Chapter 17 (The Endocrine System)

Question 1

How do cells communicate with each other

Answer 1

Gap junctions (ion channels), Neural signaling (short distances between cells), Endocrine signaling (short or long distances), Paracrine signaling (short distances)

Question 2

How do signals from outside of a cell (extracellular) communicate
with the inside of a cell (intracellular) to get the desired response?

Answer 2

Receptors, Enzymes, Second messengers, Ion channels, Transport proteins, Transcription factors

Question 3

Neural Stimuli

Answer 3

Nerve fibers supply some endocrine glands and elicit the release of their hormones

The sympathetic nervous system stimulates the adrenal medulla to secrete epinephrine and norepinephrine in situations of stress

In childbirth, nerve signals originate from stretch receptors in the uterus, travel up the spinal cord and brainstem to the hypothalamus, and stimulate the release of oxytocin

Question 4

Hormonal stimuli

Answer 4

Hormones from the hypothalamus regulate secretion by the anterior pituitary gland

Pituitary hormones stimulate other endocrine glands to release thyroid hormone, sex hormones, and cortisol

Question 5

Humoral stimuli

Answer 5

Refers to blood-borne stimuli

Rising blood glucose concentration stimulates the release of insulin

Low blood osmolarity stimulates the secretion of aldosterone

Low blood calcium level stimulates the secretion of parathyroid hormone

Question 6

Components of Amine Hormone

Answer 6

Amino acids with modified groups (e.g. norepinephrine’s carboxyl group is replaced with a benzine ring)

Question 7

Components of Peptide Hormone

Answer 7

Short chains of linked amino acids (e.g. Oxytocin)

Question 8

Components of Protein Hormone

Answer 8

Long chains of amino acids (e.g. Human Growth Hormone

Question 9

Components of Steroid Hormone

Answer 9

Derived from the lipid cholesterol (e.g. Testosterone, Progesterone

Question 10

Binding of Lipid-Soluble Hormones

Answer 10

Water-soluble hormones bind to a cell membrane receptor, initiating a cell-signaling pathway involving G proteins, adenylyl cyclase, cAMP, and protein kinases, which phosphorylate cytoplasmic proteins to carry hormone-specific changes.

Question 11

What is the Hypothalamus-Pituitary Complex?

Answer 11

The hypothalamus region lies inferior and anterior to the thalamus. It connects to the pituitary gland by the stalk-like infundibulum. The pituitary gland consists of an anterior and posterior lobe, with each lobe secreting different hormones in response to signals from the hypothalamus.

Question 12

Negative Feedback Loop

Answer 12

The release of adrenal glucocorticoids is stimulated by the release of CRH from the hypothalamus and ACTH from the anterior pituitary gland. This signaling is inhibited when glucocorticoid levels become elevated by causing negative signals to the pituitary gland and hypothalamus.

Question 13

What is the source for CRH (Corticotropin-Releasing-Hormone)?

Answer 13

Hypothalamus

Question 14

What is the target for CRH?

Answer 14

Anterior Pituitary

Question 15

What is the source of ACTH (Adrenocorticotropic Hormone)?

Answer 15

Anterior Pituitary

Question 16

What is the target ACTH?

Answer 16

Adrenal Cortex

Question 17

How do the anterior pituitary cells release hormones in response to CRH?

Answer 17

Ligands, receptors, second messengers, enzymes, pumps, ion channels, secretory vesicles

Question 18

Posterior Pituitary

Answer 18

Neurosecretory cells in the hypothalamus release oxytocin (OT) or ADH into the posterior lobe of the pituitary gland. These hormones are stored or released into the blood via the capillary plexus.

Question 19

Anterior Pituitary

Answer 19

The anterior pituitary manufactures seven hormones. The hypothalamus produces separate hormones that stimulate or inhibit hormone production in the anterior pituitary. Hormones from the hypothalamus reach the anterior pituitary vial the hypophyseal portal system.

Question 20

Release of growth hormone

Answer 20

Hypothalamus releases growth hormone-releasing hormone (GHRH)
GHRH stimulates the anterior pituitary to release growth hormone (GH)

Question 21

Glucose-sparing effect

Answer 21

Stimulates adipose cells to break down stored fat, fueling growth effects

Question 22

Growth effects

Answer 22

Increases uptake of amino acids from the blood
Enhances cellular proliferation and reduces apoptosis

Question 23

Targets of Growth effects

Answer 23

Bone cells, Muscle cells, Nervous system cells, Immune system cells

Question 24

Diabetogenic effect

Answer 24

GH stimulates the liver to break down glycogen into glucose, fueling growth effects

Question 25

Inhibition of growth hormone

Answer 25

High IGF-1 levels perceived by the hypothalamus Growth hormone-inhibiting hormone (GHIH) is released to inhibit GH release GHIH inhibits GH release in the anterior pituitary

Question 26

Hormonal Regulation of Growth

Answer 26

Growth hormone (GH) directly accelerates the rate of protein synthesis in skeletal muscle and bones. Insulin-like growth factor 1 (GF-1) is activated by growth hormone and indirectly supports the formulation of new proteins in muscle cells and bone

Question 27

Major Pituitary Hormones

Answer 27

Major pituitary hormones and their target organs

Question 28

Thyroid Gland

Answer 28

The thyroid gland is located in the neck where it wraps around the trachea. (a) Anterior view of the thyroid gland. (b) Posterior view of the thyroid gland. (c) The glandular tissue is composed primarily of thyroid follicles. The larger parafollicular cells often appear within the matrix of follicle cells.

Question 29

Classic Negative Feedback Loop

Answer 29

A classic negative feedback loop controls the regulation of thyroid hormone levels

Question 30

Parathyroid Glands

Answer 30

The small parathyroid glands are embedded in the posterior surface of the thyroid gland.

Question 31

Parathyroid Hormone in Maintaining Blood Calcium Homeostasis

Answer 31

Parathyroid hormone increases blood calcium levels when they drop too low. Conversely, calcitonin, which is released from the thyroid gland, decreases blood calcium levels when they become too high. These two antagonistic mechanisms constantly maintain blood calcium concentrations.

Question 32

Adrenal Glands

Answer 32

Both adrenal glands sit atop the kidneys and are composed of an outer cortex and an inner medulla, all surrounded by a connective tissue capsule. The cortex can be subdivided into additional zones, all of which produce different types of hormones

Question 33

Pancreas

Answer 33

The pancreatic exocrine function involves the acinar cells secreting digestive enzymes that are transported into the small intestine by the pancreatic duct. Its endocrine function involves the secretion of insulin (produced by beta cells) and glucagon (produced by alpha cells) within the pancreatic islets. These two hormones regulate the rate of glucose metabolism in the body. The micrograph reveals pancreatic islets.

Question 34

Homeostatic Regulation of Blood Glucose Levels

Answer 34

Blood glucose concentration is tightly maintained between 70 mg/dL and 110 mg/dL. If blood glucose concentration rises above this range, insulin is released, which stimulates body cells to remove glucose from the blood. If blood glucose concentration drops below this range, glucagon is released, which stimulates body cells to release glucose into the blood.