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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell.

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1 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 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 Chapter 44 Osmoregulation and Excretion

2 Fig Osmoregulation regulates solute concentrations and balances the gain and loss of water

3 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 44.1: Osmoregulation balances the uptake and loss of water and solutes Cells require a balance between osmotic gain and loss of water Osmolarity, the solute concentration of a solution, determines the movement of water across a selectively permeable membrane If two solutions are isoosmotic, the movement of water is equal in both directions If two solutions differ in osmolarity, the net flow of water is from the hypoosmotic to the hyperosmotic solution

4 Fig Selectively permeable membrane Net water flow Hyperosmotic side Hypoosmotic side Water Solutes

5 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Osmotic Challenges Osmoconformers, consisting only of some marine animals, are isoosmotic with their surroundings and do not regulate their osmolarity Osmoregulators expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment

6 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Most animals are stenohaline; they cannot tolerate substantial changes in external osmolarity Euryhaline animals can survive large fluctuations in external osmolarity

7 Fig. 44-3

8 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Marine Animals Most marine invertebrates are osmoconformers Most marine vertebrates and some invertebrates are osmoregulators Marine bony fishes are hypoosmotic to sea water They lose water by osmosis and gain salt by diffusion and from food They balance water loss by drinking seawater and excreting salts

9 Fig Excretion of salt ions from gills Gain of water and salt ions from food Osmotic water loss through gills and other parts of body surface Uptake of water and some ions in food Uptake of salt ions by gills Osmotic water gain through gills and other parts of body surface Excretion of large amounts of water in dilute urine from kidneys Excretion of salt ions and small amounts of water in scanty urine from kidneys Gain of water and salt ions from drinking seawater (a) Osmoregulation in a saltwater fish(b) Osmoregulation in a freshwater fish

10 Fig. 44-4a Excretion of salt ions from gills Gain of water and salt ions from food Osmotic water loss through gills and other parts of body surface Excretion of salt ions and small amounts of water in scanty urine from kidneys Gain of water and salt ions from drinking seawater (a) Osmoregulation in a saltwater fish

11 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Freshwater Animals Freshwater animals constantly take in water by osmosis from their hypoosmotic environment They lose salts by diffusion and maintain water balance by excreting large amounts of dilute urine Salts lost by diffusion are replaced in foods and by uptake across the gills

12 Fig. 44-4b Uptake of water and some ions in food Uptake of salt ions by gills Osmotic water gain through gills and other parts of body surface Excretion of large amounts of water in dilute urine from kidneys (b) Osmoregulation in a freshwater fish

13 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Animals That Live in Temporary Waters Some aquatic invertebrates in temporary ponds lose almost all their body water and survive in a dormant state This adaptation is called anhydrobiosis

14 Fig (a) Hydrated tardigrade (b) Dehydrated tardigrade 100 µm

15 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Land Animals Land animals manage water budgets by drinking and eating moist foods and using metabolic water Desert animals get major water savings from simple anatomical features and behaviors such as a nocturnal life style

16 Fig Water gain (mL) Water loss (mL) Urine (0.45) Urine (1,500) Evaporation (1.46) Evaporation (900) Feces (0.09)Feces (100) Derived from metabolism (1.8) Derived from metabolism (250) Ingested in food (750) Ingested in food (0.2) Ingested in liquid (1,500) Water balance in a kangaroo rat (2 mL/day) Water balance in a human (2,500 mL/day)

17 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Energetics of Osmoregulation Osmoregulators must expend energy to maintain osmotic gradients

18 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Transport Epithelia in Osmoregulation Animals regulate the composition of body fluid that bathes their cells Transport epithelia are specialized epithelial cells that regulate solute movement They are essential components of osmotic regulation and metabolic waste disposal They are arranged in complex tubular networks An example is in salt glands of marine birds, which remove excess sodium chloride from the blood

19 Fig Ducts Nostril with salt secretions Nasal salt gland EXPERIMENT

20 Fig Salt gland Secretory cell Capillary Secretory tubule Transport epithelium Direction of salt movement Central duct (a) Blood flow (b) Secretory tubule ArteryVein NaCl Salt secretion

