6.6 hormones, homeostasis, and reproduction
Transcript of 6.6 hormones, homeostasis, and reproduction
6.6 HORMONES, HOMEOSTASIS, AND
REPRODUCTIONPart 1
Understandings
Insulin and glucagon are secreted by beta and alpha cells in the pancreas, respectively, to control blood glucose concentration.
Thyroxin is secreted by the thyroid gland to regulate metabolic rate and help control body temperature.
Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
Melatonin is secreted by the
Applications/Skills
A: Causes and treatments of Type I and Type II Diabetes.
A: Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
A: Causes of jetlag and use of melatonin to alleviate it.
HOMEOSTASIS
Limits for physiological variables
Variable Limits or range
Blood pH 7.35-7.45
Blood glucose 0.8-1.0 g glucose/ L blood
Body temperature 37C/98.6F
GETTING BACK TO SET POINT
http://upload.wikimedia.org/wikipedia/commons/2/22/105_Negative_Feedback_Loops.jpg
HORMONES
Secreted by endocrine glands into the blood stream
Some have few target tissues (glucagon-hepatic cells and muscle cells) and some have many target tissues (insulin- all body cells)
https://ohgoshmygrades.files.wordpress.com/2014/11/09-endocrine-glands.jpg
THYROXINSecreted by the thyroid gland
Two forms: T3 (three iodine atoms) and T4 (four iodine atoms)
Targets almost all cells
Responsible for metabolic rate
HYPO- AND HYPERTHYROIDISM
Hypothyroidism Body doesn’t produce enough thyroxin
Slow metabolic rate
Gains weight easily
Often cold
Hyperthyroidism Weight loss
Rapid heartbeat
Nervousness/anxiety
Sensitivity to heat
LEPTINSecreted by adipose tissue
Targets hypothalamus of the brainstem
Lowers appetite
http://www.bullyextreme.com/wp-content/uploads/2013/03/leptin-weight-loss.gif
LEPTIN AND OBESITY
Greater fat stores=more leptin secretion
Obese individuals seem to be resistant to desired effects of leptin Why?
http://sevendeadlysynapses.com/wp-content/uploads/2011/05/ob-mice-leptin.gif
MELATONINSecreted by pineal gland to regulate circadian rhythm
Peak production occurs after dark
Can be altered by changing exposure to light
http://nabulsi.com/images/inside-arts/en/11665/01.jpg
JET LAG
Disruption of sleep cycles, generally due to travelling across time zones.
Can be alleviated by taking melatonin supplement until natural rhythms resume
http://www.precisionnutrition.com/wordpress/wp-content/uploads/2013/07/Precision-Nutrition-Blog-All-About-Jet-Lag-orange-Time-Zone-Clocks.jpg
INSULINSecreted by beta cells in the pancreas
Causes protein channels in cells to open
Allows for diffusion of glucose into the cell for cellular respiration
Stimulates hepatocytes to convert glucose into glycogen to be stored in the liver or in muscles
https://ntp.niehs.nih.gov/nnl/hepatobiliary/liver/hglycoacc/images/figure-004-a71199_medium.jpg
GLUCAGON
Secreted by alpha cells of the pancreas
Stimulates hydrolysis of glycogen
Increase in blood glucose levels
http://www.nicerweb.com/bio1152/Locked/media/ch45/45_12GlucoseHomeostasis.jpg
TYPE I DIABETESImmune system targets beta cells
Insufficient insulin is produced
Controlled by insulin injection
Often called “juvenile diabetes” but can develop at any age
http://blog.joslin.org/wp-content/uploads/2012/10/insulin-injection.jpg
TYPE II DIABETESCell receptors stop responding to insulin (insulin resistance)
Controlled by diet
Can be caused by genetics, poor diet, obesity, and/or age
EFFECTS OF DIABETESBlindness
Kidney failure
Nerve damage
Increased risk of cardiovascular disease
Poor wound healing leading to amputation
http://www.activeonegroup.com/wp-content/uploads/2014/10/type-2-diabetes.jpg
6.6 HORMONES, HOMEOSTASIS, AND
REPRODUCTIONPart 2
Understandings
A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.
Testosterone causes prenatal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty
Estrogen and progesterone cause prenatal development of female reproductive organs and female secondary sexual characteristics
The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.
Applications/Skills
A: The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy
A: William Harvey’s investigation of sexual reproduction in deer
S: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.
Guidance- The roles of FSH, LH, estrogen, and progesterone in the menstrual cycle are expected.- William Harvey failed to solve the mystery of sexual reproduction because effective microscopes
were not available when he was working, so fusion of gametes and subsequent embryo development remained undiscovered.
HISTORICAL PERSPECTIVE OF SEXUAL REPRODUCTION
One of the earliest theories as to how animals reproduce sexually was the 'soil and seed' theory proposed by Aristotle
According to this theory, the male produces a ‘seed' which forms an ‘egg' when mixed with menstrual blood (the ‘soil’)
The ‘egg’ then develops into a fetus inside the mother according to the information contained within the male 'seed’ alone
http://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/sexual-reproduction.html
DEBUNKING THE ’SOIL AND SEED’ THEORYWilliam Harvey studied the sexual organs of female deer after mating in an effort to identify the developing embryo
He was unable to detect a growing embryo until approximately 6 – 7 weeks after mating had occurred
He concluded that Aristotle’s theory was incorrect and that menstrual blood did not contribute to the development of a fetus
Harvey was unable to identify the correct mechanism of sexual reproduction and incorrectly asserted that the fetus did not develop from a mixture of male and female ‘seeds’
http://ib.bioninja.com.au/standard-level/topic-6-human-physiology/66-hormones-homeostasis-and/sexual-reproduction.html
HUMAN REPRODUCTIONFertilization of a female egg by a male sperm
Hormones play key role in further development and gender determination
https://www.papermasters.com/images/human-reproduction.jpeg
MALE OR FEMALE?
XX- female High estrogen and progesterone production
Development of female reproductive structures
XY- male High testosterone production
Early testes development
https://tse2.mm.bing.net/th?id=OIP.M1c56c49552cb050d624637001cc313dbH0&pid=15.1&P=0&w=275&h=188
Eight week embryo
THE ROLE OF TESTOSTERONE
Formation of male genitalia during embryonic development
Secondary sex characteristics during puberty Body hair
Enlargement of larynx
Deepening of the voice
Increased muscle mass
Enlargement of the penis
Production of sperm
Sex drive
Adapted from http://www.raw-milk-facts.com/images/Testosterone.gif
Sperm produced here in seminiferous tubulesSperm are stored here to mature
Sperm travels from epididymis to urethra
Produces seminal fluid with nutrients for sperm
Sacs that hold testes outside of the body cavity
Male sex organ; becomes erect as a result of blood engorgement to facilitate ejaculation
THE ROLE OF ESTROGEN
Formation of female genitalia during embryonic development
Secondary sex characteristics in puberty Enlargement of breasts
Growth of pubic and underarm hair
Widening of hips
Onset and regulation of the menstrual cycle
http://blogs.psychcentral.com/depression/files/2011/03/estrogen.jpg
Produce/secrete estrogen; produce/release ovum
Carries ovum/early embryo to uterus
Embryo implants/develops if pregnancy occurs
Inner lining of uterus
Lower portion of uterus that opens into the vagina
Female sex organ; canal that leads from external genitalia to cervix
Vulva External female genitalia
MORE ON ESTROGEN
Released by ovaries
Enters bloodstream
Endometrium Pituitary gland
Increases density of blood vessels in preparation of implantation
http://images.clipartpanda.com/uterus-clipart-uterus-1024x697.jpg
Releases more FSH/LH
MENSTRUAL CYCLE
Regulated by hypothalamus; 28ish days
1. Follicular Phase : low estrogen, FSH = egg develops in ovary
2. Ovulation (Day 14): LH = egg released into Fallopian tube
3. Luteal Phase : • progesterone, estrogen = lining of uterus
(endometrium) thickens to prepare for pregnancy• Egg travels down Fallopian tube, waits for fertilization
4. Menstruation (no fertilization) :• P/E = lining of uterus breaks down• Blood and unfertilized egg discharged
EFFECTS OF FSH AND LH
Target tissue: Ovaries
Increase production/secretion of estrogen
Production of Graafian follicles
Elevated levels leads to ovulation
http://legacy.owensboro.kctcs.edu/gcaplan/anat2/notes/Image721.gif
OVULATION
http://schoolbag.info/biology/humans/humans.files/image321.jpg
PROGESTERONE
Produced by corpus luteum for 10-12 days following ovulation
Maintains thickened endometrium
High levels of progesterone combined with high levels of estrogen prevent production of another Graafian follicle
HUMAN EMBRYONIC DEVELOPMENTConception: in oviduct
Implantation: in uterus
Hormones: Human Chorionic Gonadotropin (hCG): maintain estrogens in early pregnancy; pregnancy test
About 40 weeks
Egg lodged in oviduct = ectopic (tubal) pregnancy
Implantation of blastocyst
Blastocyst
Endo-metrium
Cavity
Inner cell mass
Trophoblast
EARLY POSTFERTILIZATION EVENTS
THE PILL
“Contains estrogen and progesterone
Main effect: Prevent ovulation
Other effects: Thickens cervical mucus – slows down sperm Thins uterus lining – prevent implantation of fertilized egg
Usage: active pill for 21 days, inactive pills for 7 days (“period”)
Other medical uses: Medication for mild/moderate acne Decrease painful menstruation Treat polycystic ovary syndrome (PCOS) Correct irregular menstrual cycle Reduce risk of ovarian and endometrial cancers
IVFWoman receives hormone therapy 1st two weeks: hormone injections to halt normal ovulation
2nd two weeks: hormone injections to induce superovulation
Eggs are harvested
Sperm collected from manEggs and sperm combined in culture dishUsually multiple fertilized eggs are implanted into the woman’s uterusUnused embryos frozen