the endocrine system ap chapter 45. you do not need to memorize all of the specific hormones!...
TRANSCRIPT
The Endocrine System
• AP Chapter 45
• You do not need to memorize all of the specific hormones!
• Concentrate on the thyroid, adrenal glands, pancreas, and sex hormones
• Emphasis will be on FEEDBACKS!
• The endocrine system, along with the nervous system, is responsible for coordinating our responses.
• The endocrine system is a slower system and the nervous system is a faster response.
Chemical signals
• Chemicals found in both systems and also as part of other signaling mechanisms bind to specific receptor proteins on or in target cells.
Secreted chemical signals include
– Hormones – produced by endocrine glands,
travel through the blood stream to target organs
ex – insulin, estrogen– Local regulators
(a) paracrine signals – act on neighboring cells, ex. – cytokines, interferon, prostaglandins
(b) autocrine signals – act on secreting cells itself, ex – cytokines
– Neurotransmitters - secreted by neurons at synapses
ex- serotonin, nitric oxide (NO)– Neurohormones – secreted by neurosecretory
cells, travel through the blood stream to target organs or synapses
ex- epinephrine– Pheromones – released into the environment;
between individuals
ex – insects marking trails,
mating, etc.
Fig. 45-2
Bloodvessel Response
Response
Response
Response
(a) Endocrine signaling
(b) Paracrine signaling
(c) Autocrine signaling
(d) Synaptic signaling
Neuron
Neurosecretorycell
(e) Neuroendocrine signaling
Bloodvessel
Synapse
Response
Chemical Classes of Hormones
• Three major classes of molecules function as hormones in vertebrates:
– Polypeptides (proteins and peptides)
water soluble– Amines derived from amino acids
some are water soluble, some are lipid soluble
– Steroid hormones
lipid soluble
Fig. 45-3
Water-soluble Lipid-soluble
Steroid:Cortisol
Polypeptide:Insulin
Amine:Epinephrine
Amine:Thyroxine
0.8 nm
• Lipid-soluble hormones (steroid hormones) pass easily through cell membranes, while water-soluble hormones (polypeptides and amines) do not
• The solubility of a hormone correlates with the location of receptors inside or on the surface of target cells
• Water-soluble hormones (hydrophilic) are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
• Lipid-soluble hormones (hydrophobic) diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells
Fig. 45-5-1
NUCLEUS
Signalreceptor
(a) (b)
TARGETCELL
Signal receptor
Transportprotein
Water-solublehormone
Fat-solublehormone
Fig. 45-5-2
Signalreceptor
TARGETCELL
Signal receptor
Transportprotein
Water-solublehormone
Fat-solublehormone
Generegulation
Cytoplasmicresponse
Generegulation
Cytoplasmicresponse
OR
(a) NUCLEUS (b)
Multiple Effects of Hormones
• Hormones can have multiple effects which depends on:
- the type of receptor they bind to - the specific signal transduction pathway - the specific transcription factor they activate.
• A hormone can also have different effects in different species
Fig. 45-8-1
Glycogendeposits
receptor
Vesseldilates.
Epinephrine
(a) Liver cell
Epinephrine
receptor
Glycogenbreaks downand glucoseis released.
(b) Skeletal muscle blood vessel
Same receptors but differentintracellular proteins (not shown)
Fig. 45-8-2
Glycogendeposits
receptor
Vesseldilates.
Epinephrine
(a) Liver cell
Epinephrine
receptor
Glycogenbreaks downand glucoseis released.
(b) Skeletal muscle blood vessel
Same receptors but differentintracellular proteins (not shown)
Epinephrine
receptor
Different receptors
Epinephrine
receptor
Vesselconstricts.
(c) Intestinal blood vessel
Negative feedback and antagonistic hormone pairs are common features of the
endocrine system
• Hormones are assembled into regulatory pathways
• A negative feedback loop inhibits a response by reducing the initial stimulus
• Negative feedback regulates many hormonal pathways involved in homeostasis
Fig. 45-11Pathway Example
Stimulus Low pH induodenum
S cells of duodenumsecrete secretin ( )
Endocrinecell
Bloodvessel
PancreasTargetcells
Response Bicarbonate release
Neg
ativ
e fe
edb
ack
–
Insulin and Glucagon: Control of Blood Glucose – an example of antagonistic
hormone pairs
• The pancreas has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin
• Insulin reduces blood glucose levels by– Promoting the cellular uptake of glucose– Slowing glycogen breakdown in the liver– Promoting fat storage
• Glucagon increases blood glucose levels by– Stimulating conversion of glycogen to
glucose in the liver– Stimulating breakdown of fat and protein
into glucose
– Remember: Glucagon – “Glucose ON!”
Fig. 45-12-2
Homeostasis:Blood glucose level
(about 90 mg/100 mL)
Insulin
Beta cells ofpancreasrelease insulininto the blood.
STIMULUS:Blood glucose level
rises.
Liver takesup glucoseand stores itas glycogen.
Blood glucoselevel declines.
Body cellstake up moreglucose.
Fig. 45-12-4
Homeostasis:Blood glucose level
(about 90 mg/100 mL)
Glucagon
STIMULUS:Blood glucose level
falls.
Alpha cells of pancreasrelease glucagon.
Liver breaksdown glycogenand releasesglucose.
Blood glucoselevel rises.
Remember!
GLUCOSE in the BLOOD
INSULIN GLUCAGON
Diabetes Mellitus
• Diabetes mellitus is perhaps the best-known endocrine disorder
• It is caused by a deficiency of insulin or a decreased response to insulin in target tissues
• It is marked by elevated blood glucose levels
• Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells
• Type II diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors
Fig. 45-10Major endocrine glands:
Adrenalglands
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Pancreas
Kidney
Ovaries
Testes
Organs containingendocrine cells:
Thymus
Heart
Liver
Stomach
Kidney
Smallintestine
Coordination of Endocrine and Nervous Systems in Vertebrates
• The hypothalamus receives information from the nervous system and initiates responses through the endocrine system
• Attached to the hypothalamus is the pituitary gland composed of the posterior pituitary and anterior pituitary which can control other glands
Who is the boss?
The hypothalamus has neurosecretory cells which secrete releasing and inhibiting hormones which control the pituitary gland which in turn controls other glands.
* RH, such TRH, indicates a releasing hormone
Fig. 45-14
Spinal cord
Posteriorpituitary
Cerebellum
Pinealgland
Anteriorpituitary
Hypothalamus
Pituitarygland
Hypothalamus
Thalamus
Cerebrum
The hypothalamic – pituitary axis
Hypothalamus
• The hypothalamus secretes two hormones which are stored in the posterior pituitary.
1) oxytocin – induces uterine contractions during birth and milk production
2) ADH – which decreases urine volume
Fig. 45-15
Posteriorpituitary
Anteriorpituitary
Neurosecretorycells of thehypothalamus
Hypothalamus
Axon
HORMONE OxytocinADH
Kidney tubulesTARGET Mammary glands,uterine muscles
Pituitary Gland
• The posterior pituitary stores and secretes hormones that are made in the hypothalamus
• The anterior pituitary makes and releases hormones under regulation of the hypothalamus
Fig. 45-17
Hypothalamicreleasing andinhibitinghormones
Neurosecretory cellsof the hypothalamus
HORMONE
TARGET
Posterior pituitary
Portal vessels
Endocrine cells ofthe anterior pituitary
Pituitary hormones
Tropic effects only:FSHLHTSHACTH
Nontropic effects only:ProlactinMSH
Nontropic and tropic effects:GH
Testes orovaries
Thyroid
FSH and LH TSH
Adrenalcortex
Mammaryglands
ACTH Prolactin MSH GH
Melanocytes Liver, bones,other tissues
The anterior pituitary secretes tropic hormones
• A tropic hormone regulates the function of endocrine cells or glands
• You do not need to memorize these….just realize they are TROPIC hormones and regulate other endocrine glands. You may see them in diagrams.
• The four strictly tropic hormones are– Thyroid-stimulating hormone (TSH) – Follicle-stimulating hormone (FSH)– Luteinizing hormone (LH)– Adrenocorticotropic hormone (ACTH)
(FSH and LH are reproductive hormones.)
Thyroid Gland
• T3 and T4 thyroxin, regulates metabolism
(needs dietary iodine to function properly – goiter if not enough iodine)
• Calcitonin – lowers calcium in blood – deposition in bones and secretion into kidney filtrate
“tone down the calcium”
T3 and T4
• act by binding to thyroid receptors that are distributed in almost every organ.
• Typically, this process regulates gene transcription and the subsequent production of various proteins that are involved in development, growth, and cellular metabolism
Graves Disease• an autoimmune
disorder that leads to overactivity of the thyroid gland (hyperthyroidism) and causes the thyroid to increase in size. Other symptoms are anxiety, tiredness, insomnia, irregular heart rhythms, bulging eyes.
Parathyroid Gland
• PTH parathormone – raises calcium levels in blood – from bones and reuptake in kidneys
Fig. 45-20-2
PTH
Parathyroid gland(behind thyroid)
STIMULUS:Falling blood
Ca2+ level
Homeostasis:Blood Ca2+ level
(about 10 mg/100 mL)
Blood Ca2+ level rises.
Stimulates Ca2+
uptake in kidneys
Stimulates Ca2+ release from bones
Increases Ca2+ uptake in intestines
Activevitamin D
Adrenal medulla
• Epinephrine (adrenaline) – raises metabolic rate, “fight or flight”
• Norepinephrine (noradrenaline) controls blood pressure
medulla
cortex
Adrenal cortex
• Glucocorticoids (cortisol) – glucose from noncarb sources, such as muscles
• Mineralocorticoids (aldosterone) – induces kidneys to reabsorb water and salts
• Both of these deal with long-term stress
Cushing’s Disease
Cushing's syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels
of the hormone cortisol.
•severe fatigue•weak muscles•high blood pressure•high blood glucose•increased thirst and urination•irritability, anxiety, depression•a fatty hump between the shoulders•moon face
Fig. 45-21c
(b) Long-term stress response
Effects ofmineralocorticoids:
Effects ofglucocorticoids (cortisol):
1. Retention of sodium ions and water by kidneys
2. Increased blood volume and blood pressure
2. Possible suppression of immune system
1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose
Adrenalgland
Kidney
Adrenal cortex
STRESS!
The production of these hormonesis controlled by thehypothalamus andanterior pituitary
Testes
• Androgens (testosterone) – gender, male secondary sex characteristics
Ovaries
• Estrogen – maintenance of female reproductive system and development of secondary female characteristics
• Progesterone – prepares uterus for child
Pineal Gland
• Melatonin – biological clock
Hormonal pathways work with the hypothalamus and anterior pituitary to coordinate responses
• In regulating metabolism by the thyroid:
Also, notice the positiveAND negative feedbackshere.
Hormonal pathways work with the hypothalamus and anterior pituitary to
coordinate responses
• Ex – in the gonads
• GnRH (hypothalamus) affects FSH and LH (anterior pituitary) which affects estrogens and androgens (ovaries/testes)
Testosterone Synthesis
Estrogen and progesterone
synthesis
Which endocrine gland?
• Too little of my hormone and you will feel tired and sluggish and probably gain weight.
THYROID
A malfunction in this gland can result in a giant.
Anterior Pituitary
This gland prepares me for an emergency situation by increasing my heartrate.
AdrenalGlands
This gland is also used in the digestive system. It also comes into play when I eat lots of M and M’s!
PANCREAS
This gland is called the “master gland” because it secretes nine hormones many of which control other endocrine glands by feedback control.
PituitaryGland
If this gland is not working properly, diabetes can result.
Pancreas
• If this gland is not working properly, your nerves and muscles will not function properly either due to calcium deficiency.
ParathyroidGland
• These glands do not function properly in chromosomal mutations such as in Turner’s and Klinefelter’s syndrome.
Gonads
This gland makes me wake up in the morning and ready to go!
Pineal Gland
Fig. 45-10Major endocrine glands:
Adrenalglands
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Pancreas
Kidney
Ovaries
Testes
Organs containingendocrine cells:
Thymus
Heart
Liver
Stomach
Kidney
Smallintestine
Name of
Gland
Hormone Function
A pineal Daily rhythms
B
hypothalamus
Regulates blood volume and
pressure by affecting kidneys
C Growth hormone growth
D thyroid calcitonin
E parathyroid Raises calcium levels
F Hormones for immune
system
immune
G adrenal adrenaline
H insulin Lowers blood glucose levels
I ovaries Testosterone/
J testes Testosterne/androgens Secondary female sexual
characteristics
Hormones in the reproductive system
• GnRH from the hypothalamus directs the anterior pituitary to produce FSH and LH that regulate gametogenesis and sex hormone production in males and females
• Sex hormones:
- androgens – male in the testes
- estrogens – female in the ovaries
• So in males, FSH and LH (pituitary hormones) stimulate the production of sperm and secretion of testosterone
Fig. 46-13
Hypothalamus
GnRH
FSH
Anterior pituitary
Sertoli cells Leydig cells
Inhibin Spermatogenesis Testosterone
Testis
LH
Neg
ativ
e fe
edb
ack
Neg
ativ
e fe
edb
ack
– –
–
Nourish developing sperm Secrete testosterone
Fig. 46-11
Seminalvesicle(behind bladder)
(Urinarybladder)
Prostate gland
Bulbourethralgland
Erectile tissueof penis
Urethra
ScrotumVas deferens
Epididymis
Testis
Seminal vesicle
(Urinarybladder)
(Urinaryduct)
(Rectum)
Vas deferens
Ejaculatory duct
Prostate gland
Bulbourethral gland
Vas deferens EpididymisTestisScrotum
(Pubic bone)
Erectiletissue
Urethra
Glans
Prepuce
Penis
• In females, these control the reproductive cycle – the uterine cycle (menstrual cycle) and the ovarian cycle
• In the uterus, this results in the build-up of the inner layer of the uterus called the endometrium which will be shed (menstruation) if fertilization does not occur
Fig. 46-10b
OvariesOviduct
FolliclesCorpus luteum
Uterine wallUterus
Cervix
Endometrium
Vagina
• In the ovary, these control the development of the egg in the follicle, the release of the egg (ovulation), and the disintegration of the egg follicle (corpus luteum)
Fig. 46-14(a) Control by hypothalamus
Hypothalamus
GnRH
Anterior pituitary
1
Inhibited by combination ofestradiol and progesteroneStimulated by high levelsof estradiol
Inhibited by low levels of estradiol
2 FSH LH
Pituitary gonadotropinsin blood
(b)6
FSH
LH
FSH and LH stimulatefollicle to grow
LH surge triggersovulation
3
Ovarian cycle 8(c) 7
Growing follicle Maturingfollicle
Corpusluteum
Degeneratingcorpus luteum
Follicular phase Ovulation Luteal phase
Estradiol secretedby growing follicle inincreasing amounts
Progesterone andestradiol secretedby corpus luteum
4
Ovarian hormones in blood
Peak causesLH surge
(d)5
Estradiol Progesterone 910
Estradiol levelvery low
Progesterone and estra-diol promote thickeningof endometrium
Uterine (menstrual) cycle
Endometrium
(e)
Menstrual flow phase Proliferative phase Secretory phase
Day
s
0 5 10 14 20 25 28| | |
15| | | | |
–
–
+
Ovarian cycle
• Follicular phase: FSH stimulates follicle growth
• After LH surge, ovulation occurs
• Luteal Phase: ruptured follicle becomes a corpus luteum which secretes progesterone
LHFSH
Hypothalamus
Ant Pituitary
GnRH
Follicular phase Ovulation Luteal Phase
OvarianCycle
after LH surge
Uterine cycle
• Proliferative Phase: Estrogens from growing follicle stimulate the growth of the endometrium
• Secretory Phase - After ovulation, progesterone causes the increased vascularization and development of secretory glands
• Menstrual flow phase – rapid drop of hormones cause endometrium to disintegrate
Uterine Cycle
estradiol
progesterone
MenstrualCycle
ProliferativePhase
Secretory Phase
Promote thickeningof endometrium
When levels fall, menstrualCycle begins
endometrium
Fig. 46-14b
Ovarian hormones in blood
Peak causesLH surge
Estradiol level very low
Estradiol Progesterone
Ovulation Progesterone and estra-diol promote thickeningof endometrium
Uterine (menstrual) cycle
Endometrium
0 5 10 14 20 25 28| | | | | | | |
Da
ys
15
Menstrual flow phase Proliferative phase Secretory phase
(d)
(e)
Follicle producesestrogen
Corpus Luteummaintains production of est/progesterone
What happens if female becomes pregnant?
• Implantation takes place around 7 days after conception
• Embryo secretes hCG human chorionic gonadotropin maintains est/prog by corpus luteum
• In 2nd trimester of pregnancy, placenta takes over that job
How do birth control pills work?
• Synthetic est/prog combination that works by neg feedback to inhibit GnRN production and thus FSH and LH and no ovulation
