The endocrine system Flashcards
What is the endocrine system
The endocrine system is made up of specialised ductless glands including the thyroid, adrenal and ovaries which release hormones into the blood for communication
What are hormones
Hormones are molecules that bind to receptors on target organs and trigger a specific action to be carried out
Hormones are chemical messages directly released into the blood.
What is the posterior pituitary
The posterior pituitary is found at the back of the pituitary gland and is an extension of the hypothalamus
What is the anterior pituitary
The anterior pituitary is the front portion of the pituitary gland formed from the roof of the mouth also known as a rathkes pouch
What is the pars intermedia
The pars intermedia is where the anterior and posterior pituitary fuse
What are some of the main functions of the posterior pituitary
The posterior pituitary secretes oxytocin which stimulates myometrium contraction, the let down reflex, promotes bonding and reduces nerve activity in babies brain during labour.
It also produces antidiuretic hormone
What are some of the main functions of the anterior pituitary
It produces somatotropin which promotes the growth of bones by stimulating the epiphyses of long bones to widen.
What are some of the main functions of the pars intemedia
The pars intemedia produces melanocyte stimulating hormone which controls skin pigmentation by stimulating melanocytes to produce melanin, responsible for melasma.
What is the thyroid gland
The thyroid gland is a bilobed organ that sits below the larynx and is responsible for regulating metabolism by taking iodine used to make thyroxine, and also regulates blood calcium level.
What is goitre
Goitre is a swelling of the thyroid gland due to an iodine deficiency
What is hypothyroidism
Hypothyroidism is a condition caused by an autoimmune disease or ageing which causes reduced thyroxine secretion. This leads to a reduced metabolic rate, weight gain, drop in body temp, dry hair, hair loss and dry skin. In pregnancy it can increase the risk of miscarriage and preterm birth. It can present as increased BP and anaemia
What is hyperthyroidism
Hyperthyroidism is a condition caused by graves disease that leads to an over secretion of thyroxine and an increase in metabolic rate. This leads to weight loss, hair thinning, excess heat, tachycardia, tremors, goitre, increased sweating and bulging eyes. It can cause low birth weight and premature delivery in pregnancy
What is the pancreas
The pancreas is part of both the endocrine ad digestive system, and found in the loop of duodenum. It contains the islet of Langerhans which produce glucagon by alpha cells, insulin by beta cells, ghrelin by epsilon cells and pancreatic polypeptide by PP cells.
What is ghrelin
Ghrelin is the hunger hormone that peaks before meals and binds to receptors in the hypothalamus to elicit hunger
What is pancreatic polypeptide
Pancreatic polypeptide is the satiety hormone that switches off hunger after a meal. It can be reduced in overweight people and overproduced in anorexic people.
How does the body regulate blood glucose levels
When alpha cells detect a drop in blood glucose they release glucagon which binds to hepatocytes in the liver causing them to release glucose.
When beta cells detect an increase un blood glucose levels they release insulin which binds to cell receptors causing glucose transporter protein channels to embed in the membrane allowing glucose to move in
What is gestational diabetes
Gestational diabetes is a condition found in 5% of pregnant women which raises glucose levels by inhibiting the normal action of insulin. This increases thirst and urination, and can lead to macrosomia which is where babies grow very large.
What are the adrenal glands
The adrenal glands sit on top of the kidneys and have the outer cortex and the inner medulla
What is the function of the medulla in the adrenal glands
The medulla produces adrenaline which gears the body for activity by raising HR, vasoconstriction of skin vessels and vasodilation of vessels in organs, increasing blood glucose and increases oxygen uptake.
What is the function of the cortex in the adrenal glands
The cortex takes up cholesterol to produce steroid hormones.
