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Endocrine System
 

Endocrine System

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  • 9. c. Students know how feedback loops in the nervous and endocrine systems regulate conditions in the body. Feedback loops are the means through which the nervous system uses the endocrine system to regulate body conditions. The presence or absence of hormones in blood brought to the brain by the circulatory system will trigger an attempt to regulate conditions in the body. To make feedback loops relevant to students, teachers can discuss the hormone leptin, which fat cells produce as they become filled with storage reserves. Leptin is carried by the blood to the brain, where it normally acts to inhibit the appetite center, an example of negative feedback. When fat reserves diminish, the concentration of leptin decreases, a phenomenon that in turn causes the appetite center in the brain to start the hunger stimulus and activate the urge to eat. 9. i.* Students know how hormones (including digestive, reproductive, osmoregulatory) provide internal feedback mechanisms for homeostasis at the cellular level and in whole organisms. Hormones act as chemical messengers, affecting the activity of neighboring cells or other target organs. Their movement can be traced from their point of origin to the target site. The feedback mechanism works to regulate the activity of hormones and promotes homeostasis.

Endocrine System Endocrine System Presentation Transcript

  • Chemical Signals in Animals
    • 9. c. Students know how feedback loops in the nervous and endocrine systems regulate conditions in the body.
    • 9. i.* Students know how hormones (including digestive, reproductive, osmoregulatory) provide internal feedback mechanisms for homeostasis at the cellular level and in whole organisms.
  • Hormone Dysfunction
  • Hormone Dysfunction
  • Feedback Loops
    • Feedback loops are how the nervous system uses the endocrine system to regulate body conditions.
    • The presence or absence of hormones in blood brought to the brain by the circulatory system will trigger an attempt to regulate conditions in the body.
  • Hormone Example
    • The hormone leptin, which fat cells produce as they become filled with storage reserves.
    • Leptin is carried by the blood to the brain, where it normally acts to stop hunger
    • An example of negative feedback. When fat reserves diminish, the concentration of leptin decreases, a phenomenon that in turn causes the appetite center in the brain to start the hunger stimulus and activate the urge to eat.
  • Hormones work with the Nervous System
    • For ex-ample, in the digestive system, where insulin released from the pancreas into the blood regulates the uptake of glucose by muscle cells.
    • The pituitary master gland produces growth hormone for controlling height.
  • Mode of Action: Chemical Signaling
    • 1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones)
    • 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators
  • Vertebrate Endocrine System
    • Tropic hormones ~ a hormone that has another endocrine gland as a target
    • Hypothalamus~pituitary
    • Pituitary gland
    • Pineal gland
    • Thyroid gland
    • Parathyroid glands
    • Thymus
    • Adrenal glands
    • Pancreas
    • Gonads (ovary, testis)
  • The hypothalamus & pituitary, I
    • Releasing and inhibiting hormones
    • Anterior pituitary:
    • Growth (GH)~bones √gigantism/dwarfism √acromegaly
    • Prolactin (PRL)~mammary glands; milk production
    • Follicle-stimulating (FSH) &
    • Luteinizing (LH)~ovaries/testes
    • Thyroid-stimulating (TSH)~ thyroid
    • Adrenocorticotropic (ACTH)~ adrenal cortex
    • Melanocyte-stimulating (MSH)
    • Endorphins~natural ‘opiates’; brain pain receptors
  • The pituitary, II
    • The posterior pituitary:
    • Oxytocin ~ uterine and mammary gland cell contraction
    • Antidiuretic (ADH )~ retention of water by kidneys
  • Pituitary Hormones
    • Follicle-stimulating hormone [FSH] and luteinizing hormone [LH] control the gonads
    • Thyroid-stimulating hormone [TSH] controls the thyroid, and adrenocorticotropic hormone [ACTH] regulates the formation of glucocorticoids by the adrenal cortex).
    • This master gland is itself controlled by the hypothalamus of the brain.
  • The pineal, thyroid, & parathyroid
    • Melatonin ~ pineal gland; biological rhythms
    • Thyroid hormones : Calcitonin~ lowers blood calcium Thyroxine~ metabolic processes
    • Parathyroid (PTH)~ raises blood calcium
  • The pancreas
    • Beta cells: •insulin~ lowers blood glucose levels
    • Type I diabetes mellitus (insulin-dependent; autoimmune disorder)
    • Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness in insulin targets)
  • The adrenal glands
    • Adrenal medulla (catecholamines): •epinephrine & norepinephrine~ increase basal metabolic rate (blood glucose and pressure)
    • Adrenal cortex (corticosteroids): •glucocorticoids (cortisol)~ raise blood glucose •mineralocorticoids (aldosterone)~ reabsorption of Na+ and K+
  • The gonads
    • Ovaries
    • estrogens (estradiol)~uterine lining growth; female secondary sex characteristics; gonadotropin
    • progestins (progesterone)~uterine lining growth
    • Testes
    • Steroid hormones : precursor is cholesterol
    • androgens (testosterone)~ sperm formation; male secondary sex characteristics; gonadotropin
  • Regulatory systems
    • Hormone ~ chemical signal secreted into body fluids (blood) communicating regulatory messages
    • Target cells ~ body cells that respond to hormones
    • Endocrine system/glands ~ hormone secreting system/glands (ductless); exocrine glands secrete chemicals (sweat, mucus, enzymes) through ducts
    • Neurosecretory cells ~ actual cells that secrete hormones
    • Feedback mechanisms ~ negative and positive
  • Local regulators: cells adjacent to or near point of secretion
    • Growth factors ~ proteins for cell proliferation
    • Nitric oxide (NO) ~ neurotransmitter; cell destruction; vessel dilation
    • Prostaglandins ~ modified fatty acids secreted by placenta and immune system; also found in semen