Lesson 1.2.3

1.2.3 page 2

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Adrenal Gland and Stress Reactions

 

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Like small baseball caps, the adrenal glands perch on top of the kidneys. See page 451 of the text. Further examination shows that each adrenal gland is really two glands with the adrenal cortex (meaning bark) wrapped around the adrenal medulla (meaning middle). The adrenal cortex consists of layers of secretory cells while the adrenal medulla consists of modified nerve cells. What other gland have you studied that is made of both nervous and endocrine tissue? Both parts of the adrenal gland produce and release hormones in response to stress stimuli. Remember the Student Stress! Lab that you completed in Lesson 1 and the stress that the experimenter created in the subjects? The adrenal gland would have played a significant role in bringing about changes in the subjects blood pressure and heart rate. The stress reactions of the human body comprise a wide range of reactions which prepare the body to resist any damaging or potentially damaging changes in the environment. A great variety of stimuli trigger these responses, including injury, infection and emotional responses such as fear or anger. The effectiveness of a particular stimulus varies from person to person. You may be freaking out about that exam in the afternoon but your friend may not be worried about it at all. Or the bass in your car stereo may be driving your parents nuts, but you’re enjoying the beat.

 

adrenal medulla: the central or middle part of the adrenal gland composed of modified nervous tissue which responds to sympathetic nerve signals by secreting the “fight or flight” hormones epinephrine and norepinephrine in reaction to stress

 

adrenal cortex: the outer portion of the adrenal gland composed of three distinct layers of cells which respond to hormonal signals from the anterior pituitary by producing three groups of hormones including the glucocorticoids, mineral corticoids, and gonadocorticoids; reacts to stress stimuli and affects salt and water balance



Watch and Listen

 

At this time, you may want to review and reinforce concepts about the adrenal gland and stress responses by viewing the video below.

 

Adrenal Glands