1. Visual Anatomy & Physiology First Edition Martini & Ober
Chapter 3
Cellular Level of Organization
Lecture 5
Slides 1-15; 80 min (with review of syllabus and Web sites) [Lecture 1]
Slides 16 – 38; 50 min [Lecture 2]
118 min (38 slides plus review of course Web sites and syllabus)

2. Lecture Overview Specialization and differentiation of cells
General characteristics of cells
The cell membrane
Cellular organelles (summary table)
Cell death; necrosis and apoptosis
Stem cells and progenitor cells
Cancer
Movement of substances into and out of the cell

3. Cells Are Specialized vary in size vary in shape vary in function
measured in micrometers

4. A Composite Cell hypothetical cell major parts nucleus cytoplasm
cell membrane

5. Cell Membrane outer limit of cell; isolates cell
controls what moves in and out of cell - selectively permeable
self-sealing
phospholipid bilayer
water-soluble “heads” form outer surfaces
water-insoluble “tails” form interior
permeable to lipid-soluble substances only
cholesterol stabilizes the membrane
proteins
receptors
pores, channels, carriers
enzymes
CAMS
self-markers

6. Cell Membranes

7. A Transmembrane Protein
Hydrophilic channel
Membrane Lipids

8. Cellular Organelles Table 1 of 2 CELL COMPONENT DESCRIPTION/ STRUCTURE
FUNCTION(S)
CELL MEMBRANE
Bilayer of phospholipids with proteins dispersed throughout
cell boundary; selectively permeable (i.e. controls what enters and leaves the cell; membrane transport)
CYTOPLASM
jelly-like fluid (70% water)
suspends organelles in cell
NUCLEUS
Central control center of cell; bound by lipid bilayer membrane; contains chromatin (loosely colied DNA and proteins)
controls all cellular activity by directing protein synthesis (i.e. instructing the cell what proteins/enzymes to make.
NUCLEOLUS
dense spherical body(ies) within nucleus; RNA & protein
Ribosome synthesis
RIBOSOMES
RNA & protein; dispersed throughout cytoplasm or studded on ER
protein synthesis
ROUGH ER
Membranous network studded with ribosomes
SMOOTH ER
Membranous network lacking ribosomes
lipid & cholesterol synthesis
GOLGI
“Stack of Pancakes”; cisternae
modification, transport, and packaging of proteins

9. Cellular Organelles Table 2 of 2 CELL COMPONENT DESCRIPTION/ STRUCTURE
FUNCTION(S)
LYSOSOMES
Membranous sac of digestive enzymes
destruction of worn cell parts (“autolysis) and foreign particles
PEROXISOMES
Membranous sacs filled with oxidase enzymes (catalase)
detoxification of harmful substances (i.e. ethanol, drugs, etc.)
MITOCHONDRIA
Kidney shaped organelles whose inner membrane is folded into “cristae”.
Site of Cellular Respiration; “Powerhouse of Cell”
FLAGELLA
long, tail-like extension; human sperm
locomotion
CILIA
short, eyelash extensions;
human trachea & fallopian tube
to allow for passage of substances through passageways
MICROVILLI
microscopic ruffling of cell membrane
increase surface area
CENTRIOLES
paired cylinders of microtubules at right angles near nucleus
aid in chromosome movement during mitosis

10. Cell Death Two mechanisms of cell death
Necrosis
Programmed cell death (PCD or apoptosis)
Tissue degeneration following cellular injury or destruction
Cellular contents released into the environment causing an inflammatory response
Programmed Cell Death (Apoptosis)
Orderly, contained cell disintegration
Cellular contents are contained and cell is immediately phagocytosed

11. Necrosis vs. Apoptosis Necrosis Apoptosis
Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998

12. Cellular Pathways of Apoptosis
Figure from:

13. Cellular Pathways of Apoptosis
Figure from:

14. Failure of Apoptosis - Syndactyly
Photo from:

15. Stem and Progenitor Cells
Stem cell
can divide to form two new stem cells
can divide to form a stem cell and a progenitor cell
totipotent – can give rise to any cell type (Embryonic stem cells)
pluripotent – can give rise to a restricted number of cell types
Progenitor cell
committed cell
can divide to become any of a restricted number of cells
pluripotent

16. Figure from: Hole’s Human A&P, 12th edition, 2010

17. Cancer Two types of tumors benign – usually remains localized
malignant – invasive and can metastasize; cancerous
Genes that cause cancer
oncogenes – activate other genes that increase cell division
tumor suppressor genes – normally regulate mitosis; if inactivated they will not regulate mitosis
Oncology is the study of tumors

