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Food For Thought: What fuels us? Glucose, the endocrine system, and health

Lesson 3: How does adrenalin have an effect on the body and the brain?

I. Overview Lesson 3 aims to explore the fight-or-flight response and how it relates to glucose availability in the body and the brain. Students reflect on personal adrenalin experiences to recognize how their heart rate, breathing, and memory change in this sympathetic state. Using their personal experiences and the information learned from lessons 1 & 2, students construct a model to predict how the stress hormone adrenalin affects the body. Next, students proceed through a series of three checkpoints to test their model and make revisions as needed. Finally, students use their models to explain, communicate, predict, and test the effect an adrenal rush has on the endocrine system and the body as a whole.

Connections to the driving question In this lesson students will learn about the endocrine response to stress by examining adrenalin's ability to increase glucose availability in the body and the brain. Students ultimately learn how the endocrine system is able to fuel the brain and the body in order to escape stressful situations and avoid them in the future.

Connections to previous lesson Lesson 3 focuses on the adrenalin/glucose model of the fight-or-flight response. In lesson 2, students learned how the endocrine system regulates blood glucose levels to maintain homeostasis with insulin and glucagon. In this lesson, students learn how the endocrine system can induce change rather than maintain stability during stressful situations to increase blood glucose. Building on their previous knowledge of how the endocrine system functions, students explore how the endocrine response affects them by discussing past experiences and engaging in the multiple practices of modeling.

II. Standards

National Science Education Standards: 12CLS6.3 Like other aspects of an organism’s biology, behaviors have evolved through natural selection. Behaviors often have an adaptive logic when viewed in terms of evolutionary principles. 12CLS6.2 Organisms have behavioral responses to internal changes and to external stimuli. Responses to external stimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success.

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Animals often live in unpredictable environments, and so their behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.

Benchmarks for Science Literacy: The Human Organism: Basic Functions

The human body is a complex system of cells, most of which are grouped into organ systems

that have specialized functions. These systems can best be understood in terms of the essential

functions they serve for the organism: deriving energy from food, protection against injury,

internal coordination, and reproduction.

Communication between cells is required to coordinate their diverse activities. Cells may

secrete molecules that spread locally to nearby cells or that are carried in the bloodstream to

cells throughout the body. Nerve cells transmit electrochemical signals that carry information

much more rapidly than is possibly by diffusion or blood flow

III. Learning Objectives

Learning Objective Assessment Location in Lesson

Apply knowledge of the

endocrine system to the

specific hormone

adrenalin.

Using their whiteboards, students create predictive

models of how adrenalin is working in the body.

Before moving to the checkpoints, students’

predictive models should include the six main

components of the endocrine system.

Activity 1: Using Models to

Predict

Identify and explain the

somatic effects of the

fight-or-flight response

Student explanations include:

Epinephrine travels through the blood to act on many organs including the heart, lungs, liver, muscle, intestines, eyes, and digestive tract.

Epinephrine acts in various ways on these organs to facilitate the flight-or-flight response. For example: muscle receives more glucose for energy and breathing rate increases to pull more oxygen into the lungs.

Associated Materials: U7_L1_CheckpointA_Student Sheet

Activity 2: Checkpoint A

Explain that epinephrine

improves memory

indirectly by increasing

blood glucose.

Students should be able to explain that:

Epinephrine is released by the adrenal glands into the circulatory system.

Epinephrine cannot pass the blood-brain barrier.

Epinephrine acts indirectly by triggering the release of glucose from liver cells.

Activity 2: Checkpoints B & C

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Glucose travels to the brain, passes the blood-brain barrier and can work to improve memory.

Associated Materials:

U7_L1_CheckpointB_StudentSheet

U7_L1_CheckpointC_StudentSheet

Evaluate the

evolutionary benefits

behind the flight-or-

flight response and

recognize the influence

the human mind has on

the stress response.

In discussion students explain:

The fight-or-flight response fuels the body to escape or fight an attacker. Remembering how to avoid stressful situations and encounters with attackers would be adaptive for survival.

The human imagination can induce a stress response simply by worrying and thinking about perceived stresses (will be covered in Lesson 5 as well).

Conclusion of Lesson

IV. Adaptations/Accommodations Whiteboards and dry erase markers are suggested for the main activity because students will need to be

able to revise their models. If individual white boards are not available for student groups, the

classroom whiteboard/chalkboard can be divided up so that each student group can have space to

construct and revise their model.

