Overview of A&P1 Labs

• Lab Syllabus

• Text is lab manual – bring it to each lab

• Web of Life – Lab Worksheets/Resources

• Quizzes – weekly, oral/written format– Do not be late – questions not repeated– No Make-ups– 12 taken, 10 best averaged

• Work as a team with your table

• Access to Lab

• Clean up MDufilho

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Lab 1

• Membrane transport processes

• Body Cavities, Abdominopelvic Quadrants, and Organs

• Organ locations

• Directional Terminology

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Membrane Transport Processes

• What membrane are we talking about?

• Why is it important to transport materials across the membrane?

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Membrane Transport

• Plasma membranes selectively permeable– Some molecules pass through easily; some

do not

• Two ways substances cross membrane– Passive processes– Active processes

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Types of Membrane Transport

• Passive processes– No cellular energy (ATP) required– Substance moves down its concentration

gradient

• Active processes– Energy (ATP) required– Occurs only in living cell membranes

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Passive Processes

• Two types of passive transport– Diffusion

• Simple diffusion• Carrier- and channel-mediated facilitated diffusion• Osmosis

– Filtration• Usually across capillary walls

• The ones we will do in lab today are diffusion, osmosis and filtration

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Passive Processes: Diffusion

• Collisions cause molecules to move down or with their concentration gradient – Difference in concentration between two

areas

• Speed influenced by molecule size and temperature

• This can occur in a air, water and even though a membrane

• Video clip

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PLAYPLAY Animation: Membrane Permeability

Passive Processes

• Molecule will passively diffuse through membrane if– It is lipid soluble

• oxygen, carbon dioxide

– Small enough to pass through membrane channels

– Assisted by carrier molecule

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Figure 3.7a Diffusion through the plasma membrane.

Extracellular fluid

Lipid-solublesolutes

Cytoplasm

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Passive Processes: Osmosis

• Movement of solvent (e.g., water) across selectively permeable membrane

• Water diffuses through plasma membranes– Through lipid bilayer– Through specific water channels called

aquaporins (AQPs)

• Occurs when water concentration different on the two sides of a membrane

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Figure 3.7d Diffusion through the plasma membrane.

Osmosis, diffusion of a solvent such as water through a specific channel protein (aquaporin) or through the lipid bilayer

Watermolecules

Lipidbilayer

Aquaporin

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Passive Processes: Osmosis

• Water concentration varies with number of solute particles because solute particles displace water molecules

• Osmolarity - Measure of total concentration of solute particles

• Water moves by osmosis until hydrostatic pressure (back pressure of water on membrane) and osmotic pressure (tendency of water to move into cell by osmosis) equalize

• Osmosis Video

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Passive Processes: Osmosis

• When solutions of different osmolarity are separated by membrane permeable to all molecules, both solutes and water cross membrane until equilibrium reached

• When solutions of different osmolarity are separated by membrane impermeable to solutes, osmosis occurs until equilibrium reached

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Figure 3.8a Influence of membrane permeability on diffusion and osmosis.

Membrane permeable to both solutes and water

Solute and water molecules move down their concentration gradientsin opposite directions. Fluid volume remains the same in both compartments.

Leftcompartment:

Rightcompartment:

Solution withlower osmolarity

Solution with greater osmolarity

Both solutions have thesame osmolarity: volumeunchanged

Solute

Freelypermeablemembrane

Solutemolecules(sugar)

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Figure 3.8b Influence of membrane permeability on diffusion and osmosis.

Membrane permeable to water, impermeable to solutes

Solute molecules are prevented from moving but water moves by osmosis.Volume increases in the compartment with the higher osmolarity.

Both solutions have identicalosmolarity, but volume of thesolution on the right is greaterbecause only water is free to move

Leftcompartment

Rightcompartment

Selectivelypermeablemembrane

Solutemolecules(sugar)

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Tonicity

• Tonicity: Ability of solution to alter cell's water volume– Isotonic: Solution with same non-penetrating

solute concentration as cytosol– Hypertonic: Solution with higher non-

penetrating solute concentration than cytosol– Hypotonic: Solution with lower non-

penetrating solute concentration than cytosol

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Figure 3.9 The effect of solutions of varying tonicities on living red blood cells.

Isotonic solutions

Cells retain their normal size andshape in isotonic solutions (same

solute/water concentration as insidecells; water moves in and out).

Cells lose water by osmosis and shrink in a hypertonic solution (contains a

higher concentration of solutes than are present inside the cells).

Cells take on water by osmosis until theybecome bloated and burst (lyse) in a hypotonic solution (contains a lower

concentration of solutes than are present inside cells).

Hypertonic solutions Hypotonic solutions

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Lab 1 - Procedure

• Start Osmosis procedure A or B – not both – takes about an hour to complete

• Start diffusion demo – takes about 30 min to complete

• Group Work – I hr– Learn internal organs/ abdominopelvic

quadrants with mannequins– Learn Directional Terminology

• Start filtration demo• Read results of osmosis and diffusion demos

and answer questions

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