Other Modes of Transport: Facilitated Diffusion and Active

Transport

Campbell 5.17-5.21

What are plasma membranes made of?

Membrane Structure• Made mostly of phospholipids• These form a phospholipid bilayer

Phosphate groupPolarHydrophilic Head

Fatty AcidNon-polarHydrophobic Tails

Large items and ions can’t cross membrane without gates!

Types of Membrane Transport

1. Simple Diffusion• Does NOT require energy• High to low concentration

2. Facilitated diffusion• Does NOT require energy• High to low concentration• A membrane protein is needed

3. Active transport • Requires energy• Low to high concentration• A membrane protein is needed

Passive Transport – No energy

Active Transport – requires energy

Passive transport

Types of Membrane Transport

Types of Transport Proteins•Non-specific transporter• Specific transporter

Aquaporins – facilitated diffusion- water is polar; won’t move on its own- aquaporin – pores that allow movement of water through channel protein

• Review protein structure

How glucose enters a cell- specific glucose transporter- facilitated diffusion – High to low – no energy!

What model of protein binding is this?

Active Transport – requires energy

Sodium-Potassium Pump

Bulk Transport – large amounts of substances cross the membrane

• Release to outside• Wastes, hormones,

signals

Endocytosis• Phagocytosis (eat)• Pinocytosis (drink)

Exocytosis

Animation

Ex. Phagocytosis

Video clip

part 3

Arteries transport blood away from the heart.

Veins transport blood towards the heart.

Capillaries transport gasses, nutrients, and waste into and out of the blood stream.

Show me what would happen if this is a capillary bed in the muscle tissues of a dehydrated person.

1. Exchange with cells or outside environment?

2. Nutrients, waste, O2, CO2, H2O?

Form suits function

Transport in the circulatory system

Circulatory system overview

Two hearts in one

Arteries

Capillaries (tissues)

Veins

Heart

Pulmonary circuit

Systemic circuit OxygenatedDeoxygenated

LV

RV

RA

LA

Capillaries (lungs)

ArteriesVeins

Human circulation

Alveoli are the site of gas exchange in the lungs.

Why so many?