This document provides an overview of osmoregulation and excretion in animals. It discusses key concepts such as osmosis, osmoregulation, excretion of nitrogenous waste, and the mechanisms involved. Examples of excretory structures are given for different animal groups, including the nephron in vertebrates. Feedback control of osmoregulation via hormones such as ADH and aldosterone is also summarized.

1. Osmoregulation & Excretion Kevin Kwan Jeffery Khou Jessica Dai Jason Yiu

10. Countercurrent heat exchange cont. • Countercurrent heat exchange involves a special arrangement of arteries and veins • The countercurrent heat exchange conserves heat by arteries that carry warm blood which circulate through limbs, which come into contact with veins that convey blood in the opposite direction. This arrangement facilitates heat transfer from arteries to veins along the entire length of the blood vessel. • Examples of how an ectotherm maintains higher than expected temperature: behavioral adaptations (seek ideal environments), physiological adaptations (vasoconstriction).

18. Excretion cont. Metanephridia of Earthworm

19. Malpighian Tubules of insects Excretion cont.

20. Nephron and Associated Structures Structure and Function of the Nephron: -nephron: functional unit of the vertebrate kidney -renal cortex: outer part of a mammalian kidney -renal medulla: inner part of a mammalian kidney -glomerulus: single long tubule and a ball of capillaries - Bowman’s capsule: blind end of a tubule that forms a cup-shaped swelling surrounding the glomerulus. 80% of the nephrons in the human kidney are cortical nephrons and they have reduced loops of Henle. Juxtamedullary nephrons are about 20% and have well-developed loops that extend deeply into the renal medulla.

21. The relationship of the kidney and the circulatory system: The kidneys produce urine and regulate the composition of the blood. The urine is conveyed to the urinary bladder via the ureter and to the outside via the urethra. Branches of the aorta, retinal arteries, convey blood to the kidneys; renal veins drain blood from the kidneys into the posterior vena cava. Excretion cont. Posterior Vena cava Kidney Renal artery and vein Aorta Ureter Urinary Bladder Urethra Bowman’s capsule Glomerulus Afferent arteriole from renal artery Efferent arteriole from glomerulus Branch of renal vein Proximal tubule Peritubular capillaries Distal tubule Collecting duct Loop of Henle Descending limb Ascending limb Vasa recta Renal pelvis Ureter Renal Medulla Renal cortex Juxtamedullarnephron Cortical nephron Renal cortex Renal medulla

22. Filtration of the Blood: It occurs as blood pressure forces fluid from the blood in the glomerulus into the lumen of the Bowman’s capsule. It contains a variety of substances including nitrogenous wastes. Pathway of the filtrate: (Blood filtrate to Urine) proximal tubule-> Descending limb of the loop of Henle-> Ascending limb of the loop of Henle-> Distal tubule-> Collecting duct-> renal pelvis-> drained by ureter Nephron and Associated Structures

23. Blood Vessels Associated with the Nephrons Afferent arteriole: supplies blood to each Nephron Efferent arteriole: formed by the capillaries that converge as they leave the glomerulus Peritubular capillaries: formed by vessels subdividing Vasa recta: capillaries that serve the loop for Henle

25. How the human kidney concentrates urine

27. Hormonal Control of the Kidney by Negative Feedback Circuits

29. ADH: antidiuretic hormone - Produced in the hypothalamus, stored in and released from the posterior pituitary gland, osmoreceptor cells monitor the osmolarity of the blood. If it rises about a set point of 300 mosm/L, more ADH is released into the bloodstream/reaches kidney. The main targets are the distal tubules and collecting ducts where it increases the permeability of the epithelium to water, amplify water reabsorption, reduce urine volume and prevent further increase of blood osmolarity above the set point. If negative feedback- less ADH. Only gain of additional water in food/drink can bring osmolarity back. Large intake of water-> little ADH is released thus decreases permeability of the distal tubules and collecting ducts (more urine).

31. · RAAS: renin-angiotensin-aldosterone system : part of a complex feedback circuit that functions in homeostasis, drop in blood pressure/blood volume triggers renin release from JGA. In turn, rise in blood pressure/volume from various actions of angiotensin II/aldsterone reduce the release of renin. · ADH vs RAAS : ADH is a response to an increase in osmolarity of the blood and lowers blood sodium ion concentration by stimulating water reabsorption in the kidney. RAAS responds to a fall in blood volume/pressure by increasing water and sodium ion reabsorption.

32. ANF: atrial natriuretic : a hormone/peptide that opposes the RAAS. Walls of atria of the heart release ANF in response to an increase in blood volume/pressure and inhibits the release of renin from JGA, NaCl reabsorption by the collecting ducts, reduces aldosterone release from the adrenal glands, and lower blood volume and pressure.

33. All animals have different habitats, functions of osmoregulations, physiological machines (organs) to maintain solute and water balance and excreting nitrogenous wastes.

34. AMOEBA -water enters amoeba by osmosis -excess water collects in the contractile vacuole(contains water soluble nitrogenous wastes) -osmoregulation is the main function of the contractile vacuole -EXCRETION: when the contractile vacuole is full and is ready to burst, it goes to the surface of the amoeba and uses energy from the mitochondria to release all the nitrogenous wastes. -Then, a new contractile vacuole is formed and water enters the amoeba and the same steps repeat. EXTRA CREDIT: Amoeba vs. Human ^ THAT IS SOOO COOL!!! O.O xP