chapter 18 Flashcards
Endocrine gland
Secrete products into the bloodstream
Relationship between nervous system and endocrine system
THe nervous system releases neurotransmitters which excite a nerve muscle or gland
Explain the specificity of a hormone to its target cell
Target cells have specific proteins or glycoprotein receptors that hormones bind to
Exocrine glands
secrete products into ducts which empty into body cavities or body surface
examples of endocrine glands
Pituitary, thyroid, parathyroid, adrenal, pineal
General functions of hormones
Help regulate:
Extracellular fluid, metabolism, biological clock, contraction of cardiac and smooth muscles, glandular secretion, some immune functions
explain how hormone receptors are regulated
Constantly being broken down and synthesized
Upregulation
Increases sensitivity of target cell to hormone
Downregulation
Decreases sensitivity of target cell to hormone
Circulating hormone
Hormones that travel in blood and act on distinct target cells
Local hormones
Act locally without first entering the blood stream
Three hormone divisions
Amino acid derivatives
Peptide hormones
Lipid derivatives
Amino acid derivatives
Derivatives of tyrosine
Derivatives of tryptophan
Derivatives of tyrosine
Thyroid
Catecholamines (epinephrine, norepinephrine, dopamine)
Tryptophan (seratonin, melatonin)
Peptide hormones
chains of amino acids
Glycoproteins, short polypeptides
Glycoproteins
Proteins are more than 200 amino acids long and have carbohydrate side chains
Short polypeptides/ small proteins
Short chain polypeptides (antidiuretic hormones)
Small proteins (Growth hormone and prolactin)
Lipid derivatives
Eicosanoids, steroid hormones
Eicosanoids
Derived from arachidonic acid, paracrine factors coordinate cellular activities in extracellular fluids
Steroid hormones
Derived from cholesterol and found in reproductive system, cortex of adrenal glands, kidneys
Three steps of lipid soluble hormone action
- Lipid soluble hormones bind to and activate receptors within cells
- Activated receptors alter gene expression
- New proteins alter the cells activity and result in physiological responses
First messenger of water soluble hormones
Binds to the cell membrane receptor
Second messenger
Intermediary relay molecule released inside the cell where the hormone stimulated response takes place
Examples of second messengers
ADH, TSH, Glucagon, epinephrine, cGMP
Why are water soluble hormones amplified to a much greater extent
Water soluble hormones bind to receptor which activates multiple proteins. Lipid soluble hormones are directly proportional to the number of hormone receptor complexes formed
What is the role of g proteins
Turns on adenylate cyclase which catalyzes the conversion of ATP to cAMP
Cholera
Causes g proteins to lock in activated state which can make person dehydrated
How are there so few different hormones
Different target cells respond differently to the same hormone
Describe location and structure of pituitary gland
Located in sella turcica of sphenoid bone
consists of anterior pituitary and posterior pituitary, and the infundibulum which connects it to the brain
Anterior lobe (adenohypophysis)
Synthesizes its own hormones and secretes them directly into the blood; makes up 75 percent of the pituitary gland
Posterior lobe (Neurohypophysis)
Stores and secretes hormones made in the hypothalamus
Hormones secreted by anterior pituitary gland
ACTH, TSH, GH, PRL, FSH, LH
