Campbell Biology Chapter 45: Hormones & Endocrine System PDF

Campbell Biology Third Canadian Edition Chapter 45 Hormones and the Endocrine System Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›...

Campbell Biology Third Canadian Edition Chapter 45 Hormones and the Endocrine System Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Key Concepts Hormones and other signalling molecules bind to target receptors, triggering specific response pathways Feedback regulation and coordination with the nervous system are common in endocrine systems Endocrine glands respond to diverse stimuli in regulating homeostasis, development, and behaviour Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Overview: The Body’s Long-Distance Regulators Animal hormones are chemical signals secreted into the circulatory system, and communicate regulatory messages within the body Hormones reach all parts of the body, but only target cells that have receptors for that hormone Loading… Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› The Body’s Long-Distance Regulators (1 of 4) In many species the females and males look different from each other like the elephant seals (Mirounga angustirostris) shown below. Figure 45.1 What makes male and female elephant seals look so different? Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  The Body’s Long-Distance Regulators (2 of 4) Two systems coordinate communication throughout the body hormones – endocrine system travel very slowly the blood but last > - in much longer – nervous system superfast > - but response doesn't last long Loading… Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  The Body’s Long-Distance Regulators (3 of 4) Endocrine system secretes hormones that coordinate slower but longer-acting responses, including – reproduction – development – energy metabolism – growth – behaviour Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› The Body’s Long-Distance Regulators (4 of 4) Nervous system conveys high-speed electrical signals along specialized cells called neurons These signals regulate other cells including other neurons, muscle cells and endocrine cells Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Concept 45.1: Hormones and other signalling molecules bind to target receptors, triggering specific response pathways Animals use chemical signals to communicate in diverse ways Endocrine signalling is one of several ways that information transmitted between animal cells Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Endocrine Signalling Hormones secreted into extracellular fluids by endocrine cells reach their targets via the bloodstream Endocrine signalling maintains homeostasis, mediates responses to stimuli, regulates growth and development Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Paracrine and Autocrine Signalling (1 of 2) Local regulators are molecules that act over short distances, reaching target cells solely by diffusion In paracrine signalling, target cells near the secreting cells In autocrine signalling, the target cell is also the secreting cell Figure 45.2a,b,c Intercellular communication by secreted molecules Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Paracrine and Autocrine Signalling (2 of 2) Paracrine and autocrine signalling play roles in processes such as blood pressure regulation, nervous system function, and reproduction Local regulators that mediate such signalling include the prostaglandins, which function in reproduction, the Loading… immune system and blood clotting Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Signalling by Pheromones (1 of 2) Members of an animal species sometimes communicate with pheromones These are chemicals that are released into the environment Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Signalling by Pheromones (2 of 2) Pheromones serve many functions, including – marking trails leading to food – defining territories – warning of predators – attracting potential mates Figure 45.3 Signalling by pheromones. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  14 The Japanese beetle (Popillia japonica) is a highly destructive plant pest Copyright © 2020 Pearson Education, Inc. All Rights Reserved  15 Japanese beetle Trap based on pheromones Copyright © 2020 Pearson Education, Inc. All Rights Reserved  Chemical Classes of Intercellular Signalling Factors (1 of 2) Many different chemicals function in communication between cells in animals. There are three major classes of hormones in vertebrates – Polypeptides (proteins and peptides) – Amines derived from amino acids – Steroid hormones The solubility properties of each are important for how they function Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Chemical Classes of Intercellular Signalling Factors (2 of 2) Figure 45.4 Hormones differ in structure and solubility. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Chemical Classes of Hormones Lipid-soluble hormones (steroid hormones) pass easily through cell membranes, whereas water-soluble hormones (polypeptides and amines) do not Figure 45.5 Receptor location varies with hormone type. / to let the hormone the Inside cell Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Protein and Amide Signalling Factors (1 of 2) Many of the most familiar hormones are proteins encoded by genes Example: Insulin – Produced as long, inactive prohormone polypeptide secreted when needed to reduce blood glucose Example: Growth factors – Regulate the cell cycle Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Protein and Amide Signalling Factors (2 of 2) Amine hormones are signalling factors produced from amino acids Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Lipid Signalling Factors Most lipid hormones are related to fatty acids and steroids Prostaglandins are modified fatty acids that promote fever and inflammation Many hormones, such as steroids, are derived from cholesterol Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Cellular Response Pathways (1 of 2) Water- and lipid-soluble hormones differ in their paths through a body Figure 45.5 Receptor location varies with hormone type. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Cellular Response Pathways (2 of 2) Water-soluble hormones – Are secreted by exocytosis N son – travel freely in the bloodstream – bind to cell-surface receptors Lipid-soluble hormones – diffuse across cell membranes – travel in the bloodstream bound to transport proteins – Bind to receptors in the cytoplasm or nucleus Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Hormones and the Endocrine System (1 of 4) THINK-PAIR-SHARE What do you expect would happen if the hormone receptor was mutated such that it could not bind the hormone? will arrive to the all BUT > - The hormone nothing. It would be as if it wasnt the will happen target cell. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Pathway for Water-Soluble Hormones (1 of 4) Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoskeleton, enzyme activation, or a change in gene expression Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Pathway for Water-Soluble Hormones (2 of 4) Animation: Water-Soluble Hormone Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Pathway for Water-Soluble Hormones (3 of 4) The hormone epinephrine (Adrenaline) has multiple effects in mediating the body’s response to short-term stress > - should know about this Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Pathway for Water-Soluble Hormones (4 of 4) Epinephrine binds to receptors on the plasma membrane of liver cells This triggers the release of messenger molecules that activate enzymes One of the responses in the cell is the activation of an enzyme that breaks down glycogen, which results in the release of glucose into the bloodstream Figure 45.6 Cell-surface hormone receptors trigger signal Copyright © 2021 Pearson Canada, Inc. transduction. 45 - ‹#› Pathway for Lipid-Soluble Hormones (1 of 3) The response to a lipid-soluble hormone is usually a change in gene expression When a steroid hormone binds to its cytosolic receptor, the resulting hormone-receptor complex moves into the nucleus Loading… Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Pathway for Lipid-Soluble Hormones (2 of 3) Once in the nucleus, the receptor part of the complex acts as a transcription factor, regulating transcription of specific target genes Figure 45.7 Steroid hormone receptors directly regulate gene expression. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Pathway for Lipid-Soluble Hormones (3 of 3) Animation: Lipid-Soluble Hormone Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Hormones and the Endocrine System (2 of 4) THINK-PAIR-SHARE Would you expect lipid soluble hormones to enter every cell? Would this be a problem? > - No it wouldn't go in every call since they need the specialized receptor Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Multiple Effects of Hormones The same hormone may have different effects on target cells that have – For example, the hormone epinephrine (Adrenaline) can increase blood flow to major skeletal muscles, but decrease blood flow to the digestive tract Figure 45.8 One hormone, different effects. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Specialized role of a hormone in frog metamorphosis Thyroid hormone regulates metabolism In frogs, it also controls metamorphosis of the larva into adult Figure 45.9 Major human endocrine glands. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Endocrine Tissues and Organs Endocrine cells are often grouped in ductless organs called endocrine glands, such as the thyroid and parathyroid glands, testes and ovaries – Endocrine glands secrete hormones directly into surrounding fluid In contrast, exocrine glands, such as salivary glands have ducts to carry secreted substances onto body surfaces or into body cavities Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Figure 45.10 Major human endocrine glands. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› A simple endocrine pathway Figure 45.11 A simple endocrine pathway. Stimulus will tell & to release & Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Simple Hormone Pathways Example: the release of acidic stomach contents into the duodenum stimulates endocrine cells there to secrete secretin This causes target cells in the pancreas, a gland behind the stomach, to raise the pH in the duodenum Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› A simple neuroendocrine pathway (1 of 2) In a simple Figure 45.12 simple neuroendocrine pathway. neuroendocrine pathway, the stimulus is received by a sensory neuron, which stimulates a neurosecretory cell The neurosecretory cell secretes a neurohormone, which enters the bloodstream and travels to target cells Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› A simple neuroendocrine pathway (2 of 2) Figure 45.12 simple neuroendocrine pathway. For example, suckling by an infant stimulates nervous system signals that reach the hypothalamus Nerve impulses from the hypothalamus trigger the release of oxytocin (the love hormone) from the posterior pituitary, which causes the mammary glands to secrete more milk Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Oxytocin – (previously called the Love Hormone) Copyright © 2020 Pearson Education, Inc. All Rights Reserved  Feedback Regulation A negative feedback loop inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity Positive feedback reinforces a stimulus to produce an even greater response – The previous example involving oxytocin is a positive feedback system Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Invertebrates In insects, molting and development is controlled by a combination of hormones – Prothoracicotropic hormone (PTTH) is produced in the brain and stimulates release of ecdysteroid from the prothoracic gland – Juvenile hormone promotes retention of larval characteristics – Ecdysone promotes molting (in presence of juvenile hormone) and development (in absence of juvenile hormone) of adult characteristics Figure 45.13 Regulation of insect development and metamorphosis. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Hormones and Biological Rhythms The pineal gland, located in the brain, secretes melatonin – Light/dark cycles control release of melatonin > Primary functions of melatonin appear to relate to biological rhythms associated with reproduction and daily activity levels The release of melatonin by the pineal gland is controlled by a group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN) Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Vertebrates The hypothalamus plays a central role in integrating the endocrine and nervous systems The hypothalamus receives information from the nervous system and initiates responses through endocrine signalling Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› The hypothalamus-pituitary axis Attached to the hypothalamus is the pituitary gland, composed of posterior pituitary and anterior pituitary => Figure 45.14 Endocrine glands in the human brain. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Posterior Pituitary Hormones Two hormones released from the posterior pituitary act – directly on nonendocrine tissues => Oxytocin regulates milk secretion by mammary glands – Antidiuretic hormone (ADH) regulates physiology and behaviour Figure 45.15 Production and release of posterior pituitary hormones. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Anterior Pituitary Hormones Hormone production in the anterior pituitary is controlled by releasing and inhibiting hormones secreted from the hypothalamus For example, prolactin-releasing hormone from the hypothalamus stimulates the anterior pituitary to secrete prolactin, which has a role in milk production Figure 45.16 Production and release of anterior pituitary hormones. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Thyroid Regulation: A Hormone Cascade Pathway In humans and other mammals, thyroid hormone regulates many functions If thyroid hormone level drops in the blood, the hypothalamus secretes thyrotropin-releasing hormone (TRH) causing the anterior pituitary to secrete thyroid- stimulating hormone (TSH) TSH stimulates release of thyroid hormone by the thyroid gland Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› A hormone cascade pathway Hormone cascade pathways typically involve negative feedback Figure 45.17 Regulation of thyroid hormone secretion: a hormone cascade pathway. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Disorders of Thyroid Function and Regulation Hypothyroidism, too little thyroid function, can lead to symptoms such as – Weight gain, lethargy, cold intolerance Hyperthyroidism, excessive production of thyroid hormone, can lead to – High temperature, sweating, weight loss, irritability, and high blood pressure Malnutrition can alter thyroid function Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Growth Hormone Growth hormone (GH) is secreted by the anterior pituitary gland It promotes growth directly and has diverse metabolic effects It stimulates production of growth factors An excess of GH can cause gigantism, while a lack of GH can cause dwarfism Figure 45.18 Effect of growth hormone overproduction. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Hormones and the Endocrine System (3 of 4) THINK-PAIR-SHARE How would you treat dwarfism due to lack of growth hormone? Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› 45.3 Endocrine glands respond to diverse stimuli in regulating homeostasis, development, and behaviour = The regulation of calcium ion concentration in the M circulatory system is critical because Ca2+ is an essential ion to body cells. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Parathyroid Hormone and Vitamin D: Control of Blood Calcium (1 of 2) Two antagonistic hormones regulate the homeostasis of calcium (Ca2+) in the blood of mammals – Parathyroid hormone (PTH) is released by parathyroid glands – Calcitonin is released by thyroid gland Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals Figure 45.19 The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals. & are there NOBOTEhers in des SIL Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Parathyroid Hormone and Vitamin D: Control of Blood Calcium (2 of 2) PTH increases the level of blood Ca2+ – It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys – It also has an indirect effect by stimulating kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food Calcitonin decreases the level of blood Ca2+ – It stimulates Ca2+ deposition in bones and secretion by kidneys Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands ancreas - P S BOXED other tren I NOT Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  64 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  Adrenal Hormones: Response to Stress The adrenal glands are associated with the kidneys Each adrenal gland actually consists of two glands – The adrenal medulla (inner portion) – The adrenal cortex (outer portion) Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Stress and the adrenal gland Figure 45.20 Stress and the adrenal gland. Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Hormones and the Endocrine System (4 of 4) THINK-PAIR-SHARE Do you think long term stress would have the same effect on a person with diabetes or without diabetes? Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Major human endocrine glands Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Sex Hormones (1 of 2) The gonads, testes and ovaries, produce most of the sex hormones: androgens, estrogens, and progestins All three sex hormones are found in both males and females, but in significantly different proportions Copyright © 2021 Pearson Canada, Inc. 45 - ‹#› Sex Hormones (2 of 2) The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system Testosterone causes an increase in muscle and bone mass and is often taken as supplement for muscle growth, which carries health risks Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›  72 End Copyright © 2021 Pearson Canada, Inc. 45 - ‹#›