Glands Flashcards
Exocrine glands
secrete non-hormonal products via ducts (e.g. sweat glands, mucous glands, sebaceous
glands)
Endocrine glands
secrete hormones into interstitial fluid that diffuse into tissue capillaries (e.g. pituitary gland,
thyroid gland, adrenal glands)
Endocrine
are distributed into blood to distal target cell
Paracrine
are diffused locally to neighboring target cells
Autocrine
act on the same cell that produced them
Water-soluble hormones
bind to a cell surface receptors on plasma membrane (cannot diffuse through lipid bilayer)
■ Amine hormones (epinephrine, norepinephrine, dopamine, histamine, serotonin)
■ Peptide hormones (ADH, oxytocin, GH, insulin)
■ Eicosanoid hormones (prostaglandins, leukotrienes)
Lipid-soluble hormones
diffuse through lipid bilayer and bind to intracellular receptors in cytosol or nucleus
■ Steroid hormones (testosterone, estrogen, progesterone, aldosterone, cortisol, androgen, calcitriol)
■ Thyroid hormones (T4, T3)
■ Gases (nitric oxide)
Hypothalamus
creates an important link
between nervous system and endocrine system
○ Contains neurosecretory cells that send signals to
pituitary gland, which lies direct anteroinferior to
it.
○ Regulates the actions of pituitary gland by
secreting either stimulatory or inhibitory releasing
factors
Pituitary gland
regulated by the hypothalamus,
secretes various hormones to distal target
organs throughout the body
○ Divided into anterior and posterior lobes
Together, the hypothalamus and pituitary gland form ___?
What is it for?
The hypothalamic-
pituitary axis (HPA) for diffuse endocrine
regulation
Thyroid gland
one of the largest endocrine hormone producer of
the body and the largest gland of the neck
Parathyroid glands
4 small tiny glands that sit directly posterior to the thyroid (right and left superior and inferior)
Adrenal glands
sit directly on trop of the kidneys
and are key regulators of homeostasis and sympathetic nervous
system
● Composed of an outer cortex (includes 3 zones: zona glomerulosa,
zona fasciculata, and zona reticularis) and an inner medulla
(composed of chromaffin cells)
Kidneys
● Comprised of and outer cortex and inner medulla
● Nephron is a functional unit of the urinary system
responsible for glomerular blood flow and filtration rate
● Juxtaglomerular cells located in the renal tubules are
responsible for synthesizing and secreting the hormone
renin
Pancreas
● Pancreas has a duel function in both the endocrine and GI system
● GI function is achieved through exocrine glands which secrete
important digestive enzymes that aid in breaking down complex
macronutrients (carbohydrates, lipids, protein)
● Endocrine glands comprised of islets of Langerhans cells (alpha,
beta, delta, epsilon and F cells) which all secrete a unique hormone
Ovaries
● Comprised of inner medulla and outer cortex
○ Medulla comprised of connective tissue (for structural support)
and rich in neurovasculature (for hormone and nutrient transport)
○ Cortex composed of stromal cells which becomes the ovarian
follicle (granulosa cells, thecal cells and corpus luteum)
Testes
● Divided into a series of lobules which include seminiferous tubules
● Leydig cells are important for sex hormone secretion
● Sertoli cells are supportive in function and aid in sperm maturation
Pineal gland
secretes melatonin (regulation of circadian rhythms)
Thymus
- Secretes thymosin, thymic humoral factor, thymic factor and thymopoietin.
- Responsible for maturation of T lymphocytes for the adaptive immune system
GI tract
Hormones stimulate secretion of gastric juice, increase GI motility, and regulate metabolism
○ Secretes gastrin, gastric inhibitory peptide (GIP), glucose-dependent insulinotropic peptide,
cholecystokinin (CCK), secretin, ghrelin, motilin
Placenta
Important for the exchange of nutrients and waste between mother and developing fetus
○ Secretes human chorionic gonadotropin (hCG), progesterone, estrogen, human chorionic
somatomammotropin (hCS), relaxin
Heart
secretes atrial natriuretic peptide (ANP – decreases aldosterone release by adrenal
glands and inhibits renin secretion by kidneys)
Skin
secretes cholecalciferol (precursor to vitamin D, stimulated in the presence of UV
light)
Fat
secretes leptin (appetite suppression and increases metabolism)
