Chapter 10: Homeostasis

Question 1

The Excretory System:

Answer 1

This system serves many functions, including the regulation of blood pressure, blood osmolarity, acid–base balance, and removal of nitrogenous wastes. •This includes the kidneys and the bladder.

Question 2

The Kidney produces:

Answer 2

It produces urine, which dumps into the ureter at the renal pelvis. ○ Urine is then collected in the bladder until it is excreted through the urethra.

Question 3

The kidney contains:

Answer 3

• The kidney contains a cortex and a medulla. ○ Each kidney has a hilum, which contains a renal artery, renal vein, and ureter. It contains a portal system with two capillary beds in series.

Question 4

First Capillary Bed:

Answer 4

Blood from the renal artery flows into afferent arterioles, which form glomeruli in Bowman’s capsule (the first capillary bed).

Question 5

Second Capillary Bed:

Answer 5

Blood then flows through the efferent arteriole to the vasa recta, which surround the nephron (the second capillary bed), before leaving the kidney through the renal vein.

Question 6

Bladder:

Answer 6

This has a muscular lining known as the detrusor muscle, which is under parasympathetic control. It also has two muscular sphincters. (Internal and External)

Question 7

The Internal Urethral Sphincter:

Answer 7

This sphincter consists of smooth muscle and is under involuntary (parasympathetic) control.

Question 8

The External Urethral Sphincter:

Answer 8

The external urethral sphincter consists of skeletal muscle and is under voluntary control.

Question 9

The kidney participates in solute movement through what three processes:

Answer 9

Filtration, secretion, reabsorption.

Question 10

Filtration:

Answer 10

Is one of the processes that the kidney participates in. This is the movement of solutes from blood to filtrate at Bowman’s capsule.

Question 11

Secretion:

Answer 11

Is one of the processes that the kidney participates in. This is the movement of solutes from blood to filtrate anywhere other than Bowman’s capsule.

Question 12

Reabsorption:

Answer 12

Is one of the processes that the kidney participates in. This is the movement of solutes from filtrate to blood.

Question 13

Segments of the nephron:

Answer 13

The proximal convoluted tubule (PCT), The descending limb of the loop of Henle, The ascending limb of the loop of Henle, The distal convoluted tubule (DCT), and the collecting duct.

Question 14

The proximal convoluted tubule (PCT):

Answer 14

This tubule is the site of bulk reabsorption of glucose, amino acids, soluble vitamins, salt, and water. It is also the site of secretion for hydrogen ions, potassium ions, ammonia, and urea.

Question 15

The descending limb of the loop of Henle:

Answer 15

This loop of Henle is permeable to water but not salt; therefore, as the filtrate moves into the more osmotically concentrated renal medulla, water is reabsorbed from the filtrate. The vasa recta and nephron flow in opposite directions, creating a countercurrent multiplier system that allows maximal reabsorption of water.

Question 16

The ascending limb of the loop of Henle:

Answer 16

This loop of Henle is permeable to salt but not water; therefore, salt is reabsorbed both passively and actively. The diluting segment is in the outer medulla; because salt is actively reabsorbed in this site, the filtrate actually becomes hypotonic compared to the blood.

Question 17

The Distal Convoluted Tubule:

Answer 17

This tubule: is responsive to aldosterone and is a site of salt reabsorption and waste product excretion, like the PCT.

Question 18

The collecting duct:

Answer 18

This duct is responsive to both aldosterone and antidiuretic hormone and has variable permeability, which allows reabsorption of the right amount of water depending on the body’s needs.