1. The Excretory System By Michael, Terry, & Andi

2. Introduction
-As a normal consequence of life, every cell in the body produces metabolic wastes like excess water and salts, carbon dioxide, and urea. -Urea is a compound occurring in urine and other body fluids as a product of protein metabolism. -The process by which these metabolic wastes are removed from the body is called excretion

3. What is it?
The Excretory System is the bodily system that separates and eliminates the waste from the body, usually as urine or sweat.

4. Excretory System Removes wastes and foreign substances from the blood
Removes excess substances from the blood
Provides temporary collection and storage of these excess and foreign substances
Eliminates these substances from the body

6. Main Organs
Kidneys
Ureters
Urinary Bladder
Urethra

7. The Kidneys
A Kidney is either of a pair of bean-shaped organs in the back part of the abdominal cavity that form and eliminate urine, regulate fluid, and electrolyte balance, and act as discharging glands.

8. The Kidneys They are about the size of your fist.
Located near the middle of your back, just below the rib cage.
Every day they process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water.
The waste and extra water become urine which flows to your bladder through tubes called ureters.

9. The Kidneys
Bladder- Any of various expandable membranous sacs that serve as receptacles for fluid or gas.
Ureter- A muscular tube leading the urine from a kidney to the bladder.
Urethra- The membranous tube that extends from the urinary bladder to the exterior and that in the male conveys urine.

10. The Kidneys
A fibrous, transparent renal capsule encloses each kidney and gives a fresh kidney its glistening appearance.
A fatty mass, the adipose capsule, surrounds each kidney and helps hold it in place against the muscles of the trunk wall.

11. The Kidneys Contain 3 distinct regions:
Renal Cortex- the outer portion of the kidney which is light in color
Renal Medulla- the innermost part of the kidney which is separated into a number of sections, known as the renal pyramids.
Renal Capsule- a tough fibrous layer surrounding the kidney and is covered in a thick layer of tissue.

12. The Kidneys
Renal- relating to, involving, or located in the region of the kidneys.
Renal Artery- an artery originating from the adnominal aorta and supplying the kidneys and adrenal glands and uretes.

14. The Kidneys
They breakdown the active tissues and food in the body to form the wastes in your blood.
Your body uses the food for energy and self-repair.
After the body has taken what it needs from the food, waste is sent to the blood.
Without the removal of these wastes, they would build up in the blood and damage your body.

15. Inside the Kidneys
Filtering of the blood actually occurs in tiny units inside your kidneys called nephrons.
Nephrons are the filtering and separating units of the kidney, consisting of the glomerulus and tubules.
Each kidney contains about 1 million nephrons.
Blood flows through the tubule and absorbs substances then travels around through the loop of henle and the wastes flow down the collecting duct.

16. Inside the Kidneys
In each nephron, a glomerulus intertwines with a tiny urine-collecting tube called a tubule.
A Glomerulus is a compact cluster of capillaries
A Tubule is a tiny urine-collecting tube

18. Inside the Kidneys
The tubules first receive a combination of waste materials and chemicals that your body can still use.
Then your kidneys measure out chemicals like sodium and potassium and release them back to the blood to return to the body.

19. The Kidneys
Including removing wastes, the kidneys also release three important hormones:
Erythropoietin (EPO)- stimulates the bone marrow to make red blood cells
Renin- regulates blood pressure
Calcitriol- forms vitamin D which helps maintain calcium for bones

20. The Urinary System
- All of the organs, tubes, muscles, and nerves working together to create, store and carry urine are the urinary system
The urinary system includes two kidneys, two ureters, the bladder, two sphincter muscles, and the urethra.

22. The Urinary System
Sphincter- a circular band of voluntary or involuntary muscles that encircle a orifice of the body or one of its hollow organs.
Urine- the liquid waste matter excreted by the kidneys, in humans being a yellowish, slightly acid, watery fluid.

23. The Urinary System
After the body has taken what it needs from the food, waster products are left behind in the blood.
The Urinary System works with the lungs, skin, and intestines to keep the chemicals and water in the body balanced.
This system removes a type of waste called urea from your blood.

24. The Urinary System
Average adults eliminate about a quart and a half of urine each day.
This amount can be affected by how many fluids and food the person consumes and how much fluid is lost through sweat and breathing.
Medications can also affect the amount of urine eliminated.