18. Cancer is a Genetic Disorder
Figure from: Hole’s Human A&P, 12th edition, 2010

19. Cancer Cancers are due to:
Figure from: Hole’s Human A&P, 12th edition, 2010

20. Cancer
Metastasis is the spread of a cancer from its site of origin to other areas of the body
Figure from: Hole’s Human A&P, 12th edition, 2010

21. Movements Into and Out of the Cell
Passive (Physical) Processes
require no cellular energy
simple diffusion
facilitated diffusion
osmosis
Active (Physiological) Processes
require cellular energy
active transport
endocytosis
exocytosis
transcytosis

22. Simple Diffusion
Solutes will evenly disperse in a solvent with time by diffusion. This is the lowest energy state.

23. Simple Diffusion
movement of substances from regions of higher concentration to regions of lower concentration (a physical process)
Figure from: Hole’s Human A&P, 12th edition, 2010

24. Where Would You Rather Be?
“Spread out, would ya!?”

25. Facilitated Diffusion
Figure from: Hole’s Human A&P, 12th edition, 2010
diffusion across a membrane with the help of a channel or carrier molecule
e.g, transport of glucose across cell membrane
BUT…still from a region of higher concentration to a region of lower concentration

26. Factors Influencing Diffusion Rates
Distance (shorter is faster)
Gradient size (bigger difference in concentration is faster)
Molecule size (smaller is faster)
Temperature (warmer is faster)
Electrical forces (repulsion is better)
In the body, diffusion distances are typically limited to a maximum of about 125 µm

27. Diffusion and the Cell Membrane
Carrier/channel proteins required for all but fat-soluble molecules and small uncharged molecules
oxygen, carbon dioxide and other lipid-soluble substances diffuse freely through the membrane

28. Osmosis (Special case of passive diffusion)
movement of water (solvent) through a selectively permeable membrane from regions of higher water concentration to regions of lower water concentration
*water moves toward a higher concentration of solutes

29. Osmotic Pressure/Tonicity
Osmotic Pressure (Osmolarity) – ability of solute to generate enough pressure to move a volume of water by osmosis
*Osmotic pressure increases as the number of nonpermeable solutes particles increases
isotonic – same osmotic pressure as a second solution
hypertonic – higher osmotic pressure
hypOtonic – lower osmotic pressure
0.9% NaCl 5.0% Glucose
Crenation
The O in hypotonic

30. Filtration smaller molecules are forced through porous membranes
hydrostatic pressure important in the body
molecules leaving blood capillaries
Think ‘sprinkler hose’

31. Active Transport
carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration, i.e., against a concentration gradient
sugars, amino acids, sodium ions, potassium ions, etc.
Active transport is a physiological process since it requires cellular energy

32. Endocytosis and Exocytosis
cell engulfs a substance by forming a vesicle around the substance
three types
pinocytosis – substance is mostly water
phagocytosis – substance is a solid
receptor-mediated endocytosis – requires the substance to bind to a membrane-bound receptor

33. Lecture Review The cell is
The structural and functional unit of all living matter
Smallest body structure that can perform the functions of ‘life’
Cells must specialize and differentiate, e.g., neurons (nerve cells) and muscle cells
All eukaryotic cells have several major components in common
Nucleus
Cell membrane
Cytosol
Organelles
Inclusions

34. Lecture Review TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION
GRADIENT
GENERAL
DESCRIPTION
EXAMPLE IN
HUMANS
SIGNIFICANCE
SIMPLE
DIFFUSION NO
[HIGH] TO
[LOW]
spreading out of molecules to equilibrium
O2 into cells; CO2 out of cells.
Cellular
Respiration
FACILITATED DIFFUSION
Using a special cm carrier protein to move something through the cell membrane (cm)
Process by which glucose enters cells
OSMOSIS
water moving through the cm to dilute a solute
maintenance
of osmotic pressure of 0.9%.
Same
FILTRATION
using pressure to push something through a cm (sprinkler hose)
manner in which the kidney filters things from blood
removal of metabolic wastes

35. Lecture Review TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION
GRADIENT
GENERAL
DESCRIPTION
EXAMPLE IN
HUMANS
SIGNIFICANCE
ACTIVE TRANSPORT
YES
[LOW] TO
[HIGH]
opposite of diffusion at the expense of energy
K+-Na+-ATPase pump
maintenance of the resting membrane potential
ENDOCYTOSIS
bringing a substance into the cell that is too large to enter by any of the above ways;
Phagocytosi: cell eating;
Pinocytosis: cell drinking.
Phagocytosed (foreign) particles fuse with lysosomes to be destroyed
help fight infection
EXOCYTOSIS
expelling a substance from the cell into ECF
Exporting proteins; dumping waste
Same