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From Leonardo da Vinci’s notebooks Chapter 44, pp. 931-939 Osmoregulation & Excretion.

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Presentation on theme: "From Leonardo da Vinci’s notebooks Chapter 44, pp. 931-939 Osmoregulation & Excretion."— Presentation transcript:

1 From Leonardo da Vinci’s notebooks Chapter 44, pp Osmoregulation & Excretion

2 An organism’s excretory system helps regulate the chemical composition of the body’s principal fluid (blood, coelomic fluid, or hemolymph) The excretory system selectively removes excess water and wastes from the principal fluid

3 Fig Excretory systems Breakdown of proteins and nucleic acids produces ammonia (a toxin) Ammonia NH 3 Many aquatic organisms excrete ammonia, since it can be effectively diluted with water

4 Excretory systems Breakdown of proteins and nucleic acids produces ammonia (a toxin) Ammonia NH 3 Mammalian livers convert ammonia into urea, which is much less toxic, and requires less water to excrete Fig. 44.8

5 Excretory systems Breakdown of proteins and nucleic acids produces ammonia (a toxin) Ammonia NH 3 Birds, reptiles, and some other organisms convert ammonia into uric acid, which is relatively nontoxic, and can be excreted as a semisolid without much water loss Fig. 44.8

6 Vertebrate Excretory Systems Key functions: Fig Filtration Reabsorption Secretion Excretion

7 Fig Blood enters the kidneys via the renal arteries and leaves via the renal veins Urine (excess water and wastes removed from the blood) is produced by the kidneys and is conveyed to the urinary bladder via the ureters Urine exits the body via the urethra Vertebrate Excretory Systems

8 Each kidney is divided into a cortex, medulla, and pelvis Each kidney processes about 1000 L of blood per day! Fig Vertebrate Excretory Systems

9 Nephrons = the functional units of the kidneys Packed into the renal cortex and medulla Fig Vertebrate Excretory Systems

10 Each kidney has ~ 1 million nephrons Fig Vertebrate Excretory Systems

11 A nephron consists of: a ball of capillaries known as a glomerulus Fig Vertebrate Excretory Systems

12 A nephron consists of: an afferent arteriole that leads into the glomerulus, and an efferent arteriole that leads out of the glomerulus Fig Vertebrate Excretory Systems

13 A nephron consists of: Bowman’s capsule, that surrounds the glomerulus and extends into the proximal tubule, loop of Henle, and distal tubule Fig Vertebrate Excretory Systems

14 A nephron consists of: capillaries that surround the tubules and loop of Henle, and that feed into venules returning to the renal vein Fig Vertebrate Excretory Systems

15 Filtration occurs in Bowman’s capsules: cells and large molecules remain in the blood, while blood pressure forces water and small molecules from the blood into Bowman’s capsules Fig Vertebrate Excretory Systems

16 Filtration occurs in Bowman’s capsules: cells and large molecules remain in the blood, while blood pressure forces water and small molecules from the blood into Bowman’s capsules Vertebrate Excretory Systems

17 Selective reabsorption returns important nutrients (glucose, etc.) to the blood, and occurs especially in proximal and distal tubules Fig Vertebrate Excretory Systems

18 Fig Selective reabsorption returns important nutrients (glucose, etc.) to the blood, and occurs especially in proximal and distal tubules Red arrows = active transport Blue arrows = passive transport Vertebrate Excretory Systems

19 Fig Red arrows = active transport Blue arrows = passive transport Selective secretion adds additional waste molecules to the filtrate, especially in the tubules Vertebrate Excretory Systems

20 Fig Red arrows = active transport Blue arrows = passive transport Reabsorption of water occurs along the tubules, descending loop of Henle, and collecting duct Vertebrate Excretory Systems

21 Reabsorption of water occurs along the tubules, descending loop of Henle, and collecting duct Red arrows = active transport Blue arrows = passive transport Fig Vertebrate Excretory Systems

22 The descending loop of Henle is permeable to water, but not very permeable to salt (e.g., NaCl) Red arrows = active transport Blue arrows = passive transport Fig Vertebrate Excretory Systems

23 The ascending loop of Henle is not permeable to water, but it is to NaCl Red arrows = active transport Blue arrows = passive transport Fig Vertebrate Excretory Systems

24 High concentration of NaCl outside the nephron deep in the kidneys helps concentrate urine in the collecting duct Fig Red arrows = active transport Blue arrows = passive transport Vertebrate Excretory Systems

25 Mammalian excretory systems are adapted to diverse environments

26 Mammals that live in environments with plenty of water have short loops of Henle that cannot produce concentrated urine Mammalian excretory systems are adapted to diverse environments

27 Mammals that live in very dry environments have very long loops of Henle that can produce highly concentrated urine Mammalian excretory systems are adapted to diverse environments

28 Chapter 45 Hormones and the Endocrine System

29 The endocrine system = postal system for the body

30 Hormones are the chemical messages that: Regulate aspects of behavior Regulate growth, development, & differentiation Maintain internal homeostatic conditions 4 classes of animal hormones: Peptide hormones – amino acid chains Single amino acid derivatives Steroid hormones – cholesterol based Prostaglandins – fatty-acid based

