Anatomy and Physiology chapter 3

What is a cell?

The smallest living unit in the body.

What does the cell theory explain?

– Cells are the building blocks of all organisms.

– All cells come from the division of preexisting cells.

– Cells are the smallest units that carry out life’s

essential physiological functions.

– Each cell maintains homeostasis at the cellular level.

Homeostasis at the tissue, organ, organ system, and

organism levels results from the combined feedback of

many cells.

what does cytology study? what is it a branch of?

Cytology studies the structure (anatomy) of cells and is a branch of cell biology (the study of cells).

what types of cells does the human body contain?

Sex cells which allow for reproduction (sperm in males and oocytes in females), and somatic cels (all cells but sex cells)

what are microvilli? What do they do?

extensions of the plasma membrane containing microfilaments. they increase surface area to help absorb extracellular materials.

what is the cytoskeleton? what is it essential for? what 2 components is it made up of?

proteins organized in fine filaments or slender tubes. it provides strength and support, along with movement of cellular structures and materials. It is made up of microfilaments and microtubules.

what are Cilia? what do they do?

long extensions of the plasma membrane containing microtubules, consist of 2 types (primary and motile). primary cilium act as a sensor. motile cilia move materials over cell surface. 

what are proteasomes? what do they do?

hollow cylinders of proteolytic enzymes with regulatory proteins at their ends. they break down and recycle damaged or abnormal intracellular proteins. 

what are ribosomes? what do they do?

RNA plus proteins, fixed ribosomes bind to rough endoplasmic reticulum, free ribosomes are scattered in cytoplasm. ribosomes synthesize proteins. 

what is the plasma membrane? 

a lipid bi-layer containing phospholipids, steroids, proteins and carbohydrates. it isolates and protects the cell, makes it sensitive to its environment, and controls the entry and exit of materials. 

what is the Golgi apparatus? what does it do?

stacks of flattened membranes (cisternae) containing chambers. It stores, altercates and packages secretory products and lysosomal enzymes. 

what is the endoplasmic reticulum? 

a network of membranous channels extending throughout the cytoplasm. it synthesizes secretory products, serves as intracellular storage and transport, and detoxifies drugs or toxins.

what does the rough ER do?

produces proteins thru ribosomes embedded into membrane, and modifies packages of newly synthesized membranes. 

what does the smooth ER do?

synthesizes lipids and carbohydrates, does not have ribosomes.

what are peroxisomes? what do they do?

vesicles containing degrading enzymes, they catabolize fats and other organic compounds, along with neutralizing toxic compounds generated in the process.

what is the mitochondria? what do they do?

double membrane with inner membrane folds (crystae) enclosing important metabolic enzymes. they produce 95 percent of the ATP required by the cell. 

what are lysosomes? what do they do?

vesicles that contain digestive enzymes, participate in the intracellular removal of damaged organelles or pathogens. 

what is the nucleus? what does it do?

nucleoplasm containing nucleotides, enzymes, nucleoproteins, and chromatins; surrounded by a double membrane, the nuclear envelope. it controls metabolism, stores and processes genetic information, controls protein synthesis.

what does the plasma membrane form?

the plasma membrane (aka the cell membrane) forms the outer boundary of the cell and allows for selective transport of substances.

what are the main components of the plasma membrane?

lipids and proteins

name all functions of the plasma membrane and describe each one.

Functions of the plasma membrane

– Physical isolation – separates the inside of the cell (or

cytoplasm) from the surrounding extracellular fluid

– Regulation of exchange with the environment –

controls the entry of ions and nutrients, the elimination

of wastes, and the release of secretions

– Sensitivity to the environment – sensitive to changes in

the environment and contains receptors that allow the

cell to respond to chemical signals

– Structural support – anchors cells to each other and to

extracellular materials and provides stability to tissues