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Chapter 45 ~ Chemical Signals in Animals Endocrine system ~Hormones

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Chapter 45 ~ Chemical Signals in Animals Endocrine system ~Hormones growth hormones * * * tropins (tropic hormones) stimulate growth in target organs/cells (tropic ... – PowerPoint PPT presentation

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Title: Chapter 45 ~ Chemical Signals in Animals Endocrine system ~Hormones


1
Chapter 45 Chemical Signals in
AnimalsEndocrine system Hormones
growth hormones
2
Regulatory systems
  • Hormone chemical signal secreted into body
    fluids (blood) communicating regulatory messages
  • Target cells body cells that respond to hormones
  • Endocrine system/glands hormone secreting
    system/glands (ductless) exocrine glands secrete
    chemicals (sweat, mucus, enzymes) through ducts
  • Neurosecretory cells actual cells that secrete
    hormones
  • Feedback mechanisms negative and positive

3
Local regulators cells adjacent to or near
point of secretion
  • Growth factors proteins for cell
    proliferation
  • Nitric oxide (NO) neurotransmitter cell
    destruction vessel dilation
  • Prostaglandins modified fatty
    acids secreted by placenta and immune system
    also found in semen

4
Regulation
  • Why are hormones needed?
  • chemical messages from one body part to another
  • communication needed to coordinate whole body
  • daily homeostasis regulation of large scale
    changes
  • solute levels in blood
  • glucose, Ca, salts, etc.
  • metabolism
  • growth
  • development
  • maturation
  • reproduction

growth hormones
5
Regulation Communication
  • Animals rely on 2 systems for regulation
  • endocrine system
  • system of ductless glands
  • secrete chemical signals directly into blood
  • chemical travels to target tissue
  • target cells have receptor proteins
  • slow, long-lasting response
  • nervous system
  • system of neurons
  • transmits electrical signal release
    neurotransmitters to target tissue
  • fast, short-lasting response

6
Regulation by chemical messengers
  • Neurotransmitters released by neurons
  • Hormones release by endocrine glands

endocrine gland
neurotransmitter
axon
hormone carried by blood
receptor proteins
receptor proteins
Lock Keysystem
target cell
7
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

insulin
8
Mode of Action Chemical Signaling
  • 1- Plasma membrane reception

    signal-transduction pathways
    (neurotransmitters, growth factors, most
    hormones)
  • 2- Cell nucleus reception

    steroid hormones, thyroid
    hormones, some local regulators

9
Action of lipid (steroid) hormones
steroid hormone
target cell
blood
S
1
S
cross cell membrane
protein carrier
S
2
cytoplasm
binds to receptor protein
becomes transcription factor
5
mRNA read by ribosome
S
3
plasma membrane
4
DNA
mRNA
6
7
nucleus
protein
protein secreted
ex secreted protein growth factor (hair, bone,
muscle, gametes)
10
Action of protein hormones
signal-transduction pathway
1
signal
proteinhormone
plasma membrane
P
activates G-protein
binds to receptor protein
activates enzyme
cAMP
acts as 2 messenger
receptor protein
ATP
transduction
GTP
activatescytoplasmicsignal
ATP
activates enzyme
2
secondary messengersystem
activates enzyme
cytoplasm
response
3
produces an action
target cell
11
Benefits of a 2 messenger system
1
signal
Activated adenylyl cyclase
receptor protein
Not yet activated
2
amplification
4
amplification
3
cAMP
5
amplification
GTP
G protein
protein kinase
6
amplification
  • Amplification!

enzyme
Cascade multiplier!
7
amplification
FAST response!
product
12
Maintaining homeostasis
hormone 1
lowersbody condition
gland
specific body condition
raisesbody condition
gland
Negative FeedbackModel
hormone 2
13
Vertebrate Endocrine System
  • Tropic hormones a
    hormone that has another endocrine gland as a
    target
  • Hypothalamuspituitary
  • Pituitary gland
  • Pineal gland
  • Thyroid gland
  • Parathyroid glands
  • Thymus
  • Adrenal glands
  • Pancreas
  • Gonads (ovary, testis)

14
Nervous Endocrine systems linked
  • Hypothalamus master nerve control center
  • nervous system
  • receives information from nerves around body
    about internal conditions
  • releasing hormones regulates release of hormones
    from pituitary
  • Pituitary gland master gland
  • endocrine system
  • secretes broad rangeof tropic hormones
    regulating other glands in body

hypothalamus
posterior
pituitary
anterior
15
tropic hormones target endocrine glands
hypothalamus
thyroid-stimulating hormone (TSH)
antidiuretic hormone (ADH)
posterior pituitary
Thyroid gland
anterior pituitary
Kidney tubules
adrenocorticotropic hormone (ACTH)
oxytocin
Muscles of uterus
gonadotropic hormones follicle- stimulating horm
one (FSH) luteinizing hormone (LH)
melanocyte-stimulating hormone (MSH)
growth hormone (GH)
prolactin (PRL)
Adrenal cortex
Melanocyte in amphibian
Mammary glands in mammals
Bone and muscle
Ovaries
Testes
16
The hypothalamus pituitary, I
  • Releasing and inhibiting hormones
  • Anterior pituitary
  • Growth (GH)bones vgigantism/dwarfism
    vacromegaly
  • Prolactin (PRL)mammary glands milk production
  • Follicle-stimulating (FSH)
  • Luteinizing (LH)ovaries/testes
  • Thyroid-stimulating (TSH) thyroid
  • Adrenocorticotropic (ACTH) adrenal cortex
  • Melanocyte-stimulating (MSH)
  • Endorphinsnatural opiates brain pain
    receptors

17
The pituitary, II
  • The posterior pituitary
  • Oxytocin uterine and mammary gland cell
    contraction
  • Antidiuretic (ADH) retention of water
    by kidneys

18
The pineal, thyroid, parathyroid
  • Melatonin pineal gland biological rhythms
  • Thyroid hormones Calcitonin lowers
    blood calcium Thyroxine metabolic processes
  • Parathyroid (PTH) raises blood calcium

19
Regulation of Blood Calcium
Endocrine System Control
Feedback
calcitonin
blood calcium level(10 mg/100mL)
activated Vitamin D
parathyroid hormone (PTH)
20
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

tyrosine iodine
thyroxines
21
The pancreas
  • 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)

22
Regulation of Blood Sugar
Endocrine System Control
Feedback
islets of Langerhans beta islet cells
insulin
body cells takeup sugar from blood
liver storesglycogen
reducesappetite
blood sugar level (90mg/100ml)
liver releasesglucose
triggershunger
islets of Langerhansalpha islet cells
glucagon
23
The adrenal glands
  • Adrenal medulla (catecholamines) epinephrine
    norepinephrine increase basal metabolic rate
    (blood glucose and pressure)
  • Adrenal cortex (corticosteroids) glucocorticoids
    (cortisol) raise blood glucose
    mineralocorticoids (aldosterone) reabsorption
    of Na and K

24
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
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