Transcript Unit 10 The Human Body - Jamestown Public Schools

Unit 10 The Human Body
Ch. 39 Endocrine & Reproductive
Systems
The Endocrine System
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The endocrine system is made up of
glands that release their products into the
bloodstream
These products deliver messages
throughout the body
Hormones
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Hormones - chemicals released in 1 part
of the body, that travel through the
bloodstream, & affect activities of cells in
other parts of the body; “chemical
messengers”
Target cells (receptor cells) - cells that
have receptors for a particular hormone
Glands
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A gland is an organ that produces &
releases a substance, or secretion
Exocrine glands - release their secretions
(hormones) through ducts (tubes), directly
to the organs that use them
Glands
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Endocrine glands - release their secretions
(hormones) directly into the bloodstream
Major Endocrine Glands
Hormone Action
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Steroid hormones:

Because they are lipids,
they can cross cell
membranes, passing
directly into the cytoplasm
the nuclei of target cells
&
Hormone Action
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Nonsteroid hormones:

They generally cannot pass
through the cell membrane
of their target cells
Prostaglandins
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Prostaglandins - modified fatty acids that
produce cells, affecting other nearby cells
& tissues (“local hormones”)

Ex.) some cause smooth muscle tissue to
contract
Control of the Endocrine
System
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Like most systems of the body, the
endocrine system is regulated by feedback
mechanisms that function to maintain
homeostasis
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Ex.) Pancreas releasing insulin: blood sugar
level increases after lunch, pancreas releases
insulin, blood sugar level decreases,
pancreas stops releasing insulin
Human Endocrine Glands
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The human endocrine system regulates a
wide variety of activities
Any improper functioning of an endocrine
gland may result in a disease or disorder
Human Endocrine Glands
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The major glands of the endocrine system
are: the pituitary gland, the hypothalamus,
the thyroid gland, the parathyroid glands,
the adrenal glands, the pancreas, & the
reproductive glands
Pituitary Gland
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Pituitary gland - divided into 2 parts:
anterior & posterior; it secretes 9
hormones that directly regulate many body
functions & controls the actions of several
other endocrine glands
Pituitary Gland Hormones
Hypothalamus
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The hypothalamus controls the secretions
of the pituitary gland
The close connection between the
hypothalamus & the pituitary gland, means
that the nervous & endocrine systems can
act together to help coordinate body
activities
Thyroid Gland
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The thyroid gland has the major role in
regulating the body’s metabolism
Releases thyroxin which
increases metabolism, &
cellular respiration
Thyroid Gland
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Unable to produce thyroxin produces
condition known as cretinism
2 effects of cretinism are dwarfism &
severe mental retardation
Can be prevented by adding small
amounts of iodine to table salt
Parathyroid Glands
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The 4 parathyroid glands are found on the
back surface of the thyroid gland
Hormones from the thyroid gland & the
parathyroid glands act to maintain
homeostasis of calcium levels in the blood
Adrenal Glands
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There are 2 adrenal glands that sit on top
of the kidneys, like little hats
The adrenal glands release hormones that
help the body prepare for & deal with
stress
Adrenal Glands
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The 2 hormones secreted by the adrenal
glands are: epinephrine and
norepinephrine
The hormones produce the “fight or flight”
response to stress
Pancreas
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The pancreas has both exocrine &
endocrine functions
It is a digestive gland whose enzymes help
break down food
However, different cells in the pancreas
release hormones into the blood
Pancreas
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Insulin & glucagon are released from the
pancreas to help keep the blood glucose level
stable
Insulin stimulates liver cells to remove sugar
from the blood & store it as glycogen
Glucagon stimulates the liver to break down
stored glycogen & release sugar back into the
blood
Pancreas
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Diabetes mellitus - when the pancreas
does not produce insulin
There are 2 types of diabetes, Type I and
Type II
Type I requires daily injections of insulin,
due to the fact that the body produces no
insulin
Pancreas
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Type II develops in people after the
age of 40, produces normal insulin
but cells don’t respond properly to
the hormone
Usually controlled through diet,
exercise, & medication taken orally
Reproductive Glands
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The gonads are the body’s reproductive
glands
They serve 2 important functions: the
production of gametes & the secretion of
sex hormones
Reproductive Glands
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The female gonads are the ovaries - which
produce eggs, & the hormones estrogen &
progesterone
The male gonads are the testes - which
produce sperm, & the hormone
testosterone
The Reproductive System
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Reproduction is the formation of new
individuals
If any other system of the body failed, the
result would be fatal, not the case with the
reproductive system
Reproduction is important for continuation
of the species, but not for that organism to
