Download Chapter 45: Chemical Signals 1 Hormone

Chapter 45: Chemical Signals
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Figure 45.0 A monarch butterfly just after emerging from its cocoon
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Hormone
• Chemical signal secreted into body fluids.
• Regulation/control of homeostasis, development, growth
• Specific response from specific cells—specificity
• Release from gland, act on target cell
Endocrine System (skip to slide 9)
• Endocrine glands spread through the body.
• Contain cells that secrete hormones directly to blood.
• Contrast to Exocrine (secrete to epithelial surface).
Feedback
• Positive and Negative
• Regulation of Calcium concentration—antagonistic hormones
o muscle function, bone
• Figures 1-2: Thyroid Hormone, Calcium control
Figure 45.1 An example of how feedback regulation maintains homeostasis
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Figure 45.2 Hormonal regulation of insect development (Layer 1)
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• Regulation of insect development
• Exoskeleton—must shed/molt in order to grow/develop
• Brain Hormone (BH)—from brain, stimulates prothoracic gland to
secrete ecdysone
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Figure 45.2 Hormonal regulation of insect development (Layer 2)
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Ecdysone triggers molting
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Juvenile Hormone (JH) regulates development
o Suppresses metamorphosisÆretain larval characteristics
o High JHÆmolt but stay larval
o Decreasing JHÆform pupa and become adult
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Figure 45.2 Hormonal regulation of insect development (Layer 3)
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Pupa
Figure 45.x1 Pupa
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Slide 7: Chemical Signaling
Hormone Binds plasma membrane protein and initiates STP
Signal Transduction Pathway
• Reception (specific), signal transduction, response (Signal
Transduction)
• Amplification: small amt HM produces large response.
Figure 45.3 Mechanisms of chemical signaling: a review
Steroid Hormone Animation
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Same signal can yield different response in different cells (Ach, Epi)—
depends on receptor
Steroids bind intracellular receptors
• small non polar molecules
Figure 4:
• autocrine/paracrine--Immune System—histamine, GH
• NT released by neurons--some HM can act as NT
• Circulating HM
Figure 5: Overproduction/underproduction of Growth HM
Figure 6: Epinephrine pathway—Earl Sutherland
Figure 7: Steroid Hormones (nonpolar)—from cholesterol
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Acetylcholine
Different effects on different cells
Figure 45.4 One chemical signal, different effects
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Can affect one or more tissues directly/indirectly
Direct—have direct effect on tissue
Tropic—target endo glands and cause to release hormone.
Figure 45.5 Human endocrine glands surveyed in this chapter
Adreno-cortico-tropic Hormone (ACTH) acts on Adrenal cortex cause
release of Æglucocorticoids.
*Some HM can be both direct and tropic (Growth HM)
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Table 45.1 Major Vertebrate Endocrine Glands and Some of Their Hormones
(Hypothalamus–
Parathyroid glands)
Overview of Hormones
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Table 45.1 Major Vertebrate Endocrine Glands and Some of Their Hormones
(Pancreas–Thymus)
Overview of Hormones
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Hypothalamus
• Receives Info
from body
(nerves)
• Secretions are
stored in or
regulate the
Pituitary Gland
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Posterior Pituitary (neurohypophysis)
Extension of Brain, develops from Hypothalamus—connect by duct
Stores/secretes ADH and Oxytocin
Oxytocin
• smooth muscle contraction
o contract of uterus (during labor)
ƒ give to induce labor
o mammary gland during lactation
o contract of smooth muscle in coitus
ADH (vasopressin)
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Figure 45.6a Hormones of the hypothalamus and pituitary glands
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regulate blood osmolarity
water retention by kidney
Increase osmolarityÆcells in HT shrink due to osmosisÆnerve
signal to HTÆsecrete ADH from Posterior Pituitary.
Decrease osmolarityÆslows release of ADH.
