Human A&PBIO 304 · American River College ← Week 05 pre-work

BIO 304 · Week 05 · Interactive Workbook

Hormone Mechanisms

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Part 1 of 4 · Recall

Fill in the blanks

Type the term that completes each statement, using the word bank. Pull it from memory first.

Word bank

ExamplesGPCR → IP₃ / DAG / Ca²⁺Response speedReceptor-hormone complexAmplificationExamplesHumoralReceptor locationPositive feedbackNeuralResponse speedReceptor locationAutocrineUp-regulationEndocrine

  1. insulin, glucagon, growth hormone, ADH, oxytocin, epinephrine, TSH
  2. on cell surface
  3. fast (seconds to minutes)
  4. cortisol, aldosterone, estrogen, testosterone, vitamin D, T₃/T₄
  5. intracellular (cytoplasm or nucleus)
  6. slow (hours)
  7. hormone travels via blood to distant target
  8. acts on the cell that secreted it
  9. alpha-1 receptor; vasoconstriction
  10. one hormone → many enzymes → thousands of products
  11. enters nucleus; binds hormone response element on DNA
  12. response to ion or nutrient level (parathyroid senses Ca²⁺)
  13. nerves stimulate gland (sympathetic to adrenal medulla)
  14. rising hormone amplifies release (LH surge at ovulation)
  15. low hormone → more receptors expressed

Define it: high-yield vocabulary

Write a clear definition in your own words for each term.

  1. Endocrine signaling
  2. Paracrine signaling
  3. Autocrine signaling
  4. Steroid hormone
  5. Peptide hormone
  6. Second messenger (cAMP)
  7. Membrane vs intracellular receptor
  8. Negative feedback
  9. Positive feedback
  10. Up-regulation
  11. Down-regulation
  12. Permissiveness

Part 2 of 4 · Anatomy lab

Draw and label

Box A. Steroid hormone mechanism

Directions

  1. Draw a target cell with its plasma membrane, cytoplasm, and nucleus visible.
  2. Outside the cell, draw a steroid hormone (small ring structure, label e.g., cortisol or estrogen).
  3. Show the hormone crossing the plasma membrane (it's lipid-soluble, so it passes directly through).
  4. Inside the cytoplasm, show the hormone binding an intracellular receptor protein. Label receptor.
  5. Show the hormone-receptor complex moving into the nucleus.
  6. Inside the nucleus, show the complex binding DNA at a specific gene. Label DNA, gene.
  7. Show transcription starting, then mRNA leaving the nucleus, then a new protein being made on ribosomes in the cytoplasm.
  8. Note: response takes hours (gene transcription is slow), but effects last long.
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Box B. Peptide hormone mechanism

Directions

  1. Draw a target cell with its plasma membrane and cytoplasm.
  2. Outside the cell, draw a peptide hormone (chain structure, label e.g., insulin or glucagon).
  3. Show the hormone binding to a receptor on the OUTSIDE of the plasma membrane (it cannot cross). Label the membrane receptor.
  4. Show the receptor activating a G-protein on the inside of the membrane. Label G-protein.
  5. Show the G-protein activating an enzyme (e.g., adenylyl cyclase), which converts ATP to cAMP. Label the second messenger cAMP.
  6. Show cAMP activating protein kinase A, which phosphorylates target proteins inside the cell, changing their activity.
  7. Note: response is rapid (seconds to minutes), and amplification means one hormone produces many cellular changes.
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Structures to label

Label each on your drawing.

  1. Steroid hormone
  2. Plasma membrane (lipid-soluble crosses)
  3. Cytoplasmic receptor
  4. Hormone-receptor complex
  5. Nucleus
  6. DNA
  7. Gene transcription
  8. mRNA
  9. Peptide hormone
  10. Membrane receptor
  11. G-protein
  12. Adenylyl cyclase
  13. cAMP (second messenger)
  14. Protein kinase A

Part 3 of 4 · Physiology lab

Reason it through

A. Steroid vs peptide comparison

Peptide hormones use second messengers (cAMP, IP3, Ca-squared-plus, etc.) to amplify their signal. Explain why amplification is important for water-soluble hormones acting at low concentrations.
Steroid hormones often produce long-lasting effects (hours to days). Explain mechanistically why steroid effects outlast peptide effects, and why steroid pulses are slower than peptide pulses.

B. Synthesis

1. Cortisol (a steroid) and epinephrine (a peptide-like catecholamine) both raise blood glucose during stress. Compare their speeds of action and durations, and explain why the body uses both.
2. A patient takes oral prednisone (a synthetic steroid) for several weeks, then suddenly stops. They become very ill (Addisonian crisis). Explain mechanistically why abrupt steroid withdrawal is dangerous, in terms of feedback to the hypothalamus and pituitary.
3. Insulin is a peptide and CANNOT be taken orally. Explain mechanistically why oral insulin doesn't work, while a steroid hormone like prednisone CAN be taken orally.

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