A quiz for Chapter 34

1. Two general roles for nutrients are to provide ____ and ____ .Nutrients required in small amounts that often assist in enzyme function are called ____ . Nutrients that are elements are called ____ . Nutrients that cannot be synthesized by the body are called ____ nutrients. The five major processes carried out by the digesitive systems are ___,___,___,___and___. A quiz for Chapter 34

2. 35 The Urinary System 0

3. 35.1 What Are the Major Functions of Urinary Systems? 35.2 What Are Some Examples of Invertebrate Urinary Systems? 35.3 What Are the Structures of the Mammalian Urinary System? 35.4 How Is Urine Formed? 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis? Chapter 35 At a Glance

4. Urinary systems are organ systems that produce and eliminate urine Urine is a watery fluid containing a variety of substances that have been filtered from the blood or from the interstitial fluid that bathes all cells Urine contains(1) waste products of cellular metabolism, (2)foreign substances, and (3)some ions and nutrients in excess of the body’s needs 35.1 What Are the Major Functions of Urinary Systems?

5. Excretion eliminates from the body Excretion排泄is the general process by which wastes are eliminated from the body Urinary systems excrete cellular wastes The primary cellular wastes in urine are the nitrogen-containing compounds Ammonia 氨 Urea 尿素 Uric acid 尿酸 35.1 What Are the Major Functions of Urinary Systems?

6. Excretion eliminates from the body (continued) These nitrogenous含氮的wastes are formed when cells break down the amino acids liberated 释放by protein digestion Within cells, some amino acids are used to synthesize new proteins The liberated amino groups (NH2) are released by the cells as ammonia (NH3), which is toxic Ammonia is the primary nitrogenous waste of freshwater organisms 35.1 What Are the Major Functions of Urinary Systems?

7. Excretion eliminates from the body (continued) Terrestrial animals that collect and store their urine convert ammonia into less toxic urea or uric acid (in birds and other reptiles, and insects) 35.1 What Are the Major Functions of Urinary Systems?

8. Figure 35-1 Urea formation and excretion Proteins in food are digested Amino acids are carried in the blood to body cells amino acid The cells convert the amino groups (-NH2) to ammonia, which is carried in the blood to the liver ammonia The liver converts ammonia to urea, which is less toxic urea Urea is carried in the blood to the kidneys In kidney nephrons, urea is filtered into the urine

9. Sponges and cnidarians lack urinary systems For these simple animals, diffusion and active transport through cell membranes into the surrounding water is adequate to excrete cellular wastes and maintain homeostasis The urinary systems of flatworms act primarily to maintain water balance, and those in more complex invertebrates act as filters that eliminate wastes and regulate the composition of the body fluids 35.2 What Are Some Examples of Invertebrate Urinary Systems?

10. Protonephridia原肾管 filter interstitial fluid in flatworms The urinary systems of freshwater flatworms consist of protonephridia原肾管 Protonephridia include tubules that branch throughout the body within the interstitial fluid that surrounds the flatworm’s tissues At intervals along the tubules are ciliated有纤毛的“flame cells,” 火焰细胞whose beating cilia resemble a flickering flame Flame cells produce a current that draws interstitial fluid into the tubules through the slit-like openings 35.2 What Are Some Examples of Invertebrate Urinary Systems?

11. Figure 35-2a Flatworms use protonephridia tubule interstitial fluid cilia nucleus flame cell excretory pore Flatworms use protonephridia

12. Malpighian tubules filter the hemolymph of insects Insects have an open circulatory system where hemolymph (a fluid that serves as both blood and extracellular fluid) fills the hemocoel (the body cavity) and bathes the internal tissues and organs directly Insect excretory systems consist of Malpighian tubules,马氏管small tubes that extend outward from the intestine and end blindly within the hemolymph 35.2 What Are Some Examples of Invertebrate Urinary Systems?

13. Malpighian tubules filter the hemolymph of insects (continued) Wastes and nutrients move from the hemolymph into the tubules by diffusion and active transport, and water follows by osmosis渗透 Urine is conducted into the intestine, where important solutes are secreted into the hemolymph by active transport Insects produce very concentrated urine, which is excreted along with feces 35.2 What Are Some Examples of Invertebrate Urinary Systems?