21 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 44.2: An animal’s nitrogenous wastes reflect its phylogeny and habitat The type and quantity of an animal’s waste products may greatly affect its water balance Among the most important wastes are nitrogenous breakdown products of proteins and nucleic acids Some animals convert toxic ammonia (NH 3 ) to less toxic compounds prior to excretion

22 Fig Many reptiles (including birds), insects, land snails AmmoniaUric acid Urea Most aquatic animals, including most bony fishes Mammals, most amphibians, sharks, some bony fishes Nitrogenous bases Amino acids Proteins Nucleic acids Amino groups

23 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 44.3: Diverse excretory systems are variations on a tubular theme Excretory systems regulate solute movement between internal fluids and the external environment

24 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Excretory Processes Most excretory systems produce urine by refining a filtrate derived from body fluids Key functions of most excretory systems: – Filtration: pressure-filtering of body fluids – Reabsorption: reclaiming valuable solutes – Secretion: adding toxins and other solutes from the body fluids to the filtrate – Excretion: removing the filtrate from the system

25 Fig Capillary Excretion Secretion Reabsorption Excretory tubule Filtration Filtrate Urine Concept 44.3: Diverse excretory systems are variations on a tubular theme

26 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Survey of Excretory Systems Systems that perform basic excretory functions vary widely among animal groups They usually involve a complex network of tubules

27 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Protonephridia A protonephridium is a network of dead-end tubules connected to external openings The smallest branches of the network are capped by a cellular unit called a flame bulb These tubules excrete a dilute fluid and function in osmoregulation

28 Fig Tubule Tubules of protonephridia Cilia Interstitial fluid flow Opening in body wall Nucleus of cap cell Flame bulb Tubule cell

29 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Metanephridia Each segment of an earthworm has a pair of open-ended metanephridia Metanephridia consist of tubules that collect coelomic fluid and produce dilute urine for excretion

30 Fig Capillary network Components of a metanephridium: External opening Coelom Collecting tubule Internal opening Bladder

31 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Malpighian Tubules In insects and other terrestrial arthropods, Malpighian tubules remove nitrogenous wastes from hemolymph and function in osmoregulation Insects produce a relatively dry waste matter, an important adaptation to terrestrial life

32 Fig Rectum Digestive tract Hindgut Intestine Malpighian tubules Rectum Feces and urine HEMOLYMPH Reabsorption Midgut (stomach) Salt, water, and nitrogenous wastes

33 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Kidneys Kidneys, the excretory organs of vertebrates, function in both excretion and osmoregulation

34 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Structure of the Mammalian Excretory System The mammalian excretory system centers on paired kidneys, which are also the principal site of water balance and salt regulation Each kidney is supplied with blood by a renal artery and drained by a renal vein Urine exits each kidney through a duct called the ureter Both ureters drain into a common urinary bladder, and urine is expelled through a urethra Animation: Nephron Introduction Animation: Nephron Introduction

35 Fig Posterior vena cava Renal artery and vein Urinary bladder Ureter Aorta Urethra Kidney (a) Excretory organs and major associated blood vessels Cortical nephron Juxtamedullary nephron Collecting duct (c) Nephron types To renal pelvis Renal medulla Renal cortex 10 µm Afferent arteriole from renal artery Efferent arteriole from glomerulus SEM Branch of renal vein Descending limb Ascending limb Loop of Henle (d) Filtrate and blood flow Vasa recta Collecting duct Distal tubule Peritubular capillaries Proximal tubule Bowman’s capsule Glomerulus Ureter Renal medulla Renal cortex Renal pelvis (b) Kidney structure Section of kidney from a rat 4 mm

36 Fig Key Active transport Passive transport INNER MEDULLA OUTER MEDULLA H2OH2O CORTEX Filtrate Loop of Henle H2OH2OK+K+ HCO 3 – H+H+ NH 3 Proximal tubule NaClNutrients Distal tubule K+K+ H+H+ HCO 3 – H2OH2O H2OH2O NaCl Urea Collecting duct NaCl

37 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Solute Gradients and Water Conservation Urine is much more concentrated than blood The cooperative action and precise arrangement of the loops of Henle and collecting ducts are largely responsible for the osmotic gradient that concentrates the urine NaCl and urea contribute to the osmolarity of the interstitial fluid, which causes reabsorption of water in the kidney and concentrates the urine

