Endocrine System

Question 1

What are the functions of the endocrine system? What other systems are involved int hese functions?

Answer 1

The endocrine system releases hormones, which are chemical messengers, into the blood stream ti regulate various cell functions to maintain homeostasis.

Integumentary system

• stimulates the growth of axillary and pubic hair
• activation of sebaceous gland

Skeletal system

• PTH and calcitonin regulate levels of calcium and other minerals in bone matrix and blood
• Thyroid hormones are needed for normal development and growth of the hormone

Muscular system

• Epinephrin increases blood flow to skeletal muscles during exercise
• PTH regulate calcium for muscle contraction

Nervous system

• Several hormones influence growth and development of the nervous system
• Nervous system stimulates the release of hormones

Cardiovascular system

• ADH increases blood volume
• Epinephrine inrease heart rate and force of contraction
• Several hormones elevate blood pressure during exercise

Respiratory system

• Epinephrine dilates airways during exercise
• Hormones regulate amount of oxygen carried in blood

Digestive system

• Epinephrine depresses activity of the digestive system
• Calcitron promotes absorption of dietary calcium
• Leptin suppresses appetite

Urinary system

• ADH adjust rate of water and ion loss in urine

Question 2

How do soluble and insoluble hormones travel?

Answer 2

Soluble hormones travel free in the blood, and insoluble horones bind to plasma proteins.

Question 3

What are paracrine and autocrine hormones?

Answer 3

Paracrine hormones are released by a cell, and affect nerby cells.

Autocrine hormones are released by a cell and affect the same cell.

Question 4

What are the chemical classes of hormones?

Answer 4

Lipid soluble hormones

These diffuse nto the cell, where they bind to intracellular receptors, migrate to the nucleus, and activate specific target sequences of DNA, changing gene expression (acting as transcription factors).

Water soluble hormones

The receptor for water soluble hormones is membrane-bound, and binding of the hormone activates the second messenger cascade. The hormone binding activated G-proteins within the cell that alters enzyme activity.

Question 5

Adrenalin

Answer 5

Released by the adrenal medulla

• blood vessels in skeletal muscles dilate
• Blood vessels in digestive system constrict
• Cardiac muscle contracts faster and with more force
• Liver breaks down glycogen to glucose and releases glucose into the blood stream
• Adipocytes break down triglycerides into FA and release FA into the bloodstream.

Question 6

Thyrotropin Releasing Hormone (TRH)

Answer 6

Released from the hypothalamus

• TRH stimulates TSH (thyroid stimulating hormone/throtropin) which is released from the anterior pituitary
• TSH stimulates T3 and T4 production and release from the thyroid gland
• T3 increases metabolic rate, heat production, promotes growth and development of nervous and skeletal systems
• Negative feedback loop: T3 inhibits TSH, TRH release.

Question 7

Why does goitre occur?

Answer 7

A dietary deficiency of iodine leads to goitre (enlarged thyroid gland)

• TRH and TSH are stimulated and produced which stimulates the thyroid gland
• The precursors T4 and T3 are produced but iodine is required for the final product, so there is a buildup of precursors leading to hypertrophy of the adrenal gland.

Question 8

Vasopressin

Answer 8

Antidiuretic hormone (ADH) is produced by the hypothalamus neuron, which have axons that project to the posterior pituitary.

In response to high osmolarity (e.g. dehydration) ADH is released into the boodstream

This promotes water absorption in the kidney from the filtrate, to reduce blood osmolality.

Also released in response to low blood pressure: causes vasoconstriction

Question 9

Adipose tissue

Answer 9

Adipose tissue produces the hormones leptin, adiponectin and resistin

Leptin acts in the hypothealamus to reduce apetite and increase energy expenditure, whcih regulates energy balance.

Question 10

The thyroid and parathyroid glands are located in the neck. Are the parathyroid glands imbedded in the anterior or posterior surface of the thyroid gland? Which hormones do these organs produce?

Answer 10

The parathyroid glands are located anterior to the thyroid glands. The parathyroid gland produces PTH (parathyriod hormone) and the thyroid gland produces thyroxine (T4) and T3.

Question 11

Finish the sentences:
The thyroid gland is [_______] to the trachea.
The thyroid gland is mostly ________ to the oesophagus

Answer 11

The thyroid gland is deep to trachea.

The thyroid gland is mostly ventral to the oesophagus

Question 12

How do the terms dorsal and ventral usually relate to anterior and posterior? There are some exceptions to this.

Answer 12

Dorsal = posterior

Ventral = anterior