Download The Endocrine System - bananateachersworld

Structure
and Function
of Endocrine
System
1
Identify and describe the structure and function of important
biochemical compounds, including protein and steroid
hormones (314-3)
Analyze homeostatic phenomena to identify the feedback
mechanisms involved (317-2)
•Name the parts of the endocrine system and discuss the function of each part
•Discriminate the functions of each endocrine hormone secreted by same endocrine
glands
•Analyze the action of each hormone and demonstrate its contribution in maintaining
homeostasis
•Classify hormones according to its molecular structure and actions
2
The Endocrine System
•Regulates many bodily functions
•Maintains homeostasis by regulating the production of chemicals that
affect most functions of the body
•Secretes substances that aid the nervous system
•Important regulator of growth and development
•Endocrine glands are ductless glands, unlike exocrine glands that
secrete substances into ducts.
3
Feedback
Maintaining homeostasis
hormone 1
gland
lowers
body condition
high
specific body condition
low
raises
body condition
gland
hormone 2
Negative Feedback

Response to changed body condition
◦ if body is high or low from normal level
 signal tells body to make changes that will bring body
back to normal level
◦ once body is back
to normal level,
signal is
turned off
hormone 1
gland
lowers
body condition
high
specific body condition
Regulation

How we maintain homeostasis
◦ nervous system
 nerve signals control body functions
◦ endocrine system
 hormones
 chemical signals control body functions
Hormones

Why are hormones needed?
◦ chemical messages from one body part to cells
in other parts of body
◦ communication needed
to coordinate whole body
◦ maintaining homeostasis
growth hormones
Endocrine System
 Endocrine
system releases hormones
◦ glands which secrete (release)
chemical signals into blood
 chemicals cause changes
in other parts of body
 growth hormones
 sex hormones
 response hormones
 metabolism hormones
 and more….
Responding to hormones

Lock and key system
◦ hormone fits receptor on “target” cell
target
cell
secreting
cell
can’t
read
signal
nontarget
cells
can’t
read
signal
II. Endocrine System vs Neuronal System
1. Neural & Hormonal communication
a. Similarities
i. Chemicals are stored and released
ii. Release of chemicals is due to stimulation
iii. Many different hormones &
neurotransmitters
iv. Both systems react w/specific receptors
v. Second messenger involved in both
(The first messenger reacts to the
initial signal - like an ionotropic
receptor, found in CNS only)
2. Second messenger reacts to a signal
from a first messenger (like a
metabotropic receptor) and affects
intracellular functioning; it is a
complex intracellular response that
affects functioning.
b. Differences
i. In nervous system, neurons communicate with
adjacent neurons; in hormones messages are sent
long distances
ii. Neural messages induce rapid response
compared to hormones which have slower
messages
iii. Neural messages follow the all or none principle;
hormonal messages are graded in strength
iv. Neural messages can be directed as observed in
behavior; hormonal messages are primarily
involuntary (cannot be directed)
2. Three types of hormones
a. Protein hormones – effect is on
receptors within the membrane, binds to the
receptors on the outside of membrane; its
effects are the most rapid of all the hormones
i. Oxytocin – involved in development of
relationships
ii. Adrenocorticotrophin – protein hormone;
chains of amino acids
b. Amine hormones – same relatively fast
receptor response as protein hormones
i. Epinepherine
ii. Norepinepherine
iii. Thyroid hormones
iv. Melatonin
c. Steroid hormones – binds to the
intercellular receptors; slow actions
i. Gonadal hormones
1. Estrogen, progesterone, androgens
ii. Adrenal hormones
1. Glucocorticoids, mineralocorticoids
Major Glands of the Endocrine
System
Hypothalamus
 Pituitary
 Thyroid
 Adrenal
 Gonads: Ovaries
& Testes

The Endocrine System
Consists of:
glands
secrete
into
hormones
bloodstream
to
target tissues
21
hypo
hyper
Homeostasis exists when there is a balance of
substances. Endocrine conditions are due to either
hypo (too little) or hyper (too much) secretions of
substances (hormones).
22
Hypothalamus
•Part of the nervous system. Also serves as an
endocrine gland because it releases hormones that
regulate pituitary hormones
•Hormones released have either a releasing or an
inhibiting factor
23
Pineal Gland
•Located superior and posterior to the pituitary
gland
•Releases melatonin, a hormone
affect sleep and gonad functioning
believed
to
25
Pituitary

Anterior Pituitary
- derived during embryological
development from the roof of the mouth
- connected to the hypothalamus by a
portal system (hypothalamic-pituitary
portal system)
- most of the hormones are released
from the anterior pituitary
Posterior Pituitary
- derived from nervous tissue
- two protein hormones released: oxytocin &
vasopressin
_________________________________
Two Important Points:
Hormones released from the posterior pituitary
are synthesized in the hypothalamus.

