Endocrine System 1 Flashcards
What are the differences between endocrine & nervous system?
The NS uses electrical impulses which provides much faster and briefer responses while the ES uses hormones which provide slower & more sustained responses
What are the functions of the ES?
Affect reproduction, growth, development, conception, metabolism, stress responses & aging
What is the function of endocrine glands?
Release their products directly into the bloodstream without ducts to target cells & thus are highly vascularized
What two components make up the ES?
Endocrine glands & endocrine tissue
What are endocrine glands?
Primary function to produce hormones such as the pituitary, thyroid, PT, adrenal & pineal glands
What are endocrine tissue?
Located in organs that perform other functions such as the pancreas, hypothalamus, gonads
What are hormones?
Chemical messengers released by endocrine glands into the bloodstream to stimulate or regulate specific body cells or functions
How do hormones only affect certain cell despite their wide reach?
Hormones only act on cells that have specific receptors - target cells
How many receptors does each target cell have?
2000-10,000
What is down-regulation?
An excess of hormones can decrease the receptors in target cells and decrease the effect of hormones
What is up-regulation?
A deficiency of hormones can increase the receptors in target, and increase the effects of hormones
What hormone has receptors across the body?
Thyroid hormone
What are the two types of hormones?
Local & circulating (common) hormones
What are circulatory hormones?
Circulating hormones pass from secretory cells to the bloodstream.
What are local hormones?
Affect the secretory cells that released them or neighboring cells without entering the bloodstream.
What are the two types of LH hormones?
Paracrines & autocrines
What is the function of paracrines?
LH that stimulate neighboring cells
What are the two chemical classes of hormones?
Lipid & water soluble hormones
What are lipid soluble hormones?
Steroid (Aldosterone & testosterone) & Thyroid hormones (T3, T4)
What are water-soluble hormones?
Amine, peptide & protein hormones
What are the mechanism of lipid-soluble hormones?
Bound to transport-proteins, diffuse through the plasma membrane & have intracellular receptors
What is the function of lipid-soluble hormones?
Activate intracellular receptors which generate the formation & activation of genes to synthesize new proteins that alter the cell’s activity.
What are the mechanism of water-soluble hormones?
Unbounded, cannot enter plasma membrane & have extracellular receptors
What is the function of water-soluble hormones?
Binding to their receptors cause the activation of the G protein (first messenger) which leads to a cascading series of events activating adenylate cyclase which converts ATP into cAMP which acts as the second messenger to activate protein kinases which phosphorylate cellular proteins that cause physiological responses.
What 3 factors control hormones?
Humoral, neural & hormonal stimuli
What are humoral stimuli & example?
Hormones released due to chemical changes in blood. For example PTH due to low blood Ca+2
What are neural stimuli & example?
Hormones released by nervous impulses, such as the hypothalamus which stimulates the release of ADH & Oxytocin from posterior pitutary
What is the hypothalamus-posterior pituitary axis?
Forms a nervous connection where the neurosecretory cells bodies of the hypothalamus produce hormones that are stored in their secretory axon vesicles in the posterior pituitary
How are hormones released from the posterior pituitary gland?
When hypothalamus is stimulated, it causes the release of the hormones from the posterior pituitary gland to their surrounding capillaries.
What are the two posterior pituitary hormones?
ADH - increases water absorption and oxytocin - causes contracting of birth canal walls
What are hormonal stimuli & example?
Hormones which stimulate the release of hormones from endocrine glands. For example, the hypothalamus-anterior pituitary connection causes release of hormones from the hypothalamus which stimulate hormones in the AP to release hormones that cause other endocrine organs to secrete hormones
What is the hypothalamus-anterior pituitary connection?
The hypothalamus & anterior pituitary are connected by the hypophyseal portal vein system allows which enables hypothalamic hormones to be transported to the anterior pituitary to target the tropic AP hormones
What are the seven hormones of the AP
(FSH), (LH), (ACTH) (GH)
(TSH) (MSH) & Prolactin
What is the function of FSH?
Sperm production & oocytes development & estrogen production
What is the function of LH?
Testosterone production & ovulation & oestrogen progesterone production
What is the function of (ACTH)?
Causes secretions of glucocorticoids (cortisol) from adrenal cortex
What is the function of GH?
Promotes growth of body tissues
What is the function of TSH?
Release of thyroid hormones
What are the adrenal gland hormones?
Cortex = Mineralocorticoids (Aldosterone), Glucocorticoids (Cortisol)
Medulla = Epinephrine & norepinephrine stress responses
