Unit 3: Chapter 2 - Chemical Messengers Flashcards
Pituitary gland lobes
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)
Pituitary gland characteristics
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.
Thyroid
Hormone: thyroxin
Target cells: most cells
Main effects: increases metabolic rate and therefore oxygen consumption and heat production
Thyroid characteristics
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.
Parathyroids
Hormone: parathyroid hormone
Target cells: bones and kidneys
Main effects: increases levels of calcium in the blood
Parathyroid characteristics
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
Thymus
Hormone: a group of hormones called thymosins.
Target cells: T lymphocytes
Main effects: stimulated development and maturation of disease fightings cells called T lymphocytes.
Thymus characteristics
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.
Adrenal cortex
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
Adrenal cortex characteristics
Outer part of the adrenal glands, producers over 20 different hormones (corticosteroids)
Adrenal medulla
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.
Adrenal medulla characteristics
Inner part of the adrenal glands.
Pancreas
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)
Pancreas characteristics
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.
Testes
Hormones: androgens (testosterone)
Target cells: many tissues
Main effects: stimulate sperm production, growth of skeleton and muscles, male sexual characteristics.
Testes characteristics
Produce androgens responsible for the development and maintenance of the male sex characteristics.
Ovaries
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).
Ovaries characteristics
Together with the gonadotropic hormones of the pituitary, progesterone and oestrogen regulate the menstrual cycle and are involved with the changes occurring during pregnancy.
Hypothalamus
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.
Endocrine gland
A gland that secretes a hormone (chemical) into the bloodstream (glands of internal secretion).
Exocrine gland
Glands that produce and secrete substances onto an epithelial surface by the way of a duct. Exocrine glands include; sweat, salivary, mammary.
Gland
An organ in the human body which secretes particular chemical substances for use in the body or for discharge into the surroundings.
Hormone
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).
Intercellular
Between cells
Intracellular
Inside the cell
Lipid soluble
Substances able to dissolve in lipids (fats or oils)
Water soluble
Substances able to dissolve and are soluble in water, usually not soluble in lipids
Receptor sites
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.
Target cell (or organ)
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.
Pineal gland characteristics
Found deep inside the brain, in children it is about the size of a pea. Decreases during puberty.
Pineal gland
Secrets melatonin which is in involved in the regulation of sleep patterns. Production of melatonin is stimulated by darkness and inhibited by light.