V. Timeframe for lesson

Opening of Lesson

Scare activity: 2-5 minutes

Reflection of past adrenalin rushes: 5 minutes

Main Part of Lesson

Activity 1 – Using Models to Predict: 20 minutes

Activity 2 – Using Models to Test: 20

Conclusion of Lesson

Wrap up discussion: 5 minutes

VI. Advance Prep and Materials

Homework Article:

U7_L3_Reading_SuperHumanStrength

Opening of Lesson: Scare activity and reflection of past adrenalin rushes

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Preparation:

Prepare a script to help students relax. Refer to the information at this link:

http://www.innerhealthstudio.com/visualization-relaxation.html.

Main Part of Lesson: Adrenalin Modeling

Activity 1: Using Models to Predict

Materials:

Video of man jumping away from car:

o http://www.youtube.com/watch?v=OdOOIxcUjAs

U7_L3_StartingImage

White boards and dry erase markers

Preparation:

Have video ready to be presented and have U7_L3_StartingImage ready to be projected on

screen.

Provide enough white boards and dry erase markers as there are student groups (3-5

students per group)

Activity 2: Using models to test

Materials:

U7_L3_CheckpointA_Slides (PowerPoint: Can be projected on laptops or printed).

U7_L3_CheckpointA_StudentSheet

U7_L3_CheckpointB_RatMemoryExperiment

U7_L3_CheckpointB_StudentSheet

U7_L3_CheckpointC_WhatATwist

U7_L3_CheckpointC_StudentSheet

U7_L3_CheckpointA_StudenSheet_ANSWERS (for teacher reference)

Preparation:

Print off student sheets and checkpoint materials prior to class. One per student group.

Print worksheets on different sheets of paper for each Checkpoint. (i.e., Checkpoint A = Red

worksheets, Checkpoint B = Blue, etc.)

U7_L3_CheckpointA_Slides is a PowerPoint and can be projected or can be printed on

paper in color for students to work through. For continued use, consider laminating these

slides.

Conclusion:

Materials:

U7_L3_AdrenalinModelChecklist

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U7_L3_Image_AdrenalinDiagram

Preparation:

Print off enough sheets of U7_L3_AdrenalinModelChecklist to have one for each group.

This document will allow students to check if they have everything they need in their

adrenalin model.

Optional: U7_L3_Image_AdrenalinDiagram is an image of the adrenalin model that can be

projected on the screen during class discussion if students DO NOT have their whiteboards

to reference.

VII. Resources and references

Teacher resources

Cahill, L. Stress Arousal and Effects on Memory and Performance. Found at

http://www.clta.uci.edu/documents/article4.pdf

Korol, D.L. and Gold, P.E. (1998) Glucose, memory and aging. The American Journal of Clinical

Nutrition. 67(suppl):764S-771S. Found as Gold, P.E. and Korol, D.L. (2012) Making Memories

Matter. Frontiers in Integrative Neuroscience. Found at:

http://www.frontiersin.org/Integrative_Neuroscience/10.3389/fnint.2012.00116/abstract

Supplemental information on the blood-brain barrier:

o http://neuroscience.uth.tmc.edu/s4/chapter11.html

o http://www.examiner.com/video/blood-brain-barrier-model-to-test-drugs-for-brain-

diseases

o http://www.examiner.com/video/blood-brain-barrier-model-to-test-drugs-for-brain-

diseases

References Häggström, M. (Nov 2008). Intestine – sized [Graphic in Public Domain]. Image:

Digestive_system_diagram_en.svg. Retrieved from

http://commons.wikimedia.org/wiki/File:Intestine_-_sized.png

Häggström, M. (Nov 2008). Lungs – sized [Graphic in Public Domain]. Image: Respiratory system

complete numbered.svg. Retrieved from http://commons.wikimedia.org/wiki/File:Lungs_-

_sized.png

Ilic, S., Brcic, I., Mester, M., Filipovic, M., Sever, M., Klicek, R., Barisic, I., Radic, B., Zoricic,Z., Bilic,

V., Berkopic, L., Brcic, L., Kolenc,D., Romic,Z., Pazanin, L., Seiwerth,S., Sikiric, P. (2009) Over-dose

insulin and stable gastric pentadecapeptide BPC 157. Attenuated gastric ulcers, seizures, brain

lesions, hepatomegaly, fatty liver, breakdown of liver glycogen, profound hypoglycemia and

calcification in rats. J Physiol. Pharmacol. 7:107-114.