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Figure 45.6b Hormones of the hypothalamus and pituitary glands
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Anterior Pituitary
(adenohypophysis)
• From tissue above mouth
• Connect to HT by blood vessel
• synthesize and releases HM to
blood
• Responds to releasing or
inhibiting hormones from HT
• Tropic Hormones
o TSH, ACTH, GH, FSH,
LH
(FSH and LH =
Gonadotropins)
Direct HM—GH, PRL, MSH
(melanocyte stimulating HM),
endorphins
Growth Hormone (Figure 8)
• Production of growth factors
• Promote growth (bone and cartilage)
o Direct
ƒ Regulate deposition of collagen and chondroitin
sulfate in bone and cartilage
ƒ Promotes mitosis in osteoblasts Æ build bone
o tropic—act on liver to stimulate insulin like growth factor
(IGF) Æ growth
ƒ Protein synthesis
ƒ Decrease protein catabolism and use of aa for
respiration
ƒ Release of glucose from liver (antagonist to insulin)
• Release after exercise or hours after meal to counteract decrease in
blood glucose, mobilize fat for metabolism to increase glucose.
• Problems if too much (gigantism) or not enough (dwarfism).
o Growth plate: area of growing tissue near end of long
bone.
o Low levelÆ growth plates close before normal height
(dwarf)
o High level Æ gigantism
• Can produce using bacteria
Prolactin (PRL)
• Different effects in different organisms
o mammals: lactation
o birds: fat metabolism, reproduction
o amphibians: delay metamorphosis
o fish: salt/water balance
FSH and LH (Figure 13-14)
• gonadotropins—tropic HM that act on gonads
• stimulate gonads to release testosterone, estrogen
TSH—stimulates thyroid to release TH (Figure 9)
• Released in response to TSH releasing factor from HT
ACTH- Adrenocorticotropic Hormone(Figure 10)
• production/secretion of steroids by adrenal cortex
MSH – Melanocyte Stimulating Hormone
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Change in skin color in lower vertebrate by contraction melanin in
melanophores
• mammals—
o fat metabolism, synthesis of melanin
o Raise excitability of neurons in CNS, probably affects
learning.
endorphins—inhibit pain
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Pineal Gland
• Near center of
brain.
• Secrete
melatonin.
• light sensitive
cells.
• Night
• Winter
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Figure 45.7 Two thyroid hormones
Animation
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Pineal Gland
Near center of brain
secretes melatonin
light sensitive cells or connect to eyes.
melatonin
• Inhibited by exposure to light, secreted at night
• secreted in winter
• Amount secreted coordinates with length of night
• Coordinates biological clock (circadian rhythm)
• Targets Superchiasmatic Nucleus (SCN) in HT which functions as
biological clock.
• Seasonal activities--Reproduction
o inhibits gonadotropins
• Working night shift, jet lag, seasonal depression
Thyroid Gland Figure 9
Two Lobes, around trachea, butterfly
Thyroid hormone and Calcitonin
Thyroid Hormone
• Produce Triiodothyronine (T3) and Tetraiodothyronine (T4)
• Mammals—secrete mostly T4, target cell converts to T3.
• Growth and Mental Development
• Maintain normal blood pressure, heart rate, muscle tone, digestion,
reproduction
• Metabolic rate—oxygen consumption/cellular metabolism
• Low temp or low TH levelÆHT release thyrotropin releasing
factorÆAP releases TSHÆstim release of TH
o Uncouple resp/ATP generationÆheat
o Breakdown of fats and carbsÆenergy
o Promote Protein synthesis
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Figure 45.8 Feedback control loops regulating the secretion of thyroid hormones T3
and T4
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Figure 45.9 Hormonal control of calcium homeostasis in mammals
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Figure 45.10 Glucose homeostasis maintained by insulin and glucagon
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Role in Homeostasis
• Regulated by concentration of TSH and T4.
• Hyperthyroidism: high temp, sweat, decrease weight, high bp
• Hypothyroidism: gain weight, lethargic, cold.
• Goiter
o enlarged thyroid
o Deficient iodine
o Can not synthesize TH, but brain keeps sending TSH.
