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Endocrine System
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Common Challenges
Form and function, closely correlated
Multicellularity – specialization
Specialization requires organization (internal environment differs from external)
Feedback control maintains internal environment
Hierarchical Organization of Animal Bodies
Cells form a functional animal body Levels of structural & functional
organization
Identify the 3 levels of organization
Name the four categories of animal tissues
Table 32.1
Figure 32.2
Axons of neurons
Skeletal muscle tissue
Bloodvessel
Looseconnectivetissue
Blood
Epithelial tissue
Collagenousfiber
Epithelial tissue
Lumen 10 m
Basal surface
Apical surfaceNervous tissue
Glia 20 m
PlasmaWhiteblood cells
(Co
nfo
cal
LM
)
50
m
Red blood cells
100 mElastic fiber
Nuclei
Musclecell
100 m
Regulators & Conformers
Regulators use internal mechanisms to control internal change despite external fluctuation
Conformers allow internal conditions to change with external changes Fish: Conforms to temp./ regulates solutes
HOMEOSTASIS
Internal balance Temperature,
blood pH, glucose conc.
Analogous to room temp. controls by a thermostat
THERMOREGULATION
Endotherms
Ectotherms
BALANCING HEAT LOSS & GAIN
Four physical processes RADIATION EVAPORATION CONVECTION CONDUCTIONHeat is always
transferred from an object of higher temperature to one of lower temperature
Circulatory Adaptations
Vasodilation Vasoconstriction Countercurrent
exchange
Physiological ThermostatsHypothalamus
Fever
Homeostatic Mechanisms Endocrine
Hormones Receptors Gradual
Nervous Neurons Specific pathways Immediate
Simple Endocrine Pathways Acidic stomach
juices must be neutralized in the duodenum
Endocrine cells of duodenum secrete secretin
Pancreas (exocrine & endocrine) releases bicarbonate
Integration of endocrine & nervous systems
Posterior Pituitary
Extension of hypothalamus
Oxytocin ADH FEEDBACK LOOPS
Positive feedback Negative
feedback
PATHWAYS
Water soluble (proteins) Surface receptors, triggered events,
response Signal transduction
Multiple steps (see cell signaling) Lipid soluble (steroids)
Receptors inside cell Hormone-receptor complex nucleus
alters transcription
MULTIPLE EFFECTS
Many hormones elicit more than one response.
Epinephrine: Raises blood sugar Increases blood flow
to muscles Decreases blood
flow to digestive tract
HOW?
WHAT TYPE OF GLAND?
Stomach Pancreas Ovary Sweat Hypothalamu
s Thyroid Mammary Pituitary
Testes Salivary Duodenum Parathyroid Liver Sebaceous Adrenal Tear
WHAT TYPE OF GLAND?
Stomach H Pancreas H Ovary H Sweat EX Hypothalamus
EN Thyroid EN Mammary EX Pituitary EN
Testes H Salivary EX Duodenum H Parathyroid EN Liver H Sebaceous EX
Adrenal EN Tear EX
Feedback Regulation
Mechanisms of Chemical Signaling
One chemical signal, different effects
MATCHING
•Adrenal•Thyroid•Ovary•Thymus•Testis•Hypothalamus•Pancreas•Pituitary•Parathyroid•Pineal
ANTERIOR PITUITARY
Growth hormone Prolactin Follicle stimulating hormone Lutenizing hormone Thyroid stimulating hormone Adrenocorticotropic hormone Melanocyte-stimulating
hormone
GROWTH HORMONE (GH)
Peptide hormone Promotes growth (long bones); protein
synthesis Stimulates production of growth factors IGFs ↑ during development (gigantism); adult
(acromegaly) ↓ during development (dwarfism,) treated w/
GH
PROLACTIN
Peptide very similar to GH Gonadotropic Mammary gland growth & milk production
during pregnancy Birds – regulates fat metabolism &
reproduction Amphibian – delays metamorphosis Freshwater fishes – salt & water balance