25. The Urinary System
Urea is produced when foods containing protein, like meat and poultry, are broken down in the body.
Urea is carried in the bloodstream to the kidneys.
Urea, with water and other waste, forms the urine as it passes through the nephrons and down the renal tubules.

26. The Urinary System
Urine travels from the kidneys down the ureters to the bladder.
The ureters are about 8 to 10 inches long and contain muscles that constantly tighten and relax to force urine away from the kidneys.
A kidney infection can develop if urine is allowed to stand still or back up.
Small amounts of urine are emptied into the bladder about every 10 to 15 seconds.

27. The Urinary System
The bladder is a hollow, muscular, balloon shaped organ.
It sits in your pelvis and is held in place by ligaments
The bladder swells into a round shape when full of urine and gets smaller when emptied
It can hold up to 16 ounces of urine for 2 to 5 hours

29. The Urinary System
The sphincters in the bladder help keep the urine from leaking
Nerves in the bladder tell you when it is time to empty it
When you urinate, the bladder muscles tighten and squeeze the urine out of the bladder
At the same time, the brain signals the sphincter muscles to relax and urine exits through the urethra

30. Sweat Glands Perspiration is the body’s way of cooling itself
The average person has 2.6 million sweat glands in their skin which are distributed all over the body except for the lips, nipples, and external genital organs
Sweat glands are in the layer of skin called the dermis along with nerve endings and hair follicles

31. Sweat Glands
Sweat is the process used to excrete through the pores of the skin
Pores are tiny openings in the skin for perspiration and absorption
Adult males generally sweat enough to fill a six-pack of soda cans in a day

32. Sweat Glands There are two types of sweat glands:
Eccrine- the most numerous type found all over the body
Apocrine- mostly confined to the armpits and usually end in hair follicles
Eccrine glands are smaller, are active from birth, and produce a protein free sweat

34. How Sweat is Made
Sweat can be made in response to nerve stimulation, hot air temperature, and exercise
When stimulated, the sweat glands secret a fluid similar to plasma (primary secretion)
The fluid comes from the spaces between the cells which get the sweat from the blood vessels in the dermis
The fluid then travels up through the straight duct

36. Low Sweat Production Happens during rest and cool temperatures
Cells in the straight duct reabsorb most of the sodium and chlorine from the fluid because there is enough time to reabsorb it.
The composition of this sweat is different then in primary secretion and doesn’t have as much sodium and chloride

37. High Sweat Production Happens during exercise and hot temperatures
Cells in the straight duct do not have as much time to reabsorb all the sodium and chloride and a lot of sweat makes it to the skin

38. Sweat
Sweat from the apocrine glands contain proteins and fatty acids which make it thicker and give it a yellowish color
Sweat has no odor but the bacteria on the skin and hair metabolize the proteins and acids producing an odor

39. Why we Sweat
Sweat removes excess heat and cools you when it evaporates from the skin surface
Some sweat also runs off your skin
Relative humidity of the air is a major factor on the rate of evaporation
In humid air, sweat cannot evaporate as quickly and cannot cool your body
After the sweat evaporates, it leaves salts on your skin

40. Why we Sweat
You may also sweat when you are nervous, anxious, or afraid because there is an increase in sympathetic nerve activity in your body
The increased sympathetic nerve activity in your skin changes its electrical resistance which is the key of the galvanic skin response used in lie detector tests
Sweat is mainly caused by physical or emotional activity

41. Excessive Sweating
You may also sweat when you are nervous, anxious, or afraid because there is an increase in sympathetic nerve activity in your body
The increased sympathetic nerve activity in your skin changes its electrical resistance which is the key of the galvanic skin response used in lie detector tests
Sweat is mainly caused by physical or emotional activity

42. Lungs and Liver You also excrete substances when you exhale
Lungs are either of 2 spongy, saclike respiratory organs functioning to remove carbon dioxide from the blood and provide it with oxygen
Carbon dioxide is brought out and exchanged for oxygen
Your liver also removes toxins from the blood after they are ingested or inhaled

45. Other…
Homeostasis is the tendency of a system to maintain internal stability, owing to the response of its parts to any situation
If there is not homeostasis in a cell, it can no longer survive
Negative Feedback is the process of returning part of the output of a circuit, system, or device to the input to oppose the input