12. Eutherian mammals
▫ Also known as the Placental
Mammals.
• The developing embryo is retained
within the mother’s body in the
uterus for the major part of its
development.
Direct Development
14. What are endocrine
hormones?
1 2 3
33% 33%
33%
1. Chemical signals
from one cell to
remote target cells.
2. Chemicals for direct
cell-to-cell
communication.
3. Chemicals that cross
a gap between to
adjacent cells.
15. Messenger Molecules
• Cells must communicate with one
another to coordinate cell processes
within tissues and to maintain
homeostasis.
• Cell-to-cell communication is carried out
via messenger molecules.
17. Four methods of cell-to-cell communication are
found in the human body, ranging from direct to
remote communication.
18. A muscle cell needs to tell a neighboring
muscle cell to contract. This will be
accomplished by ___ communication:
1 2 3 4
25% 25%
25%
25%
1. Direct.
2. Synaptic.
3. Paracrine.
4. Endocrine.
19. When blood sugar is high, body cells must be
stimulated to take up sugar. This is
accomplished by ___ communication.
1 2 3 4
25% 25%
25%
25%
1. Direct.
2. Synaptic.
3. Paracrine.
4. Endocrine.
21. Endocrine hormones
• Produced by endocrine (“ductless”) glands and
secreted into the bloodstream.
• Endocrine hormones may affect a wide array of
target cells to produce multiple effects.
• Two types: peptides (small proteins) and
steroids (lipids).
23. Peptide Hormones
• Peptide hormones do not enter the cell
directly. These hormones bind to
receptor proteins in the cell membrane.
• When the hormone binds with the
receptor protein, a secondary messenger
molecule initiates the cell response.
• Because peptide hormones are water
soluble, they often produce fast
responses.
24. (cytoplasm)
(nucleus)
peptide or amino
acid-derived
hormone
(first messenger)
(extracellular
fluid)
cyclic AMP-
synthesizing
enzyme
cyclic AMP
ATP
inactive
enzyme
(second messenger)
active
enzyme
reactant
product
plasma membrane
nuclear
envelope
receptor
The hormone binds to
a receptor on the plasma
membrane of a target cell
1
The activated enzymes
catalyze specific reactions
4
The second
messenger activates
other enzymes
3
Hormone–receptor binding
activates an enzyme that catalyzes
the synthesis of a second messenger,
such as cyclic AMP
2
25. Steroid Hormones
• Steroid hormones enter through the cell
membrane and bind to receptors inside
of the target cell.
• These hormones may directly stimulate
transcription of genes to make certain
proteins.
• Because steroids work by triggering
gene activity, the response is slower than
peptide hormones.
26. gene
plasma
membrane
ribosome
hormone receptor
steroid hormone
mRNA
(nucleus)
RNA polymerase
DNA
(cytoplasm)
new protein
(extracellular
fluid)
A steroid hormone
diffuses through the
plasma membrane
The hormone binds to a
receptor in the nucleus or to
a receptor in the cytoplasm
that carries it into the nucleus
The hormone–receptor
complex binds to DNA and
causes RNA polymerase to
bind to a nearby promoter
site for a specific gene
RNA polymerase catalyzes
the transcription of DNA into
messenger RNA (mRNA)
The mRNA leaves the
nucleus, then attaches to a
ribosome and directs the
synthesis of a specific protein
product
1
2
3
4
5
nuclear
envelope
27. If receptors for a hormone were blocked,
the effect would be the same as if:
1 2 3 4
25% 25%
25%
25%
1. More hormone was
added.
2. No hormone had
been released.
3. More receptors had
been added.
4. The receptors had
not been blocked.
28. Your doctor injects a hormone as a treatment for a
condition, and says it won’t take effect for at least 24
hours. What kind of hormone was used?
1 2 3
33% 33%
33%
1. Peptide
2. Steroid
3. Amino acid derived
29. • How do endocrine hormones “know”
which cells are their target cells?