38 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Two-Solute Model In the proximal tubule, filtrate volume decreases, but its osmolarity remains the same The countercurrent multiplier system involving the loop of Henle maintains a high salt concentration in the kidney This system allows the vasa recta to supply the kidney with nutrients, without interfering with the osmolarity gradient Considerable energy is expended to maintain the osmotic gradient between the medulla and cortex

39 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The collecting duct conducts filtrate through the osmolarity gradient, and more water exits the filtrate by osmosis Urea diffuses out of the collecting duct as it traverses the inner medulla Urea and NaCl form the osmotic gradient that enables the kidney to produce urine that is hyperosmotic to the blood

40 Fig Key Active transport Passive transport INNER MEDULLA OUTER MEDULLA CORTEX H2OH2O 300 H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O 1,200 H2OH2O 300 Osmolarity of interstitial fluid (mOsm/L) , NaCl 100 NaCl , H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O NaCl Urea

41 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Adaptations of the Vertebrate Kidney to Diverse Environments The form and function of nephrons in various vertebrate classes are related to requirements for osmoregulation in the animal’s habitat

42 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mammals The juxtamedullary nephron contributes to water conservation in terrestrial animals Mammals that inhabit dry environments have long loops of Henle, while those in fresh water have relatively short loops

43 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Birds and Other Reptiles Birds have shorter loops of Henle but conserve water by excreting uric acid instead of urea Other reptiles have only cortical nephrons but also excrete nitrogenous waste as uric acid

44 Fig

45 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Freshwater Fishes and Amphibians Freshwater fishes conserve salt in their distal tubules and excrete large volumes of dilute urine Kidney function in amphibians is similar to freshwater fishes Amphibians conserve water on land by reabsorbing water from the urinary bladder

46 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Marine Bony Fishes Marine bony fishes are hypoosmotic compared with their environment and excrete very little urine

47 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 44.5: Hormonal circuits link kidney function, water balance, and blood pressure Mammals control the volume and osmolarity of urine The kidneys of the South American vampire bat can produce either very dilute or very concentrated urine This allows the bats to reduce their body weight rapidly or digest large amounts of protein while conserving water

48 Fig

49 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Antidiuretic Hormone The osmolarity of the urine is regulated by nervous and hormonal control of water and salt reabsorption in the kidneys Antidiuretic hormone (ADH) increases water reabsorption in the distal tubules and collecting ducts of the kidney An increase in osmolarity triggers the release of ADH, which helps to conserve water Animation: Effect of ADH Animation: Effect of ADH

50 Fig Thirst Drinking reduces blood osmolarity to set point. Osmoreceptors in hypothalamus trigger release of ADH. Increased permeability Pituitary gland ADH Hypothalamus Distal tubule H 2 O reab- sorption helps prevent further osmolarity increase. STIMULUS: Increase in blood osmolarity Collecting duct Homeostasis: Blood osmolarity (300 mOsm/L) (a) Exocytosis (b) Aquaporin water channels H2OH2O H2OH2O Storage vesicle Second messenger signaling molecule cAMP INTERSTITIAL FLUID ADH receptor ADH COLLECTING DUCT LUMEN COLLECTING DUCT CELL

51 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mutation in ADH production causes severe dehydration and results in diabetes insipidus Alcohol is a diuretic as it inhibits the release of ADH

52 Fig Prepare copies of human aqua- porin genes. 196 Transfer to 10 mOsm solution. Synthesize RNA transcripts. EXPERIMENT Mutant 1 Mutant 2 Aquaporin gene Promoter Wild type H 2 O (control) Inject RNA into frog oocytes. Aquaporin protein RESULTS Permeability (µm/s) Injected RNA Wild-type aquaporin None Aquaporin mutant 1 Aquaporin mutant 2

53 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Renin-Angiotensin-Aldosterone System The renin-angiotensin-aldosterone system (RAAS) is part of a complex feedback circuit that functions in homeostasis A drop in blood pressure near the glomerulus causes the juxtaglomerular apparatus (JGA) to release the enzyme renin Renin triggers the formation of the peptide angiotensin II

54 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Angiotensin II – Raises blood pressure and decreases blood flow to the kidneys – Stimulates the release of the hormone aldosterone, which increases blood volume and pressure

