Download The Endocrine System

The Endocrine System
What is the function of the
endocrine system?
How does the endocrine system
maintain homeostasis?
What’s it all about?
The endocrine system is made up of
glands that release their products into
the bloodstream. These products
broadcast messages throughout the
body.
Video Clip
Hormones
Hormones are chemicals that travel
through the bloodstream and affect
the activities of other cells. Hormones
do this by binding to specific chemical
receptors on those cells.
Cells that have receptors for a
particular hormone are called target
cells.
Lock and key
Glands
A gland is an organ that produces and releases a
substance or a secretion.
Exocrine glands: release their secretions through
tubelike structures called ducts directly to the
organs that need them.
Sweat glands
Tear glands
Digestive glands
Endocrine glands: release their hormones directly
into the blood stream.
There are 10 major endocrine glands in the body
Control of the Endocrine System
Like most systems of the body; the
endocrine system is regulated by
feedback mechanisms that function to
maintain homeostasis.
Feedback
Feedback mechanisms are best described
as a process that helps keep body
conditions near a normal, steady state.
Example: An increase in the level of
insulin in the blood would result in a
decrease in the amount of glucose in the
blood.
Actions of Insulin and Glucagon
Beta cells release
insulin into the blood
Blood glucose
level increases
Body cells
absorb glucose
Blood glucose
level decreases
Liver converts
glycogen to glucose
Homeostasis: Normal blood glucose level
Blood glucose
level increases
Liver converts
glycogen to glucose
Blood glucose
level decreases
Alpha cells release
glucagon into blood
https://www.youtube.com/watch?v=CLv3Sk
F_Eag
Endocrine Glands
Hypothalamus
Pituitary gland
Parathyroid glands
Thymus
Adrenal Glands
Pineal Gland
Thyroid
Pancreas
Ovary
Testis
The Endocrine
System
regulates
Metabolism
Calcium
and glucose
levels
Response
to stress
by means
of the
by means
of the
by means
of the
by means
of the
Testes
Thyroid
Growth
Water
balance
Reproduction
by means
of the
by means
of the
Pituitary
Ovaries
Pancreas
Parathyroids
Adrenals
The Pituitary Gland: “ Master Gland”
The pituitary gland secretes nine hormones that
directly regulate many body functions and controls
the actions of several other endocrine glands.
Releases a hormone that causes the release of
estrogen.
The Pituitary Gland
Hypothalamus
The hypothalamus
controls the
secretions of the
pituitary gland.
https://www.youtube.com/watch?v=n
NLsXKkLSTs
Thyroid gland
The thyroid gland
has the major role
in regulating the
body’s metabolism.
Parathyroid Glands
Hormones from the
thyroid gland and
the parathyroid
glands maintain
homeostasis in
blood calcium
levels.
Adrenal Glands
The adrenal glands
help the body
prepare for and
deal with stress.
Also regulates the
glucose levels in
blood.
Pancreas
Insulin and glucagon
released from the
pancreas help to keep
the level of glucose in
the blood stable.
Insulin decreases blood
sugar
Glucagon increases
sugar level
Hormone Action
Hormones may be classified as
belonging to two general groups
Steroid hormones: produced from a lipid
called cholesterol, can pass through cell
membranes easily (target cells)
Non-steroid hormones: include proteins,
small peptides, and modified amino
acids: cannot pass through cell
membranes of target cells
Feedback Mechanism
Recall that feedback inhibition occurs
when an increase in any substance
“feeds back” to inhibit the process that
produced the substance in the first
place.
https://www.youtube.com/watch?v=W
VrlHH14q3o
The Reproductive System
Sexual reproduction (Review)
Meiosis -process of reduction division in
which the number of chromosomes per cell
is cut in half
Haploid- a cell that contains only a single
set of chromosomes. (single set of genes)
Gamete- Sex cell, sperm or egg
Gonads- ovaries or testes
HormonesEstrogen (female)
Testosterone (male)
Hormones
Puberty begins when the hypothalamus
signals the pituitary to produce
increased levels of two hormones that
affect the gonads.
