Unit 3: Chapter 40

Question 1

Endocrine System

Answer 1

Used chemical substances called hormones as a means of regulating and interpreting body functions.

participates in many essential body functions, including the regulation of digestion, the usage and storage of nutrients, growth and development, electrolyte and water metabolism, and reproductive functions.

Question 2

Structural Classification

Answer 2

Hormones have diverse structures, ranging from single amino acids to complex proteins and lipids. Hormones may be classified into four categories based on their chemical structure:
1. Amines and amino acids: from single amino acid
2. Peptides proteins and glycoproteins: majority, can be 3 to 200 amino acids
3. Steroids: derivatives of cholesterol
4. Fatty acids: arachidonic acid derivative, includes prostaglandins

Question 3

Role of Hormones

Answer 3

Chemical messengers that are transported in body fluids. They are highly specialized organic molecules produced by endocrine cells that exert their action on specific target cells.
Function as modulators of cellular and systemic responses.
Hormones are released from various organs that are “endocrine glands,” including the pituitary gland, thyroid gland, adrenal glands, and pancreas.
Many other organs and tissues throughout the body also actively secrete hormonal substances that regulate activities in other areas of the body.

Question 4

Synthesis and Release Hormones

Answer 4

synthesized and stored in vesicles in the cytoplasm of the endocrine cell until secretion is required. These vesicle-mediated hormones are released from the originating endocrine cell in response to some type of stimuli, which is often a negative feedback mechanism. Stimulation of the endocrine cell causes the vesicles to move to the cell membrane and release.

Question 5

Protein Hormones

Answer 5

Typically synthesized in the form of a precursor hormone that contains additional peptide units that ensure proper folding of the molecule and insertion of essential linkages.
This type of precursor hormone molecule is called a prohormone.

Question 6

Cholesterol-Based Hormones

Answer 6

are not stored in vesicles; instead, these lipid-soluble molecules, which are often produced in smooth endoplasmic reticulum, typically leave the cell as soon as they are synthesized by diffusing across the cell membrane.

Question 7

Transport

Answer 7

When hormones are released into the bloodstream, they circulate either as free, unbound molecules or as homes attached to transport carriers.

Question 8

Peptide and Protein Hormone Transport

Answer 8

are water-soluble molecules and usually do not require a transport carrier.

Question 9

Steroid and Thyroid Hormone Transport

Answer 9

are lipophilic molecules and, therefore, do require a carrier protein for transport through the blood.
Liver synthesizes specific carriers proteins for steroid and thyroid hormones.

Question 10

Half Life of a Hormones

Answer 10

the time it takes for the body to reduce the concentration of the hormone in the blood by one body to reduce the concentration of the hormones in the blood by one half is positively correlated with this % of protein binding.

Question 11

Receptors

Answer 11

complex molecular structures (usually proteins) that are located either on the cell surface or inside target cells.
The function of these receptors is to recognize a specific hormone and translate the hormonal signal into a cellular response.
The structure of these receptors is specific to a particular hormone, which allows target cells to respond to one hormone and not to others.

Question 12

Upregualtion

Answer 12

Decreased hormone levels often produce an increase in receptor numbers.
Increasing the sensitivity of the body to the hormone.
May be an adaptive response when there are low levels of hormone in the body.

Question 13

Second Messenger Interactions

Answer 13

Second Messenger Interactions
Glucagon
Insulin
Epinephrine
PTH
TSH
ACTH
FSH
LH
ADH
Secretin

Question 14

Hypothalamic-Pituitary Regulation

Answer 14

form a functional unit that exerts control over the activities of several endocrine glands and thus a wide range of physiologic functions.

Hormones of the thyroid, adrenal cortex, and the gonads are regulated by more complex loops involving the hypothalamus and anterior pituitary gland.

Question 15

Hypothalamus

Answer 15

located centrally, serves as coordinating center of the brains for endocrine, behavioral, and autonomic nerves system function.
Emotion, pain, body temp and other neural inputs are communicated to the endocrine system

Question 16

Pituitary Gland

Answer 16

connected to the floor of the hypothalamus by the pituitary stalk, with the main structural portion of the pituitary gland encased in a bony structure called the sella turcica.
The opening to the sella turcica is bridged over by the diaphragma sellae, which protects the pituitary gland from the transmission of the pressures from the cerebrospinal fluid.6 The pituitary gland is also called the “hypophysis.

Question 17

Feedback Regulation

Answer 17

In the endocrine system, sensors detect a change in the hormone level and adjust hormone secretion so that body levels are maintained within an appropriate range.
When the sensors detect a decrease in hormone levels, they initiate changes that cause an increase in hormone production.
When hormone levels rise above the set point of the system, the sensors cause the production and release of hormones decrease.

Question 18

Positive Feedback Regulation

Answer 18

positive feedback control, rising levels of a hormone cause another gland to release a hormone that is stimulating to the first.
An example is increased estradiol production during the follicular stage of the menstrual cycle causes increased gonadotropin (FSH) production by the anterior pituitary gland.
This stimulates further increases in estradiol levels until the demise of the follicle, which is the source of estradiol, results in a fall in gonadotropin levels.

Question 19

Adrenal Gland Function

Answer 19

Secretes 3 types of hormones:
Glucocorticoids, mineralocorticods and adrenal androgens.

Question 20

Imaging Non isotopic

Answer 20

includes magnetic resonance imaging (MRI) and computed tomography (CT) scanning, both of which provide important information about structural changes within solid tissue. An advantage of MRI is that it does not require the use of ionizing radiation (which is required for CT scanning).

Question 21

Imaging Isotopic

Answer 21

includes nuclear medicine imaging studies performed after administering a radioisotope, which is selectively taken up by the tissue being investigated.
Positron emission tomography (PET) scanning is another isotopic method, which is being used more widely in evaluating selected endocrine disorders, such as detecting the presence of metastatic thyroid cancers