Chap 17 The Endocrine System

How does the nervous vs endocrine system communicate to the body?

Nervous - electrical impulses and neurotransmitters

Endocrine - hormones

What are the release methods of the nervous vs endocrine system?

Nervous - releases neurotransmitters at synapses at specific target cells

Endocrine - releases hormones into blood for general distribution throughout body

Type of effect the nervous v endocrine system has on the body?

Nervous - local, specific effects

Endocrine - general, widespread effects

How long does the nervous vs endocrine system take to react to stimuli?

Nervous - 1-10 ms

Endocrine - seconds to days (adaption can take days to weeks)

How long is the action of the nervous vs endocrine system?

Nervous - stops when stimulus stops

Endocrine - can continue to respond long after stimulus stops

What is a chemical messenger (typically amino acids or cholesterol derived steroids) transported by the bloodstream that stimulate physiological responses in body cells?

Hormone

What can hormones due to cells?

• Change permeability of membrane

• Synthesize new molecules/proteins

• Alter rates of reaction

• Induce secretions

• Stimulate mitosis

True or False: Each target cell responds to hormones the same.

FALSE!

Liver cells - insulin —> glycogen

Adipocytes - insulin —> triglyceride synthesis

What are the two functional classes of hormones?

1. Lipid soluble hormones

2. Water-soluble hormones

Sex steroids, corticosteroids, thyroid hormones, and nitric oxide are examples of which hormone?

Lipid soluble

What receptor is associated with lipid soluble hormones?

Within cytosol or within nucleus

Amines, peptides, proteins, glycoproteins, and eicosanoids (ex: prostaglandin) are examples of what type of hormone?

Water-soluble

Where is the receptor for a water soluble hormone?

On the cell membrane

How do lipid soluble hormones take action?

1. Hormone diffuses through phospholipid bilayer and into cell

2. Binds to receptor turning on/off specific genes

3. New mRNA is formed —> Synthesis of new proteins

4. New proteins alter cell activity and new physiological responses

How do water soluble hormones take action

1. Hormone binds to membrane receptor

2. Receptor activates G-protein to activate adenylate cyclase

3. Adenylate cyclase converts ATP —> cyclic AMP —→ activate protein kinases

4. Protein kinases phosphorylate enzyme that lead to catalyze reactions

What are the three types of stimuli in hormone release?

1. Humoral stimulus - low concentration of Ca2+ in capillaries stimulates secretion of parathyroid hormones

2. Neural stimulus - Sympathetic fibers stimulate adrenal medulla cells to secrete catecholamines (epi and norepinephrine)

3. Hormonal stimulus - hypothalamus stimulate anterior pituitary to secrete hormones that stimulate other endocrine glands to secrete hormones

Are feedback systems positive or negative?

Negative

1. Hormone produced

2. Hormone levels increase cause target organ effects

3. Inhibits further hormone release

What are the 3 interactions of hormones?

1. Synergism - combined action of hormones is greater than additive effect

2. Permissiveness - one hormone must be present for another one to be fully effective

3. Antagonism - hormones work against each other

What is an example of synergistic hormones?

Testosterone and FSH

What is an example of permissive hormones?

Estrogen and progesterone

What is an example of antagonistic hormones?

Insulin and glucagon

What part of the brain is the major integrating link between the nervous and endocrine system?

Hypothalamus

What does the hypothalamus recieve input from?

Cortex, thalamus, limbic system, and internal organs

What hormones does the neurohypophysis secrete?

Oxytocin and ADH

What is the function of oxytocin?

• Uterine contractions

• Milk ejection

• Release during bonding and intercourse

What is the function of ADH (anti diuretic hormone?

Water retention

• Decrease urine production

• Decrease sweating

• Increase blood pressure

What does the anterior pituitary (adenohypophysis)?

1. Growth hormone

2. Thyroid stimulating hormone

3. ACTH (corticotropin)

4. Prolactin

5. FSH (gonadotropins)

6. LH

What is the function of growth hormone?

1. Stimulates cell growth

2. Mobilizes fats, spares glucose

3. Inhibited by GH inhibiting hormone (can lead to dwarfism and gigantism)

Released during development and hypoglycemia (low blood sugar)

What is the function of thyroid stimulating hormone?

1. Thyrotropin releasing hormone is released by hypothalamus

2. TSH —→ TH in thyroid (T3 and T4)

3. Balances hypo and hyperthyroidisms

4. Increases basal metabolic rate

5. TSH is inhibited by TH

What is the function of Adenocorticotropic hormone?

• Released during stress

• Targets adrenal cortex to release glucocorticoids and androgens to decrease stress effects

• Inhibited by negative feedback

• TOO MUCH = Cushings disease

• NOT ENOUGH = Addison’s

What is the function of prolaction?

• Milk production

• Decrease of dopamine when prolactin is released

What is the function of gonadotropins (FSH and LH)

• stimulates egg and sperm production

• stimulate estrogen, progesterone, and testosterone

What does the thyroid secrete?

• Thyroid hormones (T3 and T4)

• Calcitonin

What is the function of T4 and T3?

Metabolic rate, synthesis of protein, breakdown of fats, use of glucose for atp production

What is the function of calcitonin?

Responsible for calcium deposition and bone formation and stops reabsorption of bone

What blood level of hormones stimulate hypothalamus?

Low

What homeostatic imbalance: Hypothyroid syndrome: hormonal or lack of iodine, low metabolic rate, lethergy, gaining weight, excessive production of TSH —> goiter (enlargement of thyroid)

Hypothyroid syndrome

What homeostatic imbalance: Increased TH production —> increased metabolic rate, weight loss, hyperactivity, exophthalmos (protruding eyeballs) in Grave’s disease

Hyperthyroid syndrome

Which cells of the parathyroid glands produce parathyroid glands?

Chief cells

What is the function of the parathyroid glands?

Increase blood calcium levels

What hormones does the adrenal gland secrete?

1. Aldosterone - electrolyte balance

2. Cortisol - regulate glucose metabolism and other fuel

3. Androgens - sex steroids

4. Catocholamines (norepinephrine and epinephrine)

Are exocrine acinar cells digestive enzymes or hormones? Where are they located?

Near duct; digestive enzyme

Are endocrine cells digestive enzymes or hormones? Where are they located?

Near capillary, hormones

What hormones does the pancreas secrete?

Insulin and glucagon, TARGET LIVER, regulate blood glucose levels

What describes the group of disorders caused by inability to produce or use insulin?

Diabetes mellitus

What is the difference between type 1 and type 2 diabetes?

Type 1 - insulin-dependent and is absolute deficiency of insulin

Type 2 - insulin-independent diabetes cuased by down regulation of insulin receptors

causes polyuria

excessive thirst and excessive eating

What occurs when too much insulin in present?

Hyperinsulinism —→ hypoglycemia and insulin shock

What is the placenta?

Temporary endocrine organ, to help release estrogen and progesterone to regulate pregnancy and stimulate the development of the fetus and the mammary glands

What is the role of the thymus?

• Endocrine, lymphatic, and immune systems

• Hormones produced by gland promotes creation and maturation of T cells

• Thymosin

• Thymulin

• Thymopoeitin

T or F: the Thymus shrinks in size as you age

T

What does the pineal gland release?

Melatonin

What is the pineal gland made of:?

Pinealocytes and neuroglia

What does melatonin regulate?

Biological clock

What is the treatment for Jet lag and seasonal affective disorder?

Bright light

What does adipose tissue secrete?

Leptin - suppress appetite

What does the fundus of the stomach secrete?

Ghrelin - stimulates hunger