Hormones and the Endocrine System

Transcription

1 Chapter 45 Hormones and the Endocrine System PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

2 Overview: The Body s Long-Distance Regulators Animal hormones are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body Maintain homeostasis by altering target cell activity Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 2

3 Two systems coordinate communication throughout the body: the endocrine system and the nervous system The endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior The nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells 3 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4 Today we will talk about endocrine system 4 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

5 Types of Secreted Signaling Molecules Secreted chemical signals include Hormones Local regulators Neurotransmitters Neurohormones Pheromones 5 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

6 Hormones Endocrine signals (hormones) are secreted by various endocrine glands into extracellular fluids and travel via the bloodstream Hormones mediate responses to environmental stimuli and regulate growth, development, and reproduction Hormones are released from an endocrine cell, travel through the bloodstream, and interact with the receptor or a target cell to cause a physiological response Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 6

7 Fig Major endocrine glands: Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Major human endocrine glands Organs containing endocrine cells: Thymus Heart Liver Stomach Testes Pancreas Kidney Ovaries Kidney Small intestine

8 Effects on target cells Alters plasma membrane permeability Stimulates synthesis of proteins Activates or deactivates enzymes Induces secretory activity Stimulates mitosis 8 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9 Mechanisms of action Amino-acid based hormones Hormone binds to receptor on target cell Causes cascade of chemical reactions Steroid hormones: direct gene activation Diffuse into cell Bind to intracellular receptor Receptor-hormone complex binds to DNA receptor in nucleus Turns on gene, results in protein 9 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

10 Control of hormone release Fig Pathway Stimulus Example Low ph in duodenum A simple endocrine pathway Target cells Endocrine cell Blood vessel S cells of duodenum secrete secretin ( ) Action produced by hormone stimulates (in positive feedback) or inhibits (in negative feedback) further release of hormone Pancreas Response Bicarbonate release

11 Positive feedback Fig Pathway Stimulus Sensory neuron Example Suckling A simple neurohormone pathway Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target cells Smooth muscle in breasts Response Milk release

12 Invertebrate hormones In insects, molting and development are controlled by a combination of hormones: A brain hormone stimulates release of ecdysone from the prothoracic glands Ecdysone promotes molting (in the presence of juvenile hormone) and metamorphosis (in the absence of juvenile hormone Juvenile hormone promotes retention of larval characteristics 12 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

13 Fig Brain Neurosecretory cells PTTH Corpus cardiacum Corpus allatum Prothoracic gland Low JH Ecdysone Juvenile hormone (JH) EARLY LARVA LATER LARVA PUPA ADULT

14 Vertebrate hormones The hypothalamus receives information from the nervous system and initiates responses through the endocrine system Attached to the hypothalamus is the pituitary gland composed of the posterior pituitary and anterior pituitary The posterior pituitary stores and secretes hormones that are made in the hypothalamus The anterior pituitary makes and releases hormones under regulation of the hypothalamus 14 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15 Fig Pineal gland Cerebellum Spinal cord Cerebrum Thalamus Hypothalamus Pituitary gland Endocrine glands in the human brain Posterior pituitary Hypothalamus Anterior pituitary

16 Table 45-1

17 Table 45-1a

18 Table 45-1b

19 Table 45-1c

20 Table 45-1d

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22 Thank you for your attention and participation!

23 You should now be able to: 1. Explain how the antagonistic hormones insulin and glucagon regulate carbohydrate metabolism read on your own! 2. Explain how the hypothalamus and the pituitary glands interact and how they coordinate the endocrine system 3. List and describe the functions of hormones released by the following: anterior and posterior pituitary lobes, thyroid glands, parathyroid glands, adrenal medulla, adrenal cortex, gonads, pineal gland - read on your own! 23 Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings