Endocrine System 1. Hormones Func8on Classifica8on General process

Transcription

1 2/7/14 Endocrine System Endocrine System 1. Func8on Classifica8on General process Endocrine glands Single gland made up of many secretory cells Secrete many different Secretory Cells hormones Each hormone binds to different receptors on different target cells 2. Secretory control: The Pituitary gland and the hypothalamus Hormonal media8on through an axis system 3. Hormonal Regula8on Endocrine glands Stress Response Metabolism Hormones: Func8on Chemical produced and released by endocrine cells Regulates func8on of other cells There are a few of them... carried in bloodstream Can exert effects over long- distances Bind to receptor proteins on specific target cells Pass by many cells through circula8on control many bodily func8ons: Water balance Environmental/physical stress Metabolism Reproduc8on, growth, development Hormones: Func8on Endocrine glands Secretory Cells Greater rate of secre8on = greater effect on target cells Because hormones are more concentrated in blood Hormones: Classifica8on 1. Steroid hormones Lipid- soluble (diffuse through cell membranes) Binds to receptor proteins located INSIDE cell Ac8on is slow because steroid hormones produce proteins Target cells have 1000s receptor proteins Greater ability to receive more hormones = higher sensi,vity Figure 2.25d 1

2 2/7/14 Hormones: Classifica8on 2. Pep8de hormones Hormones: Classifica8on 3. Amine hormones Chains of amino acids Binds to receptors on cell membrane - enzyme- linked or G- protein coupled reac8ons Binding ac8vates 2nd messenger (camp) to ac8vate other enzymes Modified chains of amino acids Figure 2.25c New proteins Endocrine System: General process 1. Hormone binds to receptor proteins on target cell G- protein coupled, Intracellular, Enzyme- ac8vated 2. Interacts with DNA in target cell New func8ons Endocrine System 1. Func8on Classifica8on General process 2. Secretory control: The Pituitary gland and the hypothalamus Hormonal media8on through an axis system 3. Hormonal Regula8on Stress Response Metabolism Alters gene expression (may trigger protein synthesis) 3. New proteins carry out func8on Hypothalamus Maintains homeostasis by regula8ng internal environment Regulates hormones released from pituitary gland Produces some hormones secreted by the pituitary gland Controls body temperature Maintains water balance 2

3 1. Posterior pituitary Hormones secreted here are synthesized in hypothalamus Pituitary Gland 2. Anterior pituitary Hormones synthesized and secreted in endocrine cells in 8ssues Posterior Pituitary Gland 1. Median eminence 2. Infundibular stalk Contain axons of neurons from hypothalamus 3. Pars nervosa Neurons synapse with arteries Release hormones from hypothalamus to bloodstream Vasopressin (an8diure8c hormone) Oxytocin Anterior Pituitary Gland Made up of endocrine cells Hypothalamo- hypophysical portal system: 1. Hypothalamus secretes neurohormones into median eminence 2. Travel through series of vessels to anterior pituitary 3. S8mulate/inhibit release of hormones from endocrine cells in anterior pituitary Anterior Pituitary Gland Hypothalamus secretes two kinds of neurohormones Releasing hormones s8mulate anterior pituitary to release specific hormone Anterior Pituitary Gland Hypothalamus secretes two kinds of neurohormones Releasing hormones s8mulate anterior pituitary to release specific hormone Release- inhibi8ng hormones inhibit anterior pituitary from secre8ng hormones CNS controls endocrine system Internal/External signals and/or s8muli Signals integrated in CNS Secrete neurohormones Sensory receptors Motor neurons synapse with neurosecretory cells Affect endocrine glands and 8ssues 3

4 Endocrine System 1. Hormones Func8on Classifica8on General process 2. Secretory control: The Pituitary gland and the hypothalamus Hormonal media,on through an axis system 3. Hormonal Regula8on Stress Response Metabolism Hormone media8on Axis system: when secre8ons of one endocrine gland act on (mediate) the secre8ons from another Hypothalamus- anterior pituitary- thyroid axis mediates hormones released from the thyroid Hormone media8on Axis system: when secre8ons of one endocrine gland act on (mediate) the secre8ons from another Hypothalamus- Pituitary- Adrenal Cortex (HPA) axis mediates hormones released from the adrenal cortex STRESS RESPONSE Adrenal Cortex Adrenal gland secretes many hormones for several systems Glucocor,coids secreted in response to stress Promote increased blood glucose concentra8on Cor8sol is main human glucocor8coid HPA axis Nervous and endocrine systems TOGETHER mediate HPA axis Hormone media8on in the HPA axis How do nervous and endocrine systems interact to affect hormone produc8on/secre8on? 1. Synergys,c: one hormone amplifies effect of another Vasopressin + CRH à increased produc8on of CRH Vasopressin alone à minimal effect 4