Inner Health Studio. (2014). Retrieved from: http://www.innerhealthstudio.com/visualization-

relaxation.html

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Lucky man almost hit by car, escapes carnage by inches. (2010). YouTube. Retrieved from:

http://www.youtube.com/watch?v=OdOOIxcUjAs

Morris, K.A., Chang, Q., Mohler, E.G., Gold, P.E. (2010). Age-related memory impairments due to

reduced blood glucose responses to epinephrine. Neurobiology of Aging. 31: 2136-2145.

Sokal, J. E. & Sarcione, E. J. (1959). Effect of epinephrine on glycogen stores. Am. J.

Physiol, 196(6), 1253-1257.

Wise, J. (2009) When Fear Makes Us Superhuman. Scientific American. Found at:

http://www.scientificamerican.com/article.cfm?id=extreme-fear-superhuman&page=2

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VIII. Lesson Implementation **The term adrenalin and epinephrine will be used interchangeably throughout this lesson and

the rest of the unit. Make sure to let students know that these two terms refer to the exact

same chemical**

Prior to Lesson: To prepare students for the context of the lesson, students should enter the class having read:

U7_L3_Reading_SuperHumanStrength for homework.

Opening of Lesson: Assume a very calm voice. Have students close their eyes, breath slowly and deeply, and relax. Use the website http://www.innerhealthstudio.com/visualization-relaxation.html to guide a relaxation discourse. When students are in a relaxed state and least expect it, make a LOUD NOISE (dropping a symbol borrowed from the music department has worked wonderfully). This sudden loud noise, contrasted with the students’ relaxed state, should startle and surprise the students. Commotion will inevitably arise from this activity, but try to gather the attention of the class as quickly as possible. Ask the students:

Were you frightened? Reflect on what is happening to your body right now. What is happening to your body

physiologically? o Answer: I am sweating, I can feel my heart beating, I am breathing fast and deeply, I am

“on edge”, my heart jumped, I feel anxious, etc.

Explain to the students that when your body encounters surprising, scary, threatening, or intense stimuli, it has what is known as a fight-or-flight response. The fight-or-flight response is mediated by both the (1) nervous system and the (2) endocrine system. The endocrine system will be the focus of this lesson. During a fight-or-flight response, the body will release the hormone adrenalin into the bloodstream. Have any of you heard of an “adrenalin rush” before?

Teacher Pedagogical Content Knowledge: It is helpful to choose a limited amount of vocabulary words to be the focus of a unit.

In this way students gain an in-depth understanding of the important terms that

emphasize the main ideas of the unit. The main vocabulary words should be brought

up frequently throughout a unit.

The main vocabulary words for this unit are (words in bold are introduced in Lesson 3):

Homeostasis

Negative Feedback

Insulin vs. Glucagon

Fight-or-Flight Response

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Ask the students:

Can you recall ever having an adrenalin rush? What were you doing? What do you remember most about it?

o Adrenalin rushes tend to occur very shortly following or during a stressful situation, such as getting in a car accident. Memories resulting from adrenalin rushes tend to feel permanent. Small, strange details tend to be remembered, such as the food you had eaten in the meal before, who you were with, what you were wearing, etc.

For those of you who are engaged in athletic activities, such as swimming, running races, basketball, or football games do you find you remember meets and/or games more than practices? Why do you think that is?

o Before competition, adrenalin levels surge to support the upcoming activity. Ideally, performance should be at its best during competition, and the brain and body can respond very rapidly to this knowledge within seconds before the start of competition to ensure efficient energy is available to support these activities. However, since the brain takes up energy when it is in excess, your memory for these events also tends to be permanent.

Ask the class if they think adrenalin can affect memory. Does it enhance it or inhibit it? Ask a few students to state what they think and defend why they think so.

Tell students that today they will be investigating how adrenalin works in the body by constructing a model similar to the previous lesson.

Main Part of Lesson

Activity 1: Using Models to Predict

Student Misconceptions Many students believe that an adrenalin rush causes a person’s split-second reaction

to a stressful situation. It is true that adrenalin is released from the adrenal gland the

moment an organism senses a threat or danger. However, a split-second reaction

happens too fast for it to be mediated by the bloodstream and is instead caused by the

sympathetic nervous system. The body releases adrenalin into the bloodstream to

augment the nervous systems response and to signal energy stores to be utilized by

the body – almost like putting the body’s fight-or-flight response into a higher gear.

Show the following video to the class:

http://www.youtube.com/watch?v=OdOOIxcUjAs Ask students: How was this man able to jump out of the way? Students may reply that it was an adrenalin rush. This is a common misconception. Ask students: How does adrenalin travel through the body? bloodstream Do you think that adrenalin could travel throughout your whole body in less than a

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second via the bloodstream? no What is the system in the body that can send signals in less than a second? The nervous system. Therefore, when the man sees the approaching car, the man’s brain sends nerve signals to different parts of the body such as his leg muscles to jump out of the way. So if it is the nervous system that is responsible for this immediate response, where does adrenalin come in? Tell the students that nerve signals are good for this quick reaction. However, in our evolutionary past if a person needed to get out of the way of let’s say a bear, chances were, he still needed to “fight” or “flight” from that bear after the initial reaction. Therefore, the body needs a larger, more longer-lasting boost. Releasing the hormone epinephrine/adrenalin into the bloodstream provides just this boost. Project the image: U7_L3_StartingImage. To provide a foundation for students to begin their models, introduce how epinephrine is released into the bloodstream. Just as insulin is released from the pancreas, epinephrine is released from the adrenal gland. The adrenal gland sits right atop the kidneys. When a person encounters a threatening situation, the brain instantly sends signals to this gland to release epinephrine into the bloodstream. At this point tell the students to get into groups of 3-5. While passing out whiteboards to the students, inform them that they will be creating a model for how adrenalin acts in the body. At first, students will be using their models to predict; they will be constructing an explanation for how they think adrenalin is acting based on prior knowledge of Lesson 1 & 2 and their own prior experience. Next, students will progress through a series of three checkpoints to test their model. The first part of the model is already provided by the teacher through U7_L3_Starting Image illustrating that nerve signals from the brain signal the adrenal gland to release epinephrine into the bloodstream. Encourage students by telling them that they already have the knowledge to construct a fairly accurate model of how adrenalin works without even learning about it specifically. Remind students that they learned about the main components of the endocrine system in Lesson 2 and encourage them to use the diagrams they developed. Additionally, students have knowledge on adrenalin rushes from personal experience, observation, and the initial class discussion. Present the following questions via the projector to reemphasize these points and to facilitate construction of the adrenalin models:

U7_L3_StartingImage

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How can you apply what you learned from the cracker activity (the main steps of the endocrine system) to your adrenalin model?

Does an adrenalin rush give you more energy? If so, where do you think this “boost” of energy comes from?

Reflect on your own experiences: o What happens to your body during an adrenalin rush? Specifically, what organs and tissues

are affected? o Do you think epinephrine is traveling to these tissues/organs?

REMEMBER: At this point you are creating a model to make predictions. This is exactly why scientists create models. They make predictions through observation and from previous scientific knowledge. After using their models to predict, scientists test their models to see if their predictions are supported or not. If not, scientists need to revise their existing model in light of new evidence. You will be testing your model in the second part of this activity. As student groups self-direct their learning, use the time to formatively assess student progress. Be sure to be actively moving about the room posing questions and answering questions from students. Students will be asking you to approve their model before moving from checkpoint to checkpoint, so make sure to efficiently spread your time about the class. Assessment (before moving on to Checkpoint A): Before moving to the first checkpoint, Checkpoint A, student groups must show and discuss their predictive models with the teacher.

Predictive models should include the six main components of the endocrine system along with

two or three tissues/organs that adrenalin may be affecting.

Teacher Pedagogical Content Knowledge It is very helpful to ask students questions in order for them to more accurately

complete missing pieces of their model. For instance, for a student group that draws

adrenalin out in the body on its own ask them, “Does adrenalin just diffuse through the

body? How do hormones travel through the body?” This scaffold will make it likely for

the group to realize that they need to add the bloodstream into their model.

Scientific Practices: Developing and Using Models Active investigation and construction of the adrenalin model follows the dynamic

practice of scientific modeling to reflect the nature of science. Through three

checkpoints, students are given evidence of adrenalin’s actions on the body. It is up to

the students to form a model that holds true to these pieces of evidence, even if this

means revising prior held conceptions of their model.

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Activity 2: Using Models to Test In Activity 1, students will proceed through a series of checkpoints to analyze evidence in order to

support, add to, or revise their model.

Checkpoint A:

Pass out Checkpoint A materials:

U7_L3_CheckpointA_Slides (printed out or presented via computers)

U7_L3_CheckpointA_StudentSheet

Students will compare series of images of two organs/tissues. One of the images shows the

organ/tissue under the influence of epinephrine while the other one shows it under normal

circumstances. Students must decide which image corresponds to the actions of epinephrine. On their

student sheet, students rationalize their answers as to why they think these organ systems are under

the influence of adrenalin.

Before moving onto Checkpoint B:

Students must complete the questions on U7_L3_CheckpointA_StudentSheet.

