Hormones and the Endocrine System Chapter 45 Hormones and the Endocrine System

Overview: The Body’s Long-Distance Regulators Animal _______________ are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body Hormones reach ____________ of the body, but only target cells have ________ for that hormone Insect metamorphosis is regulated by hormones © 2011 Pearson Education, Inc.

Two systems coordinate communication throughout the body: the endocrine system and the nervous system The __________________ secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior The ________________ conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells © 2011 Pearson Education, Inc.

Concept 45.1: Hormones and other signaling molecules bind to target receptors, triggering specific response pathways ________________ is just one of several ways that information is transmitted between animal cells © 2011 Pearson Education, Inc.

Intercellular Communication The ways that signals are transmitted between animal cells are classified by two criteria The _______________ The ___________________ by the signal in reaching its target © 2011 Pearson Education, Inc.

Endocrine Signaling Hormones secreted into extracellular fluids by endocrine cells reach their targets via the ______________________________ Endocrine signaling maintains _____________, mediates _______________, regulates ______ ______________________ © 2011 Pearson Education, Inc.

Figure 45.2 Intercellular communication by secreted molecules. Blood vessel Response (a) Endocrine signaling Response (b) Paracrine signaling Response (c) Autocrine signaling Synapse Neuron Figure 45.2 Intercellular communication by secreted molecules. Response (d) Synaptic signaling Neurosecretory cell Blood vessel Response (e) Neuroendocrine signaling

Paracrine and Autocrine Signaling _________________ are molecules that act over short distances, reaching target cells solely by diffusion In __________________, the target cells lie near the secreting cells In __________________, the target cell is also the secreting cell © 2011 Pearson Education, Inc.

(a) Endocrine signaling Figure 45.2a Blood vessel Response (a) Endocrine signaling Response (b) Paracrine signaling Figure 45.2 Intercellular communication by secreted molecules. Response (c) Autocrine signaling

Synaptic and Neuroendocrine Signaling In________________, neurons form specialized junctions with target cells, called synapses At synapses, neurons secrete molecules called ______________ that diffuse short distances and bind to receptors on target cells In neuroendocrine signaling, specialized neurosecretory cells secrete molecules called ___________________ that travel to target cells via the bloodstream © 2011 Pearson Education, Inc.

(d) Synaptic signaling Figure 45.2b Synapse Neuron Response (d) Synaptic signaling Neurosecretory cell Figure 45.2 Intercellular communication by secreted molecules. Blood vessel Response (e) Neuroendocrine signaling

Signaling by Pheromones Members of the same animal species sometimes communicate with________________, chemicals that are released into the environment Pheromones serve many functions, including marking trails leading to food, defining territories, warning of predators, and attracting potential mates © 2011 Pearson Education, Inc.

Endocrine Tissues and Organs In some tissues, endocrine cells are grouped together in ductless organs called ____________ _______________ Endocrine glands secrete ______________ directly into surrounding fluid These contrast with _______________, which have ducts and which secrete substances onto body surfaces or into cavities Ex. Salivary glands © 2011 Pearson Education, Inc.

Major endocrine glands: Figure 45.4 Major endocrine glands: Hypothalamus Pineal gland Pituitary gland Organs containing endocrine cells: Thyroid gland Thymus Parathyroid glands (behind thyroid) Heart Liver Adrenal glands (atop kidneys) Stomach Pancreas Kidneys Small intestine Figure 45.4 Major human endocrine glands. Ovaries (female) Testes (male)

Chemical Classes of Hormones Three major classes of molecules function as hormones in vertebrates __________________ (proteins and peptides) _________________ derived from amino acids ____________________ © 2011 Pearson Education, Inc.

_______________hormones (steroid hormones) pass easily through cell membranes, while __________________hormones (polypeptides and amines) do not The solubility of a hormone correlates with the location of ______________ inside or on the surface of target cells © 2011 Pearson Education, Inc.

Water-soluble (hydrophilic) Lipid-soluble (hydrophobic) Figure 45.5 Water-soluble (hydrophilic) Lipid-soluble (hydrophobic) Polypeptides Steroids 0.8 nm Insulin Cortisol Amines Figure 45.5 Hormones differ in structure and solubility. Epinephrine Thyroxine

Cellular Response Pathways Water- and lipid-soluble hormones differ in their ____________ through a body Water-soluble hormones are secreted by ______________, travel freely in the bloodstream, and bind to ___________________ Lipid-soluble hormones ___________across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells © 2011 Pearson Education, Inc.