Hormones released from the anterior pituitary are
dormant unless directed to be released by the
hypothalamus via Releasing Factors.
Pituitary & all Hormones are Under the Control
of the Hypothalamus
Hypothalamus
RF
Anterior
Pituitary
Hormone
Posterior
Pituitary
Hormone
SH
Target
Organs
RF = Releasing Factor
Hormone
Target
Organs
SH = Stimulating
Hypothalamic Hormones:
Corticotropin
Gondotropin RF RF (CRF)
Thyrotropin Growth Hor
RF
RF
Prolactin
RF
Pituitary Hormones:
Thyrotropin SH
Adrenocorticoptropin
Luteinizing Hor. Hormone (ACTH)
Follicle SH &
Growth Hormone Prolactin
Target Gland or Structure:
Adrenal Gland
Ovaries & Testes
(cortisol)
(androgens, estrogen)
Cells of body
Thyroid Gland
(thyroxine)
Bones,
breasts &
cells of body
Adrenal Gland
i. Adrenal cortex (outer) produces about 50
different chemicals including…
1. Mineralocorticoids (outer layer)
2. Glucocorticoids, cortisol (middle layer)
3. Sex hormones (inner most layer)
a. Estrogen, progesterone androgens
note: Congenital adrenal hyperplasia – too much testosterone
produced by mother. This comes from dysfunction in adrenal gland.
ii. Adrenal medulla (inner)
1. Dopamine  Norepinepherine/Epinepherine
Thyroid Gland
1. Too little thyroxin – hypothyroidism
a. Depression (clinical or subclinical),
attention & memory problems
2. Too much thyroxin – hyperthyroidism
a. Agitation, irritability, & weight loss
*Goiters – Growths on thyroid gland
Gonads & Hormones
LH &
FSH
Growth Hormone
Cells of body in response to growth hormone
i. During childhood GH is at maximum
1. Too little and we have a small person
2. Too much and we have gigantism,
often accompanied by acromegaly
(continued growth of extremities of
bones)
a. Makes hands, feet, jaw, nose, and
eye sockets (orbits) enlarged
Oxytocin
The hormone involved in inducing labor
during childbirth
 Hormone involved in bonding
 Hormone involved in relationships
 Might be deficient in Autism

All hormones utilize feedback loops:
Autocrine response – Same as the
autoreceptors, both communicate and
terminate release
Note similarity to the CNS:
Autoreceptors – in the CNS the receptors
on presynaptic cell that are sensitive to its
own NT
Parathyroid Gland
Thymus Gland
•Four oval shaped
glands located on the
dorsal side of the
thyroid
•Regulates calcium
and phosphate levels
•Also part of the
immune system
•The hormones
secreted stimulate the
production of T and B
cells
Adrenal Glands
•A pair of glands, each one situated on top of a
kidney
•Each gland has an outer portion (adrenal cortex)
and inner portion (adrenal medulla)
•Regulates electrolytes
•Adrenal medulla secretes catecholamines
(epinephrine and norepinephrine) in response to
stress
43
Pancreas
•Helps maintain proper blood
glucose levels
•Is both an endocrine and exocrine
gland. The islets of Langerhans
serve its endocrine functions
•Two types of cells, alpha and
beta are produced by the islets of
Langerhans
Elevated
Blood sugar
Insulin is released
by the beta cells
which stimulate the
glucose to be sent to
the body’s cells and
convert unused
glucose to glycogen
Blood sugar
Low
Glucagon is
released by the
alpha cells which
stimulate stored
glycogen to be
transformed into
glucose again
46
Insulin and Glucagon Insulin
Rise in blood glucose
stimulates insulin secretion
Promotes movement
of glucose into certain cells
Stimulates formation
of glycogen from glucose
In response to insulin, blood
glucose drops toward normal
(and inhibits insulin secretion)
Artery
In response to glucagon,
blood glucose rises
toward normal (and
inhibits insulin secretion)
Pancreas
Drop in blood glucose
stimulates glucagon
secretion
Glucagon
Stimulates cells to break down
glycogen into glucose
Stimulates cells to convert
non-carbohydrates into glucose
47
Ultimately,what controls the
endocrine system?






Our emotions
Our perceptions
Our cognitions
Our experiences
Our behavior
Our response to
the environment
Higher Brain
Areas
Hypothalamus
Pituitary
Endocrine
Glands
Ovaries
•Located in the female
pelvic region one
attached to the top of
each fallopian tube
•Produce the female
hormones:
-estrogen
-progesterone
Testes
•Located in the scrotum,
a sac outside the body
•Produce spermatozoa
which fertilizes the
female ova
•Produce male sex
hormones:
-testosterone
50
Combining Form
Meaning
aden(o)
gland
adren(o)
adrenal glands
gluc(o)
glucose
glyc(o)
glycogen
gonad(o)
sex glands
pancreat(o)
pancreas
parathyroid(o)
parathyroid
thyr(o)
thyroid gland
51
Abbreviation
Meaning
ACTH
adrenocorticotropic hormone
ADH
antidiuretic hormone
CRH
corticotropin-releasing hormone
DM
diabetes mellitus
FSH
follicle-stimulating hormone
GH
growth hormone
GTT
glucose tolerance test
HCG
human chorionic gonadotropin
52
Abbreviation
Meaning
IDDM
insulin-dependent diabetes mellitus
LH
luteinizing hormone
MSH
melanocyte-stimulating hormone
NIDDM
noninsulin dependent diabetes
mellitus
PRL
prolactin
PTH
parathyroid hormone, parathormone
STH
somatotropin hormone
TSH
thyroid-stimulating hormone
53