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By the end of this section, you will be able to:
  • Describe the location and structure of the adrenal glands
  • Identify the hormones produced by the adrenal cortex and adrenal medulla, and summarize their target cells and effects

The adrenal glands    are wedges of glandular and neuroendocrine tissue adhering to the top of the kidneys by a fibrous capsule ( [link] ). The adrenal glands have a rich blood supply and experience one of the highest rates of blood flow in the body. They are served by several arteries branching off the aorta, including the suprarenal and renal arteries. Blood flows to each adrenal gland at the adrenal cortex and then drains into the adrenal medulla. Adrenal hormones are released into the circulation via the left and right suprarenal veins.

Adrenal glands

This diagram shows the left adrenal gland located atop the left kidney. The gland is composed of an outer cortex and an inner medulla all surrounded by a connective tissue capsule. The cortex can be subdivided into additional zones, all of which produce different types of hormones. The outermost layer is the zona glomerulosa, which releases mineralcorticoids, such as aldosterone, that regulate mineral balance. Underneath this layer is the zona fasciculate, which releases glucocorticoids, such as cortisol, corticosterone and cortisone, that regulate glucose metabolism. Underneath this layer is the zona reticularis, which releases androgens, such as dehydroepiandrosterone, that stimulate masculinization. Below this layer is the adrenal medulla, which releases stress hormones, such as epinephrine and norepinephrine, that stimulate the symphathetic ANS.
Both adrenal glands sit atop the kidneys and are composed of an outer cortex and an inner medulla, all surrounded by a connective tissue capsule. The cortex can be subdivided into additional zones, all of which produce different types of hormones. LM × 204. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

View the University of Michigan WebScope at (External Link) to explore the tissue sample in greater detail.

The adrenal gland consists of an outer cortex of glandular tissue and an inner medulla of nervous tissue. The cortex itself is divided into three zones: the zona glomerulosa    , the zona fasciculata    , and the zona reticularis    . Each region secretes its own set of hormones.

The adrenal cortex    , as a component of the hypothalamic-pituitary-adrenal (HPA) axis, secretes steroid hormones important for the regulation of the long-term stress response, blood pressure and blood volume, nutrient uptake and storage, fluid and electrolyte balance, and inflammation. The HPA axis involves the stimulation of hormone release of adrenocorticotropic hormone (ACTH) from the pituitary by the hypothalamus. ACTH then stimulates the adrenal cortex to produce the hormone cortisol. This pathway will be discussed in more detail below.

The adrenal medulla    is neuroendocrine tissue composed of postganglionic sympathetic nervous system (SNS) neurons. It is really an extension of the autonomic nervous system, which regulates homeostasis in the body. The sympathomedullary (SAM) pathway involves the stimulation of the medulla by impulses from the hypothalamus via neurons from the thoracic spinal cord. The medulla is stimulated to secrete the amine hormones epinephrine and norepinephrine.

One of the major functions of the adrenal gland is to respond to stress. Stress can be either physical or psychological or both. Physical stresses include exposing the body to injury, walking outside in cold and wet conditions without a coat on, or malnutrition. Psychological stresses include the perception of a physical threat, a fight with a loved one, or just a bad day at school.

The body responds in different ways to short-term stress and long-term stress following a pattern known as the general adaptation syndrome (GAS)    . Stage one of GAS is called the alarm reaction    . This is short-term stress, the fight-or-flight response, mediated by the hormones epinephrine and norepinephrine from the adrenal medulla via the SAM pathway. Their function is to prepare the body for extreme physical exertion. Once this stress is relieved, the body quickly returns to normal. The section on the adrenal medulla covers this response in more detail.

Questions & Answers

thank you sooo much bro
Fatima Reply
Fatima hw a u
any one elaborate fr me foramens of the skull and features which they transmit
icant undrestand plz
zahruuzh Reply
try to read I hop you will understand
state and explain 20 radiology uses
what are chemicals in anatomy and physiology?
Mike Reply
what can I do to find it easy for me in anatomy and physiology course
study up on the basics of the periodic chart, learn bones and muscles attachments, and learn muscles. Those take the longest to memorize. After that it should be a little easier.
what are the two types of body cells
Jennifer Reply
what is malnutrition
malnutrition refers to faulty nutrition resulting from malabsorption,poor diet or overeating. Sometimes too these food do not contain all the six food nutrients in their right proportion.
thank you
Will u be malnourished?
What's the difference between radiology and radiology
Nothing! Radiology it means the study or using of radiation in medical science it can be 1.diagnose or treatment diagnosed radiology! x- ray. ultrasound. ct-scan. mammogram. MRI. 2. treatmen- radiation oncology, like Cobalt 60. and nuclear medicine
what is X-ray?
X-ray is type of light that make it possible to see inside any object. as human body
How the nervous system develops
ayiesher Reply
From the cells at the back of an embryo
breifly explain anatomy of thorax
Hadiza Reply
How many region the rib is divided
how many bon of human being
how to study for the skeletal system
and anatomy
I really need sources immediately
I printed out all the different bones. Put them in the see through protective sheaths and got dry erase markers. I could right on them and erase to help me learn to spell the names of markings and bones.
Or go to a book store, Barnes and Noble(doesn't have to be this) and they have coloring books for anatomy. $16. Really helpful.
okay thanks and are what study tools you use to study the materials and get a better understanding
*what are
I prefer diagrams, pictures that lay out each step with the information in each step. For Example: how action potential creates muscles to move. A pictured diagram gives me a better understanding of how each piece plays a role in each step of the process.
Also for basics, such as memorizing vocab. Flash cards are great. Don't become discouraged if you don't get them all right the first times through. The more you go through them, your brain will remember pieces of information from each and help you to pull out the information 😉
okay thanks
what is the functions of the lips in human
Momboi Reply
could I say sensation?
for protection
Lips assist in speech and eating
Too many easy questions. Which bones are the axial and appendicular? What are the abbreviations for TEE, TTE, AED, A-Mode, B-Mode, and LTH? What is the difference between hypothalamus and thalamus? Where is the parathyroid located? How many True Ribs do we have?
Sovilace Reply
Transesophageal echocardiography Transthoracic Echocardiography automated external defibrillator brightnees mode Los Hermanos Taverna
what is anatomy
okello Reply
anatomy is scientific study of body structures and how they relate to each other
Are there other functions of the nucleolus apart from synthesis of RNA and formation of ribosomes
Peninah Reply
plays a role in cell response to stress
what is angle of auscultation
Bryan Reply
Anatomy which is the study of the human body structure has a couple of reasons it is been studied It helps to discover genetic disease cytology And histology which is the study of tissues Physiology is the study of function of the human cells It helps to know how the different body part works Its helps to know how part of the brain works And lastly It gives the essential to understand more about anatomy
Stephen Reply
describe the external features of a spinal cord
okoche Reply
Spinal nerves emerge in pairs, one from each side of the spinal cord along its length. The cervical nerves form a plexus (a complex interwoven network of nerves—nerves converge and branch). The cervical enlargement is a widening in the upper part of the spinal cord (C 4–T 1). Nerves that extend in
Hormones regulate certain target cell responses. These can include which of the following?
Nazareth Reply
describe the external features of spinal cord

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