When you exercise vigorously, your body loses water in the form of sweat. How do feedback mechanisms in the endocrine system help you to maintain water balance?
The hypothalamus contains cells that are sensitive to the concentration of water in the blood. When my body loses water as sweat, the concentration of dissolved materials in the blood rises. The hypothalamus responds by first signaling the posterior pituitary gland to release a hormone called ADH (antidiuretic hormone). ADH molecules are carried by the blood to the kidneys, where the removal of water from the blood is quickly slowed down. The hypothalamus also causes a thirst sensation. When I drink water, the water is absorbed into the blood. To avoid the water diluting the blood, the hypothalamus causes the pituitary to release less ADH. They kidneys respond by removing water from the blood.
A female's ovaries release about how many mature eggs in her lifetime?
a. 100 c. 50,000
b. 400 d. 400,000
Which hormones stimulate the gonads to mature?
a. FSH and LH
d. testosterone and progesterone
a FSH and LH
Because steroid hormones are made of______, they can easily cross cell membranes.
The prefix endo means "inside," while the prefix exo means "outside." How do these prefixes
reflect the function of the endocrine and exocrine glands?
Endocrine glands usually release their secretions directly into the blood, which transports the secretions throughout the body. Exocrine glands however, release their secretions outside the blood. They release their secretions through tubelike structures either out of the body or directly into the digestive system.
Pitocin is a synthetic drug that is often used to stimulate uterine contractions. Which
hormone has a similar function?
a. thyroxine c. oxytocin
b. FSH d. prolactin
Once sperm enter the female reproductive system, they usually live for only 12 to 48 hours. What could be one reason that sperm do not live long inside the female body? What effect does this have on fertilization?
Sample answer: Sperm are stored in the scrotum of the male body, which is lower in temperature than the rest of the male body or the inside of the female body. The higher temperature could limit the lifespan of sperm inside the female body. The effect on fertilization is that an egg would need to be in Fallopian tube at about the same time as the sperm arrive.
Which structure in the kidneys' nephrons is mainly responsible for the filtration of the
a. collecting duct c. glomerulus
b. loop of Henle d. Bowman's capsule
In a rare genetic disorder called Kallman syndrome, the hypothalamus produces reduced levels of the hormone that signals the pituitary to increase its production of LH. How would this disorder affect a person's development and ability to reproduce? Explain your answer.
Since the pituitary would not increase its production of LH, the person would not go through puberty. If a person does not go through puberty, he or she could not reproduce. Males would not produce sperm and females would not produce or release mature eggs.
When you are dehydrated, the pituitary gland releases antidiuretic hormone (ADH), which
causes the kidneys to reabsorb less water.
Construct a flow chart that shows the path through which sperm travel from the time they are produced until they are expelled from the male body.
Answer should show that sperm are produced in the seminiferous tubules. From there, they travel through the epididymis, vas deferens, and urethra (in the penis).
True or False:
Proteins are polymers of amino acids.
True or False:
Aspirin can relieve the pain of a headache because it inhibits the synthesis of hormones.
Nonsteroid hormones could be
a. modified amino acids.
c. small peptides.
d. all of the above.
d. all of the above
About how many sperm are in one milliliter of semen?
a. 1,000-5,000 c. 1-2 million
b. 250,000-500,000 d. 50-130 million
d. 50-130 million
Label the seven organs shown in Figure 30-3. Then construct a table
in which you describe how each functions in the excretory system.
Skin: excretes excess water, salts and a small
amount of urea as sweat; Lungs: excrete carbon dioxide and small amounts of vapor, which are waste products of cellular respiration; Liver: converts potentially dangerous nitrogen wastes into less toxic urea; Kidneys: remove excess water, urea, and metabolic wastes from the blood; Ureter: transports urine from the kidneys to the urinary bladder; Bladder: stores urine until it is released from the body; Urethra: tube through which urine is released from the body
Rattlesnake venom breaks down the walls of the glomerulus. Why does a rattlesnake bite cause
blood to appear in the urine?
The glomerulus is a dense network of capillaries found in the nephrons of kidneys. If their walls were damaged blood would enter Bowman's capsule and it would appear in the waste products. This would cause blood to appear in the urine.
Many sperm may reach an egg in a Fallopian tube at the same time. What prevents more than one sperm from fertilizing an egg?
Once a sperm nucleus has entered the egg, the cell membrane of the egg cell changes, preventing other sperm from entering the cell.
Which structure in Figure 30-1 removes excess water, urea, and metabolic waste from the
a. kidney c. urinary bladder
b. renal vein d. ureter
If a steroid hormone-receptor complex was not able to enter the nucleus of a cell, how would this affect the cell's activities?
The cell would not be able to respond to the hormone.
What role does skin play in the excretory system?
a. secretes excess water as sweat
c. absorbs water through osmosis
b. protects against pathogens
d. facilitates gas exchange
a. secretes excess water as sweat
The activity of the kidneys is controlled by hormones and by the
a. volume of nutrients.
c. composition of the blood.
b. volume of filtrate.
d. composition of the urine.
c. composition of the blood
True or False:
Feedback inhibition is the process in which a stimulus produces a response that strengthens
the original stimulus.
false, opposes or blocks
Unlike endocrine glands, exocrine glands
a. release secretions outside of the body.
b. release hormones.
c. release secretions directly into the blood.
d. are found throughout the body.
a. release secretions outside of the body
Read the following statements that describe the action of nonsteroid hormones. What is the correct order in which they occur?
1) Secondary messengers activate or inhibit a wide range of cell activities. 2) Enzymes are activated on the inner surface of the cell membrane. 3) Secondary messengers are released to relay the hormone's message within the cell. 4) The hormone binds to receptors on the cell membrane.
a. 4, 2, 3, 1 c. 4, 3, 1, 2
b. 3, 1, 2, 4 d. 3, 4, 2, 1
In Figure 34-1, structure E produces which of the following hormones when you're feeling stress about a big test?
a. calcitonin c. epinephrine
b. thyroxine d. glucagon
Feedback inhibition means that an increase in a substance will lead to a
a. decrease production of that substance.
b. increase production of that substance.
c. increase the production of other substances.
d. stop of the production of another substance.
a. decrease production of that substance
True or False:
The pancreas produces hormones that help to keep your blood glucose levels stable after eating an ice cream sundae.
When you drink a lot of water, the organ that prevents your blood from becoming too dilute by removing excess water from it is the________
Sometimes during pregnancy, the placenta forms over the cervix. Why might this be a serious condition for the mother and fetus?
Sample answer: If the placenta completely covers the cervix, it is blocking the way the baby would exit the uterus.