Unit 1 - Endocrine System

Question 1

exocrine glands

Answer 1

1. attached with a specific duct
2. secretory products: enzymes, mucous
3. secretions are released to the outer surface of the body through a duct
   e.g. salivary glands, liver, pancreas, sweat glands

Question 2

endocrine glands

Answer 2

1. ductless
2. secretes hormones
3. secretions are secreted into the blood capillaries
   e.g. pituitary, thyroid, parathyroid

Question 3

hormones (4)

Answer 3

secreted by the endocrine glands, transported throughout via blood
1. activate certain genes in the nucleus
2. change shape / structure of an enzyme
3. change rate of production of enzyme or protein via transcription/translation

Question 4

steroid vs. amine/protein

Answer 4

Steroid
* Lipid Soluble
* bind to transport proteins, enabling them to travel in the bloodstream
* slow to take effect, long lasting

Protein and Amine
* water soluble
* unable to diffuse across cell membrane
* quick to act, shorter lasting

Question 5

types of hormones w/ examples

Answer 5

Steroid - estrogen, testosterone etc
Protein - insulin, glucagon, ADH etc
Amine - epinephrine etc

Question 6

Relationship between hypothalamus and pituitary gland

Answer 6

Hypothalamus controls the secretions of hormones through the pituitary
hypothalamus secretes releasing or inhibiting factors through blood vessels to the anterior lobe
Hypothalamus produces some hormones which are passed along the nerve fibres to the posterior lobe of the pituitary gland
Hypothalamus joins the pituitary by the INFUNDIBULUM

Question 7

Anterior vs Posterior

Answer 7

Anterior
* controlled by the releasing and inhibiting factors
* has no nerves connecting it to the hypothalamus, rather connected by a large network of blood vessels in the infundibulum
*hormones produced here
Posterior
* connected to the hypothalamus by nerve fibres that pass through the infundibulum
* does not produce hormones, rather, stores and secretes hormones

Question 8

what does the hypo secrete?

Answer 8

oxytocin & adh

Question 9

How are the hormones secreted from the hypothalamus involved in homeostasis affecting specific target organs

Answer 9

The hormones secreted form the hypothalamus (oxytocin and ADH) are specialized for the uterus, breast and the kidneys. Oxytocin stimulates the contraction of the uterus and also stimulates the mammary glands, resulting in breast milk. ADH causes the kidneys to remove water from urine that is forming

Question 10

how are the secretions of the pituitary gland controlled by the hypothalamus through transport of hormones?

Answer 10

The hypothalamus secretes releasing factors which stimulates the secretion of a hormone, or inhibiting factors which slow down the secretion of a hormone. These factors travel through blood vessels to the anterior lobe of the pituitary gland

Question 11

How can hormones be lipid-soluble and able to cross cell membranes to bind with and activate intracellular receptors?

Answer 11

Steroids are lipid soluble and their mode of action follows the following four steps;
1. Hormone diffuses across the cell membrane (lipid soluble)

Hormone attaches to the receptor in the cytoplasm/ on the nucleus (hormone-receptor complex formed)
Hormone-receptor complex enters the nucleus
Hormone receptor complex activates genes/transcription of mRNA (complex binds to DNA)

Question 12

whats the difference between endocrine and exocrine glands

Answer 12

Exocrine - secrete into a duct that carries the secretion to the body surface or to one of the body cavities
I.E - sweat glands, mucous glands, salivary glands

Endocrine - secrete hormones into the extracellular fluid that surround the cells that make up the gland
I.E - hypothalamus, pituitary, thyroid, parathyroid, adrenals, pineal

Question 13

other glands and what do they secrete?

Answer 13

pineal - melatonin (sleep)
thyroid - T3 & T4
parathyroid - parathyroid hormone
thymus: thymosin
adrenal medulla: adr & nor
adrenal cortex: ald & cortisol