Lab 12
Anatomy & Physiology Part 3: Urinary & Reproductive Systems

Learning Objectives
In this lab students will:
- Continue to learn about anatomy and physiology.
- Be able to list, label and explain the functions of the organs of the urinary system.
- Be able to list, label and explain the functions of the male and female reproductive systems.

The Urinary System

• Plays a crucial role in maintaining homeostasis.
• Excretes a very toxic substance called ammonia (NH3), a nitrogenous by-product of amino acid breakdown.
• Ammonia is converted into urea in the liver, which combines NH3 with CO2.
• Some nitrogenous wastes are perspired or exhaled but, the bulk of is extracted from the blood in the kidneys.
• The Urinary system also regulates water balance, blood ion concentration & blood pH levels.
• It filters the fluid portion of the blood, reabsorbing water & important nutrients, collects toxins, cellular wastes & excess water to be excreted as urine.

Urinary system 1. Urinary system (numbers 1-6 are organs of the urinary system) 2. Kidney – bean shaped, paired organs 3. Renal pelvis – junction between the kidney and the ureter 4. Ureter – tube that drains urine from kidney to urinary bladder 5. Urinary bladder – sac-like structure that receives urine from both kidneys via the ureters. 6. Urethra (Left side with frontal section) – tube that drains urine from the urinary bladder to outside the body. 7. Adrenal gland – small gland that sits on top of both kidneys 8. Renal artery and vein – the red artery that brings blood into the kidney and the blue vein that drains blood from the kidney. 9. Inferior vena cava 10. Abdominal aorta 11. Common iliac artery and vein 12. Liver 13. Large intestine 13. Pelvis

• The urinary system consists of two kidneys, located in the lower, dorsal abdominal region.
• The Kidneys maintain water, electrolyte, and acid-base balance and filters wastes from the blood to produce urine.
• A pair of ureters drains the urine from the kidneys into the urinary bladder.
• The urinary bladder stores the urine until it can be expelled from the body.
• Urine leaves the body via a single urethra.
• The Renal artery brings blood from the abdominal aorta into the kidney.
• The Renal vein carries blood from the kidney to the inferior vena cava.
• Figure 12.1 shows the components of the urinary system.
• Now we will look at the anatomy of the kidney in more detail.

The Kidney

Image shows a lateral view of a diagram of a human kidney and a dissected kidney. Image highlights the thick outer cortex containing cortical blood vessels and the inner medulla with alternating triangular shaped renal pyramids separated by renal columns. The tip of the renal pyramids is labeled “renal papilla”. Attached to the renal medulla is a short tube called the minor calyx. Where two or more minor calyxes meet, they form a larger major calyx that drains into the larger renal pelvis located on the left side of the images and about the midpoint of the kidney. The area is called the hilum Near the renal pelvis there is a red renal artery and a blue renal vein along with the yellow renal nerve. The renal pelvis is attached to the tube-like ureter that carries urine away from the kidney.

•The term "renal" refers to the kidney.
• It is a solid organ with an outer denser region called the renal cortex and an inner portion called the renal medulla.
• Within the renal medulla there are alternating renal columns and renal pyramids
• The Renal pyramids are triangular-shaped structures that make up the bulk of the renal medulla.
• Renal columns are made of a more solid looking tissue and lie between renal pyramids.
• The Renal papilla are at the tip of the renal pyramids. They drain urine into the minor calyx.
• The Minor calyx  is a cup-shaped structure encasing and receives urine from renal papilla.
• The Major calyx occurs where several minor calyces unite to drain urine into the Renal pelvis.
• The Renal pelvis receives urine from the major calyces.
• The Ureter receives urine from the renal pelvis and carries it to the urinary bladder.
• Figure 12.2 shows the major parts of the kidney.
• Within each kidney are millions of microscopic nephrons. These are the site within the kidney where urine is made.
• Now we will look at the nephron in more detail.