Figure 10
Regulation of Calcium Level
• High Calcium
o Thyroid releases CalcitoninÆreduce calcium uptake in
kidney, stimulate deposit in bones.
• Low Calcium
o Parathyroid gland (embedded in thyroid)
ƒ Release parathyroid hormone (PTH)Æ
• Increase Calcium uptake in kidney
• Stimulate Calcium release from bone.
• Activate Vitamin D which acts with PTH on
bone and intestine.
Pancreas Figure 11
Both endocrine and exocrine (bicarbonate/digestive enzyme) functions
• Islets of Langerhans—antagonistic hormones
o alpha cells release glucagons
o beta cells release insulin
*insulin/glucagon are antagonistic
• Insulin
o Cause body cells to take glucose from blood
o Liver cells—slow glycogen breakdown
• Glucagon
o Act only on liver
o Glucose--.glycogen
Glucose needs to remain ~90mg/100mL
Diabetes mellitus—insulin deficiency or lack of response to insulin.
Glucose in urine.
Glucose present in body but can’t be utilized
• Lose water in urine with glucoseÆthirst
• Breakdown fat for energy b/c can’t use sugarsÆlower pH of blood
Type I
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autoimmune on pancreas
can’t produce insulin
early onset
insulin shots
Type II
• deficiency in insulin or receptors don’t bind
• later in life
• Control w/ diet and exercise.
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Adrenal Gland Figure 12
Adjacent to Kidneys
Two parts—cortex and medulla
Adrenal Gland
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Adrenal Medulla
Responds to signals from nervous system
Secrete epinephrine and norepinephrine (adrenaline/noradrenaline)—fight
or flight
• catecholamines—synthesized from Tyrosine.
• Stress/dangerÆincrease glycogen breakdown and glucose release
Æfatty acid release Ædilate bronchioles to increase oxygen delivery
treat asthma and allergic reactions Æblood to muscle and away from
skin/dig—vasoconstrict/dilate
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stimulated by acetylcholine and nervous system
Norepinephrine—sustain BP
Epinephrine—heart/metabolic rate
Adrenal Cortex Figure 12
• respond to endocrine signals, not nervous
• react to stress
• StressÆHT signals anterior pituitary to release ACTH
ƒ ACTH stimulates Adrenal cortex to produce
corticosteroids (hormonal steroids from adrenal
cortex).
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Corticosteroids (two types)
o Glucocorticoid—glucose metabolism
ƒ Respond to long term environmental challenge—
cold, starvation
ƒ example: cortisol
ƒ produce glc from non carb(Protein)
ƒ Deposit glycogen in liver
ƒ Gluconeogenesis—convert fat, protein,
lactateÆglucose
ƒ Breakdown of skeletal muscle protein
ƒ Raise blood pressure
ƒ suppress immune system
• use cortisone (synthetic drug) to decrease
inflammation
o Mineral Corticoid—from AC, regulate fluid/electrolytes by
effect on ion transport.
ƒ salt and water balance
ƒ aldosteroneÆkidney reabsorb Na and
waterÆincrease BP and BV.
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Figure 45.12 The synthesis of catecholamine hormones
Animation
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Sex Hormones Figure 13-14
From Gonads
Three Categories
• androgens—from testes—testosterone
• estrogens—from ovary, female reproductive system
• progestins—preparation/maint of uterus
Gonadotropins—control release of androgens and estrogens
GnRH from HTÆFSH and LH from APÆhormones from gonads.
Figure 45.13 Steroid hormones from the adrenal cortex and gonads
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Figure 45.14 Stress and the adrenal gland
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Response of Adrenal Gland
Short Term
• Epinephrine and
Norepinephrine
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glycogenÆglucose
increase blood glucose
increase BP
increase breathing rate
increase metabolic rate
changes in blood flow
Long Term
• Mineral Corticoids
(aldosterone)
– retain Na+ and H2O
– increase blood volume
– increase BP
• Glucocorticoids (Cortisol)
– breakdown fat and protein to
produce carbohydrates
– suppress immune system
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