Chapter 16 Flashcards
What are the functions of the urinary system?
Excretion of metabolic wastes, osmoregulation, regulation of acid-base balance, and secretion of hormones.
Describe excretion of metabolic wastes.
Most are nitrogenous, like urea and uric acid.
Describe osmoregulation.
Maintenance of the proper balance of water and salt in the blood. Blood volume and pressure are related to salt balance. The kidneys also regulate other ions like potassium, bicarbonate and calcium.
Describe regulation of acid-base balance.
Along with the respiratory system, the kidneys regulate the acid-base balance of the blood.
What is the pH of the blood always kept around?
7.4
Describe secretion of hormones.
Renin- leads to secretion of aldosterone. From there, aldosterone has to do with regulating blood pressure in arteries.
Erythropoietin- stimulates red blood cell production.
And vitamin D activation- to promote calcium absorption.
Describe the kidneys.
Paired, bean shaped. Located in lumbar regions. Covered by renal capsule.
What happens at the hilum on the concave side of the kidneys?
The renal artery enters and the renal vein and ureter exits.
Describe the ureters.
Small muscular tubes that conduct urine from kidney to bladder.
How do the ureters convey urine?
Peristalsis.
Describe the walls of the ureters.
Three layered,
Inner mucosa
Smooth muscle
Outer connective tissue.
Describe the urinary bladder.
Stores urine until expelled from the body, has 3 openings: two for the ureters, one for the urethra. Has expandable wall and 2 sphincter muscles.
Describe the urethra.
Small tube that leads from urinary bladder to an external opening. Removes urine from body.
When is urination triggered?
When bladder fills to 250 mL.
How does urination occur?
Stretch receptors send signals to spinal cord. Motor nerve impulses cause: sphincters to relax and bladder to contract, then urination. Brain controls this reflex.
Name and describe the three sections of the kidneys.
Renal cortex- outer granulated layer
Renal medulla- contains cone-shaped tissue masses called renal pyramids.
Renal pelvis- central cavity continuous with ureter.
What is a kidney composed of?
Millions of nephrons which has it’s own blood supply, including two capillary regions.
What happens from the renal artery?
The afferent arteriole leads to the glomerulus.
How does blood leave the glomerulus?
An efferent arteriole.
What does the efferent arteriole do?
Takes blood to the peritubular capillary network which surrounds the rest of the nephron. Blood then after enters the renal vein.
Describe the glomerular capsule.
Cup-like structure, inner layer is composed of podocytes. They form pores for passage of small molecules from capillaries. This is the first filtration of blood.
Describe the proximal convoluted tubule.
Cells with microvilli, increased surface area for absorption. Here, the nephron gives back to the blood.
What does the PCT return to the peritubular capillary network?
Sugar, sodium, chloride, and water.
Describe the loop of henle.
U-shaped tube, the function is to recover water and sodium chloride from urine to peritubular capillary network.
Describe the loop of henle in greater detail.
Has two parts: descending and ascending limb. Water diffuses out of the lower part of ascending limb. Salt is actively transported out of the upper part of the ascending limb which is impermeable to water.
Describe the distal convoluted tubule.
Hydrogen can be taken from the blood here as well as potassium and urea from blood and sometimes water. Another place of filtration.
Describe the collecting ducts.
Several nephrons connect to one collecting duct. Urine may become more concentrated with water going back to blood.