A&p Lecture 2:

Front 1

Robert Hooke

Back 1

- His research became the basis for cell theory

- He viewed slices of cork under a light microscope

(found millions of small, irregular units reminding him of small prison cells --> the term "cell")

Front 2

Cell Theory

Back 2

1. Cells are the building blocks of all plants and animals

2. All cells come from the division of preexisting cells
-- (Cells come from other cells by either mitosis or meiosis)

3. Cells are the smallest units that perform all vital physiological functions.

4. Each cells maintains homeostasis at the cellular level.

Front 3

Cytology

Back 3

the study of cells

(the study of cellular structure and function)

Front 4

Two Classes of Cells in the Human Body:

Back 4

1. Somatic cells

2. Sex cells

Front 5

Somatic cells

Back 5

all body cells except sex cells

Front 6

"Soma"

Back 6

body

Front 7

Sex cells

Back 7

Germ cells or reproductive cells

Male sex cells: sperm

Female sex cells: oocyte

Front 8

Oocyte

Back 8

a cell that develops into an egg

Front 9

Extracellular Fluid

Back 9

Interstitial Fluid

A watery medium that surrounds a cell

Front 10

Plasma Membrane (cell membrane)

Back 10

- separates the inside of the cell (cytoplasm) from the extracellular fluid (outside)

- Extremely Thin
- Contains lipids, proteins, and carbohydrates

Front 11

Cytoplasm

Back 11

the REGION of the cell found between the plasma membrane and the nuclear membrane

Front 12

Cytosol

Back 12

the liquid component of the cytoplasm

(the liquid inside the "region")

Front 13

Organelles

Back 13

Intracellular structures

Front 14

Functions of the Plasma Membrane

Back 14

1. Physical Isolation
2. Regulation of Exchange with the Environment
3. Sensitivity to the Environment
4. Structural Support

Front 15

Physical Isolation

Back 15

(a function of the Plasma Membrane)

physical barrier separating the inside of the cell from the outside environment

Front 16

Regulation of Exchange with the Environment

Back 16

(a function of the Plasma Membrane)

Can Regulate:
-- Entry of ions and nutrients
-- Elimination of Wastes and cellular products
-- Release of secretions (occurs by exocytosis)

Front 17

Sensitivity to the Environment

Back 17

(a function of the Plasma Membrane)

-- Extracellular fluid composition can alter plasma membrane

-- Can detect chemical signals through plasma receptors (proteins)

Front 18

Structural Support

Back 18

(a function of the Plasma Membrane)

Anchors cells and tissues to each other or to the extracellular matrix - provides stability to cells

Front 19

The Plasma Membrane is Composed of:

Back 19

1. Membrane Lipids

2. Membrane Proteins

3. Membrane Carbohydrates

Front 20

Membrane Lipids

Back 20

- largest component of the plasma membrane
- 42% of the weight
- fluid at body temperature

Consists of the Phospholipid Bilayer

Front 21

Phospholipid Bilayer

Back 21

- 2 layers of phospholipids (hydrophilic heads and hydrophobic tails)

- Forms a barrier to ions and water-soluble compounds

- Allows for the interior of the cell to have a different composition that the extracellular environment

(gases can diffuse bilayer easily through simple diffusion but charged ions or large particles cannot pass)

Front 22

Hydrophilic

Back 22

- Water Loving

- The heads of the phospholipids

- Face toward the watery environment on both sides of the bilayer

Front 23

Hydrophobic

Back 23

- Water Hating/Avoiding

- The fatty-acid tails of the phospholipid

- Inside membrane, away from water

Front 24

Membrane Proteins

Back 24

- second largest component of the plasma membrane
- 55% of the weight (denser than lipids)

- Two Classes

** May be located at specific locations on the cell, inside leaf or outside leaf

Front 25

Classes of Membrane Proteins:

Back 25

1. Integral Membrane Proteins

2. Peripheral Membrane Proteins

Front 26

Integral Membrane Proteins

Back 26

- Found embedded within the membrane.
(part of the membrane structure and cannot be
removed without damaging or destroying the
membrane)

- It is transverses (crosses) the width of the plasma membrane it is a transmembrane protein

- More integral proteins than peripheral proteins

Front 27

Transmembrane Protein

Back 27

Integral proteins that span the width of the membrane one of more times

Front 28

Peripheral Proteins

Back 28

- Bound to inner OR outer surface of the plasma
membrane
(Bound to only one side of bilayer)

