Endocrine

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