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39-1 The Endocrine System
39-1 The Endocrine System
The endocrine system is made up of
glands that release their products
into the bloodstream.
Thes...
Hormones
Hormones are chemicals released in
one part of the body that travel
through the bloodstream and affect
the activi...
Hormones bind to specific chemical receptors on
cells.
Cells that have receptors for a particular hormone
are called targe...
A gland is an organ that produces and releases
a secretion. There are two kinds of glands:
Exocrine glands release secreti...
Hypothalamus
The hypothalamus makes
hormones that control the
pituitary gland. In
addition, the
hypothalamus makes
hormone...
Pituitary gland
The pituitary gland
produces hormones
that regulate many of
the other endocrine
glands.
Figure 39-2 on Pag...
Parathyroid glands
The parathyroid glands
release parathyroid
hormone, which regulates
the level of calcium in the
blood.
...
Thymus
During childhood, the
thymus releases
thymosin, which
stimulates T cell
development and proper
immune response.
Fig...
Adrenal glands
The adrenal glands
release epinephrine and
norepinephrine, which
help the body respond
to stress.
Figure 39...
Testis
The testes produce
testosterone, which is
responsible for sperm
production and the
development of male
secondary se...
Ovary
Ovaries produce estrogen
and progesterone.
Estrogen is required for
the development of
female secondary sex
characte...
Pancreas
The pancreas produces
insulin and glucagon,
which regulate the level
of glucose in the blood.
Figure 39-2 on Page...
Thyroid
The thyroid produces
thyroxine, which
regulates metabolism
throughout the body.
Figure 39-2 on Page 998
Know the e...
Pineal gland
The pineal gland releases
melatonin, which is
involved in rhythmic
activities, such as daily
sleep-wake cycle...
Hormone Action
Hormones are classified as either
steroids or nonsteroids.
Steroid hormones are produced
from a lipid calle...
Steroid Hormones
Steroid hormones can cross cell
membranes easily.
Steroid Hormone Action
Hormone-receptor
complex
Nucleus
DNA
mRNA
Protein
synthesis
Altered cellular
function
Receptor
Ster...
Hormone-receptor
complex
Nucleus
DNA
mRNA
Protein
synthesis
Altered cellular
function
Receptor
Steroid hormone
A steroid
h...
Hormone-receptor
complex
Nucleus
DNA
mRNA
Protein
synthesis
Altered cellular
function
Receptor
Steroid hormone
It binds to...
Nucleus
DNA
mRNA
Protein
synthesis
Altered cellular
function
The hormone-
receptor complex
enters the nucleus,
where it bi...
Nucleus
DNA
mRNA
Protein
synthesis
Altered cellular
function
Because steroid hormones affect gene expression
directly, the...
Nonsteroid Hormones
Nonsteroid hormones cannot
pass through the cell membrane.
A nonsteroid
hormone binds to
receptors on the
cell membrane.
This activates an
enzyme on the
inside of the
membrane.
Nons...
This enzyme
activates
secondary
messengers that
carry the message
of the hormone
inside the cell.
These messengers
activat...
Prostaglandins
All cells (except red blood cells) produce
small amounts of hormone-like
substances called prostaglandins.
...
The endocrine system is regulated by
feedback mechanisms that function to
maintain homeostasis.
In feedback inhibition, an...
Controlling
Metabolism
Complementary Hormone Action
Sometimes two hormones with
opposite effects act to regulate
part of the body’s internal
envi...
Two hormones that regulate calcium
concentration are calcitonin and parathyroid
hormone (PTH).
Calcitonin decreases the le...
39-2 Human Endocrine Glands
39-2 Human Endocrine Glands
The endocrine glands are scattered throughout
the body.
The human endocrine system regulates a...
The major glands of the endocrine system
include:
• the pituitary gland
• the hypothalamus
• the thyroid gland
• the parat...
The pituitary gland secretes nine
hormones that directly regulate
many body functions and controls
the actions of several ...
The Pituitary Gland
Hypothalamus
Pituitary
gland
Posterior
pituitary
Anterior
pituitary
The hypothalamus is the part of the brain
attached to the posterior pituitary.
The hypothalamus controls the
secretions of...
Hypothalamus
Pituitary gland
The close connection between the hypothalamus
and the pituitary gland means that the
nervous and endocrine systems
act tog...
The thyroid gland is located at the base of
the neck and wraps around the upper part
of the trachea.
The thyroid gland has...
The thyroid produces thyroxine.
Thyroxine regulates the metabolic rate of cells.
Thyroid Gland
Larynx
Thyroid gland
Esophagus
Trachea
The thyroid produces thyroxine.