- less numerous than integral proteins

- easily separated from membrane

Front 29

Functions of Membrane Proteins:

Back 29

1. Receptor Proteins
2. Carrier Proteins
3. Channels
4. Anchoring Proteins
5. Recognition Proteins
6. Enzymes

Front 30

Receptor Proteins

Back 30

- Bind and respond to ligands

- Binding of the ligand can cause a change within the cell

- sensitive to the presence of ligands --> trigger changes in the activity of the cell

Front 31

Ligand

Back 31

Specific extracellular molecules

Ex: ions, hormones

Front 32

Carrier Proteins

Back 32

-Transport specific solutes through membrane
(by binding to solutes and carrying it in/out of cell)

- May or may not require energy (ATP)

Front 33

Transport Requiring Energy

Back 33

Active Transport

Ex: Sodium and Calcium transport

Front 34

Transport that Doesn't Require Energy

Back 34

Passive Transport

Ex: Glucose transport

Front 35

Channels

Back 35

- Integral protein that has a central pore (channel)

- Regulate water flow and solutes through membrane
- Many channels are HIGHLY SPECIFIC for a specific ion

** Extremely important in nerve impulse conduction and muscle contraction

Front 36

Anchoring Proteins

Back 36

** STABILIZERS

- Attach to inside (cytoskeletal) or outside (extracellular protein fibers or other cells) structures

- Stabilizes the cell

(attach the plasma membrane to other structures inside or out of the cell and stabilize its position)

Front 37

Cytoskeleton

Back 37

a network of supporting filaments in the cytoplasm

Front 38

Recognition Proteins

Back 38

** IDENTIFIERS

- Label cells as normal or abnormal --> prevents the immune system from reacting tot he cell
(the presence/absence of recognition proteins --> labeling)

- Many recognition proteins are Glycoproteins

Front 39

Enzymes

Back 39

- can be integral or peripheral proteins

- Catalyze reactions inside or outside the cell
(depends on the location of the protein and its active site)

Front 40

Rafts

Back 40

areas that mark the location of anchoring proteins and some kinds of receptor proteins that are embedded and confined to specific areas of the plasma membrane

Front 41

Membrane Carbohydrates

Back 41

- Extend outside the cell membrane

- Form a layer of sticky "sugar coat" (glycocalyx)

Front 42

Types of Membrane Carbohydrates:

Back 42

1. Proteoglycans

2. Glycoproteins

3. Glycolipids

Front 43

Functions of Glycocalyx:

Back 43

1. Lubrication and Protection

2. Anchoring and Locomotion

3. Specificity in Binding (receptors)

4. Recognition (immune response)

Front 44

Membrane Transport

Back 44

Movement of material into and out of a cell

The plasma (cell) membrane is a barrier but:
- Nutrients must get in
- Products and waste must get out

** Can be active or passive transport

see pg. 95

Front 45

Permeability

Back 45

- Determines what moves in and out of a cell/cytoplasm

Front 46

Impermeable

Back 46

A membrane that lets nothing in or out`

Front 47

Freely Permeable

Back 47

A membrane that lets ANY substance pass without difficulty

Front 48

Selectively Permeable

Back 48

- Restricts movement

- permits the free passage of some materials and restricts the passage of others

Ex: the plasma membrane

Front 49

Selective Permeability is Based on Which Factors?

Back 49

1. Size of the material
- large materials such as proteins take a lot of energy
and are harder to move out of cell
2. Electrical Charge
- inside of cell is - charge (- proteins) so + ions flow into
cell easier than - ions (opposites attract)

3. Molecular Shape
4. Lipid Solubility
- Correlation between drug potency and lipid solubility
-- The more soluble a drug is the easier it will pass a
membrane
-- Ex: Anesthetics such as Chloroform, ether can
bypass membrane

Front 50

Active Transport

Back 50

requires energy (ATP)

Front 51

Passive Transport

Back 51

no energy required

Front 52

Types of Transport:

Back 52

1. Diffusion (passive)

2. Carrier-mediated Transport (passive or active)

3. Vesicular Transport (active)

Front 53

Diffusion

Back 53

*PASSIVE
** the movement of solutes across a membrane

- Results from the random motion and collisions of ions and molecules
- The net movement of a substance from an area of higher concentration to an area of lower concentration

- All molecules are constantly in motion
- Molecules in solution move RANDOMLY


Works to eliminates the concentration gradient

water and dissolved solutes diffuse freely

Front 54

Concentration of a Solution:

Back 54

The amount of solute (dissolved substance) in a solvent (liquid component)

Front 55

Concentration Gradient

Back 55

- The difference between the concentration of solute at one area compared to another

- a potential energy gradient
- drives diffusion

Front 56

Factors Influencing Diffusion:

Back 56

1. Distance
- The distance the particle has to move
- The more it has to move, the slower the rate

2. Molecule Size
- Smaller --> faster

3. Temperature
- More heat --> faster

4. Concentration Gradient
- The greater the concentration difference, the faster
the diffusion

5. Electrical Forces
- Opposites attract
- Like charges repel

Front 57

Factors That Speed Up Diffusion:

Back 57

1. Short distance
2. Small molecule size
3. High temperature
4. Large concentration gradient
5. Opposite charges

Front 58

Ways to Diffuse across Plasma Membranes

Back 58

1. Cross the lipid portion of the membrane

2. Pass through a membrane channel

Front 59

Diffusion across Plasma Membranes

Back 59

- Can be "simple" or "channel-mediated"

Front 60

Simple Diffusion

Back 60

- materials diffuse through the lipid portions of the plasma membrane

Front 61

Substances that use Simple Diffusion:

Back 61

1. Lipid-soluble compounds:
- Alcohols
- Fatty Acids
- Steroids

2. Dissolved Gases
- Oxygen
- Carbon Dioxide

Front 62

Channel-Mediated Diffusion

Back 62

- Small passageways created by transmembrane proteins

- Transport water-soluble compounds and ions

Front 63

Factors in Channel-Mediated Diffusion:

Back 63

1. Size:
- only small molecules and ions

2. Charge:
- specifically + or -

3. Interaction with channel:
- Leak (passive) channels

Front 64

Leak Channels:

Back 64

*passive channels

- are ALWAYS open and will allow for the passage of ions in either direction
- Net flow of ions is from high --> low concentrations

Front 65

Osmosis

Back 65

the diffusion of water across a (selectively permeable) cell membrane

(moves from areas of high concentration --> low concentration)

Front 66

For Osmosis to Occur:

Back 66

1. Membrane must be freely permeable to water, and
selectively permeable to solutes

2. Water molecules diffuse across membrane toward
solution with MORE solutes (b/c concentration of water
is lower)
- More solute molecules = lower concentration of H2O
- As H2O moves to that side, the volume increases (on
the side with more solutes to "dilute" it to the same
concentration as the concentration on the other side)

Front 67

Osmotic Pressure

Back 67

the force with which pure water moves into a solution as a result of its solute concentration

Front 68

Hydrostatic Pressure

Back 68

Applied force to counter the increase in H2O volume on the opposite side (pushing against a fluid)

need hydrostatic pressure to stop osmosis
-- the amount of pressure needed = osmotic pressure

Front 69

Osmolarity

Back 69

the total solute concentration in an aqueous solution

total solute concentration

Front 70

Tonicity

Back 70

effect of the osmotic solution on cells

(how the solution affects a cell)

Front 71

The Osmotic Effect of a Solute on a Cell:

Back 71

Two fluids may have = osmolarity but different tonicity

Front 72

Isotonic

Back 72

a solution that DOES NOT cause osmotic flow of water in or out of a cell

Ex: normal saline (NaCl)

Front 73

"iso- "

Back 73

same

Front 74

"tonos"

Back 74

tension

Front 75

Hypotonic

Back 75

has less solutes and LOSES water through osmosis

Front 76

"hypo-"

Back 76

below

Front 77

Hypertonic

Back 77

has more solutes and GAINS water by osmosis

Front 78

"hyper-"

Back 78

above

Front 79

A cell in a Hypotonic Solution:

Back 79

1. Gains Water (Swells)

2. Ruptures (if left unchecked)

Ex: hemolysis of RBC's

Front 80

Crenation

Back 80

shrinking of RBC's

Front 81

A cell in a Hypertonic Solution:

Back 81

1. Loses Water (shrivels and dehydrates)

2. Shrinks

Ex: Crenation of RBC's

Front 82

Hemolysis

Back 82

rupturing of RBC's

Front 83

A cell in an Isotonic Solution

Back 83

no osmotic flow occurs

Front 84

How to Treat Severe Blood Loss

Back 84

1. 0.9% NaCl solution
- isotonic to body cells

2. Dextran
- alternative treatment
- cannot cross membranes
- Increases blood volume and pressure by causing
osmosis of H2O from tissues into blood

