Endocrinology Flashcards
(114 cards)
What are the 3 classification of hormones?
- Proteins (small peptides, polypeptides, glycopeptides)
- Lipids (steroids, eicosanoids)
- Monoamines (catecholamines, thyroid)
What is the process of steroid hormone synthesis?
Cholesterol > Pregnenolone > Progesterone
Pregnenolone/Progesterone > Testosterone > Estrogen
Progesterone > Aldosterone/Cortisol
What are the 4 ways that hormones reach their target?
- Endocrine (via blood)
- Neuroendocrine (via nerves and into the blood)
- Paracrine (sharing with nearby neighbouring cells)
- Autocrine (leave but act for itself)
- Intra (does not leave cell and act for itself)
How do hormones interact with their targets?
Binds to a receptor, which then interacts with other molecules leading to a response
What are the 2 sites for receptors?
- Cell surface receptors
Protein which bind to protein hormone and to catecholamines - Intracellular receptors
Proteins which bind to steroid hormones and to thyroid hormones
What are some examples of cell surface receptors?
- G-Protein Linked Receptors
Regulates intracellular second messengers (eg cAMP, DAG, Ca2+) (eg receptors for adrenaline, glucagon, FSH, LH, TSH, PTH) - Catalytic Receptors
Either have enzyme activity themselves, or are closely associated with an enzyme after binding to a ligand
(Example) What happens when adrenaline is secreted?
Conformation of a receptor (adrenergic receptor) > G Protein > Enzyme (adenylate cyclase) > second messenger (cAMP) > Protein kinase (PKA) > Phosphorylation of proteins > Response of target cell
What are the 3 sites of the intracellular receptor?
- Cytoplasm (steroid hormones)
- Nucleus ( sex steroids)
- Bound to DNA (thyroid hormone)
going to end up in the nucleus anyway
What is the difference between the negative feedback and positive feedback?
Negative feedback decreases variation from “ideal” or “usual” value whereas positive feedback increases variation from “usual” value
What are the 6 factors affecting hormone activity?
- Synthesis
- Secretion
- Binding to plasma protein
- Metabolism
- Number of receptors
- Response to hormone
What are the 7 difference between protein and steroid?
- Protein is water soluble
- Protein is synthesized from amino acids while steroid is synthesized from cholesterol
- Protein is stored in granules and excreted by exocytosis ; steroids are not stored and excreted by diffusion
- Protein do no need solubilization in blood ; steroid are mainly bound to plasma proteins
- Hormone receptors for protein are on target cell surface membrane; steroid is mainly intracellular
- Protein changes in intracellular signalling pathways whereas steroid regulate gene expression in target cell nucleus
- Proteins are relatively faster
What is the arrangement of the hypothalamus-pituitary unit?
Anterior pituitary, posterior pituitary, pituitary stalk, medium eminence, hypothalamus
Where is the secondary plexus located (hypothalamus)?
Anterior pituitary
What are the 2 nucleus that acts on the posterior pituitary?
Supraoptic nucleus (SON), Paraventricular nucleus (PVN)
What is the difference between the hormone transmission of anterior and posterior pituitary?
In the anterior pituitary, the neurotransmitter travel as far as the median eminence. Then transfer the hormone into the portal blood vessels. They are then carried down the pituitary stalk and then act on the receptors of the target cells in the anterior pituitary
What are the hormones and 5 target organ in the anterior pituitary?
- Ovaries & Testes
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Adrenal Cortex
- Adrenocorticotropic hormone (ACTH)
- Thyroid Gland
- Thyroid-Stimulating hormone (TSH)
- Mammary Gland
- Prolactin (PRL)
- Tissues
- Growth hormone (GH)
What are the hypothalamic hormones and its effects?
- Increases secretion of FSH and LH
- Gonadotropin releasing hormone (GnRH)
- Increases ACTH
- Corticotropin releasing hormone (CRH)
- Increases TSH
- Thyrotropin releasing hormone (TRH)
- Decreases PRL
- Prolactin inhibiting hormone (PIH)
- Increases GH
- Growth hormone releasing hormone (GHRH)
- Decreases GH
- Somatosatin (SS) or Growth hormone inhibiting hormone (GHIH)
Which is the most abundant anterior pituitary hormone?
Growth hormone
What type of hormone is the growth hormone?
- Protein hormone
Why does growth hormone does not work on other animals?
Shows specificity
How is growth hormone secreted?
Pulsatile secretion; circadian rhythm
Where does growth hormone act on (receptor)?
Cell-surface receptors ( which are associated with protein kinase activity)
What are the effects of growth hormone?
Increases growth, affects metabolism
What are the 3 sections of a bone?
- Diaphysis (shaft; middle part)
- Epiphyseal plate (cartilage)
- Epiphysis