W
O
R
K
T
O
G
E
T
H
E
R
30. Role of the Hypothalamus
• The thalamus receives sensory
information, relays some to the
hypothalamus.
• Hypothalamus monitors the body for
temperature, pH, other conditions.
• Hypothalamus signals pituitary gland if
conditions need to be corrected.
31. Role of the Hypothalamus
• The hypothalamus is also responsible for
our feelings.
So it is wrong to say “ I Love You with all of
my heart, but I Love You with all of my
hypothalamus…
32. Role of the Pituitary
• The pituitary is the “master gland” that signals other
glands to produce their hormones when needed.
• The anterior lobe of the pituitary receives signals from
the hypothalamus, and responds by sending out the
appropriate hormone to other endocrine glands.
• The posterior pituitary receives oxytocin or antidiuretic
hormone (ADH) from the hypothalamus, relays them to
the body as necessary.
33. hypothalamus
pituitary
(anterior lobe)
capillary
bed
endocrine
cell
blood flow
blood
flow
capillary
bed
pituitary
(posterior lobe)
Oxytocin and ADH
(blue triangles) are
secreted into the blood
via capillaries in the
posterior pituitary
Endocrine cells of the
anterior pituitary secrete
hormones (red squares)
in response to releasing
hormones; the pituitary
hormones enter the
bloodstream
Neurosecretory cells of
the hypothalamus produce
oxytocin and ADH
Releasing or inhibiting hormones
(green circles) are secreted into
capillaries feeding the anterior lobe
of the pituitary
Neurosecretory cells
of the hypothalamus
produce releasing and
inhibiting hormones
1
2
1
2
3
34. Pituitary Hormones
Pituitary Hormone Functions
Follicle-stimulating
hormone
Stimulates egg maturation in the ovary and release of sex
hormones.
Lutenizing hormone Stimulates maturation of egg and of the corpus luteum
surrounding the egg, which affects female sex hormones and the
menstrual cycle.
Thyroid-stimulating
hormone
Stimulates the thyroid to release thyroxine.
Adrenocorticotropic
hormone
Causes the adrenal gland to release cortisol.
Melanocyte-stimulating
hormone
Stimulates synthesis of skin pigments.
Growth hormone Stimulates growth during infancy and puberty.
Antidiuretic hormone Signals the kidney to conserve more water.
Oxytocin Affects childbirth, lactation, and some behaviors.
35. Endocrine Hormones
Gland Hormones Functions
Thyroid Thyroxine Regulates metabolism
Calcitonin Inhibits release of calcium from the bones
Parathyroids Parathyroid hormone Stimulates the release of calcium from the bones.
Islet cells (in
the pancreas)
Insulin Decreases blood sugar by promoting uptake of glucose by cells.
Glucagon Increases blood sugar by stimulating breakdown of glycogen in the liver.
Testes Testosterone Regulates sperm cell production and secondary sex characteristics.
Ovaries Estrogen Stimulates egg maturation, controls secondary sex characteristics.
Progesterone Prepares the uterus to receive a fertilized egg.
Adrenal cortex Epinephrine Stimulates “fight or flight” response.
Adrenal
medulla
Glucocorticoids Part of stress response, increase blood glucose levels and decrease
immune response.
Aldosterone Regulates sodium content in the blood.
Testosterone (in both
sexes)
Adult body form (greater muscle mass), libido.
Pineal gland Melatonin Sleep cycles, reproductive cycles in many mammals.
36. Homeostasis and Hormones
Examples:
• Thyroid and temperature control
• The thyroid produces thyroxine, which
increases metabolism. Thyroid-
stimulating hormone is released by the
pituitary.
• Thyroid, Parathyroid, and calcium
• Pancreas and glucose control
38. • Calcitonin from the thyroid inhibits calcium release
from the bones.
• Parathyroid hormone stimulates release of calcium
from the bones.
• Insulin from the pancreas lowers blood glucose by
stimulating body cells to take up glucose.
• Glucagon from the pancreas increases blood sugar
by stimulating the liver to break down glycogen into
glucose.
