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

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. Breakdown of proteins and nucleic acids produces ammonia (a toxin)
Excretory systems
Breakdown of proteins and nucleic acids produces ammonia (a toxin)
Many aquatic organisms excrete ammonia, since it can be effectively diluted with water
Fig
Ammonia NH3

4. Breakdown of proteins and nucleic acids produces ammonia (a toxin)
Excretory systems
Breakdown of proteins and nucleic acids produces ammonia (a toxin)
Mammalian livers convert ammonia into urea, which is much less toxic, and requires less water to excrete
Fig
Ammonia NH3

5. Breakdown of proteins and nucleic acids produces ammonia (a toxin)
Excretory systems
Breakdown of proteins and nucleic acids produces ammonia (a toxin)
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
Ammonia NH3

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

7. Vertebrate Excretory Systems
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
Fig

8. Fig. 44.13 Vertebrate Excretory Systems
Each kidney is divided into a cortex, medulla, and pelvis
Each kidney processes about L of blood per day!
Fig

9. Fig. 44.13 Vertebrate Excretory Systems
Nephrons = the functional units of the kidneys
Packed into the renal cortex and medulla
Fig

10. Fig. 44.13 Vertebrate Excretory Systems
Each kidney has ~ 1 million nephrons
Fig

11. Fig. 44.13 Vertebrate Excretory Systems
A nephron consists of: a ball of capillaries known as a glomerulus
Fig

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

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

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

15. Vertebrate Excretory Systems
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

16. Vertebrate Excretory Systems
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

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

18. Vertebrate Excretory Systems
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
Notice that nutrients are selectively reabsorbed from the proximal tubule.
Fig

19. Vertebrate Excretory Systems
Selective secretion adds additional waste molecules to the filtrate, especially in the tubules
Red arrows =
active transport
Blue arrows =
passive transport
Notice that ammonia (NH3) is selectively secreted into the proximal tubule.
Fig

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

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

22. Vertebrate Excretory Systems
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

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

24. Vertebrate Excretory Systems
High concentration of NaCl outside the nephron deep in the kidneys helps concentrate urine in the collecting duct
Red arrows =
active transport
Blue arrows =
passive transport
Some urea escapes from the collecting duct, but most passes out in the urine.
Fig

25. Mammalian excretory systems are adapted to diverse environments

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

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

28. Hormones and the Endocrine System
Chapter 45

29. The endocrine system = postal system for the body
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.

30. The endocrine system = postal system for the body
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
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.

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
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.

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
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.

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]
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.

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
Hormones are produced by specialized cells that have been activated by a stimulus. Hormones travel through the blood to target cells, where they either promote a prolonged and irreversible change, or a transient and reversible change.
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

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

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

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

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 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
Fig. 45.3

45. Intracellular Receptors
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
Fig. 45.3

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

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

50. Major endocrine organs and glands
Fig. 45.6

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

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

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

58. Hormone-like local regulators appear to be produced by all the body’s cells…
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

59. The same hormones are found across diverse taxa E. g
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

60. The same hormones are found across diverse taxa E. g
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

61. The same hormones are found across diverse taxa E. g
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