EXSS276 Exam 2

Exocrine Glands

These glands secrete products into ducts which then carry secretions to the target site. Examples include sweat, oil, mucous, and digestive glands.

Exo=outside the body

NOT HORMONES

Endocrine Glands

These glands secrete products into interstitial fluid of secretory cells, which then diffuse into capillaries and are carried away by blood. Examples include pituitary, thyroid, adrenal, and pineal glands.

Endo=within the body

DUCTLESS! USES HORMONES!

___________ are chemical messengers

Hormones

True or false: hormones are highly regulated

true

What do hormones carry?

information

True or false: hormones are powerful in high concentration

false; they have powerful effects even in very low concentrations

True or false: hormones act on any cells

False: specific target cells act with very specific receptors

Do hormones act in the same part of the body that they are released?

No. They are released in one part of the body, but regulate the activity of cells in other parts of the body

What are some examples of things that hormones help regulate/control?

• extracellular fluid
• metabolism
• biological clock
• contraction of cardiac & smooth muscle
• glandular secretion
• some immune functions
• growth & development
• reproduction

Circulating hormones

These travel in the blood and act on distant target cells

Local Hormones

These hormones travel in the extracellular space (not in the blood)

Paracrine: acts on neighboring cells

Autocrine: acts on the same cell that secreted it

What are the 3 general mechanisms of hormone action?

1. The hormone binds to the receptor on the cell surface or the receptor inside the target cell.

2. The cell may then synthesize new molecules, change its membrane’s permeability, or alter its reaction rates.

3. Each target cell responds.

What are the chemical classes of hormones?

1. Lipid-soluble

2. water-soluble

Lipid-Soluble hormones

bind to transport proteins to be carried in the blood

• steroids, thyroid hormones, and nitric oxide

Water-soluble hormones

circulate freely in plasma with no transporter protein required

• amines; peptides, proteins, and glycoproteins; and eicosanoids

What are the steps of action of lipid-soluble hormones? What is this process called?

DIRECT GENE ACTIVATION

1. Lipid-soluble hormones diffuse into the cell

2. activated receptor alters gene expression

3. new proteins form

4. these proteins alter cells activity

What are the steps of action of water-soluble hormones? What is this process called?

SECOND MESSENGER SYSTEM

1. hormones can’t diffuse through the plasma membrane, so it binds to according receptors in the membrane

2. FIRST MESSENGER: the hormone that binds to the cell membrane receptor

3. SECOND MESSENGER: cAMP: released inside the cell where hormone-situated response take place

describe the amplification of hormone effects

when a single molecule of hormone binds to a receptor, this activates about 100 G-proteins. Each G-protein activates and AC, which then produces about 1000 cAMP. Each cAMP activates a protein kinase which may act on over 1000 substrate molecules!

What causes hormones to be released into the blood?

3 types of stimuli: humoral, neural, and hormonal

Humoral stimuli

(blood or fluid): hormone release in response to changes in extracellular fluids

Neural stimuli

non-voluntary process in which the nervous system stimulates hormone release

Hormonal stimuli

release of a hormone in response to another hormone

Hypothalamus

the major integrating link between the nervous and endocrine system

What does the hypothalamus receive input from?

cortex, thalamus, limbic system, and internal organs

What does the hypothalamus control?

pituitary gland with 9 releasing and inhibiting hormones

The hypothalamus and the pituitary gland regulate:

virtually all aspects of growth, development, metabolism, and homeostasis

Why is the pituitary gland called the master gland?

There are so many physiologic functions affected:

maturation - growth

reproduction

metabolism

circulation

bone metabolism

body temperature

water balance

Hypothalamus Anterior lobe hormones

ACTH (adrenocorticotropin hormone)

TSH (thyroid stimulating hormone)

FSH (follicule stimulating hormone)

LH (luteinizing hormone)

Human Growth Hormone (hGH)

Prolactin (PRL)

Hypothalamus posterior lobe hormones

ADH (antidiuretic hormone), Vasopressin

Oxytocin

Releasing hormones (RH)

control the release of hormones from anterior pituitary

Releasing hormones are made in the:

hypothalamus

Releasing hormones are released into the:

hypophyseal portal system, and then travel to the anterior pituitary

Hypothalamus: thyroid hormone (TRH) releasing hormone

corresponding pituitary hormone:

thyrotropin (TSH)

Hypothalamus: Growth Hormone (GHRH) releasing hormone

corresponding pituitary hormone:

growth hormone (hGH)

Hypothalamus: Corticotropin (CRH) releasing hormone

corresponding pituitary hormone:

adrenocorticotropin

Hypothalamus: gonadotropin (GnRH) releasing hormone

corresponding pituitary hormone:

Follicle stimulating (FSH)

Luteinizing Hormone (LH)

Hypothalamus: prolactin (PIH) inhibiting hormone

corresponding pituitary hormone:

prolactin (PRL)

What are the two pituitary hormones that do not need to be stimulated by the hypothalamus?

oxytocin

vasopressin (ADH)

What is the target of thyrotropin (TSH)?

stimulate thyroid gland, stimulate TH production

What is the target of adrenocorticotropin (ACTH)?

stimulate adrenal cortex

stimulate cortisol production

What are the targets of follicle-stimulating (FSH) and Luteinizing Hormone (LH)?

stimulate gonads

What pituitary hormones have organs or tissues as their target?

growth hormone (GH)

prolactin (PRL)

oxytocin

vasopressin (ADH)

What pituitary hormones have endocrine glands as their targets?

Thyrotropin (TSH)
Growth Hormone (GH)
Adrenocorticotropin (ACTH)
Follicle Stimulating (FSH)
Luteinizing Hormone (LH)
Prolactin (PRL)
Oxytocin
Vasopressin (ADH)

What is the target of growth hormone (GH)?

Stimulate protein synthesis in tissues, maturation, bone growth, increase glucose and lipolysis

What is the target of Prolactin (PRL)?

mammary gland (lactation, reproduction)

What is the target of oxytocin?

labor contractions and lactation

What is the target of vasopressin (ADH)?

vasoconstrictor and renal water reabsorption

What is a possible result of an overactive thyroid?

Pituitary Gland Hyperplasia (excessive growth)

What is hGH essential for?

normal growth during childhood and adolescence

What is the most plentiful anterior pituitary hormone?

hGH

hGH promotes synthesis and secretion of small protein hormones called:

insulin-like growth factors (IGF)

What is the function of IGFs?

stimulate growth and regulate metabolism

How to hGH and IDF stimulate growth?

• common target cells are liver, skeletal
muscle, cartilage and bone
• Increases growth & cell division by
increasing amino acid uptake & protein
synthesis
• Stimulate lipolysis, fatty acids used for ATP
• Spares use of glucose for ATP production,
keeps blood glucose levels high enough to
supply brain

What is the difference of hypersecretion of hGH during childhood vs adulthood?

during childhood, when the bones are more malleable, normal body proportions will see enhanced growth

during adulthood hands, feet, and face are mostly affected

What hormones are released by the thyoid?

T4 = thyroxine

T3 = triiodothyronine

calcitonin (calcium metabolism)

What regulates T3 and T4?

Between the hypothalamus and anterior pituitary: Thyroid Releasing Hormone (TRH)

then, between anterior pituitary and thyroid gland: Thyroid-stimulating Hormone (TSH)

What is the metabolic role of T3 and T4?

in the mitochondria, they are responsible for:

• increased O2 consumption

• increased ATP production via glucose and FFA

• Production of Heat

• increased BMR

What are the roles of t4 and t3 in growth and development?

they assist in the brain, bone, muscle tissue, and stimulate protein synthesis and accelerate tissue growth

what are the neuroendocrine roles of t3 and t4?

enhancing the effects of epinephrine, glucagon, and growth hormone (which stimulates protein synthesis and accelerates tissue growth)

Hyperthyroidism

• Weight loss
• Feeling hot
• Fatigue, irritability, jittery feeling &
behavior
• Treatment: radioactive iodine,
ablation

Hypothyroidism

• Weight gain
• Feeling cold
• Fatigue, slowed thinking, lethargy
• Treatment: TSH

What stimulates the release of t4 and t3?

• low blood levels of t3 and t4

• low metabolic rate

• increase in ATP demand (cold temp, increased energy expenditure, hypoglycemia, high altitude, pregnancy)

Calcitonin functions

Regulates calcium homeostasis (with PTH)

lowers blood levels of calcium (inhibits bone resorption by osteoclasts

builds bone (incorporates calcium into bone matrix)

Calcitonin is ______ the blood and transferred to the bones, while PTH is _________ the bone and transferred to the blood.

pulled from

What is released by the Parathyroid glands?

parathyroid hormone (PTH)

Parathyroid Hormone function

• increases blood calcium level

• decrease blood phosphate level

• increases the number and activity of osteoclasts (break down bone) = promotes bone resorption and releases calcium

• stimulate the kidneys to secrete calcitriol and cause reabsorption of Ca2+ from food

What are the two parts of adrenal glands?

outer cortex

inner medulla

Outer cortex produces:

3 types of hormones from 3 zones of cortex

Inner medulla produces:

catecholamines:

1. epinephrine

2. norepinephrine

3. dopamine

What are the 3 hormones of the adrenal cortex?

mineralocorticoids (mineral homeostasis) → aldosterone

glucocorticoids (glucose homeostasis) → cortisol

androgens (steroid hormones with masculine effects) → testosterone

aldosterone

increased reabsorption of NA and H2)

increased excretion of K+ and H+ in the urine

goal: regulate NA and K levels in the body

Regulated by: renin-angiotensin

Anti-Diuretic Hormone (ADH) / Vasopressin: where is it made and stored?

