The Endocrine System

1
The Endocrine System

• Honors
• Physiology

2
(No Transcript)
3
(No Transcript)
4
What are hormones?

• Hormones
• send messages
• act locally or at a distance
• work quickly or slowly
• can be created/excreted by cells, tissues or
  organs, collectively known as glands
• secreted via epithelial cells ? extracellular
  fluid ? blood stream ? receptors on target cells
• ducts are not used by endocrine system

5
Comparison to Nervous System
Fig. 13.2
6
Comparison to Nervous System
Entity Nervous Sys Endocrine Sys
Cell type Neurons Epithelial
Chemical signal Neurotransmitter Hormone
Specificity of response Receptors on postsynaptic cell Receptors on target cells
Speed Milliseconds Seconds to hours
Length of effect Brief Brief or long
7
Example of Hormonal RegulationTodays Lab

• Thyroxine
• Released from thyroid gland
• Target cells all over body
• Influences metabolism
• Thyroid stimulating hormone (TSH)
• Released from anterior pituitary gland
• Target thyroid gland
• Signal release thyroid hormones!

8
Endocrine SystemRelative Stability of Hormone
Concentrations

• Negative feedback maintains stable hormone levels

Fig. 13.11
9
Endocrine System3 Ways To Control Hormonal
Secretions
Fig. 13.8
10
Example Negative Feedback Controls Blood Glucose
Levels

• What happens when your blood glucose gets too low?

Fig 13.36
11
Example Negative Feedback Controls Blood Glucose
Levels

• What happens when your blood glucose gets too
  high?

Fig 13.36
12
Steroid Hormones
Fig. 13.5
13
Steroid Hormones

• Lipid soluble
• Receptor in the nucleus
• binds hormone ? gene transcription
• mRNA is then translated into a protein in the
  cytoplasm
• Examples
• estrogen, testosterone
• aldosterone, cortisol

14
Nonsteroid Hormones
Fig. 13.7
15
Nonsteriod Hormones

• Cannot move through lipid bilayer
• Instead they bind to receptors in cell membrane
• Examples
• TSH
• Epinephrine
• Glucagon

16
Hypothalamus

• Regulates other glands to tell them when to
  release their hormones

Fig. 13.9
17
Pituitary Gland
Fig. 13.9
18
Anterior Pituitary

• Adrenocorticotropic hormone (ACTH)
• Target adrenal cortex, stimulates cortisol
  release
• influences protein and fat metabolism
• Gonadotropins
• follicle stimulating hormone (FSH)
• egg or sperm maturation
• For egg, stimulates release of egg from follicle
  mid cycle
• luteinizing hormone (LH)
• Stimulates release of sex hormones

19
Anterior Pituitary cont.

• Growth Hormone (GH)
• bone growth/osteogenesis
• Melanocyte Stimulating Hormone (MSH)
• skin color, includes tanning
• Prolactin (PRL)
• lactation
• Thyroid Stimulating Hormone (TSH)
• stimulates thyroid secretions

20
Robert P. Wadlow8 11
Yikes, his anterior pituitary released too much
growth hormone!
Age Height
8 6
14 75
18 84
22 811
21
Anterior Pituitary cont.

• How am I going to remember all of this???
• A Green Giant Makes PRetty Things
• ACTH
• Gonadotropins (FSH, LH/ICSH)
• GH
• MSH
• PR
• TSH

22
Posterior Pituitary

• Antidiuretic Hormone (ADH)
• decreases urine formation
• when you are dehydrated, your body says dont
  lose water!, so ADH is increased
• increased ADH concentrated urine
• Oxytocin
• smooth muscle contractions in the uterus during
  childbirth
• Recent studies bonding hormone

23
Posterior Pituitary cont.

• Why do you urinate more when you drink caffeine?
• Your body recognizes caffeine as a toxin that it
  needs to expel from the body
• Caffeine is a diuretic it makes you urinate
• it inhibits secretion of ADH
• you dont get the dont lose water! signal
• so you expel more water to try and flush out the
  toxin

24
Pineal Gland

• Melatonin
• Helps regulate circadian rhythms (sleep-wake
  cycle)

25
Thyroid

• Thyroxine or tetraiodothyronine (T4)-and
  Triiodothyronine (T3)
• regulate your food metabolism (break down
  glucose, fat protein to create energy)
• increase temperature, growth and development

26
Fig. 13.16
27
Thyroid Parathyroid

• Thyroid releases Calcitonin
• lowers calcium levels in the blood
• Parathyroid releases Parathyroid Hormone (PTH)
• increases calcium levels in the blood

Fig. 13.24
28
Pancreas
Fig. 13.34

• Insulin
• Glucagon
• Islets of Langerhans
• regulate blood glucose levels
• Both hormones created in the

29
Pancreas cont. Islets of Langerhans

• Alpha Cells
• Make Glucagon
• Released when your blood sugar levels get low
• Increases blood glucose levels by breaking down
  glycogen (storage form of glucose in the liver)
  and noncarbohydrates into glucose

• Beta Cells
• Make Insulin
• Released when your blood sugar levels get high
• Tells your body cells to take sugar in, and
  decreases blood glucose levels by stimulating the
  liver to form glycogen

30
Pancreas cont.

• Diabetes- cant regulate your blood glucose
• Type I - Juvenile
• Islets of Langerhans dont work properly cannot
  create sufficient insulin (or glucagon)
• usually need insulin injections (why not glucagon
  injections?)
• usually inherited
• Type II - Adult onset
• Insulin receptors throughout body dont work
  properly
• usually can use oral treatment
• related to weight gain
• About 17 million people in the US have diabetes!

31
Adrenal Glands

• Adrenal Medulla
• epinephrine/adrenalin
• norepinephrine/noradrenalin
• Increases blood glucose, heart rate, etc.
• Blood vessels constrict in digestive tract and
  kidneys, dilate in blood vessels of the muscles

Fig. 13.28
32
Adrenal Glands cont.

• Adrenal Cortex
• Aldosterone
• Target cells in kidneys
• Maintain Na and K balance
• Cortisol
• Glucose, protein and fat metabolism
• Anti inflammatory
• Androgens
• supplement gonad sex hormones

33
Reproductive Organs

• Ovaries
• Estrogen
• stimulates egg maturation
• secondary female sex characteristics
• Progesterone
• maintains uterine lining in case of implantation
• Testes
• Testosterone
• regulates spermatogenesis
• secondary male sex characteristics

34
(No Transcript)
35
Adrenal Glands cont.

• Addison disease
• Cortisol hyposecretion
• low Na, high K , dehydration, low glucose, can
  be very serious
• Cushing syndrome
• Cortisol hypersecretion (usually
• by too much ACTH)
• High Na, low K, high glucose,
• water retention

36
Thyroid cont.

• Graves disease
• too much hormone
• Hyperthyroidism
• Hashimotos disease
• too little hormone
• Hypothyroidism