The Nephron

Figure 12.3 highlights the 3 main parts of a nephron; 1) The glomerulus, a ball of capillaries that bring blood to be filtered to the renal tubules: located in the cortex. 2) The Bowman’s capsule, the cup-shaped structure which surrounds the glomerulus and receives the filtrate from the glomerulus. 3) The renal tubules, including the convoluted tubules (proximal and distal) and the Loop of Henle, where nutrients are selectively reabsorbed into the blood while wastes are left behind in collecting tubules for eventual excretion as urine. • Bowman’s capsule is the start of the renal tubules. It encases glomerulus and is located in the cortex • The proximal convoluted tubule is the coiled first section of the renal tubules and is located in the cortex. • The Loop of Henle is the straight section of renal tubules that dip down via the descending loop of Henle, into the medulla and then back up, via the ascending loop of Henle, into the cortex. • The distal convoluted tubule is the coiled third section if the renal tubules also located in the cortex. • The collecting ducts receive urine from the renal tubules. • The Peritubular capillary network is a network of capillaries that surround renal tubules and aid in absorption and secretion of substances to adjust the contents of the urine and the blood.

• These microscopic structures are the functional units of the kidney.
• They are the microscopic structures in which urine is made.
• The nephron has 3 main parts;
1) The glomerulus, a ball of capillaries that bring blood to be filtered to the renal tubules: located in the cortex.
2) The Bowman’s capsule, which surrounds the glomerulus and receives the filtrate from the glomerulus.
3) The renal tubules, including the convoluted tubules (proximal and distal) and the Loop of Henle, where nutrients are selectively reabsorbed into the blood while wastes are left behind in collecting tubules for eventual excretion as urine.
•  Bowman’s capsule is the start of the renal tubules. It encases glomerulus and is located in the cortex
• The proximal convoluted tubule is the coiled first section of the renal tubules and is located in the cortex.
•  The Loop of Henle is the straight section of renal tubules that dip down via the descending loop of Henle, into the medulla and then back up, via the ascending loop of Henle, into the cortex.
• The distal convoluted tubule is the coiled third section if the renal tubules also located in the cortex.
• The collecting ducts receive urine from the renal tubules.
• The Peritubular capillary network is a network of capillaries that surround renal tubules and aid in absorption and secretion of substances to adjust the contents of the urine and the blood.
• Figure 12.3 shows the parts of the nephron and their location in the renal cortex or renal medulla.

Click on the image of the nephron below to watch a drop of filtrate form and travel through the urinary system.

Animation starts with the text “The fluid portion of the blood is first filtered in millions of microscopic nephrons within each kidney”. Next, we see a greatly magnified diagram of a nephron. A small yellow drop of fluid first appears in the Bowman’s capsule as the words Bowmans’s capsule enlarge and shrink. Next the drop of fluid enters the proximal convoluted tubule as the words proximal convoluted tubule enlarge and shrink. Next the drop of fluid enters the descending loop of Henle as the words descending loop of Henle enlarge and shrink. Next the drop of fluid enters the loop of Henle as the words loop of Henle enlarge and shrink. Next the drop of fluid enters the ascending loop of Henle as the words ascending loop of Henle enlarge and shrink. Next the drop of fluid enters the distal convoluted tubule as the words distal convoluted tubule enlarge and shrink. Next the drop of fluid enters Collecting duct as the words collecting duct enlarge and shrink. We see the drop of fluid descend through the collecting duct and exit via the renal papilla as the words renal papilla enlarge and shrink. Next appears a screen that reads “The filtrate from many collecting ducts drain through the macroscopic renal papilla and into a minor calyx. Now a diagram of od kidney appears. We can see structures inside the kidney. The drop of fluid is seen leaving the renal papilla and entering a minor calyx as the words monor calyx enlarge and shrink. Next the drop of fluid enters the major calyx as the words major calyx enlarge and shrink. Next the drop of fluid enters the renal pelvis as the words renal pelvis enlarge and shrink. Next the drop of fluid enters the ureter as the word ureter enlarges and shrinks. A screen appears that reads “The urine then continues through the remainder of the urinary system”. A diagram of the remaining macroscopic structures of the urinary system appears. The drop of urine travels through a ureter as the word ureter enlarges and shrinks. Next the drop of urine enters the urinary bladder as the words urinary bladder enlarge and shrink. Next the drop of urine enters the urethra as the word urethra enlarges and shrinks. Finally, the drop of urine exits the body as the words Outside the body enlarge and shrink.

Urinalysis

• Urine is a filtrate of your blood.
• Doctors examine your urine because it tells a lot about what is going on in the rest of your body.
• Table 12.1 lists substances that a doctor looks for in urine along with the normal values and conditions indicated if it is present in the urine.