55 Fig Renin Distal tubule Juxtaglomerular apparatus (JGA) STIMULUS: Low blood volume or blood pressure Homeostasis: Blood pressure, volume Liver Angiotensinogen Angiotensin I ACE Angiotensin II Adrenal gland Aldosterone Arteriole constriction Increased Na + and H 2 O reab- sorption in distal tubules

56 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Homeostatic Regulation of the Kidney ADH and RAAS both increase water reabsorption, but only RAAS will respond to a decrease in blood volume Another hormone, atrial natriuretic peptide (ANP), opposes the RAAS ANP is released in response to an increase in blood volume and pressure and inhibits the release of renin

57 Fig. 44-UN1 Animal Freshwater fish Bony marine fish Terrestrial vertebrate H 2 O and salt out Salt in (by mouth) Drinks water Salt out (active transport by gills) Drinks water Salt inH 2 O out Salt out Salt inH 2 O in (active trans- port by gills) Does not drink water Inflow/Outflow Urine Large volume of urine Urine is less concentrated than body fluids Small volume of urine Urine is slightly less concentrated than body fluids Moderate volume of urine Urine is more concentrated than body fluids

58 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 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 Chapter 45 Hormones and the Endocrine System

59 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 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 Hormones reach all parts of the body, but only target cells are equipped to respond Insect metamorphosis is regulated by hormones

60 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 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

61 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 45.1: Hormones and other signaling molecules bind to target receptors, triggering specific response pathways Chemical signals bind to receptor proteins on target cells Only target cells respond to the signal

62 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig. 45-2a Blood vessel Response (a) Endocrine signaling (b) Paracrine signaling (c) Autocrine signaling

63 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig. 45-2b Response (d) Synaptic signaling Neuron Neurosecretory cell (e) Neuroendocrine signaling Blood vessel Synapse Response

64 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Pheromones Pheromones are chemical signals that are released from the body and used to communicate with other individuals in the species Pheromones mark trails to food sources, warn of predators, and attract potential mates

65 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Water-soluble Lipid-soluble Steroid: Cortisol Polypeptide: Insulin Amine: Epinephrine Amine: Thyroxine 0.8 nm Chemical Classes of Hormones

66 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Hormone Receptor Location: Scientific Inquiry In the 1960s, researchers studied the accumulation of radioactive steroid hormones in rat tissue These hormones accumulated only in target cells that were responsive to the hormones These experiments led to the hypothesis that receptors for the steroid hormones are located inside the target cells Further studies have confirmed that receptors for lipid-soluble hormones such as steroids are located inside cells

67 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Researchers hypothesized that receptors for water-soluble hormones would be located on the cell surface They injected a water-soluble hormone into the tissues of frogs The hormone triggered a response only when it was allowed to bind to cell surface receptors This confirmed that water-soluble receptors were on the cell surface

68 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig MSH injected into melanocyte Nucleus Melanosomes do not disperse MSH injected into interstitial fluid (blue) Melanosomes disperse Melanocyte with melanosomes (black dots) RESULTS

69 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cellular Response Pathways Water and lipid soluble hormones differ in their paths through a body Water-soluble hormones are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors Lipid-soluble hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells

70 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Signaling by any of these hormones involves three key events: – Reception – Signal transduction – Response

71 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Signal receptor TARGET CELL Signal receptor Transport protein Water- soluble hormone Fat-soluble hormone Gene regulation Cytoplasmic response Gene regulation Cytoplasmic response OR (a) NUCLEUS (b)

72 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Multiple Effects of Hormones The same hormone may have different effects on target cells that have – Different receptors for the hormone – Different signal transduction pathways – Different proteins for carrying out the response A hormone can also have different effects in different species

73 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Glycogen deposits  receptor Vessel dilates. Epinephrine (a) Liver cell Epinephrine  receptor Glycogen breaks down and glucose is released. (b) Skeletal muscle blood vessel Same receptors but different intracellular proteins (not shown) Epinephrine  receptor Different receptors Epinephrine  receptor Vessel constricts. (c) Intestinal blood vessel

74 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Signaling by Local Regulators In paracrine signaling, nonhormonal chemical signals called local regulators elicit responses in nearby target cells Types of local regulators: – Cytokines and growth factors – Nitric oxide (NO) – Prostaglandins