survive
Sexual Development
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For the 1st 6 weeks of development, male
& female embryos are identical
During the 7th week, primary reproductive
organs begin to develop
Hormones produced by those organs
(gonads), will determine whether the
embryo develops physically into a male or
female
Sexual Development
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Neither the testes nor the ovaries are
capable of producing active reproductive
cells until puberty
Puberty - a period of rapid growth & sexual
maturation, when the reproductive system
becomes fully functional
The Male Reproductive System
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The main function of the male reproductive
system is to produce & deliver sperm
Scrotum - external sac that holds the
gonads, (external to reduce heat so sperm
won’t die)
Seminiferous tubules - tiny tubules tightly
coiled where the sperm are produced
The Male Reproductive System
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Sperm - male sex cells (gametes)
The Male Reproductive System
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Epididymis - structure that sperm move
into, to mature & be stored until released
Vas deferens - tube that carries sperm
from the epididymis, to the urethra, to be
released
Penis - urethra carries sperm out of body
through the penis
The Male Reproductive System
The Female Reproductive
System
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The main function of the female
reproductive system is to produce ova
(eggs)
In addition, the female reproductive
system prepares the female’s body to
nourish a developing embryo
The Female Reproductive
System
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Follicles - each ovary contains 400,000
clusters of cells surrounding a single egg,
to help it mature
Ovulation - when a follicle has completely
matured, its egg is released
The Female Reproductive
System
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Egg - female sex cells (gametes)
Fallopian tubes - tube from each ovary,
that carries the egg to the uterus
The Female Reproductive
System
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Uterus - location of egg a couple days
after ovulation, where embryo develops if
fertilization takes place
Cervix - the outer end of the uterus
Vagina - a canal that leads to the outside
of the body
The Female Reproductive
System
The Menstrual Cycle
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Menstrual cycle - when an egg develops &
is released from an ovary
The menstrual cycle has 4 phases:
follicular phase, ovulation, luteal phase, &
menstruation
The Menstrual Cycle
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The Follicular Phase
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Development of an egg
Ovulation
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Lasts 3-4 days, a mature
egg is released into 1 of
the fallopian tubes
The Menstrual Cycle
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Luteal Phase
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The remaining ruptured follicle, which
continues to release hormones
Menstruation - when the lining of the
uterus sheds, lasts about 3-7 days (period)
Sexually Transmitted Diseases
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Sexually transmitted diseases - diseases
spread from 1 person to another through
sexual contact
Common STDs are chlamydia, syphilis, &
gonorrhea (caused by a bacteria)
Sexually Transmitted Diseases
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Others caused by viruses include: HIV,
hepatitis B, genital herpes, & genital warts
Fertilization
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When an egg is fertilized, the process of
human development begins
In this process, a single cell, the size of a
period at the end of a sentence,
undergoes cell divisions
that results in the
formation of a new
human being
Fertilization
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Fertilization - the process of a sperm
joining an egg, usually occurs in the
fallopian tube
Zygote - a fertilized egg
Early Development
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The stages of early development include:
implantation, gastrulation, & neurulation
Implantation - when the blastocyst
implants itself in the uterine wall
At this point, cells differentiate - develop
into specific types of tissues in the body
Early Development
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Gastrulation - the formation of 3 cell
layers; the beginning of all of the organs &
tissues of the embryo will form from these
3 layers
Early Development
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Neurulation - the development of the
nervous system, occurs shortly after
gastrulation
Early Development
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Placenta - connections between mother &
developing embryo
The embryo needs a supply of nutrients &
oxygen, & a way to get rid of carbon
dioxide & wastes
Nutrients & oxygen diffuse from the
mother’s blood into the baby’s blood
Early Development
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At the same time, carbon dioxide &
metabolic wastes diffuse from the baby’s
blood into the mother’s blood, to be
excreted
The placenta is the embryo’s organ of
respiration, nourishment, & excretion
The Placenta
Early Development
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Fetus - after 8 weeks of development, the
embryo is then called a fetus
The umbilical cord connects the fetus to
the placenta
Pregnancy, is divided into 3 trimesters,
during the 3rd, the organ systems mature,
& the fetus grows in size & mass
Later Development
Childbirth
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After 9 months, the fetus is ready for birth
Oxytocin, a hormone released from the
pituitary gland, causes contractions to
begin
The contractions become more frequent &
powerful
Childbirth
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The cervix opening expands until it is large
enough for the baby’s head to pass
through
Contractions of the uterus force the baby
out through the vagina