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The Endocrine System

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The Endocrine System Anatomy and Physiology – PowerPoint PPT presentation

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Title: The Endocrine System


1
The Endocrine System
  • Anatomy and Physiology

2
Endocrine System
  • Endocrine organs secrete hormones directly into
    body fluids (blood)
  • Hormones are chemical messengers that only affect
    target cells that have a special receptor on the
    cell surface

3
Hormones
  • Are of two types steroid and nonsteroid, usually
    peptide (protein)
  • Steroid hormones may enter the cell through the
    cell membrane, but nonsteroid hormones cannot

4
Nonsteroid hormones
  • These hormones, usually proteins, cannot get
    through the cell membrane.
  • They must attach to a receptor on the outside of
    the membrane
  • They use a 2nd messenger system to get the
    message into the cell, to achieve the desired
    response

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6
Pass it on!
7
2nd messenger system
A chain reaction
8
Endocrine Glands
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10
Control of Hormones
  • Most often controlled by negative feedback
  • This means a gland or system is sensitive to the
    concentration of the substance it secretes, or a
    product it controls

11
Control of Hormones
  • If high levels of a hormone or product are
    detected, then the gland is inhibited (shut off)
  • If low levels are detected, more must be needed,
    so the gland is not inhibited (allowed to turn on)

12
Control of Hormones
  • What turns on and off each gland varies
  • Some have many steps involved, like a chain
    reaction

13
Control of Hormones
14
Control of Hormones
Growth hormone is controlled by a releasing and
an inhibiting hormone. Which one is secreted in
greater concentration determines whether GH is
released or not.
15
Control of Hormones
16
Hypothalamus controls Pituitary
17
Hypothalamus controls Pituitary
18
Hormones of the Pituitary
Master gland
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Growth Hormone
  • Stimulates cell growth and division
  • Under-secretion can be dwarfism, with correct
    proportions and normal mental development
  • Over-secretion can be gigantism

21
61 normal males hand
Twelve year olds hand
Twelve years old 65
Gigantism
22
Hypopituitary Dwarfism
23
Posterior Pituitary
Vasopressin is also called ADH antidiruetic
hormone
24
Thyroid Gland
  • Secretes three hormones
  • Thyroxine (T4), Triiodothyronine (T3)
  • Calcitonin

25
Thyroid Hormones
  • T3 and T4 control metabolism
  • Undersecretion in childhood could cause
    cretinism in adults called myxedema with
    sluggishness, obesity
  • Oversecretion can be Graves disease

Graves disease
Cretinism
26
Goiter
  • Enlarged thyroid gland
  • Caused by lack of iodine
  • Iodine is required to make T4, and if not
    present, the thyroid keeps working to the point
    of enlargement, yet cannot make T4

27
Thyroid Control
  • TRH (TRF) from hypothalamus to pituitary
  • TSH from pituitary to thyroid
  • T3 and T4 (thyroxine) from thyroid
  • Negative feedback

28
Parathyroid
  • Parathyroid gland secretes parathyroid hormone
    (PTH)
  • PTH increases blood calcium and decreases blood
    phosphate
  • Parathyroid gland can sense level of calcium in
    the blood

29
Parathyroid
  • Osteoblasts are cells that build bone
  • Osteoclasts are cells that break down bone to
    release calcium
  • If calcium is low in the blood, PTH stimulates
    osteoclasts
  • If calcium is high in the blood, PTH inhibits
    osteoclasts
  • Controlled by the parathyroid glands, sensing the
    amount of blood calcium

30
Parathyroid
31
Parathyroid
  • Your body sacrifices bone tissue to maintain
    correct levels of calcium in the blood.

32
Thyroid helps with calcium
  • The thyroid gland also helps with calcium
    regulation
  • It secretes calcitonin, which decreases level of
    blood calcium by encouraging the kidney to
    excrete calcium and inhibiting osteoclasts
  • PTH and calcitonin are opposites

33
Adrenal Hormones
  • Adrenal glands on each kidney
  • Inner part is called medulla
  • Outer part is called cortex
  • Each section produces different hormones

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35
Adrenal Hormones
  • Cortex produces cortisol (hydrocortisone)
  • Stimulates carbohydrate metabolism
  • Reduces inflammation
  • Stimulates muscle growth

36
Cortisol from Adrenal cortex
  • Undersecretion leads to Addison disease, can be
    fatal by disturbing electrolyte balance
  • Oversecretion is Cushing syndrome, alters
    carbohydrate and protein metabolism, and
    electrolyte balance

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38
Adrenal Hormones
  • Cortex also produces aldosterone
  • Acts on kidney to increase uptake of sodium
  • Essential for survival because of its role in
    water and solute balance

39
Adrenal Hormones
  • Medulla produces epinephrine, also called
    adrenaline
  • Fight or Flight
  • Increases heart rate, blood pressure, glucose
    level, and blood flow to heart and lungs

40
Pancreas
  • Functions as both endocrine and exocrine gland
  • Endocrine hormones are insulin and glucagon
  • Exocrine digestive enzymes

41
Pancreas
42
Pancreas
  • Special clusters of cells called the Islets of
    Langerhans secrete hormones
  • Alpha cells secrete glucagon
  • Beta cells secrete insulin

43
Pancreas
  • Glucagon stimulates the liver to break down
    glycogen into glucose
  • Stimulated by low blood sugar

44
Pancreas
  • Insulin stimulates the liver to form glycogen and
    promotes the absorption of glucose into cells
  • Lowers blood sugar
  • Stimulated by high blood sugar

45
Diabetes Mellitus
  • Lack of insulin
  • Cells are starving cannot get glucose into the
    cell without insulin, thus weight loss is a
    symptom
  • Kidneys try to get rid of excess sugar,
    increasing urine output and thirst

46
Diabetes Mellitus
47
Diabetes Mellitus
High blood sugar damages blood vessels, leading
to complications Complications includecoronary
artery disease, retinal damage, kidney damage,
and problems from poor circulation in the
peripheral areas
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