Endocrine Lecture Flashcards
Endocrine Gland
Ductless gland that secretes its product (hormone) into circulation, influences activity of distant tissues
Hormone
Chemical substance synthesized and secreted by an endocrine gland into blood to all parts of the body
Target
Tissue with specific receptors that respond to hormonal stimulus
Paracrine
Hormone secreted by cell, diffuses into extracellular fluid, affects neighboring cell function
Autocrine
Hormone secreted by cell, affect its own function by binding to its cell surface receptors
Neuroendocrine
Hormone secreted by neuron, reaches the circulation, influences the function of other cells at another location in the body
Neurotransmitter
Chemical substance released by axon terminal into synapse, acts locally to control nerve cell function
NE and Epi
Secreted by adrenal medulla = hormone
Secreted by SNS = neurotransmitter
Anterior pituitary
Growth Hormone Adrenocorticotropin hormone Thyroid stimulating hormone Follicle-stimulating hormone Luteinizing hormone Prolactin
Posterior pituitary
Vasopressin (antidiuretic hormone)
Oxytocin
Adrenal cortex
Cortisol
Aldosterone
Androgens
Adrenal medulla
NE
Epi
Thyroid gland
Thyroxine
Triodothyronine
Calcitonin
Pacreas
Insulin
Glucagon
Ovaries
Estrogen
Progesterone
Testosterone
Testes
Testosterone
Estrogen
Placenta
Chorionic gonadotropin
Estrogens
Progesterone
Somatomammotropin
Chemical Classes of Hormones
Proteins & Polypeptides (3-200 aa) – (pp: >100)
Steroids (cholesterol= precursor)
Amines ( derived from tyrosine)
Protein hormones
Pituitary
Pancreas
Parathyroid Hormones
- Usually hydrophilic (hard to diffuse by themselves)
Protein and Polypeptide Hormone synthesis
Stored in secretory vesicles until needed
- Synthesized in rough ER as PREPROhormone
- Cleaved to PROhormone in ER and transferred to golgi
Packaged into secretory vesicles and cleaved to active form and inactive fragments
Secreted via exocytosis
Peptide hormones?
Water soluble
Easily enter circulatory system
Diffuse to target cells
Steroid Hormone Synthesis
Synthesized from cholesterol Not stored within cells Lipid soluble Diffuse across membrane Enter interstitial fluid and then blood where they bind to plasma proteins (not water soluble)
Thyroid Hormone Synthesis (amine)
Bind to a protein called thyroglobulin stored in follicles
Secretion: spllit from this protein
Combine with plasma protein thyroxine-binding globulin
– Thyroxine and triiodothyronine
Adrenal Medullary Hormones (amine)
Taken up into preformed vesicles and stored until secreted
Released by exocytosis
Exist in bound and free forms in plasma
– Epi and NE