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Endocrine System

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Title: Endocrine System


1
Chapter 15
  • Endocrine System

2
Points to Ponder
  • What is the endocrine system?
  • Compare and contrast exocrine and endocrine
    glands.
  • What are steroid and peptide hormones?
  • Name the major glands and their functions in the
    endocrine system.
  • What is diabetes (Type 1 and 2) and how might you
    prevent Type 1?
  • How do the endocrine nervous systems work with
    the rest of the systems in the body to maintain
    homeostasis?

3
Endocrine system
15.1 Endocrine glands
  • Mostly comprised of glands
  • Secretes hormones that move through the
    bloodstream to target cells
  • Results in a slow but a prolonged response

4
Endocrine system
15.1 Endocrine glands
5
What is a target cell?
15.1 Endocrine glands
6
Exocrine vs. endocrine glands
15.1 Endocrine glands
  • Exocrine glands secrete their products into ducts
    that carry these products to other organs or
    outside the body
  • Endocrine glands secrete their products directly
    into the bloodstream

7
What are hormones?
15.1 Endocrine glands
  • Hormones are chemical signals that promotes
    communication between cells, body parts and even
    individuals
  • Hormones
  • Prostaglandins local hormones affect neighboring
    cells and thus are not carried in the bloodstream
  • Pheromones chemical signals that influence the
    behavior of other individuals
  • Peptide hormones bind to a receptor in the
    plasma membrane causing the formation of cAMP
    which activates a cascade of enzymes
  • Steroid hormones lipids that enter a cell and
    affect gene activity and thus protein synthesis

8
Action of peptide hormones
15.1 Endocrine glands
9
Action of steroid hormones
15.1 Endocrine glands
10
Major glands of the endocrine system
15.2 Hypothalamus and pituitary gland
  • Hypothalamus
  • Posterior pituitary gland
  • Anterior pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas
  • Testes
  • Ovaries
  • Thymus gland
  • Pineal gland

11
1. Hypothalamus
15.2 Hypothalamus and pituitary gland
  • Regulates internal environment through the
    autonomic nervous system
  • Helps control heartbeat
  • Helps control body temperature
  • Helps control water balance
  • Controls glandular secretions

12
2. Posterior pituitary gland
15.2 Hypothalamus and pituitary gland
  • Stores antidiuretic hormone (ADH) and oxytocin
    that are produced by the hypothalamus
  • ADH regulates water balance by reabsorbing water
    into the bloodstream
  • Oxytocin causes uterine contractions during
    childbirth and allow milk to be released during
    nursing

13
3. Anterior pituitary gland
15.2 Hypothalamus and pituitary gland
  • Controlled by hypothalamic-releasing and
    hypothalalmic-inhibiting hormones
  • Hormones produced by the anterior pituitary
  • Thyroid-stimulating hormone (TSH) stimulates the
    thyroid to produce thyroid hormones
  • Adrenocorticotropic hormone (ACTH) stimulates
    the adrenal cortex to produce cortisol
  • Gonadotropic hormones stimulate gonads to
    produce sex cells and hormones
  • Prolactin (PRL) stimulates mammary glands to
    develop and produce milk only after childbirth
  • Melanocyte-stimulating hormone (MSH) causes skin
    cells to produce melanin
  • Growth hormone (GH) promotes skeletal and
    muscular growth

14
The hypothalamus and pituitary
15.2 Hypothalamus and pituitary gland
15
What happens when the body produces too much or
too little GH?
15.2 Hypothalamus and pituitary gland
  • Pituitary dwarfism too little GH is produced
    during childhood that results in small stature
  • Giantism too much GH is produced during
    childhood that results in poor health
  • Acromegaly overproduction of GH as an adult
    that results in larger than normal feet, hands,
    and face

16
What happens when GH is produced in improper
results during childhood?
15.2 Hypothalamus and pituitary gland
17
What happens when GH is produced in high amounts
during adulthood?
15.2 Hypothalamus and pituitary gland
18
4. Thyroid gland
15.3 Thyroid and parathyroid glands
  • A large gland located below the larynx
  • Iodine is needed in the diet to allow the thyroid
    gland to produce its hormones
  • It produces
  • Thyroid hormone (TH) regulates metabolism
  • Calcitonin helps lower blood Ca2 levels by
    stimulating the deposition of calcium in the
    bones

19
Thyroid abnormalities
15.3 Thyroid and parathyroid glands
  • Simple goiter thyroid enlarges due to lack of
    iodine in the diet
  • Hypothyroidism low blood levels of thyroid
    hormones
  • Congenital hypothyroidism thyroid does not
    develop properly and is characterized in a short,
    stocky person that may be mentally retarded
  • Myxedema hypothyroidism in adults characterized
    by lethargy, weight gain, loss of hair, cold
    intolerant and thick, puffy skin
  • Hyperthyroidism excess thyroid hormones in the
    blood
  • Exophthalimic goiter such as seen in Graves'
    disease and is characterized by enlargement of
    the thyroid gland, protrusion of the eyes,
    hyperactive and suffers from insomnia
  • Thyroid tumor can also cause hyperthyroidism

20
Thyroid abnormalities
15.3 Thyroid and parathyroid glands
21
5. Parathyroid glands
15.3 Thyroid and parathyroid glands
  • Small glands embedded in the surface of the
    thyroid gland
  • Produces parathyroid hormone (PTH)
  • causes blood Ca2 level to increase by promoting
    osteoclast activity
  • Promotes reabsorption of Ca2 by the kidneys

