Homeostasis Through Chemistry The Endocrine System Topic 6.6
Comparing NS & ES Animals have two systems of internal communication and regulation The nervous system Response time: Fast, quick Signals: electrical Specialized cells: neurons The endocrine system Response time: slower, longer Signals: chemical Specialized glands: endocrine glands
Figure 32.9 (a) Signaling by hormones Stimulus (b) Signaling by neurons Stimulus Hormone Signal travels everywhere. Endocrine cell Nerve impulse Cell body of neuron Axon Signal travels to a specific location. Blood vessel Nerve impulse Axons Response Response 2014 Pearson Education, Inc.
Hormones Three major classes of molecules Proteins and peptides Amines derived from amino acids Steroids Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Water-Soluble Hormones SECRETORY CELL Hydrophobic or hydrophilic? Can hydrophilic molecules cross the plasma membrane? Receptors: Binding: Effect: Different receptors for the hormone Different signal transduction pathways Different proteins for carrying out the response VIA BLOOD Nuclear response Signal receptor Signal transduction pathway Cytoplasmic response DNA TARGET CELL OR Hormone molecule NUCLEUS
The major human endocrine glands Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Ovary (female) Figure 45.6 Testis (male) Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Hypothalamus and pituitary gland
Hypothalamus and pituitary gland integrate and control many functions of the endocrine system Hypothalamus: region o/t brain sexual dimorphism estrogen receptor distribution in males,females result of neonatal steroid exposure neurosecretory cells some produce direct-acting hormones stored & released in posterior pituitary tropic hormone cells tropic? (see next slide) Neurosecretory cells of the hypothalamus Posterior pituitary Hypothalamus HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles Axon Anterior pituitary
Hypothalamic tropic hormones secreted into the blood and transported to the anterior pituitary Tropic Effects Only FSH, follicle-stimulating hormone LH, luteinizing hormone TSH, thyroid-stimulating hormone ACTH, adrenocorticotropic hormone Nontropic Effects Only Prolactin MSH, melanocyte-stimulating hormone Endorphin Nontropic and Tropic Effects Growth hormone Hypothalamic releasing hormones (red dots) Neurosecretory cells of the hypothalamus Portal vessels Endocrine cells of the anterior pituitary Pituitary hormones (blue dots) HORMONE FSH and LH TSH ACTH Prolactin MSH Endorphin Growth hormone Figure 45.8 TARGET Testes or ovaries Thyroid Adrenal cortex Mammary glands Melanocytes Pain receptors in the brain Liver Bones Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Endocrine IB Understandings Insulin & Glucagon ß and å cell respectively control blood glucose concentration Insulin: gets glucose in (into the cells) Glucagon: if glucose is gone, signals liver to release glucose (into the blood)
Diabetes Mellitus Diabetes mellitus, perhaps the best-known endocrine disorder Is caused by a deficiency of insulin or a decreased response to insulin in target tissues Is marked by elevated blood glucose levels Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Type I diabetes mellitus (insulin-dependent diabetes) Is an autoimmune disorder immune system destroys the beta cells of the pancreas treated: insulin added to the blood Type II diabetes mellitus (non-insulin-dependent diabetes) either deficiency of insulin or, more commonly, by reduced responsiveness of target cells due to some change in insulin receptors treated: insulin and lifestyle Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Control & effect of thyroid hormones Two negative feedback loop ex.: Effect of T3 & T4 Stimulate metabolism Influence development and maturation Too much: Hyperthyroidism Graves Disease
Graves Disease
Melatonin Secreted by pineal gland; regulates sleep cycle Can reduce effects of Jet Lag (induces earlier sleep cycle)
Leptin Secreted by cells in adipose tissue acts on hypothalamus: inhibits appetite