Endocrine

• Produces chemical messages for the body• Controls body functions with chemicals• Chemical are called hormones• Location where chemicals are produced are

glands, (group of cells that make special chemicals for the body

• Chemicals travel in the blood stream• Operates on feedback mechanisms• Ex: epinephrine – the fight or flight chemical

released in stressful situations

• Two types of hormones• Steroid – passes directly through cell

membrane• Binds to receptor proteins in specific cells to

form hormone receptor complex • Enters nucleus and binds to a DNA control

sequence• Transcription of specific genes to mRNA• mRNA move into cytoplasm and directs protein

synthesis

• Nonsteroid: cannot pass through cell membrane• Binds to receptors on the cell membrane• Activates enzyme on surface of cell membrane• Enzyme activates secondary messengers that

carry hormone into cell• cAMP, nucleotides and fatty acids can act as

secondary messengers• Messengers can activate or inhibit cell activities

Glands

• Pituitary – secretes 9 hormones - (HGH) stimulates skeletal growth, controls water levels in blood, keeps thyroid gland functioning properly and stimulates the process of pregnancy– Bean sized located in the base of the brain

• Thyroid – controls the rate of metabolism– Located in the front of the neck

• Parathyroid – controls calcium in the blood – Located in the neck behind the thyroid

• Thymus – regulates immune system to help fight disease

• Located on top of the heart

• Adrenal – releases epinephrine and norepinephrine that deals with stress

• Located on top of the kidneys

• Pancreas – controls blood sugar (also part of the digestive tract

Reproductive glands

• Gonads – production of gametes and secretion of sex hormones

• Ovaries – (female) hormones for reproduction

• Testes – (male) hormones for reproduction

Endocrine disorders

• Usually caused by an imbalance (to much or to little of a chemical)

• Insulin – controls the amount of blood sugar in the body

• Responds when food is eaten, cells are given instructions to take in glucose when the blood sugar increase

• diabetes mellitus – conditions where the pancreas doesn’t make enough insulin

• May require a person to take insulin shots to help balance glucose levels

• Growth hormone – stunted growth due to the pituitary glands failure to produce enough growth hormone (dwarfism)

• Some conditions can be treated with medication to correct if found soon enough

• Over active pituitary glands can result in over growth of the body (gigantism)

• Goiter – cause by a lack of iodine in the diet

• Body lacks thyroxine

• Thyroxine speeds up metabolism

• Thyroxine deficient cells are less active, can cause a body to be fatigued, weight gain and additional problems

• Used to be called “rich mans disease”

Reproduction

• 1st 6 weeks of development embryos are identical in appearance

• 7th week – primary reproductive organs begin to develop

• Hormones released by testes (testosterone) and ovaries (estrogen) determine if embryo will be male or female

• After birth, gonads continue to produce small amounts of sex hormones that influence the development of reproductive organs

• Neither the testes or ovaries can produce active reproductive cells until puberty

• Puberty – rapid growth and sexual maturation during which the reproductive system becomes fully functional.

• Puberty varies among individuals but usually starts between ages 9 to 15 and starts on average 1 year earlier in females

• Hypothalamus increases production of FSH and LH

Male Reproductive

• Function – produce and deliver sperm

• Primary organ is testes developed in the abdominal cavity and will descend just before or after birth into scrotum where temp is about 3° lower than body temp

• Within each testis are hundreds of tubules called seminiferous tubules where sperm is produced (millions)

• Sperm moves to the epididymis where fully mature are stored

• Sperm moves to the vas deferens extending into the abdominal cavity and eventually merges with the urethra

• Urethra is the tube that leads to the exterior of the body through the penis (urine and sperm exit body in same structure)

• Release of sperm through the penis is controlled by the autonomic nervous system

Female Reproductive

• Function is to produce ova and prepare female body for developing embryo

• Primary organ ovaries located in the pelvic region of the abdominal cavity

• Produce one mature ovum (egg) a month

• Each ovary contains about 400,000 primary follicles, clusters of cells surrounding a single egg

• Females are born with thousands of immature eggs but only about 400 will actually be released

• Approx. every 28 days, FSH increases and a follicle gets larger and completes the 1st meiotic cell division

• When meiosis is complete, a single large haploid egg and 3 polar bodies are produced (where disintegrate)

• Egg is released in process called ovulation

• Follicle breaks open and egg enters opening of Fallopian tube (two) and is pushed along fluid-filled tube by cilia (egg can be fertilized here, not good)