41. Other hormone roles
• Controlling sleep cycles (melatonin)
• Controlling reproductive cycles
(melatonin, sex hormones)
• Growth (growth hormone)
• Responding to stress or emergencies
(epinephrine and other hormones)
42. Hormones Everywhere!
• Many other organs besides the
endocrine glands produce hormones.
• Kidneys produce several hormones that
regulate blood pressure, which is
essential for kidney function.
• The digestive system produces several
hormones that regulate appetite.
43. Low body fat stimulates leptin production, which
stimulates appetite. The mouse is obese because its
low leptin levels give it an enormous appetite. Leptin
injections return the mouse’s weight to normal.
Humans sometimes have a leptin issue, too, but the
problem is a bad leptin receptor on body cells. Alas,
leptin injections won’t cure that.
The obese mouse
on the left does
not produce
enough leptin, a
hormone
produced by fat
cells.
44. Hormones Everywhere!
• Testosterone and estrogen drive lust;
dopamine, norepinephrine, and serotonin
create attraction; and oxytocin and
vasopressin mediate attachment.
• The hypothalamus of the brain plays a
big role in this, stimulating the production
of the sex
hormones testosterone and estrogen
from the testes and ovaries
45. Hormones Everywhere!
• High levels of dopamine and a related
hormone, norepinephrine, are released
during attraction. These chemicals make us
giddy, energetic, and euphoric, even leading to
decreased appetite and insomnia – which
means you actually can be so “in love” that you
can’t eat and can’t sleep. In fact,
norepinephrine, also known as noradrenalin,
may sound familiar because it plays a large
role in the fight or flight response, which kicks
into high gear when we’re stressed and keeps
us alert.
46. Hormones Everywhere!
• Attraction seems to lead to a reduction
in serotonin, a hormone that’s known to
be involved in appetite and mood.
• Oxytocin is often nicknamed “cuddle
hormone” for this reason. Like dopamine,
oxytocin is produced by the
hypothalamus and released in large
quantities during intercourse,
breastfeeding, and childbirth.
Editor's Notes
The nature of development is related to the reproductive strategy of a particular species.
Direct and indirect development are terms that describe different processes of animal development.
Because they’re so different from their parents, larvae rarely eat the same foods; indeed, the larvae of a given species may live in entirely different habitats than do the adults.
It’s widely believed that the dissimilarity of the larvae and the adults helps prevent them from competing for the same resources, and so allows for larger population sizes.
This is advantageous because the larger is the size of a population, the less vulnerable it is to extinction.
1. Eventually, the animal undergoes a process of metamorphosis in which its body form changes from that of a larva to that of a sexually-mature adult.
2. Where they can change dramatically
an animal's birth form is very different from the adult form. The embryo hatches from the egg in a larval form. The larva undergoes a drastic metamorphosis in order to achieve its adult stage.
Animals that undergo indirect development lay numerous eggs. Because the eggs are small, they have relatively little yolk. Due to the small amount of yolk, the larva develops and hatches rapidly.
In animals with direct development, there is no distinctive larval stage. By the time they’re hatched or born, the young animals look more or less like smaller versions of their parents.
Young, sexually-immature animals are sometimes called nymphs to distinguish them from sexually-mature adults
These are typically those where females produce smaller numbers or large yolky eggs containing sufficient food reserves for elaborate development.
They increase in size as they grow older, but do not change overall form.
Extended development is sustained by transfer of nutrients from mother to embryo through the placenta or during milk suckling when the young is born.
Placental mammals all bear live young, which are nourished before birth in the mother's uterus through a specialized embryonic organ attached to the uterus wall, the placenta.
The placenta serves as a pathway for nutrient exchange to supply the needs of a developing mammalian embryo .
At birth, young eutherians are essentially independent with little support required from the parent.
Oxytocin- pituitary octapeptide that stimulates especially in the contraction of the uterine muscle and the secretion of milk
Norepinephrine – monoamine that is a transmitter in neourons of SNS and other parts of CNS – adrenal medulla
