Download Endocrine System

Endocrine System
Brain Pop
Endocrine System
General Characteristics:
1. composed of glands that produce
chemical messengers (hormones)
which affect and influence body
functions
2. important in maintaining homeostasis
Hormones:
1. chemicals released in one part of
the body which travel through the
blood and bind to specific receptors
on specific cells (called target cells),
where a cell reaction or function is
changed
Endocrine glands:
1. Pituitary gland – often called the
master gland
a. Hangs from the hypothalamus under
the middle of the brain
b. Provides brain to body
c. Hormones include:
i. Growth hormone
ii. Follicle stimulating hormone (FSH) –
necessary for egg or sperm production
iii. Luteinizing hormone (LH) – prepares lining of
uterus for fertilized egg to implant
iv. Thyroid stimulating hormone (TSH) –
promotes release of thyroxin from thyroid
Endocrine glands (con’t):
2.
Hypothalamus – controls secretions of
pituitary gland
a. The close connection between the
hypothalamus & the pituitary gland means
that the nervous & endocrine systems can
act together to help coordinate body
activities
3.
Thyroid gland – produces thyroxin which
regulates body metabolism
4.
Parathyroid glands – parathyroid hormone
helps maintain homeostasis of calcium levels
in blood
5. Adrenal glands – has 2 parts
a. Cortex (outer part) – produces
corticosteroids which help control
such things as metabolic rates and
sodium/potassium uptake by the
kidney
b. Medulla (inner part) – produces
epinephrine (adrenalin) and
norepinephrine (noradrenalin) which
are responsible for the “fight or
flight” responses to stress
Endocrine glands (con’t):
6. Pancreas – produces insulin and
glucagon to control blood sugar
levels
a. Lack of insulin results in diabetes mellitus
or high sugar in blood and urine. If
untreated, can result in death
Endocrine Glands (con’t)
7. Thymus - During childhood,
the thymus releases thymosin,
which stimulates T-cell
development
• Butterfly shaped gland in
middle of chest
Endocrine glands (con’t):
8. Reproductive glands – produce sex
hormones
a. Ovary – produces….
i.
Estrogen - produces female secondary sex
characteristics and eggs
ii. Progesterone – prepares the uterus for
implantation
Endocrine glands (con’t):
b. Testis – produces…
i.
Testosterone – is responsible for male
secondary sex characteristics and sperm
production
Review
• Hormones are important parts of
feedback mechanisms which maintain
homeostasis in the body
• Remember: feedback inhibition occurs
when an increase in any substance
“feeds back” to inhibit the process that
produced the substance in the first place
• Sometimes 2 hormones with opposite
effects act to regulate part of the body’s
internal environment
• For example…..
The Endocrine
System
regulates
Growth
Water
balance
Reproduction
Metabolism
Calcium
and glucose
levels
Response
to stress
by means
of the
by means
of the
by means
of the
by means
of the
by means
of the
by means
of the
Testes
Thyroid
Pituitary
Ovaries
Pancreas
Parathyroids
Adrenals
Reproductive- Maturity Required
• Brain Pop- Reproductive
System
Reproductive System
• Reproduction is the formation
of new individuals
– It is the only system NOT
functional at birth!
– It is the only system you can live
without!!
• Failure of the reproductive
system to function is not fatal,
but it is the single most
important system for the
continuation of a species
• The reproductive system
produces, stores, and releases
specialized sex cells known as
gametes
• Male & female gametes fuse
together to form a zygote, the
single cell from which all cells
of the human body develop
Puberty
• Puberty is a period of rapid growth
& sexual maturation during which
the reproductive system becomes
fully functional
• Onset of puberty usually occurs
between the ages of 9 and 15 &
begins about one year earlier in
females than in males
• Puberty begins when
hypothalamus signals pituitary to
produce increased levels of
follicle-stimulating hormone (FSH)
and luteinizing hormone (LH)
Male Reproductive System
• FSH and LH stimulate cells in
the testes to produce
testosterone
• FSH and testosterone
stimulates the development of
sperm
• The main function of the male
reproductive system is to
produce & deliver sperm
Structures of the Male Reproductive
System
• The testes develop within the abdominal
cavity & descend into the scrotum just
before birth
– The scrotum is an external sac that
keeps the testes about 1 to 3 degrees
lower than normal body temperature,
which is important for sperm
development
• Within each testis are tiny tubules called
seminiferous tubules where sperm are
produced by meiosis
Sperm Development
• Sperm produced in the
seminiferous tubules then move
into the epididymis where they are
stored until they are fully mature
• From the epididymis, some sperm
are moved into a tube called the
vas deferens, which extends
upward from the scrotum into the
abdominal cavity
• The vas deferens merges with the
urethra, the tube leading to the
outside of the body through the
penis
• Glands lining the reproductive
tract (seminal vesicles,
Cowper’s glands, & prostate)
produce seminal fluid which
nourishes & protects sperm.
• The combination of sperm &
seminal fluid produces semen
Female Reproductive System
• The main function of the
female reproductive system is
to produce ova & prepare the
female’s body to nourish a
developing embryo
• The primary reproductive
organs in the female are the
ovaries, located in the
abdominal cavity
• Each ovary contains about
400,000 primary follicles,
clusters of cells surrounding a
single egg
– The follicle helps an egg mature
for release into the reproductive
tract where it can be fertilized
– Only about 400 eggs will actually
be released
Ovulation
• When a follicle has completely matured,
it breaks open and the egg is swept from
the ovary surface into a Fallopian tube
• The egg moves through the Fallopian
tube, pushed along by cilia lining the
walls
– This is when the egg can be fertilized if
sperm are present
• After a few days, the egg passes from
the Fallopian tube into the uterus, where
the fertilized egg can implant & grow
Menstrual Cycle
• The interaction of the reproductive
system & endocrine system in
females is a complex series of
periodic events called the
menstrual cycle
• The cycle takes an average of 28
days & is regulated by hormones
made by the hypothalamus,
pituitary gland, and ovaries
• It is controlled by internal feedback
mechanisms
The Menstrual Cycle
• An egg develops & is released
from the ovary
• The uterus is prepared to receive a
fertilized egg
– If fertilization occurs, the zygote
implants in the uterus & begins
embryonic development
– If fertilization does not occur, the egg
is discharged along with the lining of
the uterus
• There are 4 phases in the menstrual
cycle: follicular phase, ovulation,
luteal phase, & menstruation
The Menstrual Cycle
Sexually Transmitted Diseases
• Diseases that spread from one person to another
during sexual contact
• STDs are a serious health problem in the US
• Common bacterial STDs include chlamydia,
syphilis, & gonorrhea
• Viral STDs include hepatitis B, genital herpes,
genital warts, and AIDS
• STDs can cause infertility and, in some cases,
death
• Most importantly, STDs can be avoided
– Any sexual contact carries chance of
infection
– Abstinence from sexual contact is the safest
way to avoid STDs as well as unwanted
pregnancy