Group7

Group 7 **Endocrine System: Adrenal Glands** //E-Facilitator: Cathy//
 * //Learning Outcomes//**
 * //Locate the Adrenal Glands and differentiate between the Adrenal Medulla and the Adrenal Cortex//
 * //Describe the relationship between the Adrenal Glands and the Nervous System//
 * //List and discuss the hormones that the Adrenal Glands produce and their effects on the body//
 * //Explain why synthetic Adrenaline is often added to local anaesthetics used in dentistry//

__**Location of the Adrenal Glands and differences between the Adrenal Medulla and the Adrenal Cortex**__

The adrenal glands are a pair of glands located near the superior portion of each kidney(3). This is why they are also known as suprarenal glands (2). They are approximately
 * 3-5 cm in height
 * 2-3 cm in width
 * less than 1 cm thick
 * and weigh from 31/2 to 5 grams (3)

There are **2** structural and functional regions of the adrenal gland;

1) the outer region is called the **adrenal cortex** (1) 2) the inner region is called the **adrenal medulla** (1)

In general, the function of the adrenal glands is to produce a number of different hormones that are essential to the needs of the human body. Both parts of the adrenal glands perform very separate functions as they produce different hormones (1) (3). *This will be discussed in greater depth later on* .



Diagram from http://training.seer.cancer.gov/module_anatomy/unit6_3_endo_glnds3_adrenal.html (2)


 * __The relationship between the Adrenal Glands and the Nervous System__**

The adrenal glands are an endocrine gland that help regulate the bodies internal organs. They are part of the bodies autonomic nervous system meaning they are not under conscious control in the body. They respond to hormones that are released involuntarily by the pituitary gland under command from the hypothalamus. The hypothalamus detects any imbalance by positive or negative feedback and releases hormones to stimulate other endocrine glands which either help with stimulate the sympathetic or parasympathetic nervous system (5). The adrenal glands are part of the sympathetic nervous system which help prepare the body for physical activity. Stimulation of the sympathetic nervous system results in a number of responses including constriction of blood vessels supplying the skin, dilation of blood vessels supplying the heart and skeletal muscles, dilation of the bronchioles to facilitate increased ventilation, and release of glucose from the liver. The nerve endings use adrenaline and noradrenalin as a neurotransmitter (6).

The actions of the autonomic nervous system are largely **involuntary** (in contrast to those of the sensory-somatic system). It also differs from the sensory-somatic system is using two groups of motor neurons to stimulate the effectors instead of one.(9)

The autonomic nervous system has two subdivisions, the
 * The first, the **preganglionic neurons**, arise in the CNS and run to a [|ganglion] in the body. Here they [|synapse] with
 * **postganglionic neurons**, which run to the effector organ (cardiac muscle, smooth muscle, or a gland).
 * **sympathetic nervous system** and the
 * **parasympathetic nervous system**.(9)

The preganglionic motor neurons of the sympathetic system arise in the spinal cord. They pass into sympathetic [|ganglia] which are organized into two chains that run parallel to and on either side of the spinal cord.

The preganglionic neuron may do one of three things in the sympathetic ganglion: The neurotransmitter of the preganglionic sympathetic neurons is **[|acetylcholine]** (**ACh**). It stimulates action potentials in the postganglionic neurons. The neurotransmitter released by the postganglionic neurons is **[|noradrenaline]** (also called **norepinephrine**). The action of noradrenaline on a particular gland or muscle is excitatory is some cases, inhibitory in others. (At excitatory terminals, [|ATP] may be released along with noradrenaline.)
 * synapse with postganglionic neurons which then reenter the spinal nerve and ultimately pass out to the sweat glands and the walls of blood vessels near the surface of the body.
 * pass up or down the sympathetic chain and finally synapse with postganglionic neurons in a higher or lower ganglion
 * leave the ganglion by way of a cord leading to special ganglia (e.g. the solar plexus) in the viscera. Here it may synapse with postganglionic sympathetic neurons running to the smooth muscular walls of the viscera. However, some of these preganglionic neurons pass right on through this second ganglion and into the **[|adrenal medulla]**. Here they synapse with the highly-modified postganglionic cells that make up the secretory portion of the adrenal medulla.(9)

The **release of noradrenaline** In short, stimulation of the sympathetic branch of the autonomic nervous system prepares the body for emergencies: for "**fight or flight**".
 * stimulates [|heartbeat]
 * raises [|blood pressure]
 * dilates the pupils
 * dilates the [|trachea and bronchi]
 * stimulates the conversion of liver [|glycogen] into glucose
 * shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart
 * inhibits peristalsis in the gastrointestinal (GI) tract
 * inhibits contraction of the bladder and rectum

