The Endocrine The Endocrine SystemSystem

Honors Honors

Physiology Physiology

What are hormones?What are hormones? Hormones:Hormones:

send messages send messages act locally or at a distanceact locally or at a distance work quickly or slowly work quickly or slowly can be created/excreted by cells, tissues or can be created/excreted by cells, tissues or

organs, collectively known as “glands”organs, collectively known as “glands” secreted via epithelial cells secreted via epithelial cells extracellular fluid extracellular fluid

blood stream blood stream receptors on target cells receptors on target cells ducts are not used by endocrine systemducts are not used by endocrine system

Comparison to Nervous Comparison to Nervous SystemSystem

Fig. 13.2

Comparison to Nervous Comparison to Nervous SystemSystem

EntityEntity Nervous SysNervous Sys Endocrine SysEndocrine Sys

Cell typeCell type NeuronsNeurons EpithelialEpithelial

Chemical Chemical signalsignal

NeurotransmitterNeurotransmitter HormoneHormone

Specificity of Specificity of responseresponse

Receptors on Receptors on postsynaptic cellpostsynaptic cell

Receptors on Receptors on target cellstarget cells

SpeedSpeed MillisecondsMilliseconds Seconds to hoursSeconds to hours

Length of Length of effecteffect

Brief Brief Brief or longBrief or long

Example of Hormonal Example of Hormonal Regulation—Today’s LabRegulation—Today’s Lab

ThyroxineThyroxine Released from thyroid Released from thyroid

glandgland Target: cells all over bodyTarget: cells all over body Influences metabolismInfluences metabolism

Thyroid stimulating Thyroid stimulating hormone (TSH) hormone (TSH) Released from anterior Released from anterior

pituitary glandpituitary gland Target: thyroid glandTarget: thyroid gland Signal: “release thyroid Signal: “release thyroid

hormones!”hormones!”

Endocrine System—Relative Stability of Endocrine System—Relative Stability of Hormone ConcentrationsHormone Concentrations

Negative feedback Negative feedback maintains stable maintains stable hormone levels hormone levels Fig. 13.11

Endocrine System—3 Ways To Endocrine System—3 Ways To Control Hormonal SecretionsControl Hormonal Secretions

Fig. 13.8

Example: Negative Feedback Example: Negative Feedback Controls Blood Glucose LevelsControls Blood Glucose Levels What What

happens happens when your when your blood blood glucose glucose gets too gets too low?low?

Fig 13.36

Example: Negative Feedback Example: Negative Feedback Controls Blood Glucose LevelsControls Blood Glucose Levels What What

happens happens when your when your blood blood glucose glucose gets too gets too high?high?

Fig 13.36

Fig. 13.5

Steroid HormonesSteroid Hormones

Steroid HormonesSteroid Hormones

Lipid soluble Lipid soluble Receptor in the nucleus Receptor in the nucleus

binds hormone binds hormone gene transcription gene transcription

mRNA is then translated into a protein in the mRNA is then translated into a protein in the cytoplasmcytoplasm

ExamplesExamples estrogen, testosteroneestrogen, testosterone aldosterone, cortisolaldosterone, cortisol

Nonsteroid HormonesNonsteroid Hormones

Fig. 13.7

Nonsteriod HormonesNonsteriod Hormones

CannotCannot move through lipid bilayer move through lipid bilayer Instead they bind to receptors in cell Instead they bind to receptors in cell

membranemembrane Examples:Examples:

TSHTSH EpinephrineEpinephrine Glucagon Glucagon

HypothalamusHypothalamus Regulates other glands to tell them when Regulates other glands to tell them when

to release their hormonesto release their hormones

Fig. 13.9

Pituitary GlandPituitary Gland

Fig. 13.9

Anterior PituitaryAnterior Pituitary

Adrenocorticotropic hormone (ACTH)Adrenocorticotropic hormone (ACTH) Target: adrenal cortex, stimulates cortisol releaseTarget: adrenal cortex, stimulates cortisol release influences protein and fat metabolisminfluences protein and fat metabolism

GonadotropinsGonadotropins follicle stimulating hormone (FSH) follicle stimulating hormone (FSH)

egg or sperm maturation egg or sperm maturation For egg, stimulates release of egg from follicle mid cycleFor egg, stimulates release of egg from follicle mid cycle

luteinizing hormone (LH) luteinizing hormone (LH) Stimulates release of sex hormonesStimulates release of sex hormones

Anterior Pituitary cont.Anterior Pituitary cont.

