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The kidneys also possess endocrine function. Erythropoietin (EPO) is released by kidneys in response to low blood oxygen levels. EPO triggers an increase in the rate of production of red blood cells in the red bone marrow. EPO has been used by athletes (e.g. cyclists) to improve performance because more RBCs mean more oxygen can be transported. However, EPO doping has its risks, because it thickens the blood and increases strain on the heart; it also increases the risk of blood clots and therefore heart attacks and stroke.

Endocrine Glands and Their Associated Hormones
Endocrine Gland Associated Hormones Effect
Pituitary (anterior) growth hormone promotes growth of body tissues
prolactin promotes milk production
thyroid-stimulating hormone stimulates thyroid hormone release
adrenocorticotropic hormone stimulates hormone release by adrenal cortex
follicle-stimulating hormone stimulates gamete production
luteinizing hormone stimulates androgen production by gonads in males; stimulates ovulation and production of estrogen and progesterone in females
Pituitary (posterior) antidiuretic hormone stimulates water reabsorption by kidneys
oxytocin stimulates uterine contractions during childbirth
Thyroid thyroxine, triiodothyronine stimulate metabolism
calcitonin reduces blood Ca 2+ levels
Parathyroid parathyroid hormone increases blood Ca 2+ levels
Adrenal (cortex) aldosterone increases blood Na + levels
cortisol, corticosterone, cortisone increase blood-glucose levels
Adrenal (medulla) epinephrine, norepinephrine stimulate fight-or-flight response
Pancreas insulin reduces blood-glucose levels
glucagon increases blood-glucose levels

Regulation of hormone production

Hormone production and release are primarily controlled by negative feedback, as described in the discussion on homeostasis. In this way, the concentration of hormones in blood is maintained within a narrow range. For example, the anterior pituitary signals the thyroid to release thyroid hormones. Increasing levels of these hormones in the blood then give feedback to the hypothalamus and anterior pituitary to inhibit further signaling to the thyroid gland ( [link] ).

Art connection

The hypothalamus secretes thyrotropin-releasing hormone, which causes the anterior pituitary gland to secrete thyroid-stimulating hormone. Thyroid-stimulating hormone causes the thyroid gland to secrete the thyroid hormones T3 and T4, which increase metabolism, resulting in growth and development. In a negative feedback loop, T3 and T4 inhibit hormone secretion by the hypothalamus and pituitary, terminating the signal.
The anterior pituitary stimulates the thyroid gland to release thyroid hormones T 3 and T 4 . Increasing levels of these hormones in the blood result in feedback to the hypothalamus and anterior pituitary to inhibit further signaling to the thyroid gland. (credit: modification of work by Mikael Häggström)

Section summary

Hormones cause cellular changes by binding to receptors on or in target cells. The number of receptors on a target cell can increase or decrease in response to hormone activity.

Hormone levels are primarily controlled through negative feedback, in which rising levels of a hormone inhibit its further release.

The pituitary gland is located at the base of the brain. The anterior pituitary receives signals from the hypothalamus and produces six hormones. The posterior pituitary is an extension of the brain and releases hormones (antidiuretic hormone and oxytocin) produced by the hypothalamus. The thyroid gland is located in the neck and is composed of two lobes. The thyroid produces the hormones thyroxine and triiodothyronine. The thyroid also produces calcitonin. The parathyroid glands lie on the posterior surface of the thyroid gland and produce parathyroid hormone.

The adrenal glands are located on top of the kidneys and consist of the adrenal cortex and adrenal medulla. The adrenal cortex produces the glucocorticoids, mineralocorticoids, and gonadocorticoids. The adrenal medulla is the inner part of the adrenal gland and produces epinephrine and norepinephrine.

The pancreas lies in the abdomen between the stomach and the small intestine. Clusters of endocrine cells in the pancreas form the islets of Langerhans, which contain alpha cells that release glucagon and beta cells that release insulin. The kidneys produce erythropoietin. The gonads produce steroid hormones, including testosterone in males and estrogen and progesterone in females.

Art connections

Goiter, a disease caused by iodine deficiency, results in the inability of the thyroid gland to form T 3 and T 4 . The body typically attempts to compensate by producing greater amounts of TSH. Which of the following symptoms would you expect goiter to cause?

  1. Hypothyroidism, resulting in weight gain, cold sensitivity, and reduced mental activity.
  2. Hyperthyroidism, resulting in weight loss, profuse sweating and increased heart rate.
  3. Hyperthyroidism, resulting in weight gain, cold sensitivity, and reduced mental activity.
  4. Hypothyroidism, resulting in weight loss, profuse sweating and increased heart rate.

[link] A

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Questions & Answers

information for blood vessels
Sumit Reply
helps pump blood through body
scott
arteries carry blood away from the heart while veins return it to the heart
Reverian
veins have thinner outer walls because blood pressure in them is very low compared to arteries with thicker outer walls to withstand the higher blood pressure.
Oliver
cell, tissue, organ, organism, organ system,
Gheida Reply
please what are the characteristics of a good respiratory system?
Salomon Reply
thin wall ,a moist inner surface ,a huge combined surface area and a rich blood supply.
Nchimunya
Help me am confused what is the cell membrane as a partially permeable membrane
Janelle Reply
it is the ability of a molecules to cross a cell membrane depending on their both size and chemical properties.
Andrews
Based on my previous understanding of biological systems, a cell membrane is a semi-permeable membrane made up of a phospholipids bi-layer. The polar head consisting of phosphate and the hydrophobic end made up of lipids.
Abayomi
Smallest bone of rabbit is
Sahrukh Reply
difference between catebolism and anebolism
Anthvanath Reply
identify the causes of infertility in human beings
Rodrick Reply
Describe how a healthy pregnancy could be maintained
Rodrick
Huaman largest bone
Sahrukh
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Salamin Reply
Samllest bone
Sahrukh
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AlfredOfficial Reply
by DNA tests
lasford
thanks
AlfredOfficial
How to test
Salamin
How many bones of 1 year childrean
R.k Reply
208
Rani
A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults
Manali
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R.k
A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults h
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R.k
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Manali
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it's 300 bones because it a baby
Jasper
babies have 300 bones in which it fuses to become 206 as an adult.
Andrews
it has 300 bones ,nchimunya
Nchimunya
figure of male reproduction
Rani Reply
front view of male reproductive system
Rani
front view of male reproductive system
Rani
what is Actin? I don't understand this definition
Rhonda Reply
Actin is a family of globular multi-functional proteins that form microfilaments. 
Lauren
difference between throat and lyrnx
Lone
what is the difference between a vaccine and a antiserum
Silver Reply
An antiserum contains antibodies already produced and is used to pass on immune responses. A vaccine contains a substance that stimulates the production of antibodies to create an immune response.
Nana
A vaccine a preparation of antigens for one (or more) diseases that is given to stimulate active immunity and protect against the disease (s). while an antiserum either neutralizes the "infection " or stimulates your immune system to attack an infection.
Oliver
what is deoxyribonucleic acid
Carlene Reply
A negatively charged molecule; polymer of nucleotides found in the nucleus of a cell ... DNA.
Abayomi
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Asali
Hi
Janelle
hi
Oliver
hello
Rani
how are you doing?
Jasper
DNA is genetic material which is present in cell DNA is made up of nitrogen base,phosphate group and pentose sugar.
Manali
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Jasper
give a front view of male reproductive system
Rani
to maintain certain biological activities of cell
jeeni Reply

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Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
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