Lecture 12: Endocrine and Pituitary Gland Flashcards
What is the endocrine system?
A group of glands and tissues that release chemical messengers (hormones) into the blood stream which activate or inhibit specific target cells.
What are the functions to endocrine system?
- Growth and development.
- Reproduction
- Electrolyte, water and nutrient
balance - Regulation of metabolism and energy balance.
What are the two types of hormones?
Hydrophilic - water soluble (insulin)
Hydrophobic - lipid soluble (cortisol, testosterone and estrogen)
How are hydrophilic hormones released onto bloodstream?
Peptide/protein molecules that are released by exocytosis from secretory vesicles when stimulated.
How are hydrophobic molecules released onto bloodstream?
Secretory cells convert steroid hormone precursors into active hormones which diffuse by simple diffusion. Transported in blood attached to plasma proteins.
What are the two forms of hormone messaging mechanisms?
- Cell surface signaling: Used by hydrophilic hormones that bind to receptor on external surface of target cell (faster but shorter effect).
- Intracellular signaling: Used by hydrophobic hormones whose receptors are located inside target cells cytoplasm or nucleus (Slower, but longer effect).
What is the difference between cell surface and intracellular signaling?
Cell surface: Second chemical messengers.
Intracellular: Activates particular genes that change behavior of the cell.
What is the difference between synergistic, antagonistic and tropic?
Synergistic: Overlapping functions with another hormone and promote similar outcome (glucagon and epinephrine).
Antagonistic: Opposite effect on a variable compared to another hormone (Insulin vs. glucagon).
Tropic: If their target is an endocrine gland or tissue and it alters the release of another hormone. (Thyroid Stimulating Hormone TSH triggers release of Thyroid hormone).
How can endocrine gland/tissues be stimulated to release their hormone product?
- Hormonal stimulus
- Humoral stimulus
- Neural stimulus
What is humoral stimulus?
Release of hormones in response to changing levels of ions or nutrients present in body fluids.
What is neural stimulus?
Stimulus received through neurons. Example is sympathetic nerve impulses to release epinephrine and norepinephrine from adrenal glands.
Difference between anterior and posterior lobes of pituitary gland.
Anterior lobe: Made up of endocrine tissue.
Posterior lobe: Made up of nervous tissue.
What is the anterior pituitary made up of?
Glandular tissue and produces its own hormones. Communication is achieved through blood vessels.
Which two specific hypothalamic hormones control the release of each anterior pituitary gland hormone?
- One hypothalamic releasing hormone
- One hypothalamic inhibiting hormone
What are the steps in stimulating anterior pituitary hormone secretion?
- Neurosecretory cells in hypothalamus secrete a releasing hormone.
- Releasing hormone travels through the portal vein to the anterior pituitary.
- Releasing hormone triggers secretion of anterior pituitary hormone which goes into general circulation of the body.
What are some hormones released by anterior pituitary?
- Follicle Stimulating hormone and Luteinizing hormone
- Growth hormone
- Prolactin (milk production)
- Adrenocorticotropic hormone
- Thyroid stimulating hormone
Which hormone from hypothalamus stimulates release of FSH and LH?
Gonadotropin releasing hormone (GnRH)
What are some growth hormone homeostatic imbalances?
- Gigantism
- Acromegaly (Thickening of bones in face, hands and feet).
What is the function of prolactin?
Stimulates the mammary glands to produce milk. Prolactin does not cause the milk to be ejected; this is the job of oxytocin.
What is the function of adrenocorticotropic hormone?
Regulates our long term stress response through the release of cortisol and other hormones.
What is the function of thyroid stimulating hormone?
Regulates our metabolic rate through the release of thyroid hormone (T3/T4).
What is the function of posterior pituitary?
It releases hormones made by neurosecretory cells of the hypothalamus.
This includes antidiuretic hormone (ADH) regulates hydration and oxytocin (OT).
What is the function of antidiuretic hormone?
Acts on the kidneys to remove water from the fluids destined to be excreted as urine and return it back into the bloodstream.
(Stimulated by elevated levels of sodium ions in the blood).
What effect does caffeine and alcohol have on ADH?
Inhibits the release of ADH and may lead to dehydration.
