Components of the Endocrine System Flashcards
What are the 7 major endocrine glands?
- Endocrine tissues of pancreas
- Parathyroid glands
- Pituitary gland
- Thyroid gland
- Adrenal glands
- Gonads (testes and ovaries)
- Placenta
What are major functions of hormones
- Reprod
- Growth and development
- Metabolism
- Internal environment (response to stress)
- Maintenance of calcium homeostasis
Describe endocrine glands -> size of tissue, vascular supply, distance it secretes chemicals
- small tissues
- rich vascular supply
- secretes across long-distance chem signals that travel in blood to target organ
Endocrine system diagram
What are the 4 steroid hormones?
What are the 2 main amino-acid derived hormones?
What type of hormone is insulin?
protein/peptide hormone
What are the 5 steps of protein/peptide hormone synthesis?
- Preprohormone generated at ribosomes - directed to ER lumen by signal sequence amino acids
- Signal peptide cleaved in ER generating inactive prohormone
- Prohormone passes from ER through the golgi apparatus
- Secretory vesicle buds off golgi - enzymes cleave prohormone to generate inactive hormone
- Secretory vesicle releases active hormone into extracellular space via exocytosis
- Hormone moves into circulation for transport to target cell
What are the steps upon protein/peptide hormone binding to cell receptor?
- Peptide hormone binds to its receptor
- Initiation of secondary messenger cascade
- Hormone effect
What are steroid hormones derived from?
Cholesterol
What are the steps for synthesis of steroid hormones?
- Rate of steroidogenesis controlled by protein hormones
- Steroidogenic acute regulatory protein moves cholesterol
- Type of steroid hormone that can be synthesised by a particular cell type and is dictated by its complement of peptide hormone receptors (for eg ACTH stim cortisol synthesis in adrenal while LH stim testosterone synth)
What are the steps of steroid synth MoA?
- Steroid hormone diffuses through the plasma memb and binds to intracellular receptor
2 + 3. Receptor-hormone complex enters nucleus and binds to specific region of DNA
4 + 5. DNA binding initiates transcription of gene to mRNA which directs protein synthesis
What are 3 stimuli that alter the rate of hormone secretion?
- Changes in plasma levels of ions (Ca+, Na2+) or nutrients
- Neurotransmitters released from neuronal endings on endocrine cell
- Another hormone
How does cortisol concentration fluctuate throughout the day?
- high in the morning
- low at night
How do hormones get transported in the blood?
Either:
- circulate freely in plasma
- bound to carrier proteins (provides a reservoir of hormone) -> binding proteins also slow the metabolism of hormones
