Chemical Signals in Animals

1
Chemical Signals in Animals
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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.

3
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.

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Homeostasis

• Blood calcium level

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Homeostasis

• rises
  
• Blood calcium level

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Homeostasis

• rises
  
• Blood calcium level

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Homeostasis

• calcitonin
• rises
• Blood calcium level

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Homeostasis

• calcitonin
• rises
  lowers
• Blood calcium level

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Homeostasis

• calcitonin
• rises
  lowers
• Blood calcium level
• 
  drops

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Homeostasis

• calcitonin
• rises
  lowers
• Blood calcium level
• 
  drops

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Homeostasis

• calcitonin
• rises
  lowers
• Blood calcium level
• 
  drops
• parathyroid
• hormone
• (PTH)

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Homeostasis

• calcitonin
• rises
  lowers
• Blood calcium level
• raises
  drops
• parathyroid
• hormone
• (PTH)

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Homeostasis

• insulin
• rises
  lowers
• Blood glucose level
• raises
  drops
• glucagon

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Homeostasis

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

T4
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Homeostasis

• Thyroid stimulating hormone (TSH)
• is made by the anterior pituitary.

T4
TSH
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Homeostasis

• TSH releasing hormone (TRH)
• is made by the hypothalamus.

T4
TRH
TSH
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Homeostasis

• A buildup of T4 signals the hypothalamus
• to stop making TRH.

T4
TRH
TSH
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Homeostasis

• A buildup of TSH does the same thing.

T4
TRH
TSH
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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.

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Some Important Glands

• Hypothalamus pituitary
• Control of other glands,
• Growth (GH)
• Menstruation lactation
• Many other functions.

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Some Important Glands

• Pineal
• Biological rhythms
• Thyroid Parathyroid
• Homeostasis (calcitonin PTH)
• Pancreas
• Blood glucose (insulin glucagon).

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Some Important Glands

• Adrenal
• Stress (epinephrine norepinephrine)
• Gonadal
• Androgens, estrogen, progestin.

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Hormonal control of the menstrual cycle
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Hormonal control of the menstrual cycle
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hypothalamus
follicle
pituitary
uterus menstruation
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POSITIVE FEEDBACK
hypothalamus
follicle
GnRH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
GnRH
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
30
POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
35
POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
follicle
estrogen
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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POSITIVE FEEDBACK
hypothalamus
estrogen
Ovulation!
GnRH
estrogen
thickens
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen
GnRH
estrogen
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen
GnRH
estrogen
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen
GnRH
estrogen
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
GnRH
estrogen progesterone
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
GnRH
estrogen progesterone
develops endometrium
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
Stop!
GnRH
estrogen progesterone
develops endometrium
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
Stop!
GnRH
estrogen progesterone
develops endometrium
ovum
FSH LH
pituitary
uterus
45
NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
Stop!
GnRH
estrogen progesterone
develops endometrium
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
GnRH
estrogen progesterone
ovum
FSH LH
pituitary
uterus
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NEGATIVE FEEDBACK
hypothalamus
corpus luteum
estrogen progesterone
GnRH
estrogen progesterone
ovum
FSH LH
pituitary
uterus menstruation
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BACK TO THE BEGINNING
hypothalamus
follicle
GnRH
pituitary
uterus menstruation
49
Vocabulary Review

• hormone
• endocrine
• target cells
• homeostasis
• calcitonin
• PTH
• insulin
• glucagon

tropic hormone pheromone hypothalamus pituitary th
yroid pancreas adrenal gonadal