Endocrine System PDF

Endocrine System Discuss the differences between neural and endocrine mechanisms of control of body functioning. ➔​ Endocrine system: uses chemical messengers that affects any tissue with a receptor for that specific chemical ◆​ Slightly slower to respond ◆​ Can take days...

Endocrine System Discuss the differences between neural and endocrine mechanisms of control of body functioning. ➔​ Endocrine system: uses chemical messengers that affects any tissue with a receptor for that specific chemical ◆​ Slightly slower to respond ◆​ Can take days for action to take place ◆​ Lasts long in activity ➔​ Nervous system: uses neurons to send electrical signals around the body (action potentials) ◆​ Stimulates muscles and glands ◆​ Responds to stimulus very quickly ◆​ Regulates body activity ◆​ Short lived Differentiate exocrine and endocrine glands. ➔​ Exocrine glands: secretes into a duct ➔​ Endocrine glands: ductless, produce hormones ◆​ Highly vascular **Some organs have both endocrine and exocrine glands** Identify the neuroendocrine link, and discuss its functioning. ➔​ Neuroendocrine link: stimulates the activity of the exocrine gland ◆​ Hypothalamus- major regulator center for endocrine activity ​ Sends nervous signals and sends precursor signals that activate other endocrine glands List and differentiate the types of chemical messengers. ➔​ Hormones: chemical messengers secreted in one part of the body but have an effect in another part of the body ➔​ Autocrines: chemicals produced by a cell that change the activity of that cell ➔​ Paracrines: chemical secreted by a cell that does not affect the cell that secretes it, but neighboring cells ◆​ Local regulators ➔​ Pheromones: chemical produced by one individual that changes the behavior of another individual ◆​ Both attractive (sexual) and repulsive (stress) Identify the cells at which hormones exert their effects, and discuss the generalized effects hormones can produce. Hormone Actions ➔​ Target cells: cells that have a receptor for a specific hormone ◆​ Surface of cell ◆​ One hormone can have different effects on different cells ➔​ Open or close ion channels ◆​ Changes membrane potentials and permeability ➔​ Stimulate protein synthesis ◆​ Many are enzymes- speed up rate of activity ➔​ Activate or deactivate enzymes ➔​ Promote secretion ◆​ Mucus, proteins, hormones ➔​ Stimulate mitosis: cell division ◆​ Growth hormones Describe the chemical classifications of hormones. ➔​ Amino acid based: most hormones in our body are derived by proteins ◆​ Peptide hormones- water soluble (can't cross the plasma membrane) ➔​ Steroid: derived from cholesterol (lipid) ◆​ Steroids= lipid soluble ◆​ Receptor on the inside of the cell ◆​ 2 sources: produced by cortex of adrenal gland or gonads (testes/ovaries) ➔​ Eicosanoid: biologically active lipids that function mostly local but not immediately local ◆​ Not true hormones ◆​ Prostaglandins and Leukotrienes: signaling Describe the two major mechanisms by which these two classes of hormones bring about their effects. Steroid Action Non-Steroid Action (Amino-acid ​ Direct mechanism based) ​ Activate genes ​ Indirect mechanism  ​ Protein synthesis ​ Involves G proteins and secondary messengers Process: Process: 1.​ Hormone diffuses through 1.​ Cyclic AMP mechanism plasma membrane 2.​ PIP-calcium mechanism 2.​ Binds with intracellular receptor 3.​ Activated complex binds to receptor protein on DNA 4.​ Transcription initiated 5.​ mRNA translated 6.​ Proteins produced Discuss the two models of amino acid-based action. ➔​ Cyclic AMP mechanism: secondary messenger=cAMP*** 1.​ Hormone binds to membrane receptor 2.​ Modified receptor binds with G protein 3.​ G protein is activated 4.​ Activated G protein activates adenylate cyclase 5.​ Adenylate cyclase generates cAMP (monophosphate) from ATP (triphosphate) 6.​ cAMP stimulates protein kinase reactions 7.​ Proteins are phosphorylated 8.​ Phosphodiesterase degrades cAMP ​ Hormone has a temporary affect ➔​ PIP-calcium mechanism: secondary messenger=Calcium*** 1.​ Hormone binds to membrane receptor 2.​ Modified receptor binds with G protein 3.​ G protein is activated 4.​ Activated G protein activates phospholipase 5.​ Phospholipase splits PIP2 into DAG and IP3 6.​ DAG activates protein kinases 7.​ IP3 triggers release of calcium from ER 8.​ Calcium acts as additional second messenger Identify the factors that control hormone action.  ➔​ Hormone level in bloodstream ◆​ Quantity released- more released: greater response ➔​ # receptors in/on target cells ➔​ Receptor affinity: ability to bind to hormone receptors ◆​ Upregulation: increases # of receptors for greater effect ​ Example: blood glucose regulation ◆​ Downregulation: shuts off the regulation of the hormone (occurs with stress) ​ Example: stressing so much your body no longer responds to it List three kinds of interaction that different hormones acting on the same target cell can have. 1.​ Permissiveness: one hormone increases the effectiveness of another hormone 2.​ Synergism: two hormones producing the same action increase the response 3.