• After a few days, egg passes from Fallopian tube into the uterus

• Uterus is ready to receive egg

• Outer part of uterus is cervix which leads to a canal called the vagina that leads to the outside of the body

• After puberty the interaction between the reproductive and endocrine system in females forms a complex series of events called the menstrual cycle (continues until mid-40’s)

• Uterus prepares for egg, if fertilized, embryo implants and development begins

• If not, discharged with lining of uterus

4 Phases

• 1) Follicular: begins when estrogen is low, hypothalamus produces FSH and LH and cause the follicle to mature

• Egg enlarges and surrounding cells produce more estrogen and levels in blood begin to rise causing lining of uterus to thicken (take about 10 days)

• 2) Ovulation: shortest phase, 4 days, hypothalamus sends releasing hormones to tell pituitary gland to make more FSH LH and causes the follicle to rupture and release mature egg which is swept up into the Fallopian tube

• 3) Luteal : as egg moves through Fallopian tube, ruptured follicle turns yellow changes to corpus luteum and begins to release progesterone which stimulates growth and development of blood supply and surrounding tissue

• During first 2 days of luteal phase, the chances of fertilization are the greatest (10 to 14 days from last menstrual cycle)

• 4) Menstruation: if fertilization doesn’t take place, within 2 to 3 days the egg will pass through the uterus, the corpus luteum will disintegrate, the old follicle breaks down producing less estrogen and progesterone and the lining of uterus detaches from uterine wall and all of this material is expelled out of the body through the vagina lasting about 3 to 7 days.

• Process repeats.

Fertilization and Development

• Fertilization: process of joining egg (haploid) and sperm (haploid) form diploid(2N); contains a set of chromosomes from each parent

• Fertilized egg is called zygote• While in the Fallopian tube, the zygote

undergoes mitosis, as each cell divides the number of cells doubles, 4 days after fertilization, cell is a solid ball of approx. 64 cells called a morula

• 3 stages of early development• Implantation: morula forms cavity in

center, forming a hollow structure with an inner cavity called a blastocyst which in 6 to 7 days attaches to uterus

• Embryo secretes enzymes that digest a path into the soft tissue

• Cell begins to differentiate due to gene activation

• Gastrulation: formation of 3 cell layers, ectoderm, mesoderm, endoderm called primary germ layers: all organs and tissues will developed from them

• Endoderm – digestive system

• Ectoderm – skin and nervous system

• Mesoderm – internal tissues and organs

• Neurulation: development of the nervous system

• Extraembryonic membranes: amnion and chorion

• Amniotic sac: fluid filled sac which cushions and protects embryo

• Chorion: 3rd week of development – outermost membrane

• chorionic villi form on outer surface and extend to uterine lining

• Resulting membrane is the placenta – connection between mother and embryo and performs respiration, nourishment and excretion

• At 8 weeks of development embryo is called a fetus

• At 3 months, most major organs and tissues are fully formed, umbilical cord connects fetus to placenta and fetus is 8 cm long and a mass of 28 grams

Development

• Stem cells – unspecialized, undifferentiated cells found in fetal tissue and bone marrow and brains of adults

• 4th 5th 6th months, tissues become more complex and specialized and more tissues begin to function; heart becomes audible, bones begin changing, hair grows on skin, movement

• Last 3 months, organ systems mature and fetus grows in size and mass

• Lungs and other organs undergo series of changes to prepare of life outside the uterus

• Babies born before 8 months are premature and have breathing problems and CNS problems

• At 9 months oxytocin is released from pituitary gland that will begin contractions of large involuntary muscles in uterine wall

• As contraction become more frequent and stronger, cervix expands, amniotic sac breaks and is released

• Born head first, baby will cough/cry to remove fluid from lungs, umbilical cord is cut (navel)

• Infancy – 1st 2 years of life, rapid growth, teeth appear, language is imitated and understood

• Childhood: 2 years to 13, motor coordination, permanent teeth, long bones of skeletal system reach 80% of adult length, personality, social skills, reasoning

• Adolescence: puberty to adulthood, sex hormones start puberty that produces growth spurt that will slow in mid-adolescences as long bones stop growing and ossification takes place, higher thinking skills develop and personality changes

Diseases

• Bacterial infections: Chlamydia, syphilis (fatal), gonorrhea (treatment, antibiotics)

• Viruses: hepatitis B, HIV, HPV, genital herpes (no cure)

Multiple Births

• Two eggs released and both are fertilized by different sperm, fraternal twins are born

• Single zygote splits apart producing identical embryo’s, always the same sex