Growth Hormone (GH)Growth Hormone (GH) bone growth/osteogenesisbone growth/osteogenesis

Melanocyte Stimulating Hormone (MSH)Melanocyte Stimulating Hormone (MSH) skin color, includes tanningskin color, includes tanning

Prolactin (PRL)Prolactin (PRL) lactationlactation

Thyroid Stimulating Hormone (TSH)Thyroid Stimulating Hormone (TSH) stimulates thyroid secretionsstimulates thyroid secretions

Robert P. WadlowRobert P. Wadlow8’ 11”8’ 11”

AgeAge HeightHeight

88 6’6’

1414 7’5”7’5”

1818 8’4”8’4”

2222 8’11”8’11”

Yikes, his anterior pituitary released too much growth hormone!

Anterior Pituitary cont.Anterior Pituitary cont. How am I going to remember all of How am I going to remember all of

this???this??? AA GGreen reen GGiant iant MMakes akes PRPRetty etty

TThingshings AACTHCTH GGonadotropins (FSH, LH/ICSH)onadotropins (FSH, LH/ICSH) GGHH MMSHSH PRPR TTSHSH

Posterior PituitaryPosterior Pituitary

Antidiuretic Hormone (ADH)Antidiuretic Hormone (ADH) decreases urine formationdecreases urine formation when you are dehydrated, your body says when you are dehydrated, your body says

“don’t lose water!”, so ADH is increased“don’t lose water!”, so ADH is increased increased ADH = concentrated urineincreased ADH = concentrated urine

Oxytocin Oxytocin smooth muscle contractions in the uterus smooth muscle contractions in the uterus

during childbirthduring childbirth Recent studies = “bonding” hormoneRecent studies = “bonding” hormone

Posterior Pituitary cont.Posterior Pituitary cont.

Why do you urinate more when you drink Why do you urinate more when you drink caffeine? caffeine? Your body recognizes caffeine as a toxin Your body recognizes caffeine as a toxin

that it needs to expel from the bodythat it needs to expel from the body Caffeine is a Caffeine is a diureticdiuretic – – it makes you urinateit makes you urinate

it it inhibitsinhibits secretion of ADH secretion of ADH you don’t get the “don’t lose water!” signalyou don’t get the “don’t lose water!” signal so you expel more water to try and flush out the so you expel more water to try and flush out the

toxintoxin

Pineal GlandPineal Gland

MelatoninMelatonin Helps regulate circadian rhythms (sleep-Helps regulate circadian rhythms (sleep-

wake cycle)wake cycle)

ThyroidThyroid

Thyroxine or tetraiodothyronine (TThyroxine or tetraiodothyronine (T44)-and )-and

Triiodothyronine (TTriiodothyronine (T33)) regulate your food metabolism (break down regulate your food metabolism (break down

glucose, fat & protein to create energy)glucose, fat & protein to create energy) increase temperature, growth and increase temperature, growth and

developmentdevelopment

Fig. 13.16

Thyroid & ParathyroidThyroid & Parathyroid

Thyroid releases Thyroid releases CalcitoninCalcitonin lowers calcium levels lowers calcium levels

in the bloodin the blood

Parathyroid releases Parathyroid releases Parathyroid Hormone Parathyroid Hormone (PTH) (PTH) increases calcium increases calcium

