Lab 14: Urinary system & Reproductive system
When you are prepared for the section of the Lab Practical on Week 14 Learning Objectives in Week 15, you will be able to:
- Identify organs of the urinary system and their functions.
- Identify regions of the kidney and of the nephron and how they are involved in urine production.
- Identify parts of the male reproductive system and describe their functions.
- Identify parts of the female reproductive system and describe their functions.
- Identify structures within the ovary and describe how they are connected to oocyte maturation.
- Describe the pathway of gametes as they travel through male and female bodies.
The Urinary system
You are likely familiar with the urinary system’s role in cleansing the blood and ridding the body of wastes through the production of urine, but there are many other important functions that the urinary system participates in. The urinary system plays a role in regulation of pH, blood pressure, the concentration of solutes in the blood, and the concentration of red blood cells. The kidneys also perform the final synthesis step of vitamin D production, converting calcidiol to calcitriol, the active form of vitamin D.
Urine is a fluid of variable composition that requires specialized structures to remove it from the body safely and efficiently. Blood is filtered, and the filtrate is transformed into urine at a relatively constant rate throughout the day in the kidneys. This processed liquid is transported via the ureters to the urinary bladder, where it is stored until a convenient time for excretion. Urine then exits the body via the urethra. All structures involved in the transport and storage of the urine are large enough to be visible to the naked eye (Figure 14.1).
This transport and storage system not only stores the waste, but it protects the tissues from damage due to the wide range of pH and osmolarity of the urine, prevents infection by foreign organisms, and for the male, provides reproductive functions.
Kidneys
The kidneys lie on either side of the spine in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, well protected by muscle, fat, and ribs. The left kidney is located at about the T12 to L3 vertebrae, whereas the right is lower due to slight displacement by the liver (Figure 14.2). They are roughly the size of your fist. The male kidney is typically a bit larger than the female kidney. The kidneys are well vascularized, receiving about twenty-five percent of the cardiac output at rest.
A frontal section through the kidney reveals an outer region called the renal cortex and an inner region called the medulla (Figure 14.3). The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the renal pyramids (medullary pyramids) and renal papillae. The papillae are bundles of collecting ducts that transport urine made