22
Regulation of blood calcium
15.3 Thyroid and parathyroid glands
23
6. Adrenal glands
15.4 Adrenal glands
  • Glands that sit on top of the kidneys
  • 2 parts of each gland
  • Adrenal medulla controlled by the nervous system
  • Adrenal cortex portions are controlled by ACTH
    from the anterior pituitary

24
Adrenal medulla
15.4 Adrenal glands
  • Inner portion of the adrenal glands
  • Hypothalamus initiates stimulation of hormone
    secretion in the adrenal medulla
  • Produces hormones that allow a short-term
    response to stress (fight or flight response)
  • Epinephrine (adrenaline)
  • Norepinephrine

25
Adrenal cortex
15.4 Adrenal glands
  • Outer portion of the adrenal glands
  • Produces hormones that provide a long-term
    response to stress
  • 2 major types of hormones
  • Mineralocorticoids
  • regulate salt and water balance
  • e.g. aldosterone (targets the kidney)
  • Glucocorticoids
  • regulate carbohydrate, protein and fat metabolism
  • Suppress the bodys inflammatory response
  • e.g. cortisol and cortisone

26
Summary of the adrenal glands
15.4 Adrenal glands
27
Adrenal glands can malfunction
15.4 Adrenal glands
  • Addisons disease hyposecretion of
    glucocorticoids by the adrenal cortex
    characterized by bronzing of the skin

28
Adrenal glands can malfunction
15.4 Adrenal glands
  • Cushing syndrome hypersecretion of
    glucocorticoids by the adrenal cortex
    characterized by weight gain in the trunk of the
    body but not arms and legs

29
7. Pancreas
15.5 Pancreas
  • Fish-shaped organ behind the stomach
  • Composed of 2 tissues
  • Exocrine produces and secretes digestive juices
  • Endocrine (islets of Langerhans) produces and
    secretes hormones
  • Insulin secreted when blood glucose is high and
    stimulates uptake of glucose by cells (muscle and
    liver)
  • Glucagon secreted when blood glucose is low and
    stimulates the breakdown of glycogen in the liver

30
Regulation of blood glucose
15.5 Pancreas
31
Health focus What is diabetes?
15.5 Pancreas
  • Inability to control blood glucose levels
  • There are two types Type 1 and Type 2
  • 18 million people in the US have diabetes
  • General symptoms
  • Frequent urination
  • Unusual hunger and/or thirst
  • Unexplained change in weight
  • Blurred vision
  • Sores that heal slowly or not at all
  • Excessive fatigue
  • Long-term effects are blindness, loss of limbs,
    nerve deterioration, kidney and cardiovascular
    disease

32
Diabetes Understanding the 2 types
15.5 Pancreas
  • Type 1
  • Usually early-onset
  • Autoimmune disorder that tends to run in families
  • Pancreatic cells are attacked and cannot produce
    insulin
  • Need insulin injections
  • Type 2
  • Usually adult-onset and most common type
  • Tends to occur in obese, sedentary people
  • Cells do not respond to insulin
  • Usually diet and exercise are important for
    controlling this and may even prevent this!

33
8. Testes
15.6 Other endocrine glands
  • Gonads found in males
  • Produce androgens (e.g. testosterone)
  • Stimulates growth of the penis and testes
  • Responsible for 2 male sex characteristics such
    as facial, underarm and pubic hair
  • Prompts the larynx and vocal cords to enlarge
    resulting in a lower voice
  • Promotes muscular strength

34
9. Ovaries
15.6 Other endocrine glands
  • Gonads found in females
  • Produce estrogen and progesterone
  • Stimulates growth of the vagina and uterus
  • Responsible for secondary sex characteristics
    such as female body hair, fat distribution and
    breast development
  • Responsible for egg maturation
  • Regulates the uterine cycle

35
Bioethical focus You decide
15.6 Other endocrine glands
  • Hormone replacement therapy (HTR) is often used
    to counteract some of the problems associated
    with menopause or to prevent an increased risk of
    osteoporosis
  • 2002 a study found that HTR
  • May have risks that outweigh the benefits
  • Does not significantly increase the quality of
    life
  • Significantly increased the risk of breast cancer
  • May increase the risk of cardiovascular disease
  • Can prevent fractures as a result of osteoporosis

36
10. Thymus gland
15.6 Other endocrine glands
  • Lies beneath the sternum
  • This gland is largest and most active during
    childhood
  • T lymphocytes mature here
  • Secretes hormones called thymosins that aid in
    differentiation of lymphocytes

37
11. Pineal gland
15.6 Other endocrine glands
  • Located in the brain
  • Secretes melatonin that regulates the sleep/wake
    cycle (circadian rhythm)
  • May also regulate sexual development

38
Hormones from other tissues
15.6 Other endocrine glands
  • Erythropoietin secreted by the kidney to
    increase red blood cell production
  • Leptin produced by fat cells and acts on the
    hypothalamus to give a feeling of being satiated
  • Prostaglandins
  • A groups of potent chemicals that are not carried
    in the bloodstream but work locally on
    neighboring cells
  • Some cause smooth muscle contraction
  • Major impact on reproductive organs
  • Many other roles in the body
  • Aspirin and ibuprofen block the synthesis of these

39
Homeostasis
15.7 Homeostasis
  • The nervous and endocrine systems are important
    in maintaining homeostasis by
  • The hypothalamus bridges regulatory functions of
    both systems
  • The nervous system is able to respond to changes
    in the external environment

40
How the nervous and endocrine systems work with
other body systems
15.7 Homeostasis
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