1. KIDNEYS AND OSMOREGULATION
Corresponds with chapter 36

2. Excretion
Excretion is the removal from the body of waste products of the metabolic pathways
Excretory organs tend to be tubular in both invertebrates and vertebrates

3. The breakdown of various molecules forms nitrogenous wastes.
amino acids energy OR amino acids fats or carbs
Removes the amino group (NH2) and excretes it in the form of ammonia, urea, or uric acid
the removal of the amino group requires a set amount of energy
however when converting it the energy required changes

4. Ammonia little energy needed
H toxic requires a lot of fluids to keep it under control
N –H nitrogenous excretory product(w/ water)
fish and aquatic animals H

5. Urea O
H2N-C-NH2
Needs energy
Less toxic than ammonia
Excreted in moderately concentrated solution
(allows body water to be conserved)
Advantage for terrestrial animals with limited access to water
Main form of waste for sharks, adult amphibians, and mammals

6. Uric acid Long complex series of enzymatic reactions that requires a lot of ATP Poorly soluble in water, it forms crystals Water conservation is needed because it can be concentrated more readily than urea, excreted in a dehydrated form Excreted by insects reptiles and birds

7. Possible to predict metabolic waste based on anatomy and environment
EXTRA CREDIT:

8. Excretory organs among invertebrates
Most animals have tubular organs that regulate the water and salt balance of the body
excrete metabolic wastes into the environment
May utilize other organs
Look at three examples, the planarian, the earthworm, and the arthropods

9. Planarians
two strands of branching excretory tubules,
open to the outside through the excretory pores
flame cells along the tubules.each has a cluster of beating cilia
cilia allows the fluid to move through the body and out
rids the body of excess water and excretes waste

10. Earthworms
body has segments and each segment has its own excretory structure nephridia
nephridium has an ciliated opening and excretory pore
as fluid moves through the tubule the composition is modified
urine has salts, metabolic wastes, and water
urine produced is equal to about 60% of its body weight. Excretion of ammonia is consistent

11. Extra credit
give an example of an animal that doesn’t excrete what it was classified to excrete.
why not?

12. Insects
long set of thin tubules called Malpighian tubules attached to the gut
uric acid is actively transported from surrounding hemolymph into these tubules
water follows salt gradient established by active transport of K+
water and other materials are reabsorbed at the rectum uric acid excreted at the anus
insects-> water =little rebsorbtion
insects -> dry=lot of reabsorbtion-> semisolid mass of uric acid

13. Arthropods (others)
excretory organs given different name,but the function is similar
crustaceans remove wastes through diffusion across gills
possess excretory organ green gland, in ventral portion of head region
fluid collects in the tubules but is modified by time as it leaves
Shrimp and pill bugs have Maxillary glands in maxillary segments
Spiders, scorpions and other arachnids have coxal glands, located near one or more appendages
Spherical sacs, wastes are collected from the surrounding blood and discharged at the pores at one to several pairs of appendages

14. Osmoregulation in Aquatic Vertebrates
Osmoregulation- to maintain particular ion concentrations in blood
Essential to maintain homeostasis b/c
Ions like Ca2+, Na+, K+ and PO4- affect systems of the body
Necessary b/c few vertebrates have blood that is isotonic to the sea water

15. concentration of various ions in blood is less than seawater
Cartilaginous fish
concentration of various ions in blood is less than seawater
blood plasma nearly isotonic with water b/c they pump it full of urea
gives their blood same tonicity of water
Do regulate concentration of solutes and have rectal glands that rids the body of excess salt
Marine bony fish
Blood plasma is hypertonic to the marine environment (high in salts)
avoid getting dehydrated
lose water by osmosis, counteract by drinking sea water
constant drinking causes the fish to acquire lots of salt, actively transport out into the sea through the gills
kidneys conserve the water
produces small amount of isotonic urine
Freshwater Bony Fish
osmotic problems opposite to the marine
gain water across gills and body surfac
never drink water
actively transport salt into blood across membrane of gills
eliminate excess water by producing large quantities of dilute urine, discharge urine =1/3 of their body weight

16. Extra credit What glands does a pill bug have?
What glands does a spider have?

17. Osmoregulation among Terrestrial Vertebrates
Biological systems are affected by disruptions to dynamic homeostasis
dehydration
Kangaroo rat
form concentrated urine(20x more concentrated than its blood plasma)
survives using metabolic water derived using cellular respiration
never drinks water
adaptions allows for it to remain in water-salt balance

18. Seagulls, Reptiles, and Mammals
kidneys are good at conserving water
are able to drink sea water, unlike us
seabirds and reptiles have salt glands that pump the salt out
Birds
glands located near eye produces salty solution that is excreted through nostrils and drips off
In Sea Turtles salt gland is modified tear gland sea snakes located beneath the tongue
Commandeered a gland meant for another purpose to pump salt from the blood plasma and leave behind the water.