GONADOTROPINS
Follicle stimulating hormone (FSH): Glycoprotein Target (female, follicle) (male, seminiferous
tubules) Stimulates gamete production (ova & sperm)
Lutenizing hormone (LH)/(ICSH): Glycoprotein Stimulates ovaries & testes Female (corpus luteum) Male (interstitial cells) ↑ hormone production from gonads
OTHER ANTERIOR PITUITARY HORMONES Thyroid stimulating hormone
Glycoprotein Stimulates thyroid
Melanocyte stimulating hormone Peptide Stimulates melanocytes Mammals – fat metabolism
Adrenocorticotropic hormone Peptide Stimulates adrenal cortex
Thyroid GlandThyroxine: • Regulates metabolism in most body cells• Regulates rate of cellular respiration• Growth & differentiation• Mental development• ↓Cretinism (child) & Myxedema (adult)• ↑Graves disease/Goiter
Calcitonin:•Lowers blood calcium
Feedback control loops regulating the secretion of thyroid hormones T3 & T4
Hormonal control of calcium homeostasis
Hypofunction causes TETANY
Heterocrine gland, makes 2 peptide hormones
Glucagon: secreted by alpha cells◦Targets the liver◦Raises blood sugar
Insulin: secreted by beta cells◦Targets all body cells◦Lowers blood sugar◦Type I Diabetes Mellitus: hereditary autoimmune,
insufficient insulin, sugar in urine, juvenile onset◦Type II Diabetes Mellitus: lack of insulin
receptors, non-insulin dependent, maturity onset
GLUCOSE HOMEOSTASIS
Diabetes Mellitus – Type IPhysiological complications1. Hyperglycemia2. Increase in protein & fat metabolism3. Glycosuria4. Ketosis (from oxidation of fatty acids)5. Acidosis (blood pH drops below 7.4)6. Dehydration (increase in urine)
ADRENAL GLANDS
•located on top of kidney•adrenal cortex – outer portion•adrenal medulla – inner portion
Adrenal Medulla
•Makes catecholamines•Chromaffin cells•Epinephrine•Norepinephrine•Fight or flight response - bioenergetic boost - glycogen breakdown - fatty acid release - heart rate & stroke vol. - dilate bronchioles - shunting of blood•Regulated by ANS
Adrenal Cortex: responds to endocrine signals, ACTH • glucocorticoids - cortisol - cortisone• mineralocorticoids - aldosterone• gonadocortcoids - testosterone - progesterone• essential to life• Cushing’s disease - hypersecretion• Addison’s disease - hyposecretion
Short term stress response1. Glycogen glucose2. ↑ blood pressure3. ↑ breathing rate4. ↑ metabolic rate5. Change blood patterns6. ↓ urine output
Long term stress responseMineralocorticoids Glucocorticoids1. Retention of Na+ 1. proteins & fats & H2O kidneys broken down2. ↑ blood volume ↑ blood sugar and pressure 2. Immune system
suppressed
Gonadal steroids
Androgens Testosterone Stimulate development & maintenance of male
reproductive system Male secondary sex characteristics
Estrogens Estradiol Stimulate development & maintenance of female
reproductive system Female secondary sex characteristics
Progestins Progesterone Preparing & maintaining the uterus (supports
growth & development of an embryo)
SIGNAL TRANSDUCTION PATHWAYS
Steroid hormone action: - affects protein synthesis- different kinds of cells respond differently to the same steroid hormone; acceptor proteins associated w/ different genes
Peptide hormone action: affects cell activity
Enzyme activation, cellular secretion, permeability changes etc.
Long Distance Signaling
PheromoneAutocrine Signaling
Oxytocin
Short Distance Signaling
QuorumSensing
InterleukinNeuro-
transmitter
Outside the Body
Signaling
Paracrine Signaling
Prostaglandin
Direct contact
communication
Inside the Body
Signaling
Endocrine Signaling
Testosterone
Estrogen