Water- soluble hormone Lipid- soluble hormone Figure 45.6-1 SECRETORY CELL Water- soluble hormone Lipid- soluble hormone VIA BLOOD Transport protein Signal receptor TARGET CELL Signal receptor Figure 45.6 Receptor location varies with hormone type. NUCLEUS (a) (b)

Water- soluble hormone Lipid- soluble hormone Figure 45.6-2 SECRETORY CELL Water- soluble hormone Lipid- soluble hormone VIA BLOOD Transport protein Signal receptor TARGET CELL OR Signal receptor Figure 45.6 Receptor location varies with hormone type. Cytoplasmic response Gene regulation Cytoplasmic response Gene regulation NUCLEUS (a) (b)

Pathway for Water-Soluble Hormones Binding of a hormone to its receptor initiates a ________________ pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression © 2011 Pearson Education, Inc.

The hormone ____________ has multiple effects in mediating the body’s response to short-term stress Epinephrine binds to receptors on the plasma membrane of _____________ cells This triggers the release of messenger molecules that activate enzymes and result in the release of ___________ into the bloodstream © 2011 Pearson Education, Inc.

G protein-coupled receptor Figure 45.7-1 Epinephrine Adenylyl cyclase G protein G protein-coupled receptor GTP ATP Second messenger cAMP Figure 45.7 Cell-surface hormone receptors trigger signal transduction.

G protein-coupled receptor GTP Figure 45.7-2 Epinephrine Adenylyl cyclase G protein G protein-coupled receptor GTP ATP Second messenger cAMP Figure 45.7 Cell-surface hormone receptors trigger signal transduction. Protein kinase A Inhibition of glycogen synthesis Promotion of glycogen breakdown

Pathway for Lipid-Soluble Hormones The response to a lipid-soluble hormone is usually a change in ______________________ ________________ hormones, and the hormonal form of ___________enter target cells and bind to protein receptors in the cytoplasm or nucleus Protein-receptor complexes then act as ___________________ in the nucleus, regulating transcription of specific genes © 2011 Pearson Education, Inc.

Estradiol (estrogen) receptor Figure 45.8-1 Hormone (estradiol) EXTRACELLULAR FLUID Estradiol (estrogen) receptor Plasma membrane Hormone-receptor complex Figure 45.8 Steroid hormone receptors directly regulate gene expression.

Estradiol (estrogen) receptor Figure 45.8-2 Hormone (estradiol) EXTRACELLULAR FLUID Estradiol (estrogen) receptor Plasma membrane Hormone-receptor complex NUCLEUS CYTOPLASM Figure 45.8 Steroid hormone receptors directly regulate gene expression. DNA Vitellogenin mRNA for vitellogenin

Multiple Effects of Hormones The same hormone may have different effects on target cells that have Different ______________ for the hormone Different ______________________________ © 2011 Pearson Education, Inc.

Same receptors but different intracellular proteins (not shown) Figure 45.9 Same receptors but different intracellular proteins (not shown) Different receptors Different cellular responses Different cellular responses Epinephrine Epinephrine Epinephrine  receptor  receptor  receptor Glycogen deposits Figure 45.9 One hormone, different effects. Vessel dilates. Vessel constricts. Glycogen breaks down and glucose is released from cell. (a) Liver cell (b) Skeletal muscle blood vessel Intestinal blood vessel (c)

Signaling by Local Regulators _________________ are secreted molecules that link neighboring cells or directly regulate the secreting cell Types of local regulators ______________ and ________________ __________________ © 2011 Pearson Education, Inc.

In the immune system, prostaglandins promote __________ and ______________ and intensify the sensation of pain Prostaglandins help regulate _______________ _______________, an early step in formation of blood clots © 2011 Pearson Education, Inc.

Coordination of Neuroendocrine and Endocrine Signaling The endocrine and nervous systems generally act __________________ to control reproduction and development For example, in larvae of butterflies and moths, the signals that direct molting originate in the brain © 2011 Pearson Education, Inc.

In insects, molting and development are controlled by a combination of hormones A _____________(PTTH) stimulates release of ________________from the prothoracic glands _______________________ promotes retention of larval characteristics _______________________ promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics © 2011 Pearson Education, Inc.

