Unit 3: Chapter 2 - Chemical Messengers

Question 1

Pituitary gland lobes

Answer 1

Anterior lobe of the pituitary:

Follicle Stimulating Hormone:
Target organ(s): ovaries and testes
Main effects: growth of follicles (female) and production of sperm (males).

Luteinising Hormone:
Target organs: ovaries and testes
Main effects: ovulation and maintenance of the corpus luteum (females) and secretion of testosterone (males)

Growth Hormone:
Target organs: all cells
Main effects: growth and protein synthesis

Thyroid-Stimulating Hormone:
Target organs: thyroid gland
Main effects: secretion of hormones from the thyroid.

Adrenocorticotropic Hormone:
Target Organs: Adrenal cortex
Main effects: secretion of hormones from the adrenal cortex

Prolactin:
Target organs: mammary glands
Main effects: milk production

Posterior lobe of the pituitary:

Antidiuretic Hormone:
Target organs: Kidneys
Main effects: Reabsorption of water

Oxytocin:
Target organs: uterus and mammary glands
Main effects: contractions of uterus during childbirth (uterus) and release of milk (mammary glands)

Question 2

Pituitary gland characteristics

Answer 2

Lies just under the hypothalamus, is joined to the hypothalamus by a stalk called the infundibulum. It’s not much bigger than a large pea, 13mm in diameter.

Question 3

Thyroid

Answer 3

Hormone: thyroxin
Target cells: most cells
Main effects: increases metabolic rate and therefore oxygen consumption and heat production

Question 4

Thyroid characteristics

Answer 4

Located in the neck, just below the larynx. Consists of two lobes that lie on either side of the trachea. Joined by a narrow piece of tissue that lies across the front of the trachea.

Question 5

Parathyroids

Answer 5

Hormone: parathyroid hormone
Target cells: bones and kidneys
Main effects: increases levels of calcium in the blood

Question 6

Parathyroid characteristics

Answer 6

4 glands. Each is about the size of a small pea and are embedded in the rear surface of the lobes of the thyroid gland

Question 7

Thymus

Answer 7

Hormone: a group of hormones called thymosins.
Target cells: T lymphocytes
Main effects: stimulated development and maturation of disease fightings cells called T lymphocytes.

Question 8

Thymus characteristics

Answer 8

Located just above the heart and just behind the sternum (breastbone). The thymus is largest in infants and children but begins to shrink after puberty.

Question 9

Adrenal cortex

Answer 9

Hormone: corticosteroids including: aldosterone and cortisol
Target cells: kidney (aldosterone) and most cells (cortisol)
Main effects: aldosterone increases reabsorption of sodium ions and excretion of potassium ions.
Cortisol promotes normal metabolism, helps the body deal with stress and promotes the repair of damaged tissues

Question 10

Adrenal cortex characteristics

Answer 10

Outer part of the adrenal glands, producers over 20 different hormones (corticosteroids)

Question 11

Adrenal medulla

Answer 11

Hormones: adrenaline and noradrenaline
Target cells: most tissues
Main effects: prepares the body for fight-or-flight responses, reinforces the effects of the sympathetic nervous system. Noradrenaline increases the rate and force of the heartbeat.

Question 12

Adrenal medulla characteristics

Answer 12

Inner part of the adrenal glands.

Question 13

Pancreas

Answer 13

Hormones: insulin and glucagon
Target cells: most cells (insulin) and liver and fat storage tissues (glucagon)
Main effects: stimulates uptake of glucose, lowers blood glucose level (insulin). Stimulates breakdown of glycogen and fat; increases blood glucose level (glucagon)

Question 14

Pancreas characteristics

Answer 14

Lies just below the stomach, alongside the duodenum. It is both an endocrine and an exocrine gland. The exocrine part secretes digestive enzymes into the small intestine through the pancreatic duct. Within the pancreas are clusters of special cells called the Islets of Langerhans that secrete two important hormones.

Question 15

Testes

Answer 15

Hormones: androgens (testosterone)
Target cells: many tissues
Main effects: stimulate sperm production, growth of skeleton and muscles, male sexual characteristics.

Question 16

Testes characteristics

Answer 16

Produce androgens responsible for the development and maintenance of the male sex characteristics.

Question 17

Ovaries

Answer 17

Hormones: oestrogens and progesterone
Target cells. Many tissues (oestrogen) and uterus and mammary glands (progesterone)
Main effects: stimulate development of female characteristics, regulate the menstrual cycle (oestrogen). Regulates menstrual cycle and pregnancy, prepares mammary glands for secretion of milk (progesterone).

Question 18

Ovaries characteristics

Answer 18

Together with the gonadotropic hormones of the pituitary, progesterone and oestrogen regulate the menstrual cycle and are involved with the changes occurring during pregnancy.

Question 19

Hypothalamus

Answer 19

Located at the base of the brain, regulates many of the basic functions of the body such as body temperature, water balance and heart rate. Many of the functions of the hypothalamus are carried out by the pituitary gland.

Question 20

Endocrine gland

Answer 20

A gland that secretes a hormone (chemical) into the bloodstream (glands of internal secretion).

Question 21

Exocrine gland

Answer 21

Glands that produce and secrete substances onto an epithelial surface by the way of a duct. Exocrine glands include; sweat, salivary, mammary.

Question 22

Gland

Answer 22

An organ in the human body which secretes particular chemical substances for use in the body or for discharge into the surroundings.

Question 23

Hormone

Answer 23

A chemical secretes by an endocrine gland. They may be in the form of proteins, amines or steroids. They are transported through the body in the blood. Hormones may have an effect on all the cells in the body or only particular ones or target organs. These changes are made to regulate the body environment and maintain it (homeostasis).

Question 24

Intercellular

Answer 24

Between cells

Question 25

Intracellular

Answer 25

Inside the cell

Question 26

Lipid soluble

Answer 26

Substances able to dissolve in lipids (fats or oils)

Question 27

Water soluble

Answer 27

Substances able to dissolve and are soluble in water, usually not soluble in lipids

Question 28

Receptor sites

Answer 28

A molecular site or the docking port on the surface of, or within, a cell, usually involving proteins that are capable of recognizing and binding with specific molecules.

Question 29

Target cell (or organ)

Answer 29

Any cell that has a specific receptor to a particular hormone which therefore that specific hormone can have an effect on that cell or organ.

Question 30

Pineal gland characteristics

Answer 30

Found deep inside the brain, in children it is about the size of a pea. Decreases during puberty.

Question 31

Pineal gland

Answer 31

Secrets melatonin which is in involved in the regulation of sleep patterns. Production of melatonin is stimulated by darkness and inhibited by light.