BIOL 252: Ch 16 Endocrine System

Describe the functions of the endocrine system.

Reproduction, growth, homeostasis, and emergency response

Which work faster: nervous or endocrine signals?

Nervous is faster with electrical signal.

Which lasts longer: nervous or endocrine signals?

Endocrine signals last longer, takes a while for hormones to get broken down.

Define hormone.

A hormone is a long distance chemical (ligand) secreted by cells into extracellular fluid.

Which have ducts?

Exocrine

Which release secretions that work right when they are released?

Exocrine

Which release hormones into the bloodstream?

Endocrine

Identify the endocrine organ described as located in the anterior neck; produces key hormones for metabolism.

Thyroid gland

Identify the endocrine organ described as produces the hormones that are stored in the posterior pituitary.

Hypothalamus

Identify the endocrine organ described as a mixed gland, located behind the stomach and close to the small intestine.

Pancreas

Identify the endocrine organ described as paired glands suspended in the scrotum.

Testes

Identify the endocrine organ described as bilobed gland located in the sella turcica.

Pituitary gland

Identify the endocrine organ described as found in the pelvic cavity of the female concerned with ova and female hormone production.

Ovary

Identify the endocrine organ described as found in the upper thorax overlying the heart; large during youth.

Thymus

Identify the endocrine organ described as found in the roof of the third ventricle of the brain.

Pineal gland

Identity organ labeled #1.

Pineal gland

Identity organ labeled #2.

Parathyroid glands

Identity organ labeled #3.

Pancreas

Identity organ labeled #4 (only found in male).

Testes

Identity organ labeled #5.

Hypothalamus

Identity organ labeled #6.

Pituitary gland

Identity organ labeled #7.

Thyroid gland

Identity organ labeled #8.

Thymus

Identity organ labeled #9.

Adrenal glands

Identity organ labeled #10 (only found in female).

Ovary

What are the chemical classes of hormones?

Amino acid and steroid

Give 2 examples of steroid hormones.

Estrogen, testosterone, aldosterone, cortisol, and androgens

Give 2 examples of amino acid/peptide hormones.

Epinephrine, norepinephrine, oxytocin, ADH, growth hormone, and PTH

Can amino acid based hormones enter cells?

No

What pathway do amino acid hormones use to signal?

G protein and second messenger

What lipid organic molecule is the precursor for all steroid hormones?

Cholesterol

Can steroids cross the plasma membrane and enter cells?

Yes

Which class of hormone stimulates second messengers release? Amino acid or steroid?

Amino acid

Which class of hormones stimulates protein synthesis?

Steroid

How do you know if a cell is a target cell for a specific hormone?

It will have the receptor that the hormone can bind to

If blood sugar is above set point, the pancreas will release insulin to lower blood sugar. When will insulin release stop?

When set point is restored.

If the hormone is released in direct response to blood levels of a particular chemical (sugar, calcium etc.), that would be described as __________ control.

humoral

If the nervous system stimulates hormone release, that would be described as __________ control.

neural

If another hormone stimulates and endocrine gland to cause hormone release, that would be described as __________ control.

hormonal

Give some examples of hormones released by the humoral secretion control method.

Blood sugar or calcium regulating hormones

Give some examples of hormones released by the neural secretion control method.

Epinephrine and norepinephrine

Give some examples of hormones released by the hormonal secretion control method.

Many, TRH-TSH-T3, CRH-ACTH-cortisol, and GnRH-
FSH-eggs, etc.

Inside which major organ can the hypothalamus and pituitary be found?

Brain

What is the exact location of the pituitary gland (bone marking from A + P 1)?

In the sella turcica of the sphenoid bone

Name the stalk that connects the hypothalamus to the pituitary.

Infundibulum

What is another name for the posterior pituitary?

Neurohypophysis

What is another name for the anterior pituitary?

Adenohypophysis

Which part of the pituitary is connected to the hypothalamus by neurons?

Posterior

Which part of the pituitary is connected to the hypothalamus by capillary beds in sequence?