75 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Prostaglandins help regulate aggregation of platelets, an early step in formation of blood clots

76 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 45.2: Negative feedback and antagonistic hormone pairs are common features of the endocrine system Hormones are assembled into regulatory pathways

77 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Major endocrine glands: Adrenal glands Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Pancreas Kidney Ovaries Testes Organs containing endocrine cells: Thymus Heart Liver Stomach Kidney Small intestine

78 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Insulin and Glucagon: Control of Blood Glucose Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis The pancreas has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin

79 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Homeostasis: Blood glucose level (about 90 mg/100 mL) Glucagon STIMULUS: Blood glucose level falls. Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Blood glucose level rises. STIMULUS: Blood glucose level rises. Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. Blood glucose level declines. Body cells take up more glucose. Insulin

80 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 45.3: The endocrine and nervous systems act individually and together in regulating animal physiology Signals from the nervous system initiate and regulate endocrine signals

81 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Coordination of Endocrine and Nervous Systems in Invertebrates In insects, molting and development are controlled by a combination of hormones: – A brain hormone stimulates release of ecdysone from the prothoracic glands – Juvenile hormone promotes retention of larval characteristics – Ecdysone promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics

82 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Ecdysone Brain PTTH EARLY LARVA Neurosecretory cells Corpus cardiacum Corpus allatum LATER LARVA PUPAADULT Low JH Juvenile hormone (JH) Prothoracic gland

83 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Coordination of Endocrine and Nervous Systems in Vertebrates 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

84 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 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

85 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Spinal cord Posterior pituitary Cerebellum Pineal gland Anterior pituitary Hypothalamus Pituitary gland Hypothalamus Thalamus Cerebrum

86 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Table 45-1b

87 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Table 45-1c

88 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Table 45-1d

89 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Posterior Pituitary Hormones The two hormones released from the posterior pituitary act directly on nonendocrine tissues

90 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Posterior pituitary Anterior pituitary Neurosecretory cells of the hypothalamus Hypothalamus Axon HORMONE Oxytocin ADH Kidney tubulesTARGETMammary glands, uterine muscles

91 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Oxytocin induces uterine contractions and the release of milk Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further stimulates the milk glands This is an example of positive feedback, where the stimulus leads to an even greater response Antidiuretic hormone (ADH) enhances water reabsorption in the kidneys

92 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Anterior Pituitary Hormones Hormone production in the anterior pituitary is controlled by releasing and inhibiting hormones from the hypothalamus For example, the production of thyrotropin releasing hormone (TRH) in the hypothalamus stimulates secretion of the thyroid stimulating hormone (TSH) from the anterior pituitary

93 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Hypothalamic releasing and inhibiting hormones Neurosecretory cells of the hypothalamus HORMONE TARGET Posterior pituitary Portal vessels Endocrine cells of the anterior pituitary Pituitary hormones Tropic effects only: FSH LH TSH ACTH Nontropic effects only: Prolactin MSH Nontropic and tropic effects: GH Testes or ovaries Thyroid FSH and LHTSH Adrenal cortex Mammary glands ACTHProlactinMSHGH MelanocytesLiver, bones, other tissues

94 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Hormone Cascade Pathways 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 hormone cascade pathway The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland Hormone cascade pathways are usually regulated by negative feedback

95 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Cold Pathway Stimulus Hypothalamus secretes thyrotropin-releasing hormone (TRH ) Negative feedback Example Sensory neuron Neurosecretory cell Blood vessel Anterior pituitary secretes thyroid-stimulating hormone (TSH or thyrotropin ) Target cells Response Body tissues Increased cellular metabolism – Thyroid gland secretes thyroid hormone (T 3 and T 4 ) –

96 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Tropic Hormones A tropic hormone regulates the function of endocrine cells or glands The four strictly tropic hormones are – Thyroid-stimulating hormone (TSH) – Follicle-stimulating hormone (FSH) – Luteinizing hormone (LH) – Adrenocorticotropic hormone (ACTH)

97 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Nontropic Hormones Nontropic hormones target nonendocrine tissues Nontropic hormones produced by the anterior pituitary are – Prolactin (PRL) – Melanocyte-stimulating hormone (MSH)

98 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Prolactin stimulates lactation in mammals but has diverse effects in different vertebrates MSH influences skin pigmentation in some vertebrates and fat metabolism in mammals

