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PUBH 6011: Week 7 Latest Update Exam | Questions and
Verified Answers | 100% Correct | Grade A +
Absorption - ANSWER All pollutants must cross a cellular
membrane barrier to enter the body; influenced by the
membrane barrier
Membrane barrier - ANSWER Made of phospholipids and
proteins; influences absorption; uncharged (hydrophobic
molecules can cross), most charged (polar) molecules are
excluded; protein channels and pores facilitate absorption of
some materials
Passive diffusion - ANSWER Transfer across the membrane with
no energy needed; follows concentration gradient; depends on
size, hydrophobicity, and ionization; small, hydrophobic
molecules can readily cross
Hydrophobicity - ANSWER Have no charges; don't interact with
and dissolve in water
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Ionization - ANSWER When molecules have a charge that stops
them from crossing membranes by passive diffusion
Facilitated diffusion - ANSWER Works via protein pores or
carrier proteins; extend an direction determined by
concentration gradients; often for essential nutrients
Active transport - ANSWER Requires energy (ATP) to move
molecules across membrane; usually transport against
concentration gradient (from low to high); transport proteins
for specific molecules
Membrane barriers - ANSWER Stomach, small intestine, large
intestine, different pH environments, skin, lungs
Skin - ANSWER All passive diffusion; factors like thickness and
amount of hair can influence absorption
Lungs - ANSWER Gases and vapors are primarily absorbed
through passive diffusion; aerosols and particles are absorbed
depending on size (sometimes absorbed through phagocytosis
by alveolar macrophages go to lymphatic system, not blood)
PUBH 6011: Week 7 Latest Update Exam | Questions and
Verified Answers | 100% Correct | Grade A +
Absorption - ANSWER All pollutants must cross a cellular
membrane barrier to enter the body; influenced by the
membrane barrier
Membrane barrier - ANSWER Made of phospholipids and
proteins; influences absorption; uncharged (hydrophobic
molecules can cross), most charged (polar) molecules are
excluded; protein channels and pores facilitate absorption of
some materials
Passive diffusion - ANSWER Transfer across the membrane with
no energy needed; follows concentration gradient; depends on
size, hydrophobicity, and ionization; small, hydrophobic
molecules can readily cross
Hydrophobicity - ANSWER Have no charges; don't interact with
and dissolve in water
, 2|Page
Ionization - ANSWER When molecules have a charge that stops
them from crossing membranes by passive diffusion
Facilitated diffusion - ANSWER Works via protein pores or
carrier proteins; extend an direction determined by
concentration gradients; often for essential nutrients
Active transport - ANSWER Requires energy (ATP) to move
molecules across membrane; usually transport against
concentration gradient (from low to high); transport proteins
for specific molecules
Membrane barriers - ANSWER Stomach, small intestine, large
intestine, different pH environments, skin, lungs
Skin - ANSWER All passive diffusion; factors like thickness and
amount of hair can influence absorption
Lungs - ANSWER Gases and vapors are primarily absorbed
through passive diffusion; aerosols and particles are absorbed
depending on size (sometimes absorbed through phagocytosis
by alveolar macrophages go to lymphatic system, not blood)
