Transcript Chapter 39 - Midway ISD

CHAPTER 39
Endocrine system and Reproductive system
39-1 ENDOCRINE SYSTEM
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Hormones – 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. Regulated by feedback mechanisms to
maintain homeostasis.
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Exocrine Glands – release secretions directly
into the organs that use them.
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Target Cells—The cells that hormones bind to and
affect.
Ex: Sweat, tears, digestive juices.
Endocrine Glands – release secretions directly
into blood stream.
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Ex: Hormones!
39-2 HUMAN ENDOCRINE GLANDS
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Pituitary Gland
Divided into two parts: Anterior and Posterior.
 Base of the skull, secretes 9 hormones that directly regulate
many body functions and endocrine glands.
 See pg. 1004 for hormones.
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Hypothalamus
Attached to the posterior pituitary, controls the secretions of
the pituitary gland through the usage of control hormones.
 Allows the nervous and the endocrine systems to work closely
together.
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Thyroid Gland
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Wraps around trachea, major role in regulating metabolism by
releasing 2 hormones with opposite effects.
Parathyroid Gland
Attached to thyroid, maintain homeostasis and calcium levels in blood
 Ex: if blood calcium levels are high, releases calcitonin to reduce
calcium absorption; if levels are low, releases PTH to increase
absorption of calcium
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Adrenal Glands
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Sit at the top of the kidneys, release hormones that help the body
prepare for stress.
 Cortex – produces corticosteroids.
 Cortisol
 Medulla – releases epinephrine and norepinephrine (adrenaline)
 Fight or Flight response begins here!
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Pancreas
Has exocrine and endocrine functions
 Releases digestive enzymes into the small intestine (exocrine)
and releases hormones (insulin and glucagon) into the blood
to regulate blood sugar levels
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Reproductive Glands
Serve two functions: To produce gametes and also to secrete
sex hormones.
 Ovaries – produce ova (eggs), secrete estrogen and
progesterone (hormones)
 Testes – produce sperm, produce testosterone (hormone)
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39-3 THE REPRODUCTIVE SYSTEM

Puberty – period of rapid growth and sexual
maturation when the reproductive organs are
fully developed
 Male
Reproductive System
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Main function is to produce and deliver sperm
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Structures
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scrotum – external sac that holds the testes
seminiferous tubules – produces sperm
epididymis – stores mature sperm
vas deferans – some sperm move into this tube
urethra – tube that connects to the vas
deferens and leads to the outside of the
body
penis – anatomical structure of a male
semen – combination of sperm and seminal fluid
 Female
Reproductive System
Main function to produce ova and nourish the embryo – produce
one mature egg each month
• Structures
 Follicles – clusters of cells surrounding an egg
 Ovulation – mature egg is released
 Fallopian tubes – tube that moves the egg to the uterus
 Uterus – organ where embryo grows
 Vagina – canal that leads to the outside of the body
 Menstrual cycle (4 phases)
• Follicular phase – follicle matures and uterine lining thickens
• Ovulation – egg released into fallopian tube
• Luteal phase – at beginning of luteal phase is best chance for
pregnancy; also when embryo implants in uterus
• Menstruation – occurs if egg is not fertilized, uterine lining and
ova exit the body
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39-4 FERTILIZATION AND
DEVELOPMENT
 Fertilization
– process of an egg being joined by
a sperm (N+N=2N)
 Zygote – fertilized egg cell
 Implantation – blastocyst attaches itself to
the uterine wall
 Gastrulation – formation of three cell
layers
 Neurulation – development of the nervous
system
 Placenta – connection between mother and
embryo
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Fetus – after eight weeks of development
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Control of development
Still an unknown process
 End of three months all organs are developed
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Later Development –
4th 5th and 6th month – tissues and organs become more highly
developed
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Last 3 Months – organ systems develop further and fetus grows
in size
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Childbirth
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Hormone – Oxytocin – Causes contractions to start – cervix
expands and baby is pushed out of the vagina
Infancy – first 2 years of life
 Childhood – from infancy to puberty
 Adolescence – from puberty to adulthood
 Adulthood – 25 - 35 years of age and beyond
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