Thyroxine regulates the metabolic rat...
Thyroid Disorders
Hyperthyroidism: the body produces too much
thyroxine. It is characterized by elevated
temperature and m...
The four parathyroid glands are found on
the back surface of the thyroid gland.
Hormones from the parathyroid
glands act t...
Parathyroid Glands
Thyroid gland
Parathyroid glands
The adrenal glands are two pyramid-
shaped structures that sit on top of the
kidneys, one gland on each kidney.
The adrena...
Adrenal Glands
Adrenal gland
Kidney
Epinephrine and norepinephrine:
•increase heart rate, blood pressure, and
blood flow to the muscles.
•cause air passageway...
The pancreas has both exocrine
and endocrine functions.
•It is a digestive gland whose
secretions break down food.
•It pro...
Insulin and glucagon
(produced by pancreas) help
to keep the level of glucose in
the blood stable.
Insulin stimulates cells in the liver and muscles to
remove sugar from the blood and store it as
glycogen or fat.
Glucagon...
Diabetes Mellitus
•When the pancreas fails to
produce or properly use insulin,
diabetes mellitus occurs.
56
The gonads are the body’s reproductive
glands.
The gonads serve two important
functions: the production of
gametes, and th...
The female gonads—the ovaries—
produce eggs.
The male gonads—the testes—
produce sperm.
The gonads also produce sex
hormon...
The ovaries produce the female sex hormones
estrogen and progesterone.
Progesterone prepares the uterus for the arrival of...
The testes produce testosterone, which is needed
for normal sperm production and development of
male physical characterist...
39-3 The Reproductive System
Sexual Development
•In humans, the reproductive system
produces, stores, and releases specialized
sex cells known as gamet...
•Puberty is a period of rapid growth and
sexual maturation during which the
reproductive system becomes fully
functional.
...
Puberty begins when the hypothalamus signals
the pituitary to produce increased levels of two
hormones that affect the gon...
The main function of the male
reproductive system is to produce and
deliver sperm.
A sperm cell consists of:
• a head, which
contains the
nucleus
• a midpiece, which
contains energy-
releasing
mitochondria...
Male Reproductive System
Urinary bladder
Vas deferens
Pubic bone
Urethra
Penis
Seminal vesicle
Rectum
Prostate gland
Bulbo...
The testes are located in an external sac called
the scrotum.
The scrotum is located outside the body cavity,
where it is ...
Within each testis are clusters of hundreds of tiny
tubules called seminiferous tubules.
The seminiferous tubules are tigh...
Sperm produced in the seminiferous
tubules, within the testis, move into
the epididymis, where they mature
and are stored.
From there, sperm move into a tube called the vas
deferens, which extends up from the scrotum into
the abdominal cavity.
S...
Glands lining the reproductive tract produce
seminal fluid.
Seminal fluid nourishes sperm and protects them
from the acidi...
Male reproductive diagram
Seminiferous tubules- In testes,
where sperm are made (meiosis)
Epididymis- where sperm matures ...
The Female Reproductive System
•The primary reproductive organs in the
female are the ovaries.
•The ovaries are located in...
The main function of the female
reproductive system is to produce eggs.
In addition, the female reproductive system
prepar...
Fallopian tube
Ovary
Uterus
Urinary bladder
Pubic bone
Urethra
Vagina
Rectum
Cervix
Female Reproductive System
Egg Development
•Each ovary contains about 400,000 primary
follicles, which are clusters of cells
surrounding a single egg...
Egg Release
•When a follicle has matured, its
egg is released from the ovary in
a process called ovulation.
•The follicle ...
•While in the Fallopian tube, an
egg can be fertilized.
•After a few days, the egg passes from the
Fallopian tube into the...
The Menstrual Cycle
•The menstrual cycle is controlled by
internal feedback mechanisms between
the reproductive system and...
During the menstrual cycle, an egg develops and
is released from an ovary.
The uterus is prepared to receive a fertilized ...
The menstrual cycle has four phases:
•follicular phase
•ovulation
•luteal phase
•menstruation
The Menstrual Cycle
Menstrual Cycle
Ovulation
•The follicular phase begins when
estrogen levels in the blood are low.
•The anterior pituitary secretes FSH and
LH, which cause a follicle to develop to
maturity.
•As the follicle develops, cel...
Ovulation
•This phase occurs midway through the
cycle and lasts 3–4 days.
•The pituitary gland produces more FSH
and LH.
•...
Luteal Phase
•The luteal phase begins after the egg is
released.
•The first few days of the luteal
phase is when fertiliza...
