Hormones that Affect Metabolism. Two Major Glands Thyroid Gland Parathyroid Gland.
Introductory Questions #8 1)Name the nine major endocrine glands found in the body. Which one is...
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Transcript of Introductory Questions #8 1)Name the nine major endocrine glands found in the body. Which one is...
Introductory Questions #8
1) Name the nine major endocrine glands found in the body. Which one is called the “master gland”?
2) Name three major local regulators that act on nearby target cells. (pgs. 947-948)
3) Name three key molecules that play a role in the signal transduction pathway (typical reactions in the endocrine system).
4) How is the anterior part of the pituitary gland different from the posterior part? Name the hormones secreted from each area. Which region secretes fewer types of hormones?
5) Using the table on pg. 949, name the hormone(s) that:-Raises blood-calcium levels
-maintains metabolic processes
Homeostasis & Osmoregulation
Chapter
• It assists the kidneys by– making urea from ammonia– breaking down toxic chemicals
The liver is vital in homeostasis
Homeostasis: regulation of internal environment
• Thermoregulation internal temperature
• Osmoregulation solute and water balance
• Excretion nitrogen containing waste
Regulation of body temperature• Thermoregulation• 4 physical processes:• Conduction~transfer of heat between
molecules of body and environment• Convection~transfer of heat as
water/air move across body surface• Radiation~transfer of heat produced
by organisms• Evaporation~loss of heat from liquid
to gas
• Sources of body heat:• Ectothermic: determined by
environment• Endothermic: high metabolic rate
generates high body heat
• Bears don’t technically hibernate– They do enter a dormant state, when their body
temperature drops by several degrees
• Bears are endotherms– Endothermic animals derive
most of their body heat from metabolism
– Ectothermic animals warm themselves mainly by absorbing heat from their surroundings
Let Sleeping Bears Lie
• Dormant bears have internal homeostatic mechanisms that compensate for fluctuations in the external environment
– Thermoregulation maintains the body temperature within
a tolerable range– Osmoregulation controls the
gain and loss of water and dissolved solutes
– Excretion is the disposal of metabolic wastes
• Body temperature regulation requires adjustment to heat gained from or lost to an animal’s environment
Heat is gained or lost in four ways
Figure 25.1
Convection Radiation
Evaporation
Conduction
• Hormonal changes may increase heat production by raising the metabolic rate
– Fur and feathers help the body retain heat– Shivering, as these honeybees are doing, also
increases metabolic heat production
Figure 25.2A
Regulation during environmental extremes
• Torpor~ low activity; decrease in metabolic rate
• 1- Hibernation long term or winter torpor (winter cold and food scarcity); bears, squirrels
• 2- Estivation short term or summer torpor (high temperatures and water scarcity); fish, amphibians, reptiles
• Both often triggered by length of daylight
AP Biology 2004-2005
Chapter 45.
Endocrine SystemHormones
AP Biology 2004-2005
Regulation Why are hormones needed?
chemical messages from one body part to another
communication needed to coordinate whole body
homeostasis & regulation metabolism growth development maturation reproduction
growth hormones
AP Biology 2004-2005
Regulation & Communication Animals rely on 2 systems for regulation
endocrine system ductless gland which secrete
chemical signals directly into blood chemical travels to target tissue slow, long-lasting response
nervous system system of neurons, central
nerve system transmits “electrical” signal to
target tissue fast, short-lasting response
AP Biology 2004-2005
Regulation by chemical messengers
AxonNeurotransmitter
Endocrine gland
Receptor proteins
Hormonecarried by blood
Target cell
Neurotransmitters released by neurons Hormones release by endocrine glands
AP Biology 2004-2005
Classes of Hormones Protein-based hormones
polypeptides small proteins: insulin, ADH
glycoproteins large proteins + carbohydrate: FSH, LH
amines modified amino acids: epinephrine, melatonin
Lipid-based hormones steroids
modified cholesterol: sex hormones, aldosterone
AP Biology 2004-2005
How do hormones act on target cells Lipid-based hormones
lipid-soluble diffuse across membrane & enter cells
bind to receptor proteins in cytoplasm & then this hormone-receptor complex moves into nucleus
bind to receptor proteins in nucleus bind to DNA as transcription factors
AP Biology 2004-2005
Nucleus
Cytoplasm
Steroid hormone (S) passes through plasma membrane.
Inside target cell, the steroid hormone binds to a specific receptor protein in the cytoplasm or nucleus.
Hormone-receptor complex enters nucleus & binds to DNA, causing gene transcription
Protein is produced.
Protein synthesis is induced.
Plasma membrane
DNAmRNA
Protein
Steroidhormone
Blood plasma
Proteincarrier
1
2
2
3
3
5
5 4
4
S
S
S
1S
Action of steroid (lipid) hormones
AP Biology 2004-2005
How do hormones act on target cellsSignal molecule
Cell surface receptorenzyme
G proteincAMP
Targetprotein
Nucleus
Cytoplasm
ATP
Protein-based hormones hydrophilic & not lipid
soluble can’t diffuse across
membrane trigger secondary (2°)
messenger pathway transmit “signal” across
membrane “signal transduction”
usually activates a series of 2° messengers multi-step “cascade”
activate cellular response enzyme action, uptake or
secretion of molecules, etc.
AP Biology 2004-2005
Action of protein hormones
3
4
GTPactivatesenzyme
activatesenzyme
activatesenzyme
Receptorprotein
cAMP
Proteinhormone
ATP
1
2
Cytoplasm
Produces an action
proteinmessengercascade
G protein
AP Biology 2004-2005
adrenal gland
Action of epinephrine (adrenalin)
3
4
GTPactivates
protein kinase-A
activatesphosphorylase
activates adenylyl cyclase
Receptorprotein cAMP
Epinephrine
ATP
1
2
Cytoplasm
G protein
Liver cell
GlucoseGlycogen
releasedto blood
AP Biology 2004-2005
Benefits of a 2° messenger system
Amplification!
Signal molecule Receptor protein Activated adenylyl cyclase
Amplification
Amplification
Amplification
Amplification
GTP G protein
2
1
3
4
5
6
7
Enzymatic product
Enzyme
Protein kinase
cAMP
Not yetactivated
AP Biology 2004-2005
Ductless glands release hormones into blood
Tropic hormones= a hormone that has another endocrine gland as a target
Endocrine system
Duct glands = exocrine(tears, salivary)
AP Biology 2004-2005
Major vertebrate hormones (1)
AP Biology 2004-2005
Major vertebrate hormones (2)
AP Biology 2004-2005
Endocrine & Nervous system links Hypothalamus = “master control center”
nervous system receives information from nerves around body
about internal conditions regulates release of hormones from pituitary
Pituitary gland = “master gland” endocrine system secretes broad range
of hormones regulating other glands
AP Biology 2004-2005
Thyroid gland
Hypothalamus
Anteriorpituitary
Gonadotropic hormones:Follicle-stimulatinghormone (FSH) & luteinizing hormone (LH)
Mammaryglandsin mammals
Musclesof uterus
Kidneytubules
Posteriorpituitary
Thyroid-stimulating Hormone(TSH)
Antidiuretic hormone(ADH)
Adrenalcortex
Boneand muscle Testis
Ovary
Melanocytein amphibian
Adrenocorticotropic
hormone (ACTH) Melanocyte-stimulating hormone(MSH)
OxytocinProlactin (PRL)
Gro
wth
hor
mon
e (G
H)
AP Biology 2004-2005
AP Biology 2004-2005
Homology in hormones
prolactin
mammals birds amphibiansfish
milkproduction
fatmetabolism
metamorphosis& maturation
salt &water
balance
growthhormone
growth& development
What does this tell you about these hormones?
same gene family
AP Biology 2004-2005
Hormones & Homeostasis Negative feedback
stimulus triggers control mechanism that inhibits further change body temperature sugar metabolism
Positive feedback stimulus triggers
control mechanism that amplifies effect lactation labor contractions
Anterior pituitary
Inhibition
–
Inhibition
Target glands
Hypothalamus
Releasing hormones(TRH, CRH, GnRH)
Tropic hormones(TSH, ACTH, FSH, LH)
–
(thyroid, adrenal cortex, gonads)
Hormones
AP Biology
Regulating blood sugar levels Islets of Langerhans Alpha cells:
•glucagon~ raises blood glucose levels
Beta cells:
•insulin~ lowers blood glucose levels
Type I diabetes mellitus
(insulin-dependent; autoimmune disorder)
Type II diabetes mellitus
(non-insulin-dependent; reduced responsiveness in insulin targets)
AP Biology 2004-2005
- triggers release of glucose by liver
- stimulates appetite
Regulating blood sugar levels
- triggers uptake of glucose by body cells
- triggers storage in liver
- depresses appetite
pancreas
pancreas
beta islet cells
alpha islet cells
Islets of LangerhansAlpha cells: •glucagon~ raises
blood glucose levelsBeta cells: •insulin~ lowers
blood glucose levelsType I diabetes mellitus (insulin-
dependent; autoimmune disorder)Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness
in insulin targets)
AP Biology 2004-2005
Regulating blood osmolarityIf amount of dissolved material in blood is too high, need to dilute blood
ADH
Dehydration Lowers blood volume & pressure
Increased waterretention
Increasedvasoconstrictionleading to higherblood pressureReduced
urine volume
Osmotic concentrationof blood increases
ADH synthesized in hypothalamus
ADH released from posterior pituitary into blood
Osmoreceptors NegativefeedbackNegative
feedback
AP Biology 2004-2005
Regulating metabolism Hypothalamus
TRH = TSH-releasing hormone
Anterior Pituitary TSH = thyroid stimulating hormone
Thyroid produces thyroxine hormones metabolism & development
bone growth mental development metabolic use of energy blood pressure & heart rate muscle tone digestion reproduction
tyrosineiodine
thyroxine
AP Biology 2004-2005
GoiterIodine deficiency causes thyroid to enlarge as it tries to produce thyroxine
AP Biology 2004-2005
Homology in hormones
Days from emergence of forelimb
TRH rises
TRH TSH Thyroxine
–35 –30 –25 –20 –15 –10 –5 0 +5 +10
Th
yro
xin
e s
ecre
tio
n r
ate
Thyroxine stimulates metamorphosis in amphibians
AP Biology 2004-2005
Regulating blood calcium levels
Increased blood Ca++
Thyroid
ParathyroidsLow blood Ca++
Parathyroidhormone (PTH)
Increased absorptionof Ca++ from intestine due to PTH activation of Vitamin D
Reabsorption of Ca++ &excretion of PO4
Osteoclasts dissolve CaPO4crystals in bone, releasing Ca++
–Negativefeedback
The Gonads• Steroid hormones: precursor is cholesterol
– Androgens (testosterone)• sperm formation• male secondary sex characteristics; gonadotropin
– Estrogens (estradiol)• uterine lining growth• female secondary sex characteristics• gonadotropin
– Progestins (progesterone)• uterine lining growth
AP Biology 2005-2006
Any Questions??