Activation of the sympathetic system is quite general because = = = = = = =The Medulla=
 * a single preganglionic neuron usually synapses with many postganglionic neurons;
 * the release of **adrenaline** from the [|adrenal medulla] into the blood ensures that all the cells of the body will be exposed to sympathetic stimulation even if no postganglionic neurons reach them directly.(7)

The adrenal medulla consists of masses of neurons that are part of the [|sympathetic branch] of the [|autonomic nervous system]. Instead of releasing their [|neurotransmitters] at a [|synapse], these neurons release them into the blood. Thus, although part of the nervous system, the adrenal medulla functions as an endocrine gland. The adrenal medulla releases: Both are derived from the amino acid [|tyrosine]. Release of adrenaline and noradrenaline is triggered by nervous stimulation in response to physical or mental stress. The hormones bind to **[|adrenergic receptors]** — [|transmembrane proteins] in the plasma membrane of many cell types. Some of the effects are: All of these effects prepare the body to take immediate and vigorous action.(9)
 * **adrenaline** (also called epinephrine) and
 * **noradrenaline** (also called norepinephrine)
 * increase in the rate and strength of the heartbeat resulting in increased [|blood pressure];
 * blood shunted from the skin and viscera to the skeletal muscles, coronary arteries, liver, and brain;
 * rise in blood sugar;
 * increased metabolic rate;
 * bronchi dilate;
 * pupils dilate;
 * hair stands on end ("gooseflesh" in humans);
 * [|clotting] time of the blood is reduced;
 * increased ACTH secretion from the anterior lobe of the pituitary.

== [|http://images.google.com.au/images?qsympathetic+nervous+system&hl=en&rls=GGLR,GGLR:2006-]7,GGLR:en&um=1&sa=X&oi=images&ct=title==

(11)
== Diagram from Endocrine system Information (5). Diagram from Answers.com (6) Diagram from Endocrine system information (5)==

__**The hormones that the Adrenal Glands produce and their effects on the body**__



Diagram from Medline Plus (4)

There are **2** structural and functional regions of the adrenal gland; 1) the outer region is called the **adrenal cortex** (1) 2) the inner region is called the **adrenal medulla** (1) Both parts of the adrenal glands perform very separate functions as they produce different hormones. However, both are essential to the healthy function of the body. (1) (3)


 * __1) Adrenal Cortex__**

The adrenal cortex secretes hormones that have an effect on the body's metabolism, on chemicals in the blood, and on certain body characteristics. The adrenal cortex secretes corticosteroids and other hormones directly into the bloodstream. (2) The **adrenal cortex** is subdivided into **3** zones according to the hormones that each zone secretes. (3)


 * the outer zone- **zona glomerulosa**
 * the middle zone- **zona fasciculata**
 * the inner zone- **zona reticularis**


 * //**Zona Glomerulosa**//

Its primary secretions are a group pf hormones called **mineralocorticoids**. They affect mineral homeostasis.(3) This means that they play a role in conserving the electrolytes and water in the body, particularly the concentrations of sodium (Na+) and potassium ions (K+). (1)(3)

Secretes mainly **glucocoticoids** which affect glucose homeostasis.The principal glucocorticoid is cortisol, which increases blood glucose levels.(2)
 * //**Zona Fasciculata**//


 * //**Zona Reticularis**//

Synthesises small amounts of androgenic steroids or androgen steroids. Male hormones (**androgens**) and female hormones (**oestrogens**) are secreted in minimal amounts in both sexes by the adrenal cortex, but their effect is usually masked by the hormones from the testes and ovaries. (2)


 * __2) Adrenal Medulla__**

The hormones secreted in the adrenal medulla, unlike those secreted by the adrenal cortex, are not essential to life. The hormones secreted assist a person in coping with physical and emotional stress.(2)(3) The **2** main hormones synthesised by the adrenal medulla are **epinephrine** and **norepinephrine**.


 * epinephrine (also called **adrenaline**) increases the heart rate and force of heart contractions, facilitates blood flow to the muscles and brain, causes relaxation of smooth muscles, helps with conversion of glycogen to glucose in the liver, and other activities.(1)

·
 * norepinephrine (also called **noradrenaline**) has little effect on smooth muscle, metabolic processes, and cardiac output, but has strong vasoconstrictive effects, thus increasing blood pressure. (1)

__**Why synthetic Adrenaline is often added to local anaesthetics used in dentistry**__ = = = = Epinephrine is the technical name used for synthetic adrenaline. Its chemical composition formula is C9H13NO3. It is often added to local anaesthetics used in dentistry because it constricts blood vessels at the site it is injected, keeping the anaesthetic in the area for a longer time. This constriction helps the anaesthetic to work more intensely for a longer time ensuring the patient operated on has a painless procedure. The epinephrine helps prepare the body for stressful situations the same way as natural adrenaline does in the ‘fight or flight’ theory. The epinephrine is intended for use in the surrounding tissues only, constricting a ’local’ area so that usually no side effects are noticed. If an anaesthetic with epinephrine is absorbed directly into the blood stream or a patient is especially sensitive to it they may feel some side effects. (8) These side effects include: It is important to note that these symptoms sometimes follow soon after an injection with a patient suffering anxiety because the patient will release natural adrenaline.(8)
 * **Dizziness**
 * **Palpitations - an irregular or unusually rapid beating of the heart**
 * **Racing heart**

If it is known that a patient has a particularly strong reaction to epinephrine then an alternate anaesthetic should be used. There are a few including : Polocaine, Isocaine or Citanest. To be certain that an anaesthetic does not have epinephrine or epinephrine-like compounds added (for epinephrine sensitive patients) you must specify with the following word plain as in Polocaine-plain, Carbocaine-plain Citanest-plain etc. These anaesthetics do not effectively work for as long as the adrenaline based anaesthetics. It is common to use several injections when using non-adrenaline based local anaethetics particularly for the maxilla. In the lower jaw they are only slightly shorter -acting. (8)


 * Diseases Associated with the Adrenal Glands**


 * __Cushing’s Disease__** ·

Cushing's syndrome is caused by the adrenal gland's excessive secretion of cortisol (hydrocortisone). Increases the adrenal gland's secretion of glucocorticoid hormones will cause Cushing's syndrome, including adrenal tumours, enlargement of the outer layers of the adrenal gland, or overproduction of adrenocorticotropic hormone (ACTH). Excess ACTH may result from pituitary tumours (Cushing's disease), as in Cushing's first group of symptomatic patients, or from inappropriate production of the hormone by other tissues. Treatment with corticosteroid drugs may also induce Cushingoid symptoms.(7)


 * __Symptoms of Cushing’s Disease__**


 * Persistent hyperglycaemia (steroid diabetes).
 * Dramatic losses in muscle.
 * Bone protein and water and salt retention leading to hypertension and edema.

__**Physical signs of cushing's Disease**__


 * Swollen ‘moon’ face.
 * Redistribution of fat to the abdomen and the posterior neck (a ‘buffalo hump’).
 * Tendency to bruise.
 * Poor wound healing.
 * Present infections may become overwhelmingly severe before producing recognizable symptoms.
 * Bones can spontaneously fracture.(7)




 * __Causes of Addison’s Disease__**


 * An autoimmune disease- the immune system attacks the adrenal glands.
 * Attributed to tuberculosis.
 * Addison disease also can be caused by fungal infections or cancer (7).

__**Symptoms of Addison’s Disease**__


 * Abnormal pigmentation of the skin & mucous membranes.
 * Bodily weakness.
 * Weight loss.
 * Low blood pressure.
 * Emotional instability.
 * Gastrointestinal upset.
 * Deficiencies in both glucocorticoids and mineralocorticoids.
 * Low sodium levels and high potassium levels (7).




 * __References__**
 * 1.http://www.umm.edu/endocrin/adrengl.htmhttp://www.umm.edu/endocrin/adrengl.htmhttp://www.umm.edu/endocrin/adrengl.htm
 * 2.http://training.seer.cancer.gov/module_anatomy/unit6_3_endo_glnds3_adrenal.htmlhttp://training.seer.cancer.gov/module_anatomy/unit6_3_endo_glnds3_adrenal.htmlhttp://training.seer.cancer.gov/module_anatomy/unit6_3_endo_glnds3_adrenal.html
 * 3. Tortora & Grabowski (1996) Principles of Anatomy and Physiology, 8th Edition, HarperCollins Publishers Inc.
 * 4.http://www.nlm.nih.gov/medlineplus/ency/imagepages/8719.htmhttp://www.nlm.nih.gov/medlineplus/ency/imagepages/8719.htmhttp://www.nlm.nih.gov/medlineplus/ency/imagepages/8719.htm
 * 5. http://www.besthealth.com/besthealth/bodyguide/reftext/html/endo_sys_fin.html#adrenal
 * 6. http://www.answers.com/topic/adrenal-gland?cat=health
 * 7. Marieb E, 2004, //Human Anatomy & Physiology//, 6th Edition, Pearson and Benjamin Cummings, USA
 * 8. http://lindacrabtree.com/cmtnews/Dentistry/Epinephrine%20in%20freezing.html
 * 9. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PNS.html
 * 10.http://home.swipnet.se/sympatiska/nervous.htm
 * 11.http://images.google.com.au/images?q=sympathetic+nervous+system&hl=en&rls=GGLR,GGLR:2006-07,GGLR:en&um=1&sa=X&oi=images&ct=title