Pancreatic beta cells can sense high levels of circulating glucose and, in response, secrete insulin, which helps move glucose out of circulation. These cells can likewise sense the resulting low circulating glucose levels, and when they do, they reduce their secretion of insulin. This is negative feedback in action; the product of beta cell activity (insulin) ultimately has the effect of reducing beta cell activity. Why does the body constantly utilize negative feedback to maintain the stable state called homeostasis? Why couldn’t it use positive feedback instead?

As defined in the text, hormones (select all that apply):

a. tend to be secreted by glands.

b. affect mostly fat, muscle, and liver cells.

c. have effects only on target cells.

d. are distributed by traveling through the bloodstream.

e. have almost instantaneous effects.

The text makes clear that hormones play critical roles in allowing us to function each day. So why are they commonly thought of as substances that cause us to act in unusual ways?

Endocrine glands secrete their materials:

a. into ducts.

b. into synapses between nerve axons and cell bodies,

c. directly into cells.

d. directly into the bloodstream or surrounding tissues.

e. into the digestive tract.

Steroid hormones are all _____ and generally bind to receptors____.

a. produced in greater amounts by males; on muscle cells

b. built around the framework of the cholesterol molecule; on fat cells

c. composed of chains of amino acids; on a target cell’s outer or plasma membrane

d. built around the framework of the cholesterol molecule; inside target cells

e. muscle-building hormones; on muscle cells

Hormone secretion is generally controlled through the mechanism of _________, which is critical in producing ______, meaning a stable internal state in the body.

a. hierarchical control; homeostasis

b. negative feedback; homeostasis

c. negative feedback; equilibrium

d. positive feedback; endothermy

e. hierarchical control; rest

The hypothalamus (select all that apply):

a. is an endocrine gland.

b. is a part of the brain.

c. is located in the medulla of the adrenal glands.

d. produces hormones released in the posterior pituitary.

e. controls release of adrenaline and noradrenaline.

The anterior pituitary gland releases ____hormones upon receipt of hormonal signals from the____.

a. two; posterior pituitary

b. two; thyroid gland

c. six; hypothalamus;

d. six; adrenal glands

e. two; hypothalamus

Insulin___, while glucagon____. (Select all that apply.)

a. is produced in pancreatic alpha cells; is produced in pancreatic beta cells

b. is produced in pancreatic beta cells; is produced in pancreatic alpha cells

c. helps move glucose into cells; helps move glucose into circulation

d. helps move glucose into circulation; helps move glucose into cells

e. is produced in relatively greater amounts between meals; is produced in relatively greater amounts just after gating

Cortisol (select all that apply):

a. is produced by the anterior pituitary gland.

b. is produced by the adrenal cortex.

c. is active in energy management.

d. is produced by the adrenal medulla.

e. is secreted during times of stress.

Light coming in through the eye is focused on a layer of tissue at the back of the eye called the _______ by means of being bent, or refracted, by both the eye’s _______ and the ________ that lies behind it.