99 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Growth Hormone Growth hormone (GH) 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 gigantism, while a lack of GH can cause dwarfism

100 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Endocrine signaling regulates metabolism, homeostasis, development, and behavior Concept 45.4: Endocrine glands respond to diverse stimuli in regulating metabolism, homeostasis, development, and behavior

101 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Thyroid Hormone: Control of Metabolism and Development The thyroid gland consists of two lobes on the ventral surface of the trachea It produces two iodine-containing hormones: triiodothyronine (T 3 ) and thyroxine (T 4 )

102 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Thyroid hormones stimulate metabolism and influence development and maturation Hyperthyroidism, excessive secretion of thyroid hormones, causes high body temperature, weight loss, irritability, and high blood pressure Graves’ disease is a form of hyperthyroidism in humans Hypothyroidism, low secretion of thyroid hormones, causes weight gain, lethargy, and intolerance to cold

103 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Normal iodine uptake High level iodine uptake

104 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Proper thyroid function requires dietary iodine for hormone production

105 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Parathyroid Hormone and Vitamin D: Control of Blood Calcium Two antagonistic hormones regulate the homeostasis of calcium (Ca 2+ ) in the blood of mammals – Parathyroid hormone (PTH) is released by the parathyroid glands – Calcitonin is released by the thyroid gland

106 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig PTH Parathyroid gland (behind thyroid) STIMULUS: Falling blood Ca 2+ level Homeostasis: Blood Ca 2+ level (about 10 mg/100 mL) Blood Ca 2+ level rises. Stimulates Ca 2+ uptake in kidneys Stimulates Ca 2+ release from bones Increases Ca 2+ uptake in intestines Active vitamin D

107 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Adrenal Hormones: Response to Stress The adrenal glands are adjacent to the kidneys Each adrenal gland actually consists of two glands: the adrenal medulla (inner portion) and adrenal cortex (outer portion)

108 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Catecholamines from the Adrenal Medulla The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) These hormones are members of a class of compounds called catecholamines They are secreted in response to stress- activated impulses from the nervous system They mediate various fight-or-flight responses

109 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Epinephrine and norepinephrine – Trigger the release of glucose and fatty acids into the blood – Increase oxygen delivery to body cells – Direct blood toward heart, brain, and skeletal muscles, and away from skin, digestive system, and kidneys The release of epinephrine and norepinephrine occurs in response to nerve signals from the hypothalamus

110 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Stress Adrenal gland Nerve cell Nerve signals Releasing hormone Hypothalamus Anterior pituitary Blood vessel ACTH Adrenal cortex Spinal cord Adrenal medulla Kidney (a) Short-term stress response(b) Long-term stress response Effects of epinephrine and norepinephrine: 2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate 1. Glycogen broken down to glucose; increased blood glucose 5. Change in blood flow patterns, leading to increased alertness and decreased digestive, excretory, and reproductive system activity Effects of mineralocorticoids: Effects of glucocorticoids: 1. Retention of sodium ions and water by kidneys 2. Increased blood volume and blood pressure 2. Possible suppression of immune system 1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose

111 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Steroid Hormones from the Adrenal Cortex The adrenal cortex releases a family of steroids called corticosteroids in response to stress These hormones are triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary Humans produce two types of corticosteroids: glucocorticoids and mineralocorticoids

112 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Glucocorticoids, such as cortisol, influence glucose metabolism and the immune system Mineralocorticoids, such as aldosterone, affect salt and water balance The adrenal cortex also produces small amounts of steroid hormones that function as sex hormones

113 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Gonadal Sex Hormones 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 different amounts

114 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 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 a supplement to cause muscle growth, which carries health risks

115 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig Embryonic gonad removed Chromosome Set Appearance of Genitals XY (male) XX (female) Male Female No surgery RESULTS

116 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Estrogens, most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics In mammals, progestins, which include progesterone, are primarily involved in preparing and maintaining the uterus Synthesis of the sex hormones is controlled by FSH and LH from the anterior pituitary

117 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Melatonin and Biorhythms 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

118 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fig. 45-UN2 Pathway Example StimulusLow blood glucose Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target cells Response Glycogen breakdown, glucose release into blood Negative feedback –


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