These hormones are follicle-stimulating
hormone (FSH) and luteinizing hormone
(LH)
FSH & LH in males stimulates the
production of testosterone
FSH & LH in females stimulates the
production of estrogen
The Female Reproductive System
The main function of the female
reproductive system is to produce ova
(egg). In addition, the female reproductive
system prepares the female’s body to
nourish a developing embryo.
Ovaries produce and release the egg
Follicles are clusters of cells that
surround a cell egg.
Female hormone is estrogen has direct
effect on the changes within the uterus.
Egg Development
Each ovary contains about 400,000
primary follicles.
The function of a follicle is to help an egg
mature for release into the reproductive
tract, where it can be fertilized. Eggs
develop within their follicles.
Approximately every 28 days, under the
influence of FSH, a follicle gets larger and
completes the first meiotic cell division.
Menstrual Cycle
Menstrual in Latin means month
About a 28 day cycle
Regulated by hormones
During the menstrual cycle, an egg
develops and is released from an ovary.
The uterus is prepared to receive a
fertilized egg.
If fertilized then the egg is implanted in the
uterus.
If an egg is not fertilized then it is
discharged along with the uterus lining.
Phases
Follicular phase- Starts with low levels
of estrogen. Body reacts releases
FSH and LH which cause a follicle to
develop.
Ovulation- shortest phase 3-4 days
sudden rush of FSH & LH causes
follicle to rupture and a mature egg is
released into one of the fallopian
tubes
Luteal Phase- Starts after the egg is released
and moves through fallopian tube. The cells of
the ruptured follicle undergo a change, turn
yellow and is called corpus luteum. This
continues to release estrogen and
progesterone.
Menstruation- If no fertilization within 2-3 days
of ovulation the egg will pass through the uterus
without implantation. Corpus luteum will begin
to disintegrate. Estrogen levels drop and the
uterus lining will detach and be discharged
along with the egg and blood. Lasts 3-7 days
Section 39-3
Figure 39–15 The Female
Reproductive System
Fallopian tube
Fallopian tube
Ovary
Urinary bladder
Ovary
Uterus
Pubic bone
Urethra
Cervix
Vagina
Rectum
Vagina
• Fetus
usually
develops in the
uterus
• Egg is fertilized in
the fallopian tube.
The Male Reproductive System
The main function of the male
reproductive system is to produce and
deliver sperm (internal fertilization)
Testes are adapted to produce sperm
cells.
Sperm (male gamete) transports
genetic information
Haploid
Testosterone
The Male
Reproductive System
Urinary bladder
Pubic bone
Vas deferens
Urethra
Penis
Large intestine
Rectum
Seminal
vesicle
Prostate gland
Scrotum
Bulbourethral gland
Epididymis
Testis
Fertilization
Fertilization occurs in the fallopian
tube
After fertilization the zygote begins to
undergo mitosis
Four days after it is a solid ball of
about 64 cells.
7 days after implantation occurs.
Placenta
The placenta is a vital organ that
connects the mother and the embryo.
It is the embryo’s organ of respiration,
nourishment and excretion. (diffusion)
It is also a means of getting rid of
metabolic wastes (excretion). CO2
passes from fetus to parent is the
greatest amount.
Wastes diffuse into the mother’s blood
from the embryo’s blood.
Their blood does not mix!
Figure 39–20 The Placenta
Amniotic sac
Placenta
Umbilical cord
Fetal
portion of
placenta
Maternal
portion of
placenta
Villus in chorion
Uterus
Amnion
Amnion
Umbilical cord
Maternal
artery
Umbilical arteries
Umbilical vein
Maternal
vein
Fetus
After 8 weeks of development the
embryo is called a fetus.
Embryonic Stem Cells
Cells that are capable of
differentiating into any type of cell.