Anterior

Which two hormones are released by the posterior pituitary?

ADH and oxytocin

What is the function of ADH?

Regulate water balance

What is the stimulus for ADH release?

Dehydration, low BP

Which organ(s) does ADH act on?

Kidney

What is the function of oxytocin?

Contract uterus during childbirth and milk ejection

What is the stimulus for oxytocin release?

Childbirth and breastfeeding

Which organ(s) does oxytocin act on?

Uterus and breast

How are oxytocin and ADH delivered to their target organs?

In bloodstream

What is the function of growth hormone?

Grow body

What are the target tissues of growth hormone?

CT, muscle, and bone

Which hormone from the hypothalamus causes growth hormone release?

Growth hormone releasing hormone (GHRH)

Which hormone from the hypothalamus inhibits growth hormone release?

Growth hormone inhibiting hormone (GHIH)

During human lifespan, when is growth hormone secretion highest?

Puberty

Which organs release insulin-like growth factors?

Liver and muscle bone

Too much growth hormone before puberty leads to:

giantism

Too little growth hormone before puberty leads to:

pituitary dwarfism

Too much growth hormone after closure of the epiphyseal plates (after puberty) leads to:

acromegaly

What is the function of TSH?

T3 and T4

What is a target organ of TSH?

Thyroid gland

What hypothalamic hormone is the stimulus for TSH release from the pituitary?

Thyroid releasing hormone (TRH)

What is the function of ACTH?

Stimulate release of hormones form adrenal cortex

What is the target organ of ACTH?

Adrenal gland, specifically cortex

What hypothalamic hormone is the stimulus for ACTH release from the pituitary?

Corticotrophic releasing hormone (CRH)

What is the function of FSH?

Stimulate gonads to release gametes

What are the target organ(s) of FSH in males?

Testes

What are the target organ(s) of FSH in females?

Ovary

What hypothalamic hormone is the stimulus for FSH release from the pituitary?

Gonadotrophic releasing hormone (GnRH)

What is the function of LH?

Stimulates gonads to release hormones

What are the target organ(s) of FSH in males?

Testes

What are the target organ(s) of FSH in females?

Ovary

Which hormone(s) are released from the gonads in response to LH in males?

Testosterone

Which hormone(s) are released from the gonads in response to LH in females?

Estrogen and progesterone

What hypothalamic hormone is the stimulus for LH release from the pituitary?

Gonadotrophin releasing hormone (GnRH)

What is the function of prolactin?

Stimulate milk production at breast

What are the target organ(s) of prolactin?

Breast

What hypothalamic hormone inhibits prolactin release from the pituitary if a female is not pregnant?

Prolactin inhibiting hormone (PIH)

Recent research has shown that prolactin inhibiting hormone is actually the neurotransmitter __________.

dopamine

How many lobes does the thyroid have?

2

The connection between the lobes is called the:

isthmus

The follicular cells are which type of tissue?

Epithelial cells, this is why people get thyroid cancer!

The jello at the center of the follicle is called:

colloid

What protein is produced by follicle cells?

Thyroglobulin

What ion is required to make thyroid hormones?

Iodine

How many iodine atoms in thyroxine (T4)?

4

How many iodine atoms in triiodothyronine (T3)?

3

What are the functions of thyroid hormones?

Increase metabolic rate

Increase body heat production

Regulate growth and development

Required for protein synthesis

Necessary for normal development of CNS in infants

Needed for normal development of reproductive system

What is the name of the disease when the thyroid is overactive?

Hyperthyroid

What will be the symptoms of overactive thyroid?

Fast heartbeat, weight loss, sweating, bulging eyes

What are some common causes of hypothyroidism?

In developing countries, iodine deficiency, in USA Hashimoto’s thyroiditis, tumors in thyroid or pituitary

Severe hypothyroidism in infants is called what?

Cretinism, mental retardation

What is goiter?

When the thyroid gland grows really large, usually due to iodine deficiency