Juvenile hormone (JH) Low JH Figure 45.10-3 Brain Neurosecretory cells Corpora cardiaca Corpora allata PTTH Prothoracic gland Juvenile hormone (JH) Low JH Ecdysteroid Figure 45.10 Regulation of insect development and metamorphosis. EARLY LARVA LATER LARVA PUPA ADULT

Concept 45.2: Feedback regulation and antagonistic hormone pairs are common in endocrine systems Hormones are assembled into _____________ _______________________ © 2011 Pearson Education, Inc.

Simple Hormone Pathways Hormones are released from an endocrine cell, travel through the bloodstream, and interact with specific receptors within a target cell to cause a __________________ response © 2011 Pearson Education, Inc.

For example, the release of acidic contents of the stomach into the duodenum stimulates endocrine cells there to secrete _________________ This causes target cells in the _____________, a gland behind the stomach, to raise the pH in the duodenum © 2011 Pearson Education, Inc.

S cells of duodenum secrete the hormone secretin ( ). Figure 45.11 Pathway Example  Stimulus Low pH in duodenum S cells of duodenum secrete the hormone secretin ( ). Endocrine cell Hormone Negative feedback Figure 45.11 A simple endocrine pathway. Blood vessel Target cells Pancreas Response Bicarbonate release

In a simple neuroendocrine pathway, the stimulus is received by a sensory neuron, which stimulates a __________________ cell The neurosecretory cell secretes a __________________________, which enters the bloodstream and travels to target cells © 2011 Pearson Education, Inc.

Hypothalamus/ posterior pituitary Figure 45.12 Pathway Example  Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Posterior pituitary secretes the neurohormone oxytocin ( ). Neurosecretory cell Positive feedback Neurohormone Blood vessel Figure 45.12 A simple neuroendocrine pathway. Target cells Smooth muscle in breasts Response Milk release

Feedback Regulation A _________________ loop inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity ___________________ reinforces a stimulus to produce an even greater response For example, in mammals ____________ causes the release of milk, causing greater suckling by offspring, which stimulates the release of more oxytocin © 2011 Pearson Education, Inc.

Insulin and Glucagon: Control of Blood Glucose _____________ (decreases blood glucose) and _____________ (increases blood glucose) are antagonistic hormones that help maintain glucose homeostasis The pancreas has clusters of endocrine cells called ______________ with _________ cells that produce glucagon and __________ cells that produce insulin © 2011 Pearson Education, Inc.

Body cells take up more glucose. Insulin Figure 45.13 Body cells take up more glucose. Insulin Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Blood glucose level rises (for instance, after eating a carbohydrate-rich meal). Blood glucose level declines. Homeostasis: Blood glucose level (70–110 mg/m100mL) STIMULUS: Blood glucose level falls (for instance, after skipping a meal). Figure 45.13 Maintenance of glucose homeostasis by insulin and glucagon. Blood glucose level rises. Liver breaks down glycogen and releases glucose into the blood. Alpha cells of pancreas release glucagon into the blood. Glucagon

Target Tissues for Insulin and Glucagon Insulin ___________blood glucose levels by Promoting the ________________________ Slowing _____________________ in the liver Promoting ______________, not breakdown © 2011 Pearson Education, Inc.

Glucagon ___________ blood glucose levels by Stimulating conversion of ___________ to __________________ in the liver Stimulating breakdown of _______and _______ into glucose © 2011 Pearson Education, Inc.

Diabetes Mellitus __________________ is perhaps the best-known endocrine disorder It is caused by a deficiency of __________ or a _________________ to insulin in target tissues It is marked by __________blood glucose levels © 2011 Pearson Education, Inc.

_____________________ (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic ________cells ____________________(non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors © 2011 Pearson Education, Inc.

Concept 45.3: The hypothalamus and pituitary are central to endocrine regulation Endocrine pathways are subject to regulation by the_______________, including the brain © 2011 Pearson Education, Inc.

Coordination of Endocrine and Nervous Systems in Vertebrates The _________________ receives information from the nervous system and initiates responses through the endocrine system Attached to the hypothalamus is the __________ ________________, composed of the posterior pituitary and anterior pituitary © 2011 Pearson Education, Inc.

The __________________ stores and secretes hormones that are made in the hypothalamus The __________________ makes and releases hormones under regulation of the hypothalamus © 2011 Pearson Education, Inc.

