AP Biology

Endocrine System

Hormones

& Homeostasis

Regents Biology

Homeostasis

Homeostasis

maintaining internal balance in the body

organism must keep internal conditions

stable even if environment changes

also called “dynamic equilibrium”

example: body temperature

humans:

too cold = shiver

too warm = sweat

lizard:

too cold = bask in sun

too warm = hide in shade

Regents Biology

Regulation

How we maintain homeostasis

nervous system

nerve signals control body functions

endocrine system

hormones

chemical signals control body functions

Regents Biology

Controlling Body Temperature

high

low

nerve signals

sweat

nerve signals

brain

body temperature

shiver brain

dilates surfaceblood vessels

constricts surfaceblood vessels

Nervous System Control Feedback

Regents Biology

Hormones

Why are hormones needed?

chemical messages from one body part

to cells in other parts of body

communication needed

to coordinate whole body

maintaining homeostasis

growth hormones

Regents Biology

Endocrine System

Endocrine system releases hormones

glands which secrete (release)

chemical signals into blood

chemicals cause changes

in other parts of body

growth hormones

sex hormones

response hormones

metabolism hormones

and more….

Regents Biology

Responding to hormones

Lock and key system

hormone fits receptor on “target” cell

targetcell

non-targetcells

secretingcell

can’tread

signal

can’tread

signal

Regents Biology

Glands Pineal

melatonin

Pituitary

many hormones: master gland

Thyroid

thyroxine

Adrenal

adrenaline

Pancreas

insulin, glucagon

Ovary

estrogen

Testes

testosterone

Regents Biology

Maintaining homeostasis

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition

gland

Feedback

Regents Biology

Negative Feedback

Response to changed body condition

if body is high or low from normal level

signal tells body to make changes that will

bring body back to normal level

once body is back

to normal level,

signal is

turned off

high

hormone 1

lowersbody condition

gland

specific body condition

Regents Biology

liver

pancreas

liver

Regulation of Blood Sugar

blood sugar level(90mg/100ml)

insulin

body cells takeup sugar

from blood

liver storessugar

reducesappetite

glucagon

pancreas

liver releases

sugartriggershunger

high

low

FeedbackEndocrine System Control

AP Biology 2006-2007

Everyone’s doing it, so

Ask Questions!!

Regents Biology

Sex & Growth Hormones

Large scale body changes

how do they work turn genes on

start new processes in the body by turning genes on that were lying “dormant”

Regents Biology

Pituitary gland hormones

Sex & reproductive hormones

FSH

follicle stimulating hormone

stimulates egg & sperm production

LH

luteinizing hormone

stimulates ovaries & testes

prepares uterus for fertilized egg

oxytocin

stimulates childbirth contractions

releases milk in nursing mothers

prolactin

milk production in nursing mothers

hormones hormones

Regents Biology

Reproductive hormones Testosterone

from testes

sperm production & secondary sexual characteristics

Estrogen from ovaries

egg production, preparing uterus for fertilized egg & secondary sexual characteristics

Regents Biology

Sperm production

over 100 million produced per day!

~2.5 million released per drop!

Male

reproductive

system

Regents Biology

spermatocytes

seminiferous

tubule

sperm

Regents Biology

Male reproductive system

Testes & epididymis

sperm production & maturation

Glands

seminal vesicles, prostate, bulbourethal

produce seminal fluid nutrient-rich

Regents Biology

Male reproductive system

Testicles

produces sperm & hormones

Scrotum

sac that holds testicles outside of body

Epididymis

where sperm mature

Vas deferens

tubes for sperm to travel from testes to penis

Prostate, seminal vesicles,

Cowper’s (bulbourethal) glands

nutrient rich fluid to feed & protect sperm

Regents Biology

Female reproductive system

Regents Biology

Female reproductive system

Ovaries

produces eggs & hormones

Uterus

nurtures fetus; lining builds up each month

Fallopian tubes

tubes for eggs to travel from ovaries to uterus

Cervix

opening to uterus, dilates 10 cm for birthing baby

Vagina

birth canal for birthing baby

Regents Biology

Female reproductive system

Regents Biology

Egg maturation in ovary

releasesprogesterone

maintainsuteruslining

produces estrogen

Regents Biology

LH

FSH

estrogen

progesterone

lining of uterus

egg developmentovulation = egg release

corpus luteum

0 7 14 21 28days

Menstrual cycle

Controlled by

interaction of

4 hormones

FSH & LH

estrogen

progesterone

Regents Biology

corpusluteumovary

Female reproductive cycle

pregnancy

maintainsuterus lining

no

yes

Feedback

estrogenegg

matures &is released(ovulation)

builds up uterus lining

FSH & LH

progesterone

progesterone

fertilized egg(zygote)

HCG

corpus luteum breaks downprogesterone drops

menstruation

corpusluteum

maintainsuterus lining

GnRH

pituitarygland

hypothalamus

Regents Biology

Female hormones FSH & LH

released from pituitary

stimulates egg development & hormone release

peak release = release of egg (ovulation)

Estrogen

released from ovary cells around developing egg

stimulates growth of lining of uterus

decreasing levels causes menstruation

Progesterone

released from “corpus luteum” in ovaries

cells that used to take care of developing egg

stimulates blood supply to lining of uterus

decreasing levels causes menstruation

Regents Biology

Fertilization

AP Biology

Any Questions??

Regents Biology

What do they do?

Maintain homeostasis

blood sugar level

temperature control

Start a new process

growth

fetal development

sexual development

Body Temperature

Regents Biology

Negative Feedback

Negative feedback

every time body is

high or low from

normal level a signal

tells the body to

make changes that

will bring body back

body temperature

control of blood sugar

Regents Biology

Regulation by chemical messengers

axon

endocrine gland

receptor proteins

target cell

Neurotransmitters released by neurons

Hormones release by endocrine glands

receptor proteins

hormone carried by blood

neurotransmitter

Regents Biology

Body Regulation

hormones hormones

Nervous system &

Endocrine system work

together

hypothalamus

“master nerve control center”

receives information from

nerves around body about

internal conditions

communicates with

pituitary gland

“master gland”

releases many hormones

sexual development, growth,

milk production, pain-relief

Regents Biology

What hormones are secreted by the

thyroid gland?

T4 (thyroxine)

T3 (tri-iodothyronine)

Regents Biology

Hypothalamus

Anterior

pituitary

Thyroid

TRH

TSH

T3 T4

Regents Biology

Hyperthyroidism

Caused by thyrotoxicosis (high T3T4)

Signs and symptoms link to HIGH

metabolic rate

Weight and muscle loss

Increased appetite

Heat intolerance and sweating

Anxiety/irritability

Regents Biology

Grave’s Disease

Autoimmune disease

Body’s immune system produces

Thyroid Stimulating Antibodies that

act on the thyroid to increase T3/T4.

Exopthalmos

Regents Biology

Hypothalamus

Anterior

pituitary

Thyroid

TRH

TSH

T3 T4

High T3T4 levels

result in inhibition

of TSH and TRH

Regents Biology

Hypothyroidism

Low T3/T4

Signs and symptoms relate to a lowered

metabolic rate

Weight gain

Lethargy

Alopecia

Sensitive to cold

Slow movements

Regents Biology

Causes of hypothyroidism

Autoimmune disease: Hashimoto’s Disease

Iodine deficiency

Previous surgery/treatment that have damaged the thyroid

Radioactive iodine therapy

Thyroidectomy

Regents Biology

Goitre

Enlarged thyroid gland

Causes:

Tumour

Graves disease

Hashimoto’s disease

Iodine deficiency

Will result in hypothyroidism