link cells.

What are transmembrane proteins?

Proteins that pass completely through the membrane.

What are peripheral proteins?

Proteins attached to one side of the membrane.

What do receptor proteins do?

Bind chemical signals and trigger cell responses.

What do channel proteins do?

Allow substances to pass through the membrane.

What is a leak channel?

A channel that is always open.

What are ligand-gated channels?

Channels that respond to chemical messengers.

What are voltage-gated channels?

Channels that respond to charge changes.

What are mechanically gated channels?

Channels that respond to physical stress.

What are carrier proteins?

Proteins that bind and transport solutes across membranes.

What are pumps?

Carrier proteins that use ATP.

What is the first messenger in the second messenger example?

Epinephrine.

What activates adenylate cyclase?

A G protein.

What is the second messenger produced from ATP?

cAMP cyclic AMP.

What are microvilli?

Fingerlike membrane extensions that increase surface area.

What is the brush border?

Dense microvilli on absorptive cells.

How much extra surface area can microvilli provide?

15 to 40 times more surface area.

What is the terminal web?

A network of actin microfilaments beneath the membrane.

cilia

Hairlike projections that move material across a cell surface.

What is a primary cilium?

A nonmotile cilium that acts as a cellular antenna.

What is the axoneme?

The microtubule core of a cilium.

What is the ciliary 9+2 arrangement?

Nine outer pairs of microtubules surrounding two central microtubules.

What is the function of dynein arms?

They bend cilia using ATP.

What is the only functional flagellum in humans?

The sperm tail.

What are pseudopods?

Temporary cell extensions used for movement and engulfing particles.

What does selectively permeable mean?

Allows some substances to pass while blocking others.

What is passive transport?

Transport that requires no ATP.

What is active transport?

Transport that requires ATP.

What is filtration?

Movement of particles through a membrane due to pressure.

What is diffusion?

Net movement from high concentration to low concentration.

What factors increase diffusion rate?

Higher temperature steeper gradient larger surface area and greater permeability.

What is osmosis?

Diffusion of water through a selectively permeable membrane.

What are aquaporins?

Water channels that speed osmosis.

What is osmotic pressure?

Pressure needed to stop osmosis.

What is osmolarity?

The concentration of nonpermeating solutes.

tonicity

The ability of a solution to affect cell volume.

What happens to cells in a hypotonic solution?

They swell and may lyse.

What happens to cells in a hypertonic solution?

They shrink or crenate.

isotonic solution

No net change in cell volume.

What is carrier-mediated transport?

Movement of substances using membrane carrier proteins.

What is specificity?

A carrier transports only certain solutes.

What is saturation?

All transport proteins are occupied.

What is a transport maximum?

The point at which all carrier proteins are occupied.

What is a uniport?

Carries one substance.

What is a symport?

Carries two substances in the same direction.

What is cotransport?

Another term for symport.

antiport

Carries two substances in opposite directions.

What is countertransport?

Another term for antiport.

What is facilitated diffusion?

Movement down a concentration gradient using a carrier without ATP.

What is primary active transport?

Uses ATP directly to move substances against their gradient.

What is secondary active transport?

Uses energy stored in ion gradients instead of ATP directly.

What is SGLT?

A sodium-glucose transporter used in secondary active transport.

How many sodium ions leave the cell per pump cycle?

3 Na+.

How many potassium ions enter the cell per pump cycle?

2 K+.

How much ATP does one sodium-potassium pump cycle use?

One ATP.

What powers the sodium-potassium pump?

ATP.

What disease results from defective chloride pumps?

Cystic fibrosis.

What is endocytosis?

Bringing materials into the cell.

What is exocytosis?

Releasing materials from the cell.

phagocytosis

Cell eating.

What is pinocytosis?

Cell drinking.

What is receptor-mediated endocytosis?

Uptake of substances using specific membrane receptors.

What is clathrin?

A protein that forms coated pits and coated vesicles.