Front 85

Carrier-Mediated Transport

Back 85

- moves ions and organic substrates

- requires specialized integral membrane proteins
(proteins bind specific ions/substrates and carry them
across membrane)
- can be passive or active

Front 86

Characteristics of Carrier-Mediated Transport:

Back 86

1. Specificity
- One transport protein, one set of substrates
- will only bind and transport a specific substance

2. Saturation Limits
- Rate depends on transport proteins, not substrate
- Availability of carrier proteins limits rate of transport
- Saturated

3. Regulation
- Cofactors such as hormones
- regulates function

Front 87

Saturation

Back 87

- When all the available carrier proteins are operating at maximum speed

- The rate of transport can't increase, regardless of the size of the concentration gradient

Front 88

Types of Carrier-Mediated Transport:

Back 88

1. Co-transport (symport)

2. Counter-transport (antiport)

Front 89

Cotransport

Back 89

*symport

- transports two substances in the same direction simultaneously

Front 90

Countertransport

Back 90

one substance moves into cell while another moves out

Front 91

Facilitated Diffusion

Back 91

- carrier-mediated transport that does NOT use energy

- Transports molecules too large to fit through channel
proteins
-- Ex: glucose; amino acids
-- Molecules bid to carrier protein's specific receptor
site
-- Protein changes shape to move molecules across
membrane

Front 92

Active Transport

Back 92

- carrier-mediated transport that REQUIRES energy (ATP)

- move substrates against concentration gradient

*Can be primary or secondary

Front 93

Types of Primary Active Transporters:

Back 93

1. Ion Pumps

2. Exchange Pumps

Front 94

Ion Pump

Back 94

- move ions (Na+, K+, Ca2+, Mg2+)

- can be used to create an ion gradient

(work to concentrate ions on one side to cause a function to occur)

Front 95

Exchange Pump

Back 95

- counter-transports two ions at the same time

Ex: Na+/K+ pump uses 1 ATP to move 3 Na+ out and 2 K+ in

Front 96

Secondary Active Transport

Back 96

Transport mechanism itself does not require energy from ATP, but the cell often needs to use ATP at a later time to preserve homeostasis.

Moves one specific substrate down its concentration gradient while moving another at the same time, regardless of its gradient (free ride)

Ex: sodium-linked cotransport

Front 97

Vesicular Transport

Back 97

*Bulk Transport

Materials move into or out of the cell in vesicles

Two Categories:
1. Endocytosis
2. Exocytosis

Front 98

Vesicles

Back 98

small membranous sacs that form at, or fuse with, the plasma membrane

Front 99

Endocytosis

Back 99

Active transport using ATP

extracellular materials packaged in vesicles at the cell surface and imported into the cell

(involves large volumes of extracellular material)

Front 100

Types of Endocytosis:

Back 100

1. Receptor Mediated:
- highly selective

2. Pinocytosis
- not selective (no receptors involved)

3. Phagocytosis
- performed by specialized cells such as macrophages

Front 101

Endosomes

Back 101

endocytic vesicles

Front 102

Pinosomes

Back 102

endosomes formed by pinocytosis

Front 103

Phagosomes

Back 103

endosomes formed by phagocytosis

Front 104

Receptor-Mediated Endocytosis:

Back 104

- Receptors (glycoproteins) bind specific target molecules (ligands) in high concentrations

- Coated vesicle (endosome) carries ligands and receptors into cell where it fuses with a lysosome to release the ligands into the cytoplasm of the cell

see pg. 93

Front 105

Pinocytosis

Back 105

"cell drinking"

the formation of endosomes filled with extracellular fluid
(endosomes "drink" extracellular fluid)

not selective (no receptor proteins)
- targets the fluid contents in general instead of specific ligands

Front 106

Phagocytosis

Back 106

"cell eating"

- produces phagosomes containing solid objects that may be as large as the cell itself

- Pseudopodia surround target object
- Fusion of pseudopodia membrane engulf large objects
in phagosomes (enzymes digest its contents)

- Performed only by specialized cells
Ex: Macrophages (protect tissues by engulfing bacteria,
debris, and abnormal materials)

Front 107

"pseudo"

Back 107

false

Front 108

"pod"

Back 108

foot

Front 109

Exocytosis

Back 109

- Granules or droplets are released from the cell
- Essentially the reverse of endocytosis

- Vesicle created inside the cell fuses with plasma membrane --> releases contents into extracellular environment

Front 110

"exo"

Back 110

outside