Download Chapter 45.

Endocrine System
Hormones
2007-2008
Regulation
 Why are hormones needed?
chemical messages from one
body part to another
 communication needed to
coordinate whole body
 daily homeostasis & regulation of
large scale changes

 solute levels in blood
 glucose, Ca++, salts, etc.
 metabolism
 growth
 development
 maturation
 reproduction
growth hormones
Regulation & Communication
 Animals rely on 2 systems for regulation

endocrine system
 system of ductless glands
 secrete chemical signals directly into blood
 chemical travels to target tissue
 target cells have receptor proteins
 slow, long-lasting response

nervous system
 system of neurons
 transmits “electrical” signal &
release neurotransmitters to
target tissue
 fast, short-lasting response
Regulation by chemical messengers
 Neurotransmitters released by neurons
 Hormones release by endocrine glands
endocrine gland
neurotransmitter
axon
hormone
carried by blood
receptor proteins
receptor proteins
target cell
Lock & Key
system
Classes of Hormones
 Protein-based hormones

polypeptides
 small proteins: insulin, ADH

insulin
glycoproteins
 large proteins + carbohydrate: FSH, LH

amines
 modified amino acids: epinephrine, melatonin
 Lipid-based hormones

steroids
 modified cholesterol: sex hormones, aldosterone
Action of lipid (steroid) hormones
steroid hormone
TARGET CELL
S
S
cytoplasm
1
BLOOD
S
protein
carrier
cross cell membrane
2
binds to receptor protein
becomes
transcription factor
5
S
3
mRNA read by ribosome
plasma membrane
4
DNA
mRNA
nucleus
6
protein
7
protein secreted
ex: secreted protein = growth factor (hair, bone, muscle, gametes)
Maintaining homeostasis
hormone 1
lowers
body condition
gland
high
specific body condition
low
raises
body condition
gland
hormone 2
Negative Feedback
Model
Nervous System Control
Feedback
Controlling Body Temperature
nerve signals
hypothalamus
dilates surface
blood vessels
sweat
high
body temperature
(37°C)
low
hypothalamus
constricts surface shiver
blood vessels
nerve signals
Endocrine System Control
Feedback
Regulation of Blood Sugar
islets of Langerhans
insulin
beta islet cells
liver stores
glycogen
body
cells take
up sugar
from blood
pancreas
liver
high
blood sugar level
(90mg/100ml)
low
triggers
hunger
liver
releases
glucose
liver
pancreas
glucagon
islets of Langerhans
alpha islet cells
reduces
appetite
Nervous & Endocrine systems linked
 Hypothalamus = “master nerve control center”



nervous system
receives information from nerves around body about
internal conditions
releasing hormones: regulates release of hormones
from pituitary
 Pituitary gland = “master gland”


endocrine system
secretes broad range
of “tropic” hormones
regulating other
glands in body
hypothalamus
posterior
pituitary
anterior
tropic hormones = target endocrine glands
hypothalamus
thyroid-stimulating
hormone
(TSH)
Thyroid gland
Adrenal
cortex
posterior antidiuretic
pituitary hormone
(ADH)
anterior
pituitary
gonadotropic
hormones:
folliclestimulating
hormone (FSH)
& luteinizing
hormone (LH)
Kidney
tubules
Muscles
of uterus
Melanocyte
in amphibian
Bone
and muscle
Testes
Ovaries
Mammary
glands
in mammals
Regulating metabolism
 Hypothalamus

TRH = TSH-releasing hormone
 Anterior Pituitary

TSH = thyroid stimulating hormone
 Thyroid


produces thyroxine hormones
metabolism & development







bone growth
mental development
metabolic use of energy
blood pressure & heart rate
muscle tone
digestion
reproduction
tyrosine
+
iodine
thyroxines
Goiter
Iodine deficiency causes thyroid to enlarge as it
tries to produce thyroxine
+
tyrosine
+
iodine
✗
✗
thyroxines
Effects of stress on a body
Stress
Nerve
Spinal cord
signals
(cross section)
Hypothalamus
Releasing
hormone
Nerve
cell
Anterior pituitary
Blood vessel
adrenal medulla
secretes epinephrine
& norepinephrine
Nerve cell
ACTH
Adrenal
gland
Adrenal cortex
secretes
mineralocorticoids
& glucocorticoids
Kidney
(A) SHORT-TERM STRESS RESPONSE
Effects of epinephrine and norepinephrine:
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood flow patterns, leading
to increased alertness & decreased
digestive & kidney activity
(B) LONG-TERM STRESS RESPONSE
Effects of
mineralocorticoids:
Effects of
glucocorticoids:
1. Retention of
sodium ions &
water by kidneys
1. Proteins & fats broken
down & converted to
glucose, leading to
increased blood
glucose
2. Increased blood
volume & blood
pressure
2. Immune system
suppressed
Any Questions??
Robert Wadlow
1918-1940
8' 11"
2009-2010
Practice Questions on Anatomy
1. Which of the following gland or set of
glands lies in closest proximity to the
pineal gland?
A. adrenals
B. pituitary
C. thymus
D. parathyroid
2. The gland that lies deep in the thoracic
cavity, just above the heart is the
A. Thyroid
B. Hypothalamus
C. Thymus
D. Pineal
3. The “master control center” that
directs the activities of the endocrine
system is the:
A. hypothalamus
B. pineal
C. thymus
D. thyroid
4. Which of the following glands is NOT
in the cranium?
A. Hypothalamus
B. Pineal
C. Thymus
D. Pituitary
5. What is TRUE of Lidid-based hormones?
A. An example is FSH (follicle stimulating
hormone)
B. They are made of modified cholesterol
C. They have a carbohydrate “ID tag”
D. One group of them are made of polypeptides
6. Which of the following is a hormone
that stimulates milk production?
A. Cortisol
B. Follicle stimulating hormone (FSH)
C. Growth hormone
D. Prolactin