Chapter 3--CELLS

CeLLs

Anatomy and Physiology 1Chapter 3 Outline

Cells

smallest living subunits of a multicellular organism

Work together with other cells oVary greatly in size and shape—usually

need a microscope More than 200 kinds of cells in humans

Cell structure

Cell membrane Nucleus Cytoplasm Organelles

– ribosomes - centrioles– Endoplasmic reticulum - cilia– Golgi apparatus - flagella– Lysosomes - microvilli– Mitochondria - vacuoles

Cell membrane (plasma membrane)

Selectively permeable Phospholipids,

cholesterol, Proteins Phospholipid bilayer—

double layer– Allows lipid-soluble

compounds to move in and out by diffusion

Cholesterol– Decreases fluidity

stabilizing the membrane

Proteins– Pores/channels– Carrier enzymes– Antigens when

combined with oligosaccharides

– Receptor sites for hormones or other compounds—triggers certain reactions in the cell

Nucleus

All cells except mature RBCs Double layered nuclear membrane Nucleolus (one or more) Bundle of DNA, RNA, & protein Forms RNA (rRNA, tRNA, & mRNA) Contains chromosomes

– 46 (double set)– Made of threads of chromatin— usually uncoiled

Coils during cell division Gene = genetic code for 1 protein Only genes for that cell are active

Cytoplasm

Liquid solution of dissolved minerals, gases, and other molecules

Contains organelles

Organelles

“Organs” of the cell

1. Ribosomes

Made of protein and rRNA

On ER or floating in cytoplasm

Synthesize protein

2. Endoplasmic reticulum (ER)

Membranous tubules that extend from the nuclear membrane to the cell membrane

2 types Rough ER

– ribosomes on the surface– Synthesizes proteins in the ribosomes

Smooth ER– no ribosomes on the surface– Synthesizes lipids

Tunnels that transport materials around the cell including lipids and proteins produced by the ER

3. Golgi apparatus

Flat membranous sacs stacked like pancakes

Synthesize and package carbohydrates Small sacs containing carbohydrates break

of and fuse with the cell membrane where it is released out of the cell

4. Mitochondria (mitochondrian)

Power house of the cell Double membrane—cristae Aerobic reactions of cell respiration ATP production Cells requiring more energy have more

mitochondria (muscle, liver) Have their own separate genes Duplicate during cell division

5. Lysosomes

Contain digestive enzymes called lysozymes

Digest bacteria during phagocytosis of WBCs

Digest worn out or damaged cells and parts cause inflammation that can damage healthy tissue if not controlled

CentriolesCentrioles

• • Rod-shapedRod-shaped • • Organize spindle Organize spindle

fibers that separate fibers that separate chromosomes during chromosomes during cell divisioncell division

Cilia (cilium)Cilia (cilium)

• • Many hair-like projections on certain Many hair-like projections on certain cellscells

• • Beat in unison causing a wave-like Beat in unison causing a wave-like motion to move things acrossmotion to move things across

the surface (DOES NOT move the cell)the surface (DOES NOT move the cell) • • Fallopian tubes, airways in lungsFallopian tubes, airways in lungs

Flagella (flagellum)Flagella (flagellum)

• • Mobile thread-like Mobile thread-like projection through projection through the cell membranethe cell membrane

• • Provides motility Provides motility (moves THE CELL)(moves THE CELL)

• • Sperm is the only Sperm is the only human cell with human cell with flagellum—has oneflagellum—has one

MicrovilliMicrovilli

• • Folds of the cell Folds of the cell membrane that membrane that increase surface area increase surface area (like an air(like an air

filter in a car)filter in a car) • • Increase absorptionIncrease absorption

—small intestine, —small intestine, kidney tubuleskidney tubules

VacuolesVacuoles

pinched off plasma pinched off plasma membrane during membrane during phagocytosis and phagocytosis and pinocytosispinocytosis

Cellular Transport MechanismsCellular Transport Mechanisms

Mechanisms to move substances in and Mechanisms to move substances in and out of the cellout of the cell– DiffusionDiffusion– OsmosisOsmosis– facilitated diffusionfacilitated diffusion– active transport active transport – FiltrationFiltration– phagocytosisphagocytosis– pinocytosispinocytosis

DiffusionDiffusion

movement of molecules from an area of greater movement of molecules from an area of greater concentration to an area of lesser concentration concentration to an area of lesser concentration along a concentration gradient until equilibrium along a concentration gradient until equilibrium is reachedis reached

Molecules randomly move until evenly dispersed Molecules randomly move until evenly dispersed in a solid, liquid, or gasin a solid, liquid, or gas

CO2 and O2 diffuse across the capillary/alveolus CO2 and O2 diffuse across the capillary/alveolus junction in the lungsjunction in the lungs

Movement occurs in all substances involved Movement occurs in all substances involved (except solids)(except solids)

OsmosisOsmosis

diffusion of water through a selectively diffusion of water through a selectively permeable membranepermeable membrane

Water moves from area of high Water moves from area of high concentration to low concentration until concentration to low concentration until equilibrium is met (regardless of volume)equilibrium is met (regardless of volume)

Same as saying moves from area of low Same as saying moves from area of low concentration of solutes to lowconcentration of solutes to low

concentration of solutes (high concentration of solutes (high concentration of water = low concentration of water = low concentration ofconcentration of

solutes and vice versa)solutes and vice versa) s s Isotonic—equal concentration of Isotonic—equal concentration of

solutes (Box 3-1)solutes (Box 3-1) • • e.g., saline during plasma donatione.g., saline during plasma donation e e Hypotonic—lower concentration of Hypotonic—lower concentration of

solutessolutes s s Hypertonic solution—higher Hypertonic solution—higher

concentration of solutesconcentration of solutes c c This occurs because the membrane will This occurs because the membrane will

not allow anything but water to crossnot allow anything but water to cross n n Small intestine and kidneysSmall intestine and kidneys

Facilitated diffusion Facilitated diffusion

diffusion of molecules through a diffusion of molecules through a membrane with help from proteins in the membrane with help from proteins in the cell membrane called transporters or cell membrane called transporters or carrier enzymescarrier enzymes

e.g., glucose, AAse.g., glucose, AAs

Active transport Active transport

energy requiring process of moving energy requiring process of moving molecules against amolecules against a

concentration gradient (lesser to greater concentration gradient (lesser to greater concentration)concentration)

Requires ATPRequires ATP Na+ pumps in nerve and muscle cells Na+ pumps in nerve and muscle cells

pump Na+ outpump Na+ out

FiltrationFiltration

substances are forced through a substances are forced through a membrane by mechanical pressuremembrane by mechanical pressure

Blood pressure created by heart pumping Blood pressure created by heart pumping forces fluids out of capillaries into the forces fluids out of capillaries into the interstitial spacesinterstitial spaces

Brings nutrients to cells and waste Brings nutrients to cells and waste products out of the blood in the kidneysproducts out of the blood in the kidneys

PhagocytosisPhagocytosis

moving cell engulfs moving cell engulfs somethingsomething

WBCs engulf bacteriaWBCs engulf bacteria Makes vaculolesMakes vaculoles

PinocytosisPinocytosis

——stationary cell engulfs somethingstationary cell engulfs something Kidney cells engulf proteins to reabsorb Kidney cells engulf proteins to reabsorb

them Makes vaculolesthem Makes vaculoles