Human Physiology U2 Exam Review

What do receptor proteins do?

Receive and transmit messages into the cell

What do integral proteins do?

Form specialized doorways for specific molecules

What are Cellular Adhesion Molecules?

• Desmosomes or gap junctions

• Associated with Contact Dependent Signals

• Basically the process of a ligand binding to a receptor

• Allow cells to stick to each other to let small molecules move from one cytoplasm to another

What are tight junctions?

• Designed to restrict movement of material between cells

• Cells link by fusing with proteins claudins and occludins

What are antigens made of?

Carbohydrate chains

List and describe the types of passive transportation

• Osmosis

• Filtration

• Facilitated diffusion

List and describe the kinds of active transportation

• Endocytosis: gets things in - general

• Exocytosis: gets things out

• Phagocytosis: Cell eating - focuses on large molecules

• Pinocytosis: Cell drinking - focuses on fluids and dissolved solutes

What is Fick’s Law of Simple Diffusion?

Movement of particles from high to low concentration is directly proportional to its concentration gradient

• Surface area, concentration gradient, and membrane permeability/membrane thickness

What does passive vs. active transport mean?

Passive requires 0 ATP, active requires ATP

Both use proteins

What does filtration use?

Uses hydrostatic pressure to move from high concentration to low

What does facilitated diffusion use?

Carrier proteins and kinetic energy

Describe the basics of diffusion

• Molecules move from high to low concentrations passively

• Movement of molecules occurs until the concentration is equal everywhere (entropy)

• Can take place in an open system or across a partition (kidneys)

What is lipophilic diffusion and what are its caveats?

• The diffusion of fat-loving molecules across a membrane

• Depends on the ability of the molecule to dissolve in the lipid inner layer of the membrane

• Surface area is proportional to diffusion rate, and molecule size + membrane thickness is inverse

What molecules is channel protein diffusion usually limited to?

Water and ions

What is the only thing that can achieve equilibrium?

Water

What are Cannon’s Four Postulates?

• Nervous regulation of internal environment (fight or flight)

• Tonic level of activity (tuning up/down to meet the needs your body has dependent on the situation it is in: bronchial dilation)

• Antagonistic controls (insulin and glucagon, calcatonin and parathyroid hormone)

• Chemical signals affect different tissues (adrenalin of eyes in fight or flight)

What are the 5 general characteristics of homeostasis?

• Receptor

• Afferent/sensory pathway

• Integrating/control center

• Efferent/motor pathway

• Effector/target

What is a practical application of gap junctions?

• Intercalated discs of cardiac tissue communicate improperly in a atrial fibrulation patient. With meds, the communication can be accurate and in sync, due to correct timing of chemical/electrical signals

• A heart attack could occur if a-fib is in a ventricle

List and describe the two kinds of membrane transporters

• Carrier proteins: Shifts/twists its shape to move a molecules

• Channel proteins: Open channels = Gap junctions, gated channels = mechanically, chemically, or electrically gated. Mechanically gated are channels that need to be physically deformed in order to allow messages to pass

What activates membrane enzymes?

Membrane receptors. They allow for membrane enzymes to have specific roles in signal transfer and receptor mediated endocytosis.

What are the modulations of signal pathways?

• Specificity: Multiple ligands for 1 receptor or vice versa. Ex: Agonists and antagonists

• Competition: Defects in signal transduction can cause disease.

• Saturation: Receptors can be up/down regulated. Ex: Drug tolerance that leads to overdose

What is a practical application of competitive signal pathway modulation?

• Beta blockers are used for a-fib patients because they block the release of a subunit, blocking too much Ca+ from releasing at once, causing the heart to contract a normal amount