19. Extra credit
Name two ions that affect the body systems.

20. Pg
Urinary system

21. The Urinary System (pg 670-673)
The urinary system includes the
Kidneys – the major organ that regulates excretion; regulator of blood compostion
Urine – the modified filtrate made by the kidneys which is conducted from the body by the other organs in the urinary system
Ureter – each kidney is connected to a ureter; a duct that takes urine from the kidney to the urinary bladder
Urinary bladder – where the kidney is stored until it is voided from the body
Urethra – through which the urine is voided from the body; in males the urethra passes through the penis while in females the opening of the urethra is ventral to that of the vagina
There is no connection between the reproductive and urinary system for females, but in males the urethra carries the sperm during ejaculation

22. Kidneys Bean shaped, reddish brown organs About the size of a fist
Each adult kidney weighs between 115 and 170 grams
Approximately 11 cm in length, 6 cm in width, and 3 cm thick
Located on either side of the vertebral column just below the diaphragm, in the lower back, where they are partially protected by the lower rib cage; right is lower
3 major parts of the kidney (actually 4)
The 3 parts are the renal cortex, the renal medulla and the renal pelvis
there is also the hilum – located medially and serves as the point of entrance and exit for the renal artery, renal vein and ureter
Renal cortex – outer region of the kidney with a somewhat granular appearance
Renal medulla – consists of 6-10 (8-18) cone shaped renal pyramids that lie on the inner side of the renal cortex, the apex of each pyramid terminates into what is called the papilla, which directs the urinary stream into what is called the minor calyx (numerous minor calyces expand into two or three open ended pouches called the major calyces, which feed into the pelvis)

23. Renal pelvis – the inner most part of the kidney, like a hollow chamber, also known as the expanded upper portion of the ureter (divides into 2 or 3 major calyces which divide into 8 minor calyces) ; urine collects in the renal pelvis and then is carried to the bladder by a ureter
Renal Vein – oxygen poor blood; drains the kidney and returns the blood to the superior vena cava
Renal artery – oxygen rich blood; brings blood to the kidney from the aorta
Ureter – the muscular tubes which propel urine from the kidneys to the urinary bladder

24. Extra credit:
what is an example of an organism that uses another gland meant for another purpose to excrete salt

25. Kidney diagram

26. Nephrons
Each kidney is composed of over 1 million tiny tubules called nephrons; approximately 1.2 million
These are the functional units of the kidney
Hollow tubes composed of a single cell layer
The nephrons of a kidney produce urine
Some are located in the renal cortex, but others dip down into the renal medulla
The blind end of a nephron is pushed in on itself to form a cuplike structure known as the glomerular capsule (bowman’s capsule) – the outer layer of the bowman’s capsule is composed of squamous epithelial cells; the inner layer is composed of specialized cells that allow the easy passage of molecules; there is a visceral layer composed of podocytes which help the kidneys filter out substances and then the parietal layer which is composed of the squamous epithelial; blood enters the nephrons at the bowman’s capsule
Then the renal artery leads to the kidney and branches into arterioles, then tiny capillaries
The glomerulus is the ball of capillaries which stays in the bowman’s capsule
Blood is filtered as it passes through the glomerulus and the plasma is forced out of the capillaries into the bowman’s capsule
This plasma is now called a filtrate

27. continued
the filtrate travels along the entire nephron, from the bowman’s capsule the filtrate passes through the proximal convoluted tubule – lined by cells with many mitochondria and tightly packed microvilli; the longest and most convoluted segement of the nephron; its cell provides a much greater surface area for reabsorption and secretion; initially the proximal tube forms several coils followed by a straight segment which descends toward the medulla
Then simple squamous epithelium appears in the loop of Henle (loop of nephron) which has a descending and ascending limb, near the end of the thick ascending limb, the nephron passes between its afferent and efferent arterioles
This short segment of the ascending limb is called macula densa
This is followed by the distal convoluted tube (lined by cuboidal cells that reabsorb sodium and chloride from the tubular filtrate)
Then several distal convoluted tubules enter one collecting duct (the distal convoluted tubules begin a short distance beyond the macula densa and extends to the point in the cortex where two or more nephrons join to form the cortical collecting duct
The collecting duct transports urine down through the renal medulla and delivers it to the renal pelvis
The filtrate is modified to form urine as it travels along the tube, the urine moves from the collecting ducts into the ureters, then into the bladder, and finally out through the urethra

29. Each nephron has its own blood supply
The renal artery branches into numerous small arteries, which branch into arterioles, one for each nephron
Each arteriole, named an afferent arteriole divides to form a capillary bed, the glomerulus, which is surrounded by glomerular capsule
The glomerulus drains into an efferent arteriole which branches into a second capillary bed around the tubular parts of the nephron, these are called peritubular capillaries, which lead to venules that join to form veins leading to the renal vein, a vessel that enters the inferior vena cava

30. Urine formation
An average human produces between 1 and 2 liters of urine
There are three steps in the process of how urine is made: filtration, reabsorption, and secretion
Glomerular filtration – the movement of small molecules across the glomerular wall into the glomerular capsule as a result of blood pressure
When blood enters the glomerulus,blood pressure is sufficient to cause small molecules such as water, nutrients, salts, and wastes to move from the glomerulus to the inside of the glomerular capusle (note that the glomerular walls are very permeable)
The molecules that leave the blood and enter the glomerular capsule are called the glomerular filtrate
Plasma proteins and blood cells are too big to enter the filtrate, so they remain in the blood as it flows into the efferent arteriole
Glomerular filtrate is protein free, but similar to blood plasma

31. Urine process continued
Tubular reabsorption takes place when substances move across the walls of the tubules into the associated peritubular capillary network
Osmosis of the water from the filtrate cannot occur yet because the osmolarity of the blood is essentially the same as that of the filtrate in the glomerular capsule
Sodium ions are actively pumped into the peritubular capillary and then chloride ions follow so now the osmolarity of the blood is such that water moves passively form the tubule into the blood, 60-70% of salt and water are reabsorbed at the proximal covoluted tubule
Urea is passively reabsorbed from the filtrate
Tubular secretion is the second way substances are removed form the blood and added to tubular fluid; this process is like the body removing harmful compounds not filtered in the glomerulus