Made in the hypothalamus, but stored and released in the
Posterior Pituitary

Anti-Diuretic Hormone (ADH) / Vasopressin: major physiological effects

– Decreases urine volume by causing kidneys to reabsorb
water
– Constriction of blood vessels, causes increased BP

Anti-Diuretic Hormone (ADH) / Vasopressin: stimuli for release

– Increased blood osmolarity, decreased blood volume form
dehydration, sweating, hemorrhage, vomiting, diarrhea

what does cortisol regulate?

metabolism and stress response

How does cortisol effect the following elements:

1. muscle fibers

2. liver

3. adipocytes

4. blood arterioles

5. WBC

1. protein breakdown (energy)

2. gluconeogenesis (energy)

3. lipolysis (energy)

4. vasoconstriction

5. inhibition of WBC and anti-inflammatory effects (slows healing)

Hormones of the adrenal medulla

1. epinephrine (80%): responsible for metabolic effects

2. norepinephrine (20%): responsible for cardiovascular effects

What are the metabolic effects of epinephrine?

• increased substrate use and mobilization

• increased glycogen breakdown

• increased lipolysis

What are the cardiovascular effects of norepinephrine?

• increased heart rate and contractility

• increased blood pressure

• increased blood flow to the heart, liver, muscles, and adipose tissue

• increased dilation of airways

What causes the release of catecholamines?

• increases in SNS activity

• decreases in blood glucose levels

• increase in emotional stress

What are the slow acting stress hormones?

ACTH → cortisol

hGH → IGFs

TSH → thyroid hormones (t3 and t4)

What are the fast acting stress hormones?

epinephrine and norepinephrine

What are the 3 steps to general adaptation syndrome of stress?

1. fight or flight (immediate)

2. resistance (longer-term)

3. exhaustion (depletion/death)

Where does insulin come from?

pancreatic beta cells

Where does glucagon come from?

pancreatic alpha cells

Insulin = promotes glucose _______ from the blood

uptake

decreases blood glucose

Glucagon = promotes _______ of glucose into blood

release

increases blood glucose

Describe how insulin and glucagon are regulated via negative feedback

• low blood glucose stimulates the release of glucagon

• high blood glucose stimulates the secretion of insulin

What role does insulin have in relation to protein?

amino acid (aa) uptake from blood

• promotes protein synthesis

• lipogenesis and glycogenesis (store energy)

• slows GNG and glycogenolysis

• important during youth and puberty

Type I - Insulin Dependent DM

• Old name “Juvenile Onset”
• absolute deficiency of insulin
• autoimmune disease, body destroys beta cells

Type II - Non-insulin dependent DM

• Old name “Adult Onset”
• Insulin produced, tissues insensitive, down-
regulation of insulin receptors

What are symptoms of diabetes mellitus?

1. excessive urine production (polyuria)

2. excessive thirst (polydipsia)

3. excessive eating (polyphagia)

What does insulin resistance do?

does not allow glucose to go into the cell

What are treatment strategies for Type 1 diabetes?

Insulin-dependent DM requires:

• insulin injections/treatments

• pancreatic beta cell transplant

What are treatment strategies for type II diabetes?

non-insulin dependent DM may need:

• may need insulin

• diet modification

• weight loss; regular exercise, caloric restriction

What is the function of the hypothalamic-pituitary gonadal axis?

in males, this regulates the production of sperm

in females, this regulates ovulation, the ovarian cycle, and the uterine cycle

What controls spermatogenesis?

hypothalamus

Effects of inhibin?

If sperm production is sufficient:
• sertoli cells release inhibin
• inhibits FSH secretion by the anterior pituitary
• decreases sperm production
If sperm production is proceeding too slowly:
• less inhibin is released by the sertoli cells
• more FSH will be secreted
• sperm production will be increased

The female reproductive cycle is controlled by monthly hormone cycle of:

anterior pituitary

hypothalamus

ovary

Describe the menstrual cycle

• involves changes in the endometrium
• preparation of uterus to receive fertilized ovum
• if implantation does not occur, the lining is shed
during menstruation