​ Antagonism: two hormones have opposite effects Explain how hormone release is regulated. ➔​ Humoral: concentration levels in the blood that activate an endocrine gland to activate a hormone ➔​ Neural: nervous stimulation can activate a gland to secrete a hormone ➔​ Hormonal: one endocrine gland is activated by a hormone produced by a different endocrine gland. ** Modified by nervous system** ** Inhibited by negative feedback** List the major endocrine organs, and describe their body locations. ➔​ Pituitary: an extension off the brain. ➔​ Thyroid: surrounds the trachea. ➔​ Parathyroid: embedded within the thyroid. ➔​ Adrenals: on top of the kidneys ➔​ Pancreas: in the abdominal cavity ➔​ Gonads: testes in the male and ovaries in the female. ➔​ Pineal: in the brain. ➔​ Thymus: is not very active in adults. Pituitary Gland:  ​ Posterior pituitary: neurohypophysis ○​ Composed of neural tissue ○​ Does not produce hormones, but secretes them ​ Anterior pituitary: adenohypophysis- outpocketing of the neural cavity ○​ Composed of glandular tissue ○​ Stimulated by the hypothalamus through a releaser which stimulates an anterior pituitary cell to secrete a tropic hormone for a target tissue ​ Infundibulum: stalk extending off of the hypothalamus Tropic Hormone: causes production of different hormones from a different gland Discuss the structure of the neurohypophysis, and describe the effects of its two hormones. ➔​ Neurohypophysis: amino acid based hormones that use the PIP mechanism of action ◆​ Oxytocin (OXY): stimulates smooth muscle contractions ​ Childbirth and milk ejection ​ Fosters nurturing and amnesiac ◆​ Antidiuretic hormone (ADH): ​ Regulates water balance ​ Prevents urine formation ○​ Alcohol suppresses ADH​ List and describe the adenohypophyseal hormones and their effects. ➔​ Adenohypophyseal: produces hormones, amino acids that use cAMP method ◆​ Growth hormone (GH): stimulates growth- cell division, protein synthesis, fat metabolism, glucose conservation ​ Overly active GH as a child: gigantism ​ Excess GH after childhood: acromegaly ​ Reduction in GH in adulthood: no problem ​ Insufficient GH in childhood: pituitary dwarfism GH Cascade ​ Hypothalamus secretes GHRH- Growth hormone releasing hormone ​ Somatotropic cells of anterior pituitary begin GH synthesis ​ GH has both direct and indirect effects on tissues  ​ Circulating GH triggers production of GHIH- Growth hormone inhibiting hormone (somatostatin) ○​ Inhibits GH and thyroid stimulating hormones ​ Production of GH stops Direct Actions of GH ​ Increases blood levels of fatty acids ​ Fats from fat stores ​ Decreases glucose uptake and metabolism ​ Diabetogenic Effect: Encourages breakdown and release of glucose from glycogen in liver Indirect Actions of GH ​ Operate through IGFs: Insulin-like Growth Factor ​ Stimulate uptake of amino acids from blood into cellular proteins ​ Stimulate uptake of sulfur into matrix of cartilage ◆​ Thyroid-stimulating hormone (TSH): stimulates development and secretion from thyroid gland ​ Aka thyrotropin TSH Cascade ​ Hypothalamus secretes TRH ​ TRH causes thyrotrope cells of anterior pituitary to produce TSH ​ Increased levels of TSH inhibit both pituitary gland and hypothalamus ​ Also stimulate production of GHIH ◆​ Adrenocorticotropic hormone (ACTH): activates adrenal cortex to produce corticosteroid ​ Help the body resist stress ACTH Cascade ​ Hypothalamus secretes CRH-Corticotropin releasing hormone ​ CRH stimulates corticotrope cells to release ACTH  ​ Increased levels of glucocorticoids stop CRH ​ ACTH secretion stops ​ Stresses that cause release: Fever, hypoglycemia and stressors ◆​ Gonadotropins: stimulate and regulate function of gonads ​ FSH (follicle stimulating hormone) and LH luteinizing hormone ​ FSH- stimulates sperm or eggs, LH stimulates gonads to produce sperm ​ Male: FSH- sperm production, LH- testosterone production ○​ Males produce gametes during puberty ​ Female:Gametes produced before birth and protected by hormones ○​ FSH stimulates ova production ○​ FSH and LH cause maturation of ○​ follicle ○​ LH triggers ovulation and promotes synthesis of ovarian hormones Gonadotropin Cascade ​ At puberty, hypothalamus secretes GnRH ​ GnRH stimulates gonadotrope cells to secrete gonadotropins ​ Gonadotropins cause gonads to mature and begin producing hormones ​ Increased levels of gonad hormones suppress FSH and LH ◆​ Prolactin: stimulates milk production and enhances testosterone production in males Prolactin Cascade (Cycling) ​ High estrogen levels stimulates release of prolactin ​ Estrogen stimulates lactotropes to secrete prolactin by suppressing PIH (Prolactin inhibiting hormone)production ​ Prolactin production brief due to ovarian hormone cycling  ​ Decreased estrogen stimulates production of PIH from hypothalamus ​ Prolactin production stops Prolactin Cascade (Pregnancy) ​ High estrogen effects same ​ PRL triggered near end of pregnancy ​ Suckling maintains PRL production ​ Lack of suckling and return of normal hormonal cycles brings about PIH production ◆​ Pro-opiomelanocortin (POMC): pro hormone ​ Can result in the production of melanin, activation of the adrenal cortex, production of