Lesson 1: The Endocrine System Flashcards
Hormones
Hormones are compounds created by cells in the body that act
as chemical signals
The organs that make hormones are mainly endocrine glands
which make up the endocrine system.
There are four classes of hormones;
proteins, steroid, peptide and amines.
Endocrine vs. Exocrine
Endocrine Function
An organ or gland is endocrine if it releases a substance directly
into the bloodstream.
Exocrine Function
An organ or gland is considered exocrine if it releases a substance through a duct.
Glands of the Endocrine
System
The glands of the endocrine system are:
Hypothalamus
Pituitary
Pineal
Thyroid
Parathyroid
Thymus
Adrenal
Pancreas
Testis/Ovary
Pituitary Gland
The workhorse of the
Endocrine System.
This gland secretes a
variety of hormones.
The gland has 2 lobes.
Anterior Lobe
Growth Hormone (GH) 🡪 regulates growth
ACTH (Adrenocorticotropic Hormone) 🡪 regulates the adrenal cortex
MSH (Melanocyte Stimulating Hormone) 🡪 regulates skin pigment
FSH (Follicle Stimulating Hormone) 🡪 controls follicle maturation (reproduction in females)
LH (Luteinizing Hormone) 🡪 controls ovulation and the formation of the corpus luteum
(reproduction in females)
ICSH 🡪 hormone required to make testosterone
Prolactin (PRL) 🡪 stimulates milk production (females)
Posterior Lobe
Oxytocin 🡪 contracts the uterus in labour
ADH (Antidiuretic Hormone) 🡪 controls water balance / conservation in urine
Hypothalamus
produces the hormones that are released by the pituitary
gland
integrates the nervous system with the endocrine system
regulates the function of the pituitary gland by secreting
releasing and inhibitory hormones
Adrenal Gland
Located in the fatty tissue surrounding the kidneys
Adrenal Cortex releases the following hormones
Aldosterone 🡪 stimulates Na absorption in the Kidneys
Cortisone 🡪 inhibits ACTH activity
Adrenal Medulla releases the following hormones
Adrenaline and Noradrenaline 🡪 regulate the fight or flight reaction
Thyroid Gland
Secretes Thyroxin 🡪 regulates metabolism
disorders associated with the thyroid gland
Hypothyroidism – thyroxin levels are
too low which leads to slow, tired,
sluggish feeling
Hyperthyroidism – thyroxin levels are
too high which leads to hyperactivity,
increased heart rate and increased
respiration
Goiter – thyroid gland swells due to
lack of Iodine
Parathyroid Gland
Secretes PTH (Parathyroid
Hormone) and Calcitonin
these hormones regulate the
calcium levels in the blood and
the calcium released by bone
Thymus Gland
Release Thymosins which are
involved in regulating the bodies
immune system
Pancreas
The Pancreas contains endocrine regions called the Islets of Langerhans
These regions contain 2 types of specialized endocrine cells
Beta Cells – these cells produce Insulin that allows the cells to take in sugar (glucose) which lowers blood sugar levels
Alpha Cells – these cells produce Glucagon which causes the liver to break down glycogen into glucoses which is then released into the blood and raises blood sugar levels
Testis (in males)
Male Gonad
At puberty releases Testosterone which regulates sperm production and controls the development and maintenance of male characteristics
Ovary (in females)
Female Gonad
At puberty releases Estrogen and Progesterone which regulate the menstrual cycle and controls and maintains female characteristics