31 The endocrine system = postal system for the body Hormones are the chemical messages that: Maintain internal homeostatic conditions Regulate growth, development, & differentiation Regulate aspects of behavior 4 classes of animal hormones: Single amino acid derivatives Peptide hormones – amino acid chains Steroid hormones – cholesterol based Prostaglandins – fatty-acid based

32 The endocrine system = postal system for the body Hormones are the chemical messages that: Maintain internal homeostatic conditions Regulate growth, development, & differentiation [ often irreversible ] Regulate aspects of behavior 4 classes of animal hormones: Single amino acid derivatives Peptide hormones – amino acid chains Steroid hormones – cholesterol based Prostaglandins – fatty-acid based

33 The endocrine system = postal system for the body Hormones are the chemical messages that: Maintain internal homeostatic conditions Regulate growth, development, & differentiation [ often irreversible ] Regulate aspects of behavior [ generally reversible ]

34 The endocrine system = postal system for the body Hormone-secreting organs are called endocrine glands, because they secrete their chemical messengers directly into body fluids In contrast, exocrine glands secrete their products into ducts Glands that secrete sweat, mucus, digestive enzymes, and milk are exocrine glands

35 Since hormones circulate to ALL cells, how do they act at only specific sites? Receptors Only cells with correct receptors (target cells) respond to hormones

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40 The target cell response is idiosyncratic (i.e., it depends on the type of cell) Fig. 45.4

41 Table 45.1 Hormones exhibit a diversity of structure and function Peptides, proteins,glycoproteins,amines,

42 Table 45.1 Hormones exhibit a diversity of structure and function Peptides, proteins,glycoproteins,amines,steroids

43 Since hormones circulate to ALL cells, how do they act at only specific sites? Receptors Only cells with correct receptors (target cells) respond to hormones Surface receptors Intracellular receptors

44 Surface Receptors Fig Most amino acid-based hormones are water soluble and target surface receptors A signal-transduction pathway is a series of molecular changes that converts an extracellular chemical signal to a specific intracellular response

45 Intracellular Receptors Fig Most steroid hormones are lipid soluble and target intracellular receptors An intracellular receptor usually performs the entire task of transducing the signal within the cell In almost all cases, this is a transcription factor, and the response is a change in gene expression

46 Major endocrine organs and glands Fig. 45.6

47 Hypothalamus-Pituitary Complex The hypothalamus receives nervous input from throughout the body The hypothalamus contains two sets of neurosecretory cells whose hormonal secretions are stored in or regulate the pituitary gland The posterior pituitary stores and secretes two hormones made by the hypothalamus The anterior pituitary consists of endocrine cells that synthesize and secrete at least 6 different hormones

48 Hypothalamus-Pituitary Complex Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Oxytocin Target effectors Smooth muscle in breast Response Milk release Fig. 45.2b The hypothalamus-posterior pituitary provides an example of a simple neurohormone pathway

49 Hypothalamus-Pituitary Complex Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Prolactin- releasing hormone Neurosecretory cell Blood capillary Prolactin Endocrine cell of pituitary Blood vessel Target effectors Response Mammary glands Milk production Hypothalamus Fig. 45.2c The hypothalamus-anterior pituitary provides an example of a simple neuroendocrine pathway

50 Major endocrine organs and glands Fig. 45.6

51 Pancreas Exocrine function Digestive secretions released into pancreatic duct to small intestines Endocrine function Islet cells Insulin Glucagon

52 Pancreas Exocrine function Digestive secretions released into pancreatic duct to small intestines Endocrine function Islet cells Insulin Glucagon

53 Pancreas Exocrine function Digestive secretions released into pancreatic duct to small intestines Endocrine function Islets of Langerhans – endocrine cells Insulin Glucagon antagonistic hormones

54 Pancreas regulates blood glucose Insulin – decrease blood glucose stimulates uptake by cells – use it or store it as fat and glycogen Glucagon increase blood glucose stimulates release by cells – breakdown fat and glycogen Diabetes mellitis defects in production, release or response to insulin

55 Pancreas regulates blood glucose Insulin – decreases blood glucose Stimulates uptake by cells – cells use it or store it as fat and glycogen Glucagon – increase blood glucose stimulates release by cells – breakdown fat and glycogen Diabetes mellitis defects in production, release or response to insulin

56 Pancreas regulates blood glucose Insulin – decreases blood glucose Stimulates uptake by cells – cells use it or store it as fat and glycogen Glucagon – increases blood glucose Stimulates release by cells – breakdown of fat and glycogen Diabetes mellitis defects in production, release or response to insulin

57 PathwayExample Stimulus High blood glucose Pancreas secretes insulin Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen synthesis, glucose uptake from blood Fig. 45.2a An example of a simple endocrine pathway Pancreas regulates blood glucose Diabetes mellitus (all forms) Results from defects in the production, release or response to insulin Receptor protein

58 These chemical messengers affect target cells adjacent to or near their point of secretion and can act very rapidly; the process is known as paracrine signaling Hormone-like local regulators appear to be produced by all the body’s cells…

59 The same hormones are found across diverse taxa E.g., Insulin is found in bacteria, fungi, protists, etc. E.g., Thyroxin is found in many vertebrates; increases metabolism in humans & controls metamorphosis in amphibians

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