Chapter 45 Reading Quiz
1.
2.
3.
Which type of cells are equipped to
respond to a hormone?
What are the three parts to a
“signal-transduction pathway”?
The endocrine tissues of which
organ regulate blood glucose levels?
1. Describe how and in what ways the
endocrine system and the nervous system are
related.



Nervous system  conveys high speed signals
along neurons
- functions in reacting to sudden environmental
changes
Endocrine system  hormone-secreting cells and
organs
- slower means of communication, function in
development
Related: homeostasis depends on both systems 
2. Describe how hormones convey information
to parts of the body.
Hormone  chemical signal that is
secreted into body fluids and
communicates regulatory messages within
body
 May reach all parts of the body, but only
the target cells will respond (receptors)
 Neurosecretory cells  specialized nerve
cells in endocrine organs and tissues that
secrete the hormones 

3. Describe what local regulators do.
They are chemical messengers that affect
target cells adjacent to or near their point
of secretion
 Example: neurotransmitters carry
information from one neuron to another or
to a muscle or gland 

4. Discuss growth factors and prostaglandins
and what their functions are.


Growth factors  peptides and proteins that
function as local regulators
- must be present for many cells to grow, divide,
and develop normally
Prostaglandins  (PG’s) modified fatty acids;
released from most types of cells into the
interstitial fluid
- function in female reproductive system (help
induce labor), induces fever and inflammation 
5. What do chemical signals do to target
tissues? How does it bind to the target?
Chemical signals are received by the target
tissues and bind to receptors
 Result depends on what the signal is and
the receiving tissue
 One chemical signal can affect different
target cells within an animal differently
 Most bind to plasma-membrane proteins,
initiating the reaction 

6. Discuss briefly how cells communicate.

Chemical signals secreted by a sending
cell either:
1. Bind to receptor proteins on the
surface of a target cell
2. Penetrate the target cell’s plasma
membrane and bind with a receptor
protein in the cytoplasm 
7. Outline the signal-transduction pathways.
When the messengers aren’t able to get
through plasma membrane
 The receptors of these signals are
components of the pathway
 The pathways convert the extracellular
chemical signal to a specific intracellular
response, changing the behavior of the
target cells 

8. How does a steroid hormone bind?

1.
2.
3.
4.
5.
6.
The lipid-soluble steroid hormone 
Passes through the plasma membrane and
Binds to a receptor protein present only in
target cells. The hormone-receptor complex
then:
Enters the nucleus and
Binds to a specific regulatory site, stimulating
The transcription of a specific gene into mRNA,
which is then
Translated into a specific protein 
9. List the nine endocrine glands found in
humans.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid gland
Pancreas
Adrenal glands
Gonads (testes & ovaries)
Pineal gland
Thymus 
(page 961)
10. What are “tropic” hormones?
Tropic hormones act on other endocrine
glands
 Target other endocrine glands (rather than
tissues or muscle)
 These are particularly important to
understanding chemical coordination 

11. Overview briefly how the hypothalamus
and pituitary integrate the functions of the
endocrine system.
The pituitary gland (endocrine) receives its
orders from the hypothalamus (part of
lower brain)
 The hypothalamus receives information
from nerves and initiates the appropriate
endocrine signals
 The pituitary is regulated by the
hypothalamus; it used to be called the
“master gland” 

12. How is the pineal gland involved in
biorhythms?





The pineal gland releases the hormone
melatonin (a modified amino acid) which is
regulated by light and dark cycles
Located near the center of our brain
Usual functions are related to reproduction
Amount secreted depends on night length
Target may be the “suprachiasmatic
nucleus” (SCN), or the biological clock 
13. Overview how the thyroid hormones
function in development, bioenergetics, and
homeostasis.
The thyroid stimulates and maintains
metabolic processes, helps lower blood
calcium level, and plays a role in
development and maturation (bone & nerve
cells)
 Consists of two lobes located on ventral
side of trachea
 Secretes triiodothyronine and thyroxine,
controlled by the hypothalamus and
pituitary 

14. Describe how parathyroid hormone and
calcitonin balance blood calcium levels.



Parathyroid hormone (PTH) raises the blood
calcium level
- increases calcium uptake in kidneys & intestines;
stimulates release from bones
Calcitonin (thyroid) lowers the blood calcium level
- reduces uptake in kidneys & intestines;
stimulates deposition in bones
These are antagonistic hormones that form a
negative feedback system (thermostat) 
15. Overview the pancreas’ hormones, where each is
secreted from, and the way this system works to
govern blood glucose levels. Discuss both types of
diabetes.
Both secreted from the islets of Langerhans
(clusters of endocrine cells)
 Insulin (lowers blood glucose level)
- from beta cells
 Glucagon (raises blood glucose level)
- from alpha cells
 Type I (insulin dependent)  autoimmune disorder
against pancreas cells (childhood)
 Type II (non insulin dependent)  deficiency or
reduced responsiveness, adulthood, hereditary 

16. Outline how the adrenal medulla and the
adrenal cortex help the body manage stress,
and the hormones associated.
Adrenal medulla  epinephrine &
norepinephrine; raises blood glucose level,
increases metabolic activities, constricts
certain blood vessels
 Adrenal cortex  glucocorticoids (raise
blood glucose level); mineralcorticoids
(promotes reabsorption of Na+ and
excretion of K+ in kidneys)


Stress response
Long term response
Short term response


1.
2.
3.
4.
5.
Medulla response
Epinephrine &
norepinephrine
Increased blood glucose
Increased blood pressure
Increased breathing rate
Increased metabolic rate
Increased alertness &
decreased kidney and
digestive activity

1.
2.

1.
2.
Mineralcorticoids
Retention of Na+ and
water by kidneys
Increased blood volume
and pressure
Glucocorticoids
Proteins & fats broken
down and converted to
glucose for blood
Immune system may be
suppressed 
17. Briefly list the gonadal steroids, and how
they regulate growth, development,
reproductive cycles, and sexual behavior.
1.
2.
3.
Androgens  support sperm formation,
promote development & maintenance of
male secondary sex characteristics
Estrogens  stimulate uterine lining
growth, promote development &
maintenance of female sex
characteristics
Progesterone  promotes uterine lining
growth 
more discussion Ch 46