1. 39-2 Human Endocrine Glands
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2. 39-2 Human Endocrine Glands
Endocrine glands are scattered throughout the body.
The human endocrine system regulates a variety of activities.
Any improper functioning of an endocrine gland may result in a disease or a disorder.
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3. 39-2 Human Endocrine Glands
The major glands of the endocrine system include:
the pituitary gland
the hypothalamus
the thyroid gland
the parathyroid glands
the adrenal glands
the pancreas
the reproductive glands
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Pituitary Gland
The pituitary gland secretes nine hormones that directly regulate many body functions and controls the actions of several other endocrine glands.
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Pituitary Gland
The pituitary gland is a structure at the base of the skull.
The gland is divided into two parts: the anterior pituitary and the posterior pituitary.
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Pituitary Gland
The Pituitary Gland
Hypothalamus
The pituitary gland, which controls many other endocrine glands, is located below the hypothalamus in the brain. The pituitary gland has two lobes: an anterior lobe and a posterior lobe.
Anterior pituitary
Posterior pituitary
Pituitary gland
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Pituitary Gland
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Pituitary Gland
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Pituitary Gland
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Hypothalamus
The hypothalamus is the part of the brain attached to the posterior pituitary.
The hypothalamus controls the secretions of the pituitary gland.
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Hypothalamus
Hypothalamus
The pituitary gland, which controls many other endocrine glands, is located below the hypothalamus in the brain.
Pituitary gland
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Hypothalamus
The hypothalamus:
- is influenced by hormone levels in the blood and by sensory information.
coordinates interactions between the nervous system and the endocrine system
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Thyroid Gland
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Thyroid Gland
The thyroid gland is located at the base of the neck and wraps around the upper part of the trachea.
It:
produces thyroxine.
thyroxine regulates the metabolic rate of cells.
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Thyroid Gland
Thyroid Gland
Larynx
Thyroid gland
Esophagus
Hormones produced by the thyroid gland and the parathyroid glands maintain the level of calcium in the blood. The thyroid gland wraps around the trachea.
Trachea
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Thyroid Gland
Thyroid Disorders
Hyperthyroidism: the body produces too much thyroxine. It is characterized by elevated temperature and metabolic rate, increased blood pressure, and weight loss.
Hypothyroidism: the body produces too little thyroxine. It is characterized by lower temperature and metabolic rate, lack of energy, and weight gain.
Goiter: enlargement of thyroid gland. Caused by an iodine deficiency.
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Parathyroid Glands
The four parathyroid glands are found on the back surface of the thyroid gland.
Hormones from the thyroid gland and the parathyroid glands act to maintain homeostasis of calcium levels in the blood.
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Parathyroid Glands
Parathyroid glands:
secrete parathyroid hormone (PTH).
PTH regulates calcium levels in the blood by increasing reabsorption of calcium in the kidneys and by increasing uptake of calcium from the digestive system.
PTH affects other organ systems, promoting proper nerve and muscle function and bone structure.
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Parathyroid Gland
Parathyroid Glands
Thyroid gland
Parathyroid glands
Hormones produced by the thyroid gland and the parathyroid glands maintain the level of calcium in the blood.
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Adrenal Glands
The adrenal glands are two pyramid-shaped structures that sit on top of the kidneys, one gland on each kidney.
The adrenal glands release hormones that help the body prepare for and deal with stress.
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Adrenal Glands
Adrenal gland
Kidney
The adrenal glands release hormones that help the body prepare for and deal with stress.
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Adrenal Glands
An adrenal gland has an outer part called the adrenal cortex and an inner part called the adrenal medulla.
Adrenal cortex
Adrenal medulla
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Adrenal Glands
Adrenal Cortex
produces over 24 steroid hormones.
the hormone aldosterone regulates reabsorption of sodium ions and the excretion of potassium ions by the kidneys.
the hormone cortisol controls the rate of metabolism of carbohydrates, fats, and proteins.
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Adrenal Glands
Adrenal Medulla:
prepares the body for energy-intense activities.
releases epinephrine and norepinephrine.
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Adrenal Glands
Epinephrine and norepinephrine:
increase heart rate, blood pressure, and blood flow to the muscles.
cause air passageways to open wider, allowing for an increased intake of oxygen.
stimulate the release of extra glucose into the blood to help produce a sudden burst of energy.
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Pancreas
The pancreas has both exocrine and endocrine functions.
It is a digestive gland whose secretions break down food.
It also produces the hormones insulin and glucagon.
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Pancreas
Insulin and glucagon help to keep the level of glucose in the blood stable.
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Pancreas
Insulin stimulates cells in the liver and muscles to remove sugar from the blood and store it as glycogen or fat.
Glucagon stimulates the liver to break down glycogen and release glucose back into the blood.
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Pancreas
Maintaining Blood Sugar Levels
When glucose levels rise, the pancreas releases insulin.
Insulin stimulates cells to take glucose out of the bloodstream.
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Pancreas
Glucose taken out of circulation is stored as glycogen in the liver (about one day’s worth of energy) and skeletal muscles.
In fat tissue, glucose is converted to lipids.
When blood glucose level drops, glucagon is released from the pancreas.
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Pancreas
Glucagon stimulates liver cells and skeletal muscles to break down glycogen and increase glucose levels.
It causes fat cells to break down fats for production of carbohydrates.
This makes more chemical energy available and helps raise the blood glucose level back to normal.
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Pancreas
Diabetes Mellitus 
When the pancreas fails to produce or properly use insulin, diabetes mellitus occurs.
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Reproductive Glands
The gonads are the body’s reproductive glands.
The gonads serve two important functions: the production of gametes, and the secretion of sex hormones.
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Reproductive Glands
The female gonads, ovaries, produce the female sex hormones estrogen and progesterone.
Progesterone prepares the uterus for the arrival of a developing embryo.
Estrogen is needed for the development of eggs and for the formation of physical characteristics of the female body.
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Reproductive Glands
The male gonads, testes, produce testosterone, which is needed for normal sperm production and development of male physical characteristics.
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