Luteal Phase
•As the egg moves in the Fallopian tube,
the follicle turns yellow and is called the
corpus luteum.
•The corp...
Progesterone stimulates growth and
development of the blood supply and
surrounding tissue.
Within a few days of implantati...
Menstruation
•If fertilization does not occur, the corpus
luteum will begin to disintegrate.
•The follicle breaks down and...
Female reproductive diagram
Ovary- egg develops & is released
Fallopian tube- Fertilization
usually happens here
Uterus- W...
Sexually Transmitted Diseases
•Diseases that spread from one person to
another during sexual contact are called
sexually t...
STDs caused by bacteria include chlamydia,
syphilis, and gonorrhea.
STDs caused by viruses include hepatitis B,
genital he...
39–4 Fertilization and Development
When an egg is fertilized, human development
begins.
In this process, a single cell undergoes a series of
cell divisions t...
Fertilization
•During sexual intercourse, sperm are
released when semen is ejaculated
through the penis into the vagina.
•...
The egg is surrounded by a protective layer that
contains binding sites to which sperm can attach.
When a sperm attaches t...
The process of a sperm joining an egg is
called fertilization.
Fertilization
After the two haploid (N) nuclei fuse,
a single diploid (2N) nucleus is
formed.
A diploid cell has a set of
...
Early Development
•While still in the Fallopian tube, the
zygote begins to undergo mitosis.
•Four days after fertilization...
The stages of early development
include implantation, gastrulation,
and neurulation.
Implantation
•As the morula grows, it becomes a hollow
structure with an inner cavity called a
blastocyst.
•6–7 days after...
Fertilization
Fertilization and Implantation
Blastocyst cells specialize due to the activation of
genes.
This process, called differentiation, is responsible
for the d...
Gastrulation
•The inner cell mass of the blastocyst
gradually sorts itself into two layers,
which then give rise to a thir...
Mesoderm
Amniotic cavity
Primitive
streak
Ectoderm
Endoderm
Early Development
The third layer is produced by a process of ...
The result of gastrulation is the
formation of three cell layers—the
ectoderm, the mesoderm, and the
endoderm.
Amniotic ca...
The ectoderm develops into the skin and nervous
system.
The endoderm forms the digestive lining and
organs.
Mesoderm cells...
Neurulation
•Gastrulation is followed by neurulation.
•Neurulation is the development
of the nervous system.
Shortly after gastrulation is complete, a block of
mesodermal tissue begins to differentiate into the
notochord.
Neural crest Neural fold
Notochord
•As the notochord develops, the neural
groove changes shape, producing neural
folds.
Neural crest Neural tube
Ectoderm
Notochord
•Gradually, these folds move together to
create a neural tube from which the
s...
Extraembryonic Membranes
•As the embryo develops, membranes
form to protect and nourish the embryo.
•Two of these membrane...
•The amnion
develops into a
fluid-filled
amniotic sac.
•The amniotic
sac cushions
and protects
the developing
embryo.
Uter...
Fingerlike projections called chorionic villi form
on the outer surface of the chorion and extend
into the uterine lining....
The chorionic villi and uterine lining form the placenta.
The placenta
•Lies between the
uterus and the
developing embryo
...
The placenta is the embryo's organ of
respiration, nourishment, and excretion.
The placenta acts as a barrier to some harmful or
disease-causing agents.
Some disease causing agents, such as German
meas...
After eight weeks, the embryo is called a
fetus.
After three months, most major organs and
tissues are formed. During this...
Later Development
•4–6 months after fertilization:
•The heart can be heard with a
stethoscope.
Bone replaces cartilage tha...
During the last three months, the organ systems
mature.
•The fetus doubles in mass.
•It can now regulate its body
temperat...
Childbirth
•About nine months after fertilization, the
fetus is ready for birth.
•A complex set of factors affects the
ons...
Multiple Births
Multiple Births
•If two eggs are released during the same
cycle and fertilized by two different
sperm, fra...
39-1
Chemicals that travel through the
bloodstream and affect the activities of
other cells are known as
a. hormones.
b. r...
39-1
Which group of hormones act on target
cells by binding directly to DNA in the
nucleus?
a. steroids
b. nonsteroids
c. ...
39-2
Diabetes mellitus is a disease that
results when the pancreas fails to
produce or properly use
a. glucose.
b. insulin...
39-2
Metabolism is regulated by
a. thyroid.
b. parathyroid.
c. adrenal glands.
d. ovaries.
39-2
The gonads are the body's
a. target cells.
b. exocrine glands.
c. reproductive glands.
d. reproductive cells.
