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Endocrine System Hormones. Definitions. Hormone : chemicals secreted by cells that regulate other cells Gland : organ whose cells secrete chemicals into other regions of the body -> Endocrine gland : ductless -> Exocrine gland : deliver hormones via ducts. Hormone-like substances.

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Presentation Transcript
definitions
Definitions
  • Hormone: chemicals secreted by cells that regulate other cells
  • Gland: organ whose cells secrete chemicals into other regions of the body

-> Endocrine gland: ductless

-> Exocrine gland: deliver hormones via ducts

hormone like substances
Hormone-like substances
  • Neuropeptides: secreted by the brain and the nerves

-> Enkephalins: inhibit pain messages traveling to the brain

-> Endorphins: regulate emotions, influence pain, affect reproduction

  • Prostaglandins: modified fatty acids with many functions, found near areas where tissue is disturbed/injured
regulation
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

regulation communication
Regulation & Communication
  • Animals rely on 2 systems for regulation
    • endocrine system
      • system of ductless glands (->extracellular fluid)
        • 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
regulation by chemical messengers
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

classes of hormones
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

how do hormones act on target cells
How do hormones act on target cells
  • Lipid-based hormones
    • hydrophobic & lipid-soluble
      • diffuse across cell membrane & enter cells
      • bind to receptor proteins in cytoplasm & nucleus
      • bind to DNA as transcription factors
        • turn on genes
  • Protein-based hormones
    • hydrophilic & not lipid soluble
      • can’t diffuse across cell membrane
      • bind to receptor proteins in cell membrane
      • trigger secondary messenger pathway
      • activate internal cellular response
        • enzyme action, uptake or secretion of molecules…
action of lipid steroid hormones
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)

action of protein hormones
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

receptorprotein

ATP

transduction

GTP

activatescytoplasmicsignal

ATP

activates

enzyme

2

secondary

messengersystem

activates

enzyme

cytoplasm

response

3

produces an action

target cell

ex action of epinephrine adrenaline

adrenal gland

Ex: Action of epinephrine (adrenaline)

signal

1

epinephrine

activatesG protein

3

activatesadenylyl cyclase

receptor

protein

in cell membrane

cAMP

GDP

transduction

4

ATP

2

GTP

activates

protein kinase-A

5

activates GTP

activates

phosphorylase kinase

cytoplasm

releasedto blood

activates

glycogen phosphorylase

7

glycogen

glucose

6

liver cell

response

benefits of a 2 messenger system
Benefits of a 2° messenger system

1

signal

Amplification!

Activated adenylyl cyclase

receptor protein

Not yet

activated

2

amplification

4

amplification

3

cAMP

5

amplification

GTP

G protein

protein kinase

6

amplification

enzyme

Cascade multiplier!

7

amplification

FAST response!

product

maintaining homeostasis

high

low

Maintaining homeostasis

hormone 1

lowersbody condition

gland

specific body condition

raisesbody condition

gland

Negative FeedbackModel

hormone 2

controlling body temperature

hypothalamus

hypothalamus

high

low

Nervous System Control

Feedback

Controlling Body Temperature

nerve signals

sweat

dilates surfaceblood vessels

body temperature

(37°C)

constricts surfaceblood vessels

shiver

nerve signals

regulation of blood sugar

pancreas

high

liver

low

pancreas

liver

Endocrine System Control

Feedback

Regulation of Blood Sugar

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

blood osmolarity

osmoreceptors inhypothalamus

increasethirst

nephron

nephron

high

JuxtaGlomerularApparatus

low

nephron

(JGA)

adrenalgland

Endocrine System Control

Feedback

Blood Osmolarity

ADH

increasedwaterreabsorption

pituitary

blood osmolarity

blood pressure

increasedwater & saltreabsorption

renin

aldosterone

angiotensinogen

angiotensin

nervous endocrine systems linked
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

slide18

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

hormone (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

regulating metabolism
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

goiter
Goiter

Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine

+

tyrosine

+

iodine

thyroxines

regulation of blood calcium

 kidney reabsorption of Ca++

thyroid

Ca++ depositedin bones

high

 Ca++uptakein intestines

low

parathyroid

 kidney reabsorption of Ca++

bones release Ca++

Endocrine System Control

Feedback

Regulation of Blood Calcium

calcitonin

blood calcium level(10 mg/100mL)

activated Vitamin D

parathyroid hormone (PTH)

female reproductive cycle

corpusluteum

ovary

yes

corpusluteum

no

Feedback

Female reproductive cycle

eggmatures &

is released(ovulation)

builds up uterus lining

estrogen

progesterone

FSH & LH

fertilized egg(zygote)

maintainsuterus lining

pituitarygland

hCG

pregnancy

progesterone

GnRH

corpus luteum breaks down

progesterone drops

menstruation

hypothalamus

maintainsuterus lining

slide24

Any Questions??

Robert Wadlow

1918-1940

8' 11"

effects of stress on a body
Effects of stress on a body

Stress

Nerve

signals

Hypothalamus

Spinal cord

(cross section)

Releasing

hormone

Nerve

cell

Anterior pituitary

Blood vessel

adrenal medulla

secretes epinephrine

& norepinephrine

Nerve cell

Adrenal cortex

secretes

mineralocorticoids

& glucocorticoids

ACTH

Adrenal

gland

Kidney

CORTEX

MEDULLA

(A) SHORT-TERM STRESS RESPONSE

(B) LONG-TERM STRESS RESPONSE

Effects of

mineralocorticoids:

1. Retention of sodium ions & water by kidneys

2. Increased blood volume & blood pressure

Effects of

glucocorticoids:

1. Proteins & fats broken down & converted to glucose, leading to increased blood glucose

2. Immune system suppressed

Effects of epinephrine and norepinephrine:

1. Glycogen broken down to glucose; increased blood glucose

2. Increased blood pressure

3. Increased breathing rate

4. Increased metabolic rate

5. Change in blood flow patterns, leading to increased alertness & decreased digestive & kidney activity