Endocrine and Reproductive Systems

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Endocrine and Reproductive Systems
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Endocrine System

• Made up of glands that release hormones into the
  bloodstream
• Hormones chemicals used to broadcast messages
• Bind to specific chemical receptors Target Cells

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Controlling the Endocrine SystemFeedback
Inhibition

• Regulated by feedback mechanisms that function to
  maintain homeostasis
• Negative feedback
• This means that the glands that stimulate the
  release of a hormone (for example, the pituitary)
  from another gland (for example, the thyroid) are
  eventually shut off, in a sense, so that too much
  hormone is not produced.
• Like an a.c. thermostat at home

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Endocrine Glands

• Glands that release hormones directly into the
  blood stream.

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• Pituitary gland
• Located in the skull
• Secretes 9 hormones that regulate many body
  functions
• controls the actions of several endocrine glands
• Hypothalamus
• controls the secretions of the pituitary gland
• These structures work together
• Allows the nervous endocrine systems to work
  together
• Coordinates body activities

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Pituitary Gland Hormones
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Thyroid Parathyroid Glands

• Major role regulate metabolism
• Makes thyroxine, which affects metabolic rates of
  cells
• Hyperthyroidism too much thyroxine
• Nervousness, elevated body temp., increased
  blood pressure, weight loss
• Hypothyroidism too little thyroxine
• Lack of energy, weight gain, goiter
• Hormones from the thyroid gland and the
  parathyroid glands maintain homeostasis in blood
  calcium levels

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• Adrenal glands
• help the body prepare for and deal with stress by
  releasing hormones
• Responsible for fight or flight
• Epinephrine, Norepinephrine
• Pancreas
• Releases insulin and glucagon
• helps to keep the level of glucose in the blood
  stable

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• Gonads the bodys reproductive glands
• Female ovaries
• Produces eggs, and sex hormones
• Estrogen responsible for producing eggs and the
  formation of physical features associated with
  the female body
• Progesterone prepares the uterus for the arrival
  of a developing embryo
• Male testes
• Produce sperm and testosterone
• Testosterone is responsible for producing sperm
  and the formation of physical features associated
  with the male body

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The Reproductive System

• Male Structures
• Testes
• Within each testis are
  seminiferous
  tubules where
  sperm are produced
• Scrotum houses the testes
• Epididymis where sperm
  fully matures
  and is stored
• Vas deferens connects the epididymis to the
  urethra
• These structures work together to produce and
  deliver sperm

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The Reproductive System

• Female Structures
• Ovaries houses
  immature eggs. Once
  an egg matures (1 every 28 days) it travels
  down the
• Fallopian tubes during its journey through the
  fallopian tubes an egg can be fertilized
• Uterus receives the fertilized egg
• Main function produce eggs. Secondary to
  prepare the female's body to nourish a developing
  embryo

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Menstrual Cycle

• If an egg is not fertilized, it is discharged
  along with the lining of the uterus
• 4 phases
• follicular phase 10days follicles (cell
  clusters) that surround the egg develop, the
  lining of the uterus thickens with nutrients
• Ovulation3-4days a mature egg is released
• Luteal phase greatest chance of fertilization
• Menstruationif the egg is not fertilized, then
  the unfertilized egg and the uterine lining are
  discharged through the vagina

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Fertilization Development

• The process of a sperm joining
  with an egg is called fertilization
• Sperm Egg Zygote
• Once the zygote forms, it undergoes mitosis
• 6-7days after fertilization,
  the embryo becomes a
  cluster of
  cells with a
  hollow center
  
  a blastocyst

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Stages of Early Development

• Implantation
• When the blastocyst attaches itself to the
  uterus
• Differentiation begins when cells begin to
  become specialized

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Stages of Early Development

• Gastrulation
• The blastocyst forms 3 layers
• Ectoderm develops into skin and nervous system
• Mesoderm develops into internal tissues organs
• Endoderm lining of digestive system and its
  organs

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Stages of Early Development

• Neurolation
• Development of the nervous system

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Extraembryonic Membranes

• During embryo development, mebmbranes develop to
  protect and nourish it
• Amniotic sac fluid-filled sac that cushions and
  protects the embryo in the uterus
• Placenta the embryos organ of respiration,
  nourishment, excretion

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Development

• After 8 weeks the embryo is a fetus
• 3 months major organs, tissues, muscles, and
  umbilical cord have formed
• Months 4-6 tissues become complex and
  specialized, AND begin to function
• Hear a heartbeat, bone continues to replace
  cartilage, hair growth, movement
• Months 7-9 organ systems mature, fetus doubles
  in mass, can regulate his/her own body
  temperature, the lungs and CNS begin to change in
  preparation for the outside world

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Embryo ? Fetus
Embryo 5-6 Weeks
Fetus at 14 weeks
Fetus at Full Term