39-2
The endocrine glands responsible for
maintaining homeostasis of calcium in
the blood are the
a. thyroid and parathyro...
39-2
Epinephrine is a hormone produced by the
adrenal medulla and is responsible for
a. the “fight or flight” response to ...
39-3
The process in which a mature egg is
released from the follicle of an ovary is
known as
a. fertilization.
b. ovulatio...
39-3
An egg passes from a Fallopian tube
into the cavity of the
a. ovary.
b. vagina.
c. uterus.
d. cervix.
Which statement best describes male sperm
cells?
a. They are motile, produced in small numbers, and larger than most body
...
39–4
Fertilization takes place in the
a. ovary.
b. Fallopian tube.
c. cavity of the uterus.
d. cervix.
39–4
The central nervous system develops
during which phase of early
development?
a. gastrulation
b. neurulation
c. implan...
39–4
The placenta is a structure that
a. belongs entirely to the mother.
b. belongs entirely to the fetus.
c. brings blood...
39–4
Which of the following is not a primary
germ layer?
a. neural tube
b. endoderm
c. ectoderm
d. mesoderm
Chapter 39- Endocrine & Reproductive Systems
Chapter 39- Endocrine & Reproductive Systems
Chapter 39- Endocrine & Reproductive Systems
Chapter 39- Endocrine & Reproductive Systems
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Chapter 39- Endocrine & Reproductive Systems

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Chapter 39- Endocrine & Reproductive Systems

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Chapter 39- Endocrine & Reproductive Systems

  1. 1. 39-1 The Endocrine System
  2. 2. 39-1 The Endocrine System The endocrine system is made up of glands that release their products into the bloodstream. These products deliver messages throughout the body. The chemicals released by the endocrine system can affect almost every cell in the body.
  3. 3. Hormones Hormones are chemicals released in one part of the body that travel through the bloodstream and affect the activities of cells in other parts of the body.
  4. 4. Hormones bind to specific chemical receptors on cells. Cells that have receptors for a particular hormone are called target cells. If a cell does not have receptors or the receptors do not respond to a hormone, that hormone has no effect on it.
  5. 5. A gland is an organ that produces and releases a secretion. There are two kinds of glands: Exocrine glands release secretions through ducts directly to the organs that use them. Endocrine glands release their secretions directly into the bloodstream.
  6. 6. Hypothalamus The hypothalamus makes hormones that control the pituitary gland. In addition, the hypothalamus makes hormones that are stored in the pituitary gland. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  7. 7. Pituitary gland The pituitary gland produces hormones that regulate many of the other endocrine glands. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  8. 8. Parathyroid glands The parathyroid glands release parathyroid hormone, which regulates the level of calcium in the blood. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  9. 9. Thymus During childhood, the thymus releases thymosin, which stimulates T cell development and proper immune response. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  10. 10. Adrenal glands The adrenal glands release epinephrine and norepinephrine, which help the body respond to stress. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  11. 11. Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  12. 12. Ovary Ovaries produce estrogen and progesterone. Estrogen is required for the development of female secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  13. 13. Pancreas The pancreas produces insulin and glucagon, which regulate the level of glucose in the blood. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  14. 14. Thyroid The thyroid produces thyroxine, which regulates metabolism throughout the body. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  15. 15. Pineal gland The pineal gland releases melatonin, which is involved in rhythmic activities, such as daily sleep-wake cycles. Figure 39-2 on Page 998 Know the endocrine glands and their functions.
  16. 16. Hormone Action Hormones are classified as either steroids or nonsteroids. Steroid hormones are produced from a lipid called cholesterol. Nonsteroid hormones include proteins, small peptides, and modified amino acids.
  17. 17. Steroid Hormones Steroid hormones can cross cell membranes easily.
  18. 18. Steroid Hormone Action Hormone-receptor complex Nucleus DNA mRNA Protein synthesis Altered cellular function Receptor Steroid hormone
  19. 19. Hormone-receptor complex Nucleus DNA mRNA Protein synthesis Altered cellular function Receptor Steroid hormone A steroid hormone enters a cell directly across its membrane.
  20. 20. Hormone-receptor complex Nucleus DNA mRNA Protein synthesis Altered cellular function Receptor Steroid hormone It binds to a receptor to form a hormone-receptor complex.
  21. 21. Nucleus DNA mRNA Protein synthesis Altered cellular function The hormone- receptor complex enters the nucleus, where it binds to a DNA control sequence. Binding initiates transcription of genes to mRNA.