14. Figure 35-2b Insects use Malpighian tubules Malpighian tubules abdomen intestine rectum hemocoel (filled with hemolymph) cellular and digestive wastes Insects use Malpighian tubules

15. Nephridia肾管 filter interstitial fluid in annelid环节动物worms and mollusks软体动物 In earthworms, mollusks, and several other invertebrates, excretion is performed by tubular structures called nephridia肾管 In the earthworm, the body cavity (the coelom体腔) is filled with extracellular fluid into which wastes and nutrients from the blood diffuse 35.2 What Are Some Examples of Invertebrate Urinary Systems?

16. Nephridia filter extracellular fluid in earthworms Each nephridium begins with a funnel-like opening, the nephrostome肾孔, ringed with cilia that direct extracellular fluid into a narrow, twisted tubule surrounded by capillaries As the fluid traverses the tubule, salts and nutrients are reabsorbed back into the capillary blood, leaving the wastes and water behind 35.2 What Are Some Examples of Invertebrate Urinary Systems?

17. Nephridia filter extracellular fluid in earthworms (continued) The resulting urine is then excreted through an opening in the body called a nephridiopore 肾管孔 Each segment in an earthworm’s body contains a pair of nephridia 35.2 What Are Some Examples of Invertebrate Urinary Systems?

18. Figure 35-2c Earthworms use nephridia coelom (filled with interstitial fluid) nephridium bladder capillary network nephrostome nephridiopore Earthworms use nephridia

19. The mammalian urinary system consists of Kidneys 肾 Ureters 输尿管 Bladder 膀胱 Urethra 尿道 These organs filter small molecules and ions out of the blood, return essential ions and nutrients, and collect and excrete substances and cellular wastes 35.3 What Are the Structures of the Mammalian Urinary System?

20. Different structures of the human urinary system produce, store, and excrete urine Human kidneys are paired organs, resembling a kidney bean 蚕豆in both shape and color, located at about waist level on either side of the spinal column The outermost layer of each kidney where urine is formed is the renal cortex肾皮质 Beneath the renal cortex lies the renal medulla肾髓质(“kidney marrow”) 35.3 What Are the Structures of the Mammalian Urinary System?

21. Different structures of the human urinary system produce, store, and excrete urine (continued) The renal medulla surrounds a branched, funnel-like chamber called the renal pelvis肾盂(“kidney bucket”), which collects urine and conducts it into the ureter The ureter is a narrow, muscular tube that contracts rhythmically to propel the urine to the bladder, a hollow, muscular chamber that collects and stores urine 35.3 What Are the Structures of the Mammalian Urinary System?

22. Different structures of the human urinary system produce, store, and excrete urine (continued) The average adult bladder can hold about a pint of urine, but the desire to urinate is triggered by smaller amounts The internal sphincter, located at the junction of the bladder and the urethra, opens automatically 35.3 What Are the Structures of the Mammalian Urinary System?

23. Different structures of the human urinary system produce, store, and excrete urine (continued) The external sphincter, slightly below the internal sphincter, is under voluntary control, allowing the brain to suppress urination unless the bladder becomes overly full Urine exits the body through the urethra, a single narrow tube about 1.5 inches long in the female and about 8 inches long in the male (where it extends through the penis) 35.3 What Are the Structures of the Mammalian Urinary System?

24. Figure 35-3 The human urinary system and its blood supply left renal artery left kidney left renal vein aorta left ureter vena cava urinary bladder urethra (in penis)

25. Figure 35-4 The internal structure and blood supply of the human kidney renal pelvis (cut away to show the path of urine) renal artery renal cortex renal medulla renal pelvis renal vein ureter collecting duct nephron urine to the bladder loop of Henle renal medulla renal cortex enlargement of a single nephron and collecting duct

26. Large quantities of blood flow through the kidneys To accomplish their functions of excreting cellular wastes and maintaining homeostasis, the kidneys filter large quantities of blood Blood enters each kidney through a renal artery and exits through a renal vein The immense极大的filtering capacity of the kidneys explains why kidney donors and kidney recipients can each survive 35.3 What Are the Structures of the Mammalian Urinary System?

27. Nephrons肾单位in the kidneys filter blood and produce urine Each human kidney is made up of more than 1 million microscopic filters called nephrons Blood carried to the kidney by the renal artery enters each nephron through a microscopically narrow arteriole Within each nephron the arteriole branches further, forming a dense capillary meshwork called the glomerulus肾小球, the first portion of the nephron 35.3 What Are the Structures of the Mammalian Urinary System?

28. Nephrons in the kidneys filter blood and produce urine (continued) This arteriole gives rise to the peritubular capillaries,肾小管管周毛细血管网which form a network surrounding the nephron The peritubular capillaries conduct the blood into a venule that joins the renal vein 35.3 What Are the Structures of the Mammalian Urinary System?

29. Nephrons in the kidneys filter blood and produce urine (continued) Each nephron has two major parts In the first portion, the glomerulus, fluid is filtered out of the blood through the porous capillary walls The second portion consists of a long, twisted tubule (“little tube”) The tubule begins with a cuplike chamber called Bowman’s capsule肾小球囊 ; 鲍氏囊, which surrounds the glomerulus and collects fluid filtered out of the blood 35.3 What Are the Structures of the Mammalian Urinary System?

30. Nephrons in the kidneys filter blood and produce urine (continued) From Bowman’s capsule, the fluid is conducted into the proximal tubule近曲小管then into the loop of Henle亨利氏环 The filtrate is converted into urine in the distal tubule远曲小管 In the renal cortex, the distal tubule empties urine into a collecting duct集合管, a larger tube that is not part of the nephron 35.3 What Are the Structures of the Mammalian Urinary System?

31. Figure 35-5 An individual nephron and its blood supply collecting duct proximal tubule distal tubule Bowman’s capsule glomerulus arterioles venule branch of the renal artery branch of the renal vein loop of Henle peritubular capillaries

32. Urine is produced in the nephrons of the kidneys during three processes 1. Filtration, during which water and most small dissolved molecules are filtered out of the blood 2. Tubular reabsorption, the process by which water and necessary nutrients are restored to the blood 3. Tubular secretion, during which wastes and excess ions that still remain in the blood are secreted into the urine 35.4 How Is Urine Formed?

33. As urine is formed, essentially all small organic nutrients, including amino acids and glucose, are filtered out of and then returned to the blood Large quantities of water and many ions are also filtered out, but their return rate is continuously adjusted to meet the body’s changing needs These ions include sodium (Na), chloride (Cl), potassium (K), calcium (Ca), hydrogen (H), and bicarbonate(HCO3 ) 35.4 How Is Urine Formed?

34. Filtration removes small molecules and ions from the blood Filtration, the first step in urine formation, occurs when water carrying small dissolved molecules and ions is forced through the walls of the capillaries that form the glomerulus Blood cells and large proteins are too large to leave the capillaries, and so remain behind in the blood 35.4 How Is Urine Formed?

35. Filtration removes small molecules and ions from the blood (continued) The fluid filtered out of the glomerular capillaries, called filtrate滤液, is collected in Bowman’s capsule and then continues through the tubule 35.4 How Is Urine Formed?

36. Figure 35-6 Urine formation and concentration Tubular reabsoption and tubular secretion: In the proximal and distal portions of the tubule, most water and nutrients are reabsorbed into the blood, and additional wastes are secreted by active transport into the tubule from the blood Filtration: Water, nutrients, and wastes are filtered from the glomerular capillaries into the Bowman’s capsule of the nephron blood leaving the glomerulus proximal tubule collecting duct distal tubule Bowman’s capsule Concentration of urine: In the collecting duct, urine may become more concentrated than the blood as water leaves by osmosis blood entering the glomerulus glomerulus loop of Henle tubular reabsorption tubular secretion Generation of high solute concentration: The loop of Henle and the collecting duct both help to produce a high solute concentration in the interstitial fluid

37. Tubular reabsorption returns important substances to the blood During tubular reabsorption, nearly all the water, essential ions, and organic nutrients such as glucose and amino acids that were removed during filtration are returned to the blood The reabsorption of water and inorganic nutrient ions (Na, Cl, K, Ca, H, and HCO3) is precisely regulated by circulating hormones, so that excess water and ions remain in the tubule for excretion 35.4 How Is Urine Formed?

38. Tubular secretion actively transports substances into the tubule for excretion During tubular secretion, remaining wastes and excess ions move from the blood into the proximal and distal tubules These wastes include excess K and H, small quantities of ammonia, many drugs, food additives, pesticides农药, and toxic substances, such as nicotine 35.4 How Is Urine Formed?