5 Hormone media8on in the HPA axis How do nervous and endocrine systems interact to affect hormone produc8on/secre8on? 1. Synergys8c 2. Permissiveness: Presence of one hormone required for other to operate Adrenaline causes vasoconstric8on ONLY if cor8sol is present Hormone media8on in the HPA axis How do nervous and endocrine systems interact to affect hormone produc8on/secre8on? 1. Synergys8c 2. Permissiveness 3. Antagonism: one hormone opposes ac8on of another Insulin promotes uptake of glucose from blood; glucagon s8mulates release of glucose into blood Endocrine System 1. Hormones Func8on Classifica8on General process 2. Secretory control: The Pituitary gland and the hypothalamus Hormonal media8on through an axis system 3. Hormonal Regula,on Stress Response Metabolism Adrenal cortex secretes glucocor8coids Alters many physical processes Reduced feeding, reproduc8on Increased heart and breathing rate Heightened alertness Release of stored energy O 2 /nutrients sent to CNS Involves autonomic NS and HPA axis 1. Stress event à Autonomic NS and HPA axis response NS: Adrenal Medulla à Epinepherine, norepinepherine HPA axis: hypothalamus à Cor8cotropin- releasing hormone (CRH); pituitaryà adrenocor8cotropin- releasing hormone (ACTH) 5

6 1. Stress event à Autonomic NS and HPA axis response Phase 1 (fast) responses: 1 à More blood to vital organs to fuel fight or flight response à To fuel muscle and heart rate increases (simple sugars easiest to convert) à To counteract increased circula8ng blood glucose 2. Signals integrated between CNS and HPA axis - epinephrine further s8mulates CRH produc8on - CRH and epinephrine increase alertness Adrenal cortex releases glucocor8coids 3. Adrenal cortex releases glucocor8coids Phase 2 (slow) responses: à More circula8ng glucose (brain func8on) à More faiy acids (func8on of other 8ssues) à More amino acids (8ssue repair) Chronic stress has long- las8ng effects Chronic responses: à Inhibited gonadotropin, GH (suppressed reproduc8on) à High blood pressure (hypertension) à Bone- thinning à Suppressed immune system à Atrophy/shrinkage of hippocampus (memory, emo8ons) Endocrine System 1. Hormones Func8on Classifica8on General process 2. Secretory control: The Pituitary gland Hormonal media8on through an axis system 3. Hormonal Regula,on Stress Response Metabolism 6

7 2/7/14 Hormonal regula8on of metabolism Cells need nutrients con8nuously Concentra8on of blood is main factor in metabolic func8oning Fats, carbohydrates, proteins Rely on stored energy sources regulate storage, mobiliza8on, conversion into useable forms Sense body s needs/requirements Hormonal regula8on: Insulin Short- term storage/release Eat Food of nutrients Insulin binds to protein receptors à facilitates Pancreas diffusion of into releases insulin target cells Decrease in blood glucose: hypoglycemic effect é storage of all three nutrients ê Blood concentra8on é uptake of glucose, faiy acids, amino acids from blood Proteins DO NOT cause spike in blood 1. Low carb meal 2. NO Surge of in blood 3. Insulin s8ll released 4. Facilitated diffusion into cells 5. Lowers blood Hormonal regula8on: Metabolic func8ons Two main hormones secreted by pancreas 1. Insulin: decreases blood concentra8on 2. Glucagon: increases blood concentra8on Carbohydrates cause spike in blood 1. High carb meal 2. Glucose in blood surges 3. Insulin released 4. Facilitated diffusion into cells 5. Lowers blood Diabe8cs don t produce insulin Blood remains high Kidneys can t filter Excreted as waste and not used for energy! Diabe8cs are told to avoid carbohydrates (simple sugars) 7

8 Hormonal regula8on: Glucagon Pep8de hormone secreted by pancreas Released when blood glucose low, amino acids high Hormonal regula8on: Glucagon S8mulates gluconeogenesis Causes blood glucose to rise: Hyperglycemic effect 8