  22. 22. Nucleus DNA mRNA Protein synthesis Altered cellular function Because steroid hormones affect gene expression directly, they can produce dramatic changes in cell and organism activity. Gene expression is altered.
  23. 23. Nonsteroid Hormones Nonsteroid hormones cannot pass through the cell membrane.
  24. 24. A nonsteroid hormone binds to receptors on the cell membrane. This activates an enzyme on the inside of the membrane. Nonsteroid hormone (first messenger)
  25. 25. This enzyme activates secondary messengers that carry the message of the hormone inside the cell. These messengers activate and inhibit many cell activities. ATP cAMP (second messenger) Enzyme activities Altered cellular function
  26. 26. Prostaglandins All cells (except red blood cells) produce small amounts of hormone-like substances called prostaglandins. Prostaglandins are modified fatty acids. They affect nearby cells and tissues, and are known as “local hormones.”
  27. 27. The endocrine system is regulated by feedback mechanisms that function to maintain homeostasis. In feedback inhibition, an increase in a substance causes a decrease in the production of the substance.
  28. 28. Controlling Metabolism
  29. 29. Complementary Hormone Action Sometimes two hormones with opposite effects act to regulate part of the body’s internal environment. Such a complementary system regulates the level of calcium ions in the bloodstream.
  30. 30. Two hormones that regulate calcium concentration are calcitonin and parathyroid hormone (PTH). Calcitonin decreases the level of calcium in the blood, while PTH increases it.
  31. 31. 39-2 Human Endocrine Glands
  32. 32. 39-2 Human Endocrine Glands The endocrine glands are scattered throughout the body. The human endocrine system regulates a variety of activities. Any improper functioning of an endocrine gland may result in a disease or a disorder.
  33. 33. The major glands of the endocrine system include: • the pituitary gland • the hypothalamus • the thyroid gland • the parathyroid glands • the adrenal glands • the pancreas • the reproductive glands
  34. 34. The pituitary gland secretes nine hormones that directly regulate many body functions and controls the actions of several other endocrine glands.
  35. 35. The Pituitary Gland Hypothalamus Pituitary gland Posterior pituitary Anterior pituitary
  36. 36. The hypothalamus is the part of the brain attached to the posterior pituitary. The hypothalamus controls the secretions of the pituitary gland.
  37. 37. Hypothalamus Pituitary gland
  38. 38. The close connection between the hypothalamus and the pituitary gland means that the nervous and endocrine systems act together to coordinate body activities.
  39. 39. The thyroid gland is located at the base of the neck and wraps around the upper part of the trachea. The thyroid gland has the major role in regulating the body's metabolism.
  40. 40. The thyroid produces thyroxine. Thyroxine regulates the metabolic rate of cells.
  41. 41. Thyroid Gland Larynx Thyroid gland Esophagus Trachea The thyroid produces thyroxine. Thyroxine regulates the metabolic rate of cells.
  42. 42. Thyroid Disorders Hyperthyroidism: the body produces too much thyroxine. It is characterized by elevated temperature and metabolic rate, increased blood pressure, and weight loss. Hypothyroidism: the body produces too little thyroxine. It is characterized by lower temperature and metabolic rate, lack of energy, and weight gain. Goiter: enlargement of thyroid gland. Caused by an iodine deficiency.
  43. 43. The four parathyroid glands are found on the back surface of the thyroid gland. Hormones from the parathyroid glands act to maintain homeostasis of calcium levels in the blood.
  44. 44. Parathyroid Glands Thyroid gland Parathyroid glands
  45. 45. The adrenal glands are two pyramid- shaped structures that sit on top of the kidneys, one gland on each kidney. The adrenal glands release hormones that help the body prepare for and deal with stress.
  46. 46. Adrenal Glands Adrenal gland Kidney
  47. 47. Epinephrine and norepinephrine: •increase heart rate, blood pressure, and blood flow to the muscles. •cause air passageways to open wider, allowing for an increased intake of oxygen. •stimulate the release of extra glucose into the blood to help produce a sudden burst of energy.
  48. 48. The pancreas has both exocrine and endocrine functions. •It is a digestive gland whose secretions break down food. •It produces insulin and glucagon.
  49. 49. Insulin and glucagon (produced by pancreas) help to keep the level of glucose in the blood stable.
  50. 50. Insulin stimulates cells in the liver and muscles to remove sugar from the blood and store it as glycogen or fat. Glucagon stimulates the liver to break down glycogen and release glucose back into the blood.
  51. 51. Diabetes Mellitus •When the pancreas fails to produce or properly use insulin, diabetes mellitus occurs.
