Section 39.1 (Exam 3/4) Hormones

Question 1

What are endocrines?

Answer 1

chemical signals secreted by epithelial cells directly into the ECF

Question 2

Where do endocrines go after they are secreted into the ECF?

Answer 2

Some diffuse locally and some go into the bloodstream where they circulate across the whole body

Question 3

What are the 3 types of endocrines?

Answer 3

Hormones, Paracrines, and Autocrines

Question 4

Do all endocrine cells exist as glands?

Answer 4

No, some exist as single cells

Question 5

What are the two types of glands in the endocrine system?

Answer 5

Endocrine and exocrine glands

Question 6

What are endocrine glands?

Answer 6

aggregations of endocrine cells that secrete hormones within the body

Question 7

What are exocrine glands?

Answer 7

secrete substances through ducts to the outside of the body

Question 8

What are neurohormones?

Answer 8

A type of hormone that are secreted by neurons and enter the bloodstream circulation

Question 9

What are pheremones?

Answer 9

chemical signals released from the body of an animal to influence the behavior of other animals

Question 10

What are the three classes of hormones?

Answer 10

Peptide/protein hormones, steroid hormones, and amine hormones

Question 11

What are some characteristics of peptide/protein hormones (e.g. insulin)?

Answer 11

Water-soluble, easily transported in blood

Cannot cross the lipid bilayer of the cell membrane, is released from the secretory cell through vesicles (exocytosis)

Question 12

What are some characteristics of steroid hormones (e.g. testosterone)?

Answer 12

Synthesized from cholesterol

Lipid-soluble; can pass through cell membranes

Travels through blood by binding to carrier molecules (not water-soluble, blood is mostly water)

Question 13

What are some characteristics of amine hormones (e.g. epinephrine)?

Answer 13

Mostly synthesized from the amino acid tyrosine

Either water-soluble or lipid-soluble

Question 14

Since they can’t pass through cell membranes, how do water-soluble hormones bind to the target cell?

Answer 14

To a large transmembrane glycoprotein receptor on the target cell with three domains

Question 15

What are the 3 domains of a large transmembrane glycoprotein receptor on a target cell?

Answer 15

• binding domain (extracellular)
• transmembrane domain (within cell membrane)
• cytoplasmic domain that extends into the cytoplasm (intracellular)

Question 16

From the point where a hormone binds to the binding domain on the receptor of a target cell, how does the hormone alter gene expression?

Answer 16

The signal travels from the binding domain to the transmembrane domain to the cytoplasmic domain.

The cytoplasmic domain alerts second messengers which can activate protein kinases or protein phosphatases.

Protein kinases phosphorylate or add a phosphate group to a protein and protein phosphatases dephosphorylate or remove a phosphate group from a protein.

The phosphate groups on these proteins ultimately alter gene expression.

Question 17

How do lipid-soluble hormones alter gene expression?

Answer 17

They diffuse directly through the cell membrane and bind to receptors within the cell.

They can enter the nucleus as well, which allows them to alter gene expression directly

Question 18

One hormone can trigger different responses in different types of cells. What response is a good example of this phenomena?

Answer 18

The fight-or-flight response

Question 19

Which two amine hormones are released during the fight-or-flight response?

Answer 19

epinephrine and norepinephrine

Question 20

What are the 4 places epinephrine and norepinephrine bind to during the fight-o-flight response, and what responses do they cause to each of the 4?

Answer 20

The heart – increasing the heart rate

Blood vessels (on organs not needed for survival) – constricting them and sending blood to heart and then muscles

Liver – break down glycogen and release glucose into the blood as a quick energy supply

Fat cells – stimulates breakdown of fats to fatty acids—another source of energy

Question 21

Individual signaling molecules are highly evolutionarily conserved. What are their functions across different species?

Answer 21

the function of the same signaling molecule can vary across different species

Question 22

What is the function of prolactin in fish, humans, birds, and amphibians?

Answer 22

In fishes – involved in osmoregulation

In humans – mammary gland development and milk production

In birds – nesting activity and incubation

In amphibians – “water drive” that returns terrestrial adults to water to breed