A&P II Lec- SG Ch. 16

Compare and contrast the nervous system to the endocrine system. (4)

SPRINTER

1. faster; short duration responses

2. via action potential & neurotransmitters

3. acts at specific locations determined by pathways

4. neurotransmitters act over very short distances

5. strength coded by frequency of action potentials

Compare and contrast the endocrine system to the nervous system. (4)

X COUNTRY

1. slower; long duration response

2. via hormones

3. diffuse locations; anywhere w/ blood

4. hormones over long distance

5. strength coded by concentration of hormone

Endocrine gland vs. Exocrine gland

1. prodcue hormones

2. lack ducts

3. release into surrounding tissues

4. rich in vascular and lymphatic drainage

Endocrine gland vs. Exocrine gland

1. non-hormones: sweat, saliva

2. ducts carry secretion to membrane surface

Identify the locations of the endocrine glands.

5 glands; thyroid, parathyroid, pituitary, pineal, adrenal

How are hormones different from paracrines and autocrines?

Autocrines are local chemical messengers that exert effects on the same cells that secrete them, meanwhile, paracrines are locally acting chemical messengers that affect cell types other than those that secrete them.

Which hormones are water-soluble?

amino acid based hormones except thyroid hormone

What about their chemistry makes them water soluble?

amino acid based hormones act on the plasma membrane receptors that activate second messengers; which effects occur quickly, but do not last long

Do they bind to extracellular or intracellular receptors and why?

extracellular; they cannot enter the cell because the cellular membrane is made up of phospholipids

Which hormones are lipid-soluble?

steroids and thyroid hormone

What about their chemistry makes them lipid-soluble?

they are made up of steroids which is a type of cholesterol (lipid), and the thyroid hormone acts like a lipid soluble.

Do they bind to extracellular or intracellular receptors and why?

intracellular; they can enter the cell and they must do that to activate direct gene activation; Receptor-hormone complex enters nucleus and binds to specific region of DNA; Helps initiate DNA transcription to produce mRNA

What is the amplification effect?

aka cascade; a small stimulus can result in a larger effect in the second messenger system

Second messenger system

Hormone (1st messenger)→ receptor → G protein → enzyme → 2nd messenger

What is direct gene activation? What kinds of hormones are capable of direct gene activation?

lipid soluble steroid hormones and thyroid hormones diffuse into target cells and bind intracellularly; Receptor-hormone complex enters nucleus and binds to specific region of DNA

Humoral Stimuli –

hormone release caused by altered levels of ions/nutrients

Neural Stimuli –

hormone release caused by neural input

Hormonal Stimuli –

hormone release caused by another hormone (tropic)

Permissiveness –

one hormone cannot exert effects without another hormone

Synergism –

more than one hormone produce same effect; causing amplification.

Antagonism –

1 or more hormone opposes the action of another hormone

Example of Permissiveness

reproductive hormones needs thyroid hormones

Example of Synergism

glucagon and epinephrine both causes liver to release glucose

Example of Antagonism

insulin and glucagon

Blood levels of hormones are controlled by

negative feedback

Blood levels of hormones are triggered by

1. endocrine glands stimuli

2. nervous system modulation

Humoral Stimuli examples

1. low calcium → parathyroid hormone

2. high blood sugar → insulin

Neural Stimuli examples

fight or flight → catecholamines

Hormonal Stimuli examples

hormones from hypothalamus → anterior lobe of pituitary gland secretes other hormones that stimulate other endocrine glands to secrete hormones (tropic= ripple effect)

‘Tropins’ or ‘tropic hormones’ are which of the three stimuli?

hormonal

Define ‘Half-Life’ –

time required for level of hormone in blood level to decrease by half

Half Lives are shorter in

water-soluble hormones because rapidly removed by kidneys

Circulation and half-life of lipid-soluble hormones (lipids)

attached to plasma proteins

Circulation and half-life of water-soluble hormones

without carriers; half life shortest in because removed by kidneys

What is another name for the neurohypophysis?

posterior pituitary gland/ posterior lobe

What hormones does the neurohypophysis store? How are they regulated? What are their functions?