  52. 52. 56
  53. 53. The gonads are the body’s reproductive glands. The gonads serve two important functions: the production of gametes, and the secretion of sex hormones.
  54. 54. The female gonads—the ovaries— produce eggs. The male gonads—the testes— produce sperm. The gonads also produce sex hormones.
  55. 55. The ovaries produce the female sex hormones estrogen and progesterone. Progesterone prepares the uterus for the arrival of a developing embryo. Estrogen is needed for the development of eggs and for the formation of physical characteristics of the female body.
  56. 56. The testes produce testosterone, which is needed for normal sperm production and development of male physical characteristics.
  57. 57. 39-3 The Reproductive System
  58. 58. Sexual Development •In humans, the reproductive system produces, stores, and releases specialized sex cells known as gametes. •Sperm + egg = zygote, the single cell from which all cells of the human body develop.
  59. 59. •Puberty is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. •When puberty ends, reproductive organs are fully developed. •Puberty usually begins between the ages of 9 and 15, and usually starts one year earlier in females than in males.
  60. 60. 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).
  61. 61. The main function of the male reproductive system is to produce and deliver sperm.
  62. 62. A sperm cell consists of: • a head, which contains the nucleus • a midpiece, which contains energy- releasing mitochondria • a tail, which propels the cell forward Head Nucleus Midpiece Mitochondria Tail
  63. 63. Male Reproductive System Urinary bladder Vas deferens Pubic bone Urethra Penis Seminal vesicle Rectum Prostate gland Bulbourethral gland Scrotum Testis Epididymis
  64. 64. The testes are located in an external sac called the scrotum. The scrotum is located outside the body cavity, where it is between 1 and 3 degrees cooler than normal body temperature. The lower temperature helps sperm development.
  65. 65. Within each testis are clusters of hundreds of tiny tubules called seminiferous tubules. The seminiferous tubules are tightly coiled and twisted together. Sperm are produced in the seminiferous tubules.
  66. 66. Sperm produced in the seminiferous tubules, within the testis, move into the epididymis, where they mature and are stored.
  67. 67. From there, sperm move into a tube called the vas deferens, which extends up from the scrotum into the abdominal cavity. Sperm enter the vas deferens, which merges with the urethra, the tube that leads to the outside of the body through the penis.
  68. 68. Glands lining the reproductive tract produce seminal fluid. Seminal fluid nourishes sperm and protects them from the acidity of the female reproductive tract. The combination of sperm and seminal fluid is called semen.
  69. 69. Male reproductive diagram Seminiferous tubules- In testes, where sperm are made (meiosis) Epididymis- where sperm matures & waits Vas deferens- tube from testes Urethra- where sperm & urine exit
  70. 70. The Female Reproductive System •The primary reproductive organs in the female are the ovaries. •The ovaries are located in the abdominal cavity.
  71. 71. The main function of the female reproductive system is to produce eggs. In addition, the female reproductive system prepares the female's body to nourish a developing embryo.
  72. 72. Fallopian tube Ovary Uterus Urinary bladder Pubic bone Urethra Vagina Rectum Cervix Female Reproductive System
  73. 73. Egg Development •Each ovary contains about 400,000 primary follicles, which are clusters of cells surrounding a single egg. •The follicle helps an egg mature for release into the reproductive tract, where it can be fertilized. •Eggs develop within their follicles.
  74. 74. Egg Release •When a follicle has matured, its egg is released from the ovary in a process called ovulation. •The follicle breaks open, and the egg is swept from the ovary into one of the two Fallopian tubes.
  75. 75. •While in the Fallopian tube, an egg can be fertilized. •After a few days, the egg passes from the Fallopian tube into the uterus. •If the egg is not fertilized it passes through the cervix, and finally out of the vagina. •The vagina leads to the outside of the body.
  76. 76. The Menstrual Cycle •The menstrual cycle is controlled by internal feedback mechanisms between the reproductive system and the endocrine system. •The menstrual cycle takes an average of 28 days.
  77. 77. During the menstrual cycle, an egg develops and is released from an ovary. The uterus is prepared to receive a fertilized egg. If the egg is fertilized, it is implanted in the uterus and embryonic development begins. If the egg is not fertilized, it is discharged.
  78. 78. The menstrual cycle has four phases: •follicular phase •ovulation •luteal phase •menstruation
  79. 79. The Menstrual Cycle Menstrual Cycle Ovulation
  80. 80. •The follicular phase begins when estrogen levels in the blood are low.
  81. 81. •The anterior pituitary secretes FSH and LH, which cause a follicle to develop to maturity. •As the follicle develops, cells surrounding the egg enlarge and produce more estrogen. •Estrogen causes the lining of the uterus to thicken.
