Endocrine System Quiz

Endocrine System Overview

• The endocrine system is a collection of glands that secrete hormones directly into the bloodstream.
• Hormones are chemical messengers that regulate various bodily functions.
• Hormones travel through the bloodstream to target tissues with specific receptors.
• The interaction between hormones and receptors triggers specific biochemical changes and activates genes.

Key Questions About Hormones

• Hormones are produced by glands and secreted into the blood.
• Hormones travel through the blood to target tissues with specific receptors.
• Hormones interact with receptors, triggering biochemical changes and activating genes for various biological responses.

How Hormones Work

• Genomic Effects: Hormones bind to receptors inside cells, changing gene activity for long-term effects.
• Nongenomic Effects: Hormones bind to receptors outside cells, producing faster effects on behavior; genes are still involved.

Chemical Communication

• Chemical communication occurs at all levels of life, including within cells, between cells, organs, individuals, and populations.
• Communication involves releasing chemical agents and detecting them through receptor activation.

Types of Chemical Mediation

• Intracrine: Chemicals act within the same cell.
• Autocrine: Cells release substances that act back on themselves; some evolved into hormones or pheromones.
• Paracrine: Chemicals affect nearby cells, like neurons releasing neurotransmitters.
• Endocrine: Hormones are secreted into the bloodstream and act on distant targets, e.g., insulin regulating blood glucose.
• Ectocrine: Substances released externally affect other individuals, e.g., pheromones.

Types of Communication

• Paracrine: Chemicals released by one cell affect nearby cells, e.g., neurotransmitters.
• Ectocrine: Chemical release into the external environment affects other individuals, e.g., pheromones.
• Endocrine: Hormones secreted into the blood travel to distant targets, e.g., hormones regulating growth.
• Autocrine: Cells secrete substances that act back on the same cell, e.g., immune cells regulating self-activation

Comparison of Pheromones, Alomones, Kairomones, and Synomones

• Pheromones: Chemical signals that communicate with members of the same species.
• Alomones: Chemical signals that benefit the sender by affecting individuals of a different species, e.g., skunk spray.
• Kairomones: Chemical signals that benefit the receiver by affecting a different species, e.g., prey odors for predators.
• Synomones: Chemical signals that benefit both the sender and receiver, e.g., floral scents and pollinators.

Do Humans Use Pheromones?

• Historically, humans were thought to use pheromones for attraction, but it's a debated topic.
• Studies on the vomeronasal organ (VNO) suggest humans may lack a functional VNO, complicating claims of pheromone detection.
• Products marketed as pheromones to increase attraction are often not strongly supported by scientific evidence.

Systems of Chemical Communication

• Endocrine System: Hormones
• Nervous System: Neurotransmitters
• Immune System: Cytokines

Integration of Systems

• Nervous, endocrine, and immune systems interact significantly.
• Immune cells and neurons have receptors for neurotransmitters, hormones, and cytokines.
• Communication similarities include receptor structures and signal transduction mechanisms.

General Features of the Endocrine System

• Endocrinology: studying endocrine glands and their hormones
• Hormones: derived from Greek word for "to excite/set into motion"
• Endocrine glands: release hormones directly into the blood
• Neurohormones: special hormones released into the blood (via nerve cells)
• Neuroendocrinology: study of the interrelationship between the nervous system and endocrine system

Endocrine vs. Exocrine Glands

• Endocrine glands release hormones directly into the bloodstream (e.g., thyroid, adrenal).
• Exocrine glands use ducts to release materials into internal or external environments (e.g., salivary, sweat).
• Some glands have both endocrine and exocrine functions, e.g., the pancreas has both

Hormones: Production and Release

• Protein/Peptide hormones: stored in secretory granules, released via exocytosis.
• Steroid hormones: not stored, produced and released on demand, derived from cholesterol.

Transport of Hormones in the Blood

• Protein/Peptide hormones: soluble in blood (aqueous solution).
• Steroid hormones: not water-soluble, bind to carrier proteins in the blood.
• Carrier proteins help regulate hormone actions.

Hormone Receptors

• Receptors are specific binding sites on cell membranes or inside cells.
• Hormones bind to receptors with high affinity and specificity.
• Hormone levels are often low, but high affinity receptors ensure potent effects.
• Cross-reactivity can occur with similar hormones at high concentrations.
• Receptor numbers influence endocrine response.

Hormone Types: Protein/Peptides and Steroids

• Protein/Peptides:
  • Water-soluble
  • Stored
  • Fast acting effect
  • Examples: Insulin, epinephrine
• Steroids:
  • Lipid-soluble
  • Not stored
  • Slow acting effect.
  • Examples: testosterone, cortisol

Anatomy and Location of Key Endocrine Organs

Types of Hormones (Protein vs Peptides)

Types of Hormones (Detail)

Some Key Hormones and their Functions

Hypothalamic Hormones

Pituitary Gland

Anterior Pituitary

Pituitary Structure and Function

Anterior Pituitary Hormones

Posterior Pituitary Hormones

Gonadal Hormones

Adrenal Hormones

Gastrointestinal Hormones

How Hormones Are Regulated