Body Systems: Excretory System (The Excretory System)

Question 1

Functions of the excretory system:

Answer 1

-maintains equilibrium of waste products.
-balance blood pH.
-water balance in body.
-regulating blood pressure.
-regulates extra cellular fluid (ECF).
-maintains equilibrium of electrolytes.

Question 2

Waste products in the urine:

Answer 2

-ammonia: deamination of amino acids by the liver, highly toxic but quickly converted to urea in the liver.
-urea: ammonia (from deamination) combined with CO2.
-uric acid: breakdown of nucleic acids (DNA).

Question 3

Urinary system:

Answer 3

-renal arteries: carry blood to kidneys from abdominal aorta.
-kidneys: filter wastes from the blood and pass to ureters (long ducts) which pass it along to the bladder.
-bladder: stores urine.
-urethra: carries urine from bladder to exterior of body. (Shorter in women, longer in men).

Question 4

Micturition (peeing):

Answer 4

-urine in bladder stimulates stretch receptors.
-parasympathetic Neurons signal smooth muscle in bladder wall.
-bladder pushes urine out of the body.
-relaxation of external urethral sphincter muscle allowing urine to pass through urethra and out of the body.

Question 5

The kidneys:

Answer 5

-outer layer = cortex.
-inner layer = medulla.
-renal pelvis = hollow area where the kidney joins the ureter. Collects urine and transports it to ureters.
-kidneys functional unit is the nephron.

Question 6

Inside the kidney (the nephron):

Answer 6

•capillary network: blood vessels that surround the tubule of the nephron.
•afferent arteriole: brings blood into glomerulus. Located in the cortex.
•efferent arteriole: brings blood out of the glomerulus. Located in the cortex.
•glomerulus (cortex): high pressure capillary bed that is the site of filtration.
•bowman’s capsule: the cup-like structure that surrounds the glomerulus receives filtrate to be turned into urine. Located in the cortex.
•proximal tubule: the section of the nephron joining the bowman’s capsule with the loop of henle. Located in the cortex.
•loop of Henle: the section of the tubule that carries filtrate from the proximal tubule to the distal tubule. Descend into medulla.
•distal tubule (cortex): carries urine from the loop of henle to the collecting duct.
•collecting ducts (cortex—>medulla): tube that carries urine from the nephrons to the renal pelvis—> many collecting ducts from many nephrons merge into renal pelvis—> ureter.