  82. 82. Ovulation •This phase occurs midway through the cycle and lasts 3–4 days. •The pituitary gland produces more FSH and LH. •The release of these hormones causes the follicle to rupture, and a mature egg is released into one of the Fallopian tubes.
  83. 83. Luteal Phase •The luteal phase begins after the egg is released. •The first few days of the luteal phase is when fertilization is most likely.
  84. 84. Luteal Phase •As the egg moves in the Fallopian tube, the follicle turns yellow and is called the corpus luteum. •The corpus luteum continues to release estrogen but also begins to release progesterone.
  85. 85. Progesterone stimulates growth and development of the blood supply and surrounding tissue. Within a few days of implantation, the uterus and the growing embryo will release hormones that keep the corpus luteum functioning for several weeks. This allows the lining of the uterus to nourish and protect the developing embryo.
  86. 86. Menstruation •If fertilization does not occur, the corpus luteum will begin to disintegrate. •The follicle breaks down and releases less hormones, which makes the uterine lining detach. •This tissue, blood, and the unfertilized egg are discharged through the vagina. •This phase is menstruation, and it lasts 3–7 days.
  87. 87. Female reproductive diagram Ovary- egg develops & is released Fallopian tube- Fertilization usually happens here Uterus- Where baby develops Vagina- birth canal
  88. 88. Sexually Transmitted Diseases •Diseases that spread from one person to another during sexual contact are called sexually transmitted diseases (STDs). •STDs are a serious problem in the U.S., infecting millions of people each year and accounting for thousands of deaths.
  89. 89. STDs caused by bacteria include chlamydia, syphilis, and gonorrhea. STDs caused by viruses include hepatitis B, genital herpes, genital warts, and HIV/AIDS.
  90. 90. 39–4 Fertilization and Development
  91. 91. When an egg is fertilized, human development begins. In this process, a single cell undergoes a series of cell divisions that results in the formation of a new human being.
  92. 92. Fertilization •During sexual intercourse, sperm are released when semen is ejaculated through the penis into the vagina. •Sperm swim through the uterus into the Fallopian tubes. •if an egg is present in one of the Fallopian tubes, its chances of being fertilized are good.
  93. 93. The egg is surrounded by a protective layer that contains binding sites to which sperm can attach. When a sperm attaches to a binding site, its head releases enzymes that break down the protective layer of the egg. The sperm nucleus enters the egg, and chromosomes from the sperm and egg are brought together.
  94. 94. The process of a sperm joining an egg is called fertilization.
  95. 95. Fertilization After the two haploid (N) nuclei fuse, a single diploid (2N) nucleus is formed. A diploid cell has a set of chromosomes from each parent cell. The fertilized egg is called a zygote.
  96. 96. Early Development •While still in the Fallopian tube, the zygote begins to undergo mitosis. •Four days after fertilization, the embryo is a solid ball of about 64 cells called a morula.
  97. 97. The stages of early development include implantation, gastrulation, and neurulation.
  98. 98. Implantation •As the morula grows, it becomes a hollow structure with an inner cavity called a blastocyst. •6–7 days after fertilization, the blastocyst attaches to the uterine wall. •The embryo secretes enzymes that digest a path into it. •This process is known as implantation.
  99. 99. Fertilization Fertilization and Implantation
  100. 100. Blastocyst cells specialize due to the activation of genes. This process, called differentiation, is responsible for the development of the various types of tissue in the body.
  101. 101. Gastrulation •The inner cell mass of the blastocyst gradually sorts itself into two layers, which then give rise to a third layer.
  102. 102. Mesoderm Amniotic cavity Primitive streak Ectoderm Endoderm Early Development The third layer is produced by a process of cell migration known as gastrulation.
  103. 103. The result of gastrulation is the formation of three cell layers—the ectoderm, the mesoderm, and the endoderm. Amniotic cavity Primitive streak Ectoderm Endoderm Mesoderm
  104. 104. The ectoderm develops into the skin and nervous system. The endoderm forms the digestive lining and organs. Mesoderm cells differentiate into internal tissues and organs.
  105. 105. Neurulation •Gastrulation is followed by neurulation. •Neurulation is the development of the nervous system.
  106. 106. Shortly after gastrulation is complete, a block of mesodermal tissue begins to differentiate into the notochord.
  107. 107. Neural crest Neural fold Notochord •As the notochord develops, the neural groove changes shape, producing neural folds.
  108. 108. Neural crest Neural tube Ectoderm Notochord •Gradually, these folds move together to create a neural tube from which the spinal cord and the nervous system develop.