levels in the bloodlevels in the bloodFig. 13.24

PancreasPancreas

InsulinInsulin GlucagonGlucagon Islets of Islets of

LangerhansLangerhans regulate blood regulate blood

glucose levelsglucose levels Both hormones Both hormones

created in the…created in the…

Fig. 13.34

Pancreas cont.Pancreas cont.Islets of LangerhansIslets of Langerhans

Alpha CellsAlpha Cells Make GlucagonMake Glucagon Released when your Released when your

blood sugar levels get blood sugar levels get lowlow

Increases blood Increases blood glucose levels by glucose levels by breaking down breaking down glycogen (storage glycogen (storage form of glucose in the form of glucose in the liver) and liver) and noncarbohydrates noncarbohydrates into glucoseinto glucose

Beta CellsBeta Cells Make InsulinMake Insulin Released when your Released when your

blood sugar levels get blood sugar levels get highhigh

Tells your body cells Tells your body cells to take sugar in, and to take sugar in, and decreases blood decreases blood glucose levels by glucose levels by stimulating the liver to stimulating the liver to form glycogenform glycogen

Pancreas cont.Pancreas cont. Diabetes- can’t regulate your blood glucoseDiabetes- can’t regulate your blood glucose

Type I - JuvenileType I - Juvenile Islets of Langerhans don’t work properly & cannot create Islets of Langerhans don’t work properly & cannot create

sufficient insulin (or glucagon)sufficient insulin (or glucagon) usually need insulin injections (why not glucagon usually need insulin injections (why not glucagon

injections?)injections?) usually inheritedusually inherited

Type II - Adult onsetType II - Adult onset Insulin Insulin receptorsreceptors throughout body don’t work properly throughout body don’t work properly usually can use oral treatmentusually can use oral treatment related to weight gainrelated to weight gain

About 17 million people in the US have diabetes!About 17 million people in the US have diabetes!

Adrenal GlandsAdrenal Glands

Adrenal MedullaAdrenal Medulla epinephrine/adrenalinepinephrine/adrenalin norepinephrine/noradrenalinnorepinephrine/noradrenalin

Increases blood glucose, heart rate, Increases blood glucose, heart rate, etc.etc.

Blood vessels constrict in digestive Blood vessels constrict in digestive tract and kidneys, dilate in blood tract and kidneys, dilate in blood vessels of the musclesvessels of the muscles

Fig. 13.28

Adrenal Glands cont.Adrenal Glands cont.Adrenal CortexAdrenal Cortex

AldosteroneAldosterone Target cells in kidneysTarget cells in kidneys Maintain NaMaintain Na++ and K and K++ balance balance

CortisolCortisol Glucose, protein and fat metabolismGlucose, protein and fat metabolism Anti inflammatoryAnti inflammatory

AndrogensAndrogens supplement gonad sex hormones supplement gonad sex hormones

Reproductive OrgansReproductive Organs

OvariesOvaries EstrogenEstrogen

stimulates egg maturation stimulates egg maturation secondary female sex characteristicssecondary female sex characteristics

ProgesteroneProgesterone maintains uterine lining in case of implantationmaintains uterine lining in case of implantation

TestesTestes TestosteroneTestosterone

regulates spermatogenesisregulates spermatogenesis secondary male sex characteristicssecondary male sex characteristics

Adrenal Glands cont.Adrenal Glands cont. Addison diseaseAddison disease

Cortisol hyposecretionCortisol hyposecretion low Nalow Na++, high K , high K ++, dehydration, low glucose, , dehydration, low glucose,

can be very serious can be very serious Cushing syndromeCushing syndrome

Cortisol hypersecretion (usually Cortisol hypersecretion (usually by too much ACTH)by too much ACTH)

High NaHigh Na++, low K+, high glucose, , low K+, high glucose, water retentionwater retention

Thyroid cont.Thyroid cont.

Grave’s diseaseGrave’s disease too much hormonetoo much hormone

HyperHyperthyroidismthyroidism

Hashimoto’s diseaseHashimoto’s disease too little hormonetoo little hormone

HypoHypothyroidismthyroidism