• 2 hormones; oxytocin and antidiuretics (ADH)

• stored in axon terminals in posterior pituitary and released into blood when neurons fire

What is the hypothalamic-hypophyseal tract?

connection between hypothalamus and posterior pituitary; arises from neurons in nuclei of hypothalamus

What is another name for the adenohypophysis?

anterior pituitary gland/ anterior lobe

What is the adenohypophysis made up of?

glandular tissue

What hormones does the adenohypophysis produce? How are they regulated? What are their functions?

6; growth hormone, prolactin, thyroid stimulating hormone, follicle stimulating hormone, adrenocorticotropic hormone, luteinizing hormone

What is the hypophyseal portal system?

connection between hypothalamus and anterior pituitary gland which consists of:

• Primary capillary plexus

• Hypophyseal portal veins

• Secondary capillary plexus

Briefly describe the structures found in the thyroid gland.

follicles; thyroid hormone, colloid; fluid of follicle when containing thyroglobulin and iodine, parafollicular; calcitonin

What hormones does the thyroid gland produce? How are they regulated? What are their functions?

• follicular cells → thyroid hormone; negative feedback (regulates metabolism)

• parafollicular cells → calcitonin; produced in response to high Ca levels (regulated by parathyroid hormone)

What hormone does the parathyroid gland produce? How is it regulated? What are its functions?

parathyroid hormone; release of calcium from bone to bloodstream; maintain calcium levels (homeostasis)

Briefly describe the structures found in the adrenal gland.

suprarenal glands; 2 glands in one

• cortex- 3 layers of glandular tissue that synthesize and secrete different hormones

• medulla- nervous tissue that is part of sympathetic nervous system

What hormones does the adrenal gland produce? How are they regulated? What are their functions?

cortex;

• mineralocorticoid → aldosterone

• glucocorticoid → cortisol

• gonadocorticoid → androgen

medulla;

catecholamines → epinephrine and norepinephrine

short-term stress

automatic nervous system and adrenal medulla: catecholamines mitigate fight/flight response

long-term stress

large increase in ACTH target the cortex; not only induces cortisol release, but also cause aldosterone release; continues to induce fight/flight response

What hormone does the pineal gland produce? How is it regulated? What are its functions?

melatonin

Briefly describe the structures found in the pancreas.

pancreatic islets; alpha and beta cells

What hormones does the pancreas produce? How are they regulated? What are their functions?

insulin and glucagon

What hormones do the gonads produce? How are they regulated? What are their functions?

they produce same steroid sex hormones as those in adrenal cortex but in GREATER amounts

Diabetes insipidus

HYPOsecretion of ADH

ADH deficiency due to damage to hypothalamus or posterior pituitary

syndrome of inappropriate ADH secretion (SIADH)

HYPERsecretion of ADH

• in children w/ cancer, or in adults w/ hypothalamic injury or general anesthesia

• retention of fluid, headache, disorientation

• management req. fluid retention and blood Na level monitoring

anterior pituitary hormones are _________ hormones

peptide

all anterior pituitary hormones except ___________

activate target cells via second messenger system

What hormones do adipose tissue, the heart, kidneys, skeleton, skin, and thymus produce? What are their functions?

Briefly describe how age influences the endocrine system.

High concentrations of _________ cause vasoconstriction, so also called vasopressin

antidiuretics (ADH)

Diabetes insipidus

• Hyposecretion of ADH because damage to the hypothalamus and or posterior pituitary gland

• Output of large amounts of urine → induces thirst

Syndrome of inappropriate ADH secretion (SIADH)

– Hypersecretion of ADH
– Can occur in children with cancer, or in adults following hypothalamic injury or
general anesthesia
– Retention of fluid, headache, disorientation
– Management requires fluid restriction and blood sodium level monitoring *diluted balloon

acromegaly

HYPERsecretion of GH caused by ant. pit. tumor

pituitary dwarfism

HYPOsecretion of GH

reach height of only 4 feet

hyperparathyroidism

due to parathyroid gland tumor

calcium leaches from bones

elevated Ca levels depresses nervous system and forms kidney stones

hypoparathyroidism

results in tetany, respiratory paralysis, and death in 3-4 days

Hypersecretion of TH

Graves’ disease

Exophthalmos- buldging eyes