  109. 109. Extraembryonic Membranes •As the embryo develops, membranes form to protect and nourish the embryo. •Two of these membranes are the amnion and the chorion.
  110. 110. •The amnion develops into a fluid-filled amniotic sac. •The amniotic sac cushions and protects the developing embryo. Uterus Amnion Fetus Amniotic sac Placenta Umbilical cord
  111. 111. Fingerlike projections called chorionic villi form on the outer surface of the chorion and extend into the uterine lining. Fetal portion of placenta Maternal portion of placenta Maternal artery Maternal vein Umbilical vein Umbilical arteries Umbilical cord Amnion Chorionic villus Mom & baby blood do NOT mix!!
  112. 112. The chorionic villi and uterine lining form the placenta. The placenta •Lies between the uterus and the developing embryo •provides nutrients to the fetus.
  113. 113. The placenta is the embryo's organ of respiration, nourishment, and excretion.
  114. 114. The placenta acts as a barrier to some harmful or disease-causing agents. Some disease causing agents, such as German measles and HIV can cross the placenta. Some drugs, including alcohol and medications also can penetrate the placenta and affect development.
  115. 115. After eight weeks, the embryo is called a fetus. After three months, most major organs and tissues are formed. During this time, the umbilical cord also forms. The umbilical cord connects the fetus to the placenta.
  116. 116. Later Development •4–6 months after fertilization: •The heart can be heard with a stethoscope. Bone replaces cartilage that forms the early skeleton. A layer of soft hair grows over the fetus’s skin. The fetus grows and the mother can feel it moving.
  117. 117. During the last three months, the organ systems mature. •The fetus doubles in mass. •It can now regulate its body temperature. •The central nervous system and lungs completely develop.
  118. 118. Childbirth •About nine months after fertilization, the fetus is ready for birth. •A complex set of factors affects the onset of childbirth.
  119. 119. Multiple Births Multiple Births •If two eggs are released during the same cycle and fertilized by two different sperm, fraternal twins result. •A single zygote may split apart to produce two embryos, which are called identical twins.
  120. 120. 39-1 Chemicals that travel through the bloodstream and affect the activities of other cells are known as a. hormones. b. receptors. c. enzymes. d. messengers.
  121. 121. 39-1 Which group of hormones act on target cells by binding directly to DNA in the nucleus? a. steroids b. nonsteroids c. proteins d. second messengers
  122. 122. 39-2 Diabetes mellitus is a disease that results when the pancreas fails to produce or properly use a. glucose. b. insulin. c. glucagon. d. carbohydrate.
  123. 123. 39-2 Metabolism is regulated by a. thyroid. b. parathyroid. c. adrenal glands. d. ovaries.
  124. 124. 39-2 The gonads are the body's a. target cells. b. exocrine glands. c. reproductive glands. d. reproductive cells.
  125. 125. 39-2 The endocrine glands responsible for maintaining homeostasis of calcium in the blood are the a. thyroid and parathyroid glands. b. adrenal and pituitary glands. c. hypothalamus and thyroid glands. d. gonads.
  126. 126. 39-2 Epinephrine is a hormone produced by the adrenal medulla and is responsible for a. the “fight or flight” response to stress. b. controlling the level of insulin in the blood. c. maintaining proper levels of sodium and potassium in the blood. d. regulating the water content of the body.
  127. 127. 39-3 The process in which a mature egg is released from the follicle of an ovary is known as a. fertilization. b. ovulation. c. menstruation. d. meiosis.
  128. 128. 39-3 An egg passes from a Fallopian tube into the cavity of the a. ovary. b. vagina. c. uterus. d. cervix.
  129. 129. Which statement best describes male sperm cells? a. They are motile, produced in small numbers, and larger than most body cells. b. They are motile, produced in large numbers, and smaller than most body cells. c. They are nonmotile, produced in small numbers, and larger than most body cells. d. They are nonmotile, produced in large numbers, and smaller than most body cells.
  130. 130. 39–4 Fertilization takes place in the a. ovary. b. Fallopian tube. c. cavity of the uterus. d. cervix.
  131. 131. 39–4 The central nervous system develops during which phase of early development? a. gastrulation b. neurulation c. implantation d. fertilization
  132. 132. 39–4 The placenta is a structure that a. belongs entirely to the mother. b. belongs entirely to the fetus. c. brings blood from the mother and fetus close together. d. provides an impermeable barrier between the mother and the fetus.
  133. 133. 39–4 Which of the following is not a primary germ layer? a. neural tube b. endoderm c. ectoderm d. mesoderm

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