Cerebrum Pineal gland Thalamus Hypothalamus Cerebellum Pituitary gland Figure 45.14 Cerebrum Pineal gland Thalamus Hypothalamus Cerebellum Pituitary gland Spinal cord Hypothalamus Figure 45.14 Endocrine glands in the human brain. Posterior pituitary Anterior pituitary

Posterior Pituitary Hormones The two hormones released from the posterior pituitary act directly on nonendocrine tissues _______________ regulates milk secretion by the mammary glands _____________________ regulates physiology and behavior © 2011 Pearson Education, Inc.

Mammary glands, uterine muscles Figure 45.15 Hypothalamus Neurosecretory cells of the hypothalamus Neurohormone Axons Posterior pituitary Anterior pituitary Figure 45.15 Production and release of posterior pituitary hormones. HORMONE ADH Oxytocin TARGET Kidney tubules Mammary glands, uterine muscles

Anterior Pituitary Hormones Hormone production in the _______________ is controlled by releasing and inhibiting hormones from the hypothalamus For example, prolactin-releasing hormone from the hypothalamus stimulates the anterior pituitary to secrete ___________________, which has a role in milk production © 2011 Pearson Education, Inc.

Liver, bones, other tissues Figure 45.16 Tropic effects only: FSH LH TSH ACTH Neurosecretory cells of the hypothalamus Nontropic effects only: Prolactin MSH Nontropic and tropic effects: GH Hypothalamic releasing and inhibiting hormones Portal vessels Endocrine cells of the anterior pituitary Posterior pituitary Pituitary hormones Figure 45.16 Production and release of anterior pituitary hormones. HORMONE FSH and LH TSH ACTH Prolactin MSH GH TARGET Testes or ovaries Thyroid Adrenal cortex Mammary glands Melanocytes Liver, bones, other tissues

Table 45.1 Table 45.1 Major Human Endocrine Glands and Some of Their Hormones

Thyroid Regulation: A Hormone Cascade Pathway A hormone can stimulate the release of a series of other hormones, the last of which activates a nonendocrine target cell; this is called a _______________________________ The release of ______________hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland Hormone cascade pathways typically involve negative feedback © 2011 Pearson Education, Inc.

Figure 45.17 Pathway Example Stimulus Cold Sensory neuron  Hypothalamus Hypothalamus secretes thyrotropin-releasing hormone (TRH ). Neurosecretory cell Releasing hormone Blood vessel  Anterior pituitary secretes thyroid-stimulating hormone (TSH, also known as thyrotropin ). Anterior pituitary Tropic hormone Negative feedback Thyroid gland secretes thyroid hormone (T3 and T4 ). Figure 45.17 A hormone cascade pathway. Endocrine cell Hormone Target cells Body tissues Increased cellular metabolism Response

Disorders of Thyroid Function and Regulation _________________, too little thyroid function, can produce symptoms such as Weight gain, lethargy, cold intolerance __________________, excessive production of thyroid hormone, can lead to High temperature, sweating, weight loss, irritability, and high blood pressure __________________can alter thyroid function © 2011 Pearson Education, Inc.

Thyroid hormone refers to a pair of hormones ____________disease, a form of hyperthyroidism caused by autoimmunity, is typified by protruding eyes Thyroid hormone refers to a pair of hormones _________________, with three iodine atoms _________________, with four iodine atoms Insufficient dietary ____________ leads to an enlarged thyroid gland, called a ___________ © 2011 Pearson Education, Inc.

Evolution of Hormone Function Over the course of evolution the function of a given hormone may _______ between species For example, thyroid hormone plays a role in metabolism across many lineages, but in frogs has taken on a unique function: stimulating the _______________ of the tadpole tail during metamorphosis ______________ also has a broad range of activities in vertebrates © 2011 Pearson Education, Inc.

_____________________________________ regulates skin color in amphibians, fish, and reptiles by controlling pigment distribution in melanocytes In mammals, MSH plays additional roles in __________ and _______________ in addition to coloration © 2011 Pearson Education, Inc.

Tropic and Nontropic Hormones A ________ hormone regulates the function of endocrine cells or glands Three primarily tropic hormones are __________________________ _______________________________ © 2011 Pearson Education, Inc.

It promotes growth directly and has diverse metabolic effects __________________ is secreted by the anterior pituitary gland and has tropic and nontropic actions It promotes growth directly and has diverse metabolic effects It stimulates production of growth factors An excess of GH can cause ______________, while a lack of GH can cause dwarfism © 2011 Pearson Education, Inc.