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ENDOCRIN SYSTEM :question: - Coggle Diagram
ENDOCRIN SYSTEM
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The major function
of the endocrine system is it secretes hormones that coordinate slower but longer-acting responses
including reproduction, development, energy metabolism, growth, and behavior.
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What are the organs of the endocrine system?
3.
Liver
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4.
Stomach
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Gastrin hormone is given to blood.Gastrin: This stimulates the release of HCl and pepsinogen for digestion by acting on the gastric glands
2.
Heart
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Atrial natriuretic factor (ANF) also called atrial natriuretic peptide (ANP), is a peptide hormone which is secreted by cardiac cells of the body. Heart cells of atrial walls release this hormone to regulate the blood volume and arterial blood pressure. The atrial natriuretic factor is a potential vasodilator, it dilates the blood vessels to reduce the pressure. In response to the high blood pressure, cardiac cells secrete Atrial natriuretic factor which leads to vasodilatation (dilation of the blood vessels) and thus, decreases the blood pressure.
5.
Kidney
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Erythropoietin (EPO), is another peptide hormone secreted by a non-endocrine tissue, kidney. It is also known as hemopoietin. Erythropoietin secreted by the juxtaglomerular cells of the kidney, functions by triggering the RBC production in the bone marrow, especially when the oxygen level in the blood reduces. Erythropoetin are given to the blood.
1.
Thymus
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Thymus is the primary lymphoid organ of the immune system. It secretes thymic
hormone. It is needed for development of T-lymphocytes .
6.
Small Intestine
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Secretin and cholecystokinin hormones are given to blood. Secretin: Secretin stimulates the exocrine portion of the pancreas for the secretion of water and
bicarbonate ions.Cholecystokinin: CCK stimulates the secretion of pancreatic enzymes and bile by the pancreas and gallbladder respectively.
:check:Hormones are released from an endocrine cell, travel through the bloodstream, and interact with the receptor or a target cell to cause a physiological response
:check:Negative feedback and antagonistic hormone pairs are common features of the endocrine system.
:check:A negative feedback loop inhibits a response by reducing the initial stimulus
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Negative feedback
regulates many hormonal pathways involved in homeostasis
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Negative Feedback
:check:1.A negative feedback loop controls the synthesis and secretion of hormones by the thyroid gland. This loop includes the hypothalamus and pituitary gland in addition to the thyroid.
:check:4.Eventually, the levels of thyroid hormones in the blood start to fall too low again. When that happens, the hypothalamus releases TRH, and the loop repeats.
:check:3. This continues until the blood levels of thyroid hormones are high enough. At that point, the thyroid hormones feedback to stop the hypothalamus from secreting TRH and the pituitary from secreting TSH. Without the stimulation of TSH, the thyroid gland stops secreting its hormones.
:check:2.When the levels of thyroid hormones circulating in the blood fall too low, the hypothalamus secretes thyrotropin releasing hormone (TRH). This hormone travels directly to the pituitary gland through the thin stalk connecting the two structures. In the pituitary gland, TRH stimulates the pituitary to secrete thyroid stimulating hormone (TSH). TSH, in turn, travels through the bloodstream to the thyroid gland and stimulates it to secrete thyroid hormones.
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Positive Feedback Mechanism
:check:1.Prolactin is a non-steroid endocrine hormone secreted by the pituitary gland. One of the functions of prolactin is to stimulate a nursing mother’s mammary glands to produce milk. The regulation of prolactin in the mother is controlled by a positive feedback loop that involves the nipples, hypothalamus, pituitary gland, and mammary glands.
:check:2.Positive feedback begins when a baby suckles on the mother’s nipple. Nerve impulses from the nipple reach the hypothalamus, which stimulates the pituitary gland to secrete prolactin. Prolactin travels in the blood to the mammary glands and stimulates them to produce milk.
:check:3.The release of milk causes the baby to continue suckling, which causes more prolactin to be secreted and more milk to be produced. The positive feedback loop continues until the baby stops suckling at the breast..
:star: Antagonistac Mechanism
:ballot_box_with_check: Hormones that act to return body conditions to within acceptable limits from opposite extremes are called antagonistic hormones.
:check:1.Bundles of cells in the pancreas called pancreatic islets contain two kinds of cells, alpha cells and beta cells. These cells control blood glucose concentration by producing the antagonistic hormones insulin and glucagon
:check:2.Beta cells secrete insulin. When the concentration of blood glucose rises (after eating, for example), beta cells secrete insulin into the blood. Insulin stimulates the liver and most other body cells to absorb glucose.
:check:3.Liver and muscle cells convert the glucose to glycogen (for short‐term storage), and adipose cells convert the glucose to fat. In response, glucose concentration decreases in the blood, and insulin secretion discontinues (through negative feedback from declining levels of glucose).
:check:4.Alpha cells secrete glucagon. When the concentration of blood glucose drops (during exercise, for example), alpha cells secrete glucagon into the blood. Glucagon stimulates the liver to release glucose.
:check:5.The glucose in the liver originates from the breakdown of glycogen and the conversion of amino acids and fatty acids into glucose. When blood glucose levels return to normal, glucagon secretion discontinues
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Some examples of Endocrine System Diseases
:check:Diabetes mellitus
:check:Acromegaly (overproduction of growth hormone)
:check:Addison’s disease (decreased production of hormones by the adrenal glands)
:check:Cushing’s syndrome (high cortisol levels for extended periods of time)
:check:Graves’ disease (type of hyperthyroidism resulting in excessive thyroid hormone production)
:check:Hashimoto’s thyroiditis (autoimmune disease resulting in hypothyroidism and low production of thyroid hormone), hyperthyroidism (overactive thyroid), hypothyroidism (underactive thyroid)
:check:Prolactinoma (overproduction of prolactin by the pituitary gland)
RESOURCES
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https://www.cliffsnotes.com/study-guides/anatomy-and-physiology/the-endocrine-system/antagonistic-hormones
https://bio.libretexts.org/Courses/Community_College_of_Vermont/Human_Biology_(Gabor_Gyurkovics)/12%3A_Endocrine_System/12.03%3A_Endocrine_Hormones#:~:text=A%20negative%20feedback%20loop%20controls,as%20shown%20in%20Figure%2012.3
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https://www.healthgrades.com/right-care/endocrinology-and-metabolism/endocrine-disorders
Endocrine Sytem Lecture Note
Endocrin Glands
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2. THYROID GLAND
:CHECK:The thyroid gland consists of two lobes on the ventral surface of the trachea.
Proper thyroid function requires dietary iodine for hormone production.
:CHECK:The main hormone of thyroid gland is the iodine-containing hormone called
thyroxine.
The second hormone released from thyroid gland is
calcitonin
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Calcitonin is released by the thyroid gland :ballot_box_with_check:
Calcitonin decreases the Ca2+ level of blood
It stimulates Ca2+ deposition in bones and decreases reabsorbtion of Ca2+ in kidneys and increases excretion of Ca2+ by urine
Works antagonistacally with parathyroid hormone to balance calcium (Ca2+) in the blood of mammals
Thyroxine hormone stimulate metabolism and influence development and maturation. :ballot_box_with_check:
o Increase aerobic respiration, therefore oxygen consumption and energy production
o Increase protein synthesis during growth and develeopment
o Increase blood pressure and heart beat rate and metabolic rate
o There is no one target organ, all organs respond.
Disorders in thyroid:Hypothyroidism,Goiter,Cretinism,Graves’ disease.. :check:
3.PARATHYROID GLAND
:check:Parathyroid hormone (PTH) is released by the
parathyroid glands.
:check:ÇParathyroid glands, variably located on the back of the thyroid
gland.
:check:Work antagonistacally with calsitonin hormone secreted from
thyroid gland.
1.PITUITARY GLAND
A. POSTERIOR PITUITARY HORMONES
1) Oxytocin
Oxytocin induces uterine contractions and the release of milk. Suckling sends a message to the hypothalamus via the nervous system to release oxytocin, which further
stimulates the milk glands. This is an example of positive feedback,where the stimulus leads to an even greater response
2) Antidiuretic Hormone or Vazopressin (ADH)
ADH enhances water reabsorption from collecting ducts in kidneys resulting less water in urine.
• Balance osmotic pressure of blood
• Secretion of ADH is controlled by a negative feedback mechanism as follows;
• Less water in blood , hypothalamus ,ADH , kidney , reabsorbs water makes blood more dilute / makes urine more concentrated
• As blood becomes dilute, ADH is no longer released; this is a case of negative feedbac
ADH deficiency leads to the syndrome of Diabetes Insipidus
B.ANTERIOR PITUITARY HORMONES
Prolactin :check:
Mammary Glands
Prolactin (PRL)
MSH :check:
Melanocytes
Melanocyte-stimulating hormone (MSH)
ACTH :check:
Adrenal Cortex
Adrenocorticotropic hormone (ACTH)
GH :check:
Liver,bones and other tissues
Growth Hormone (GH)
TSH :check:
Thyroid
Thyroid-stimulating hormone (TSH)
FSH and LH :check:
Testes or ovaries
Follicle-stimulating hormone (FSH)-Luteinizing hormone (LH)
4.ADRENAL GLANDS
-The adrenal glands are small yellow masses of tissue that lie in contact with the upper ends of kidneys. They work independently from kidneys. Each adrenal gland actually consists of two parts:
:check: Adrenal medulla (inner portion)
:check: Adrenal cortex (outer portion)
A)ADRENAL MEDULLA HORMONES
The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).
These hormones are members of a class of compounds called catecholamines.
They are secreted in response to stress-activated impulses from the nervous system.
They mediate various fight-or-flight responses.
B) ADRENAL CORTEX HORMONES
The adrenal cortex releases a family of steroids called corticosteroids in response to stress.
These hormones are triggered by a hormone cascade pathway via the hypothalamus and anterior pituitary.
ACTH released from anterior pituitary control the adrenal cortex hormones secretion.
Humans produce 3 types of corticosteroids:
i. Glucocorticoids,
Cortisol
Cortisone
ii. Mineralocorticoids
Aldosterone
iii. Androgens
Steroid sex hormones
5.GONADAL SEX HORMONES
-Testosterone is male sex hormone
:check:The gonads, testes in males and ovaries in females, produce most of the sex hormones:
i. Estrogens
ii. Progesterone
iii. Androgens.
-Estrogen is released from follicle and responsible for maintenance of the female reproductive system.
-Progesterone, are primarily involved in preparing and maintaining the uterus.
6.PANCREAS
It is a mixed type of gland that shows both endocrine and exocrine functions.
Islets of Langerhans have two kinds of cells. Alpha cells secrete glucagon and ß - cells secrete insulin. Both hormones are given to the blood directly. Therefore, they function as endocrine glands.
Insulin:check:
Decrease blood glucose level
Works antagonistacally with glucagon to adjust blood glucose level
Increase the permeability of cells to take glucose except brain cells
Stimulate conversion of glucose to glycogen as storage form in liver and muscles
Increase the glucose metabolism in cells (conservation of glucose to glycogen or lipids)
Glukagon:check:
Increasee blood glucose level
Works antagonistacally with insulin to adjust blood glucose level
Functions in conservation of glycogen to glucose into liver
Stimulates passage of glucose from cells (especially liver cells) into blood
Stimulate fat breakdown
Increases absorption of glucose in the ileum
7.PINEAL GLAND
The pineal gland, located in the brain, secretes melatonin, primarily at night.
Light/dark cycles control release of melatonin.