Table 12.1 contains the following columns: substance, Normal values, condition and Possible causes. The first substance listed is glucose, normal condition is negative, condition is glycosuria, possible cause is diabetes mellitus. The second substance listed is albumin/(protein), normal condition is negative, condition is proteinuria, possible cause is glomerulonephritis, hypertension. The third substance listed is ketones, normal condition is negative, condition is ketoosuria, possible cause is diabetes mellitus, starvation. The fourth substance listed is bilirubin, normal condition is negative, condition is bilirubinsuria, possible cause is liver disease. The fifth substance listed is red blood cells, normal condition is negative, condition is hematuria, possible cause is bleeding in the urinary tract. The last substance listed is pH, normal condition is 4.5-7.8, condition is glycosuria, possible causes are acidic: diabetes mellitus, metabolic acidosis or alkaline: urinary tract infection, metabolic alkalosis.

The Reproductive System

• Responsible for the production of gametes, fertilization & development of a fetus.
• Gonads are the main organs of the reproductive system.
• The gonads are responsible for producing gametes (sex cells)
• Ovary - is the female gonad. It produces gametes called ova or eggs.
• Testis - is the male gonad. It produces gametes called sperm.
• Gonads also secrete sex hormones.
• Estrogen and progesterone are the hormones the female gonad produces.
• Testosterone is the hormone produced by the male gonad.
• Hormones are responsible for proper functioning of the reproductive systems and secondary sexual characteristics.

Female Reproductive System

Figure 12.4 shows a lateral view of the female reproductive systems. Highlighted is the Uterine (fallopian) tube connecting the ovary to the uterus. The small ovary (the organ where eggs are produced). The thick-walled uterus attached to the uterine (fallopian) tube and the vagina. The vagina, tube between the uterus and outside the body. The external female genitalia including labium minus and labium majus. And, the cervix, the opening between the uterus and the vagina.

• The female reproductive system is more complex than the male because in addition to producing ova or eggs it also provides the site for fertilization (union of sperm and egg) and growth of the fetus.
• Use Figure 12.4 as a reference to identify the following organs of the female reproductive system.
• Ovaries - produce eggs (ova) and secrete female sex hormones.
• Uterine tube ( Fallopian tubes) – transport eggs to the uterus and is normal site of fertilization.
• Uterus – site of fetal development.
• Cervix – opening of uterus into vagina.
• Vagina - receives penis and sperm during copulation; also the birth canal.
• Labia major – outer pair of skin folds that cover and protect vaginal opening.
• Labia minor – inner pair of skin folds that cover and protect vaginal opening.
• Clitoris – sensitive erectile tissue.

Male Reproductive System

Figure 12.5 shows a lateral view of the male reproductive systems. Highlighted is the Seminal vesicle, a small organ that is connected to the vas deferens and is near the urinary bladder. The Prostate gland, the organ through which the vas deferens enters and meets up with the urethra. The small Bulbourethral (Cowper) gland, a small organ attached to the distal urethra. The Ductus (vas) deferens, a tube connecting the testis and the urethra. The epididymis, the site above the testis where sperm mature. The testis, the male organ, held outside the body that is the site where sperm are made. The scrotum, the sac containing the testis, the urethra within the penis, the external male genitalia. Also highlighted is the urinary bladder, the organ that collects and stores urine. And the ureter, the tube that leads from the kidneys to the urinary bladder.

• The male reproductive system is built to produce sperm and deposit it into the female reproductive system.
• Use Figure 12.5 as a reference and identify the following organs of the male reproductive system.
• Testes - produce sperm and secrete male sex hormones.
• Epididymis - site for immature sperm to mature.
• Vas deferens - transports sperm to the urethra.
• Seminal vesicles - adds alkaline fructose fluid to nourish sperm.
• Prostate gland - adds a milky fluid to the semen that activates the sperm.
• Bulbourethral (Cowper's) gland - adds a thick mucus fluid to the semen.
• Urethra - transports sperm and urine outside the body.
• Penis - copulatory organ; delivers sperm to the female reproductive system.
• Glans penis - the larger, distal end of the penis; covered by the prepuce.
• Prepuce - the foreskin that covers the glans penis.
• Scrotum - provides protection and temperature regulation for the testicles.

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Non-majors College Biology Lab Manual © 2021 by Marie McGovern Ph.D. is licensed under CC BY-NC 4.0