Chemical Signals in Animals

Chemical Signals in Animals

•A hormone is a chemical secreted into the blood (or other body fluids) that communicates a regulatory message

•Secreted by endocrine glands (“ductless glands”)

•May affect whole body or only target cells

•Important for maintaining homeostasis.

Chemical Signals in Animals

•Nervous system and endocrine system are very closely interrelated

•Some hormones are secreted by nerve cells

•Some act as both hormones and neurotransmitters.

Homeostasis

Blood calcium level

Homeostasis

rises

Blood calcium level

Homeostasis

rises

Blood calcium level

Homeostasis

calcitonin

rises

Blood calcium level

Homeostasis

calcitonin

rises lowers

Blood calcium level

Homeostasis

calcitonin

rises lowers

Blood calcium level

drops

Homeostasis

calcitonin

rises lowers

Blood calcium level

drops

Homeostasis

calcitonin

rises lowers

Blood calcium level

drops parathyroid hormone (PTH)

Homeostasis

calcitonin

rises lowers

Blood calcium level

raises drops parathyroid hormone (PTH)

Homeostasis

insulin

rises lowers

Blood glucose level

raises drops glucagon

Homeostasis

The thyroid makes thyroxin (T4), which controls metabolic rate and other functions.

T4

Homeostasis

Thyroid stimulating hormone (TSH)

is made by the anterior pituitary.

T4TSH

Homeostasis

TSH releasing hormone (TRH)

is made by the hypothalamus.

T4TSHTRH

Homeostasis

A buildup of T4 signals the hypothalamus

to stop making TRH.

T4TSHTRH

Homeostasis

A buildup of TSH does the same thing.

T4TSHTRH

Hormonal Signals

Some are local and affect only neighboring cells. These are broken down within seconds

Tropic hormones affect other endocrine glands

Pheromones affect other organisms

Receptors can be on the cell surface or intracellular.

Some Important Glands

Hypothalamus & pituitary

•Control of other glands,

•Growth (GH)

•Menstruation & lactation

•Many other functions.

Some Important Glands

Pineal

•Biological rhythms

Thyroid & Parathyroid

•Homeostasis (calcitonin & PTH)

Pancreas

•Blood glucose (insulin & glucagon).

Some Important Glands

Adrenal

•Stress (epinephrine & norepinephrine)

Gonadal

•Androgens, estrogen, progestin.

Hormonal control of the menstrual cycle

Hormonal control of the menstrual cycle

hypothalamus

pituitaryuterus

menstruation

follicle

POSITIVE FEEDBACK

GnRH

hypothalamus

pituitary

follicle

uterus

POSITIVE FEEDBACK

GnRH

FSH & LH

hypothalamus

pituitary

follicle

uterus

POSITIVE FEEDBACK

thickens

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

hypothalamus

pituitary

follicle

uterus

estrogen

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

hypothalamus

pituitary

follicle

uterus

estrogen

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH & LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH

& LH

estrogen

estrogen

hypothalamus

pituitary

follicle

uterus

thickens

POSITIVE FEEDBACK

GnRH

FSH

& LH

estrogen

estrogen

Ovulation!

hypothalamus

pituitaryuterus

thickens

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen

estrogen

corpus luteum

hypothalamus

pituitaryuterus

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen

estrogen

corpus luteum

ovum

hypothalamus

pituitaryuterus

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen

estrogen

corpus luteum

ovum

hypothalamus

pituitaryuterus

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

hypothalamus

pituitaryuterus

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

hypothalamus

pituitaryuterus

develops endometrium

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

Stop!

hypothalamus

pituitaryuterus

develops endometrium

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

Stop!

hypothalamus

pituitaryuterus

develops endometrium

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

Stop!

hypothalamus

pituitaryuterus

develops endometrium

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

hypothalamus

pituitaryuterus

ovum

corpus luteum

NEGATIVE FEEDBACK

GnRH

FSH

& LH

estrogen & progesterone

estrogen & progesterone

hypothalamus

pituitaryuterus

menstruation

ovum

corpus luteum

BACK TO THE BEGINNING

GnRH

hypothalamus

pituitary

follicle

uterusmenstruation

Vocabulary Reviewhormone

endocrine

target cells

homeostasis

calcitonin

PTH

insulin

glucagon

tropic hormone

pheromone

hypothalamus

pituitary

thyroid

pancreas

adrenal

gonadal