39. Tubular secretion actively transports substances into the tubule for excretion (continued) Tubular secretion, which occurs primarily by active transport, takes place in both the proximal and distal tubules When the filtrate leaves the distal tubule, it has become urine 35.4 How Is Urine Formed?

40. Figure E35-2 Details of urine formation TUBULAR REABSORPTION TUBULAR SECRETION FILTRATION OF BLOOD CONCENTRATION OF URINE HCO3- H+ 300 Ca2+ H+ K+ NaCl Cl- Na+ nutrients some drugs some drugs * Ca2+ H2O K+ H2O HCO3- * H2O distal tubule proximal tubule Bowman’s capsule NaCl H2O renal cortex 300 renal medulla NaCl H2O osmotic concentration of interstitial fluid (in milliosmosis) NaCl 600 * H2O H2O (interstitial fluid) urea NaCl 900 * H2O H2O mechanism under study osmosis 1,200 active transport loop of Henle diffusion controlled by ADH collecting duct

41. Vertebrate urinary systems help maintain homeostasis in several ways, including: 1. Retaining small organic nutrients within the blood and interstitial fluid 2. Regulating the water and ion content of the blood to maintain the proper blood osmolarity渗透压 3. Maintaining the proper pH of the blood by regulating hydrogen and bicarbonate ion concentrations 4. Secreting substances that help regulate blood pressure and blood oxygen content 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

42. The kidneys regulate the water and ion content of the blood One important function of the kidney is to regulate blood osmolarity, a measure of its concentration of ions and other solutes 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

43. The kidneys regulate the water and ion content of the blood (continued) Human kidneys filter out about half a cup of fluid from the blood each minute, fine-tuning the composition of the blood and helping to maintain homeostasis If the kidneys did not reabsorb this water, the rate of filtration would require that we drink nearly 50 gallons of water a day 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

44. The kidneys regulate the water and ion content of the blood (continued) Reabsorption of water occurs passively through the tubule and collecting duct Reabsorption of water into the blood occurs passively by osmosis as the filtrate travels through the tubule and collecting duct When the filtrate enters the distal tubule, most of its water has already been reabsorbed 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

45. The kidneys regulate the water and ion content of the blood (continued) The interstitial fluid within the renal medulla contains high concentrations of salt and urea Salt enters the fluid from the loop of Henle, and urea enters from the collecting duct As urine travels through the collecting duct to the renal pelvis, it passes through the interstitial fluid, which becomes increasingly concentrated in salt and urea from the upper to the lower regions of the medulla 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

46. The kidneys regulate the water and ion content of the blood (continued) Water permeability渗透性of the distal tubule and collecting duct is regulated by ADH抗利尿激素（antidiuretic hormone） The amount of water reabsorbed in the distal tubule and collecting duct depends on their permeability to water Water permeability throughout the tubule and collecting duct is controlled by numbers of aquaporins水通道蛋白, which are water channel proteins 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

47. The kidneys regulate the water and ion content of the blood (continued) Water permeability of the distal tubule and collecting duct is regulated by ADH (continued) In contrast, aquaporin numbers in the distal tubule and the collecting duct membranes are controlled by antidiuretic hormone (ADH) Receptors in the hypothalamus monitor blood osmolarity 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

48. The kidneys regulate the water and ion content of the blood (continued) For example, when water is lost during dehydration If blood osmolarity exceeds an optimal level, the hypothalamus stimulates the pituitary gland to release ADH In response to ADH, cells of the distal tubule and collecting duct insert more aquaporins into their membranes, increasing their permeability to water 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

49. The kidneys regulate the water and ion content of the blood (continued) For example, when water is lost during dehydration (continued) The more concentrated extracellular fluid draws water out by osmosis, restoring water to the blood through nearby capillaries Under normal conditions, some ADH is always present in the blood Within the hypothalamus, receptors monitor blood osmolarity, which increases when water is lost 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?

50. The kidneys regulate the water and ion content of the blood (continued) Blood osmolarity is controlled by negative feedback When blood osmolarity returns to normal, the receptors in the hypothalamus signal the pituitary to reduce ADH release down to a baseline level If you drink too much water, ADH secretion will be temporarily blocked, causing you to excrete large amounts of very dilute urine 35.5 How Do Vertebrate Urinary Systems Help Maintain Homeostasis?