Ask the students if their model was supported, required additions, or needed revision in light of

new evidence.

At this point, students’ models should include the following:

o Epinephrine traveling to and acting on: the heart, lungs, liver, muscles, intestines, eyes,

and digestive tract. Students should also briefly draw and/or write how these

tissues/organs react to epinephrine.

After all groups are done with Checkpoint A, take a few minutes to discuss with the whole class tissues

that adrenalin is acting on by referencing U7_L3_CheckpointA_StudentSheet_ANSWERS. Most likely

groups will have come to different conclusions for most tissues. Have groups share why they chose one

slide over the other. Be sure to acknowledge that although some groups may have been wrong, they

provided thoughtful solid reasoning. This happens constantly in science, as scientists make inaccurate

predictions that are grounded in good reasoning. It is only through testing our predictions that we come

to a valid explanation.

Checkpoint B:

Pass out the Checkpoint B materials:

U7_L3_CheckpointB_RatMemoryExperiment

U7_L3_CheckpoinB_StudentSheet

Students will read about the effects of epinephrine on memory through the use of a technique called

The Inhibitory Avoidance Task. Students will perform experiments using this task via a computer

simulation later in Lesson 4.

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Before moving onto Checkpoint C:

Students must complete U7_L3_CheckpointB_StudentSheet

Ask the students if their model was supported, required additions, or needed revision in light of

new evidence.

At this point, students’ models should include the following:

o Show that epinephrine is somehow having an action on the brain to enhance memory.

Important: Students will most likely draw epinephrine acting directly on the brain. From

what students have learned about the endocrine system and from the evidence they

have acquired thus far, this is a very reasonable theory. However, in Checkpoint C

students will learn that epinephrine does not act on the brain directly because it cannot

pass the blood-brain-barrier. Therefore, allow them to move onto the next activity even

if they have epinephrine binding to receptors on the brain. Revising their models in

Checkpoint C will further reveal to students how scientific knowledge and scientific

models are subject to change in light of new evidence.

Student Misconceptions Although epinephrine plays a significant and important role in forming memories, it is

not the only reason why we remember events or knowledge. There are many other

factors including other biological factors, past experiences, levels of attention,

repetition of events, etc.

Checkpoint C:

Pass out the Checkpoint C materials:

U7_L3_CheckpointC_WhatATwist!

U7_L3_CheckpointC_StudentSheet

This checkpoint introduces students to the blood-brain-barrier. Students learn that epinephrine cannot

pass the blood brain barrier, but that glucose can. In addition, students are presented with a graph that

reveals that glucose increases memory similarly to epinephrine.

Before completing Checkpoint C to receive the Adrenalin Model Checklist:

Students must complete U7_L3_CheckpointC_StudentSheet

Ask students if their model was supported, required additions, or needed revision in light of new

evidence.

If students have not done so, at this point models should include the following:

o Epinephrine does not enter the brain because it is blocked by the blood-brain barrier.

Epinephrine is able to enhance memory by increasing blood glucose levels. Having more

glucose traveling through the blood to the brain enhances memory formation.

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Final Model Building:

Once students have completed Checkpoint C, pass out the U7_L3_AdrenalinModelChecklist. At this

point, student models should be almost completely accurate. However, to make sure that students

include the major criteria of the model, and to provide repetition on the information students just

analyzed, students should use the checklist to make sure their model is complete. If possible, groups

should keep their whiteboard drawings for Lesson 4. If this is not practical or possible you can use the

U7_L3_Image_AdrenalinDiagram (Located with Lesson 3 materials as well as Lesson 4) for the following

day. You can also project this image during the conclusion of this lesson.

Conclusion of Lesson In the past lesson, students saw that insulin and glucagon were released or not released depending on

the amount of glucose in the blood stream. What is the stimulus for the case of adrenalin? Can our

minds regulate blood glucose? Ask the students to contemplate the evolutionary importance of the

fight-or-flight response.

Why would a system like this have evolved? Why might it be evolutionarily advantageous for

adrenalin to increase memory?

o To protect us from predators and famine.

Why might it be evolutionarily advantageous for adrenalin to increase memory?

o Remembering a life-threatening event would help an organism learn to better avoid a

stressful event or to better act during a stressful event.

It seems like everyone in this room has experienced an adrenalin rush. I doubt many of you

have ever been in danger of a saber-tooth tiger. So then, why do you all still experience

adrenalin rushes? What are the stresses of the twenty-first century?

o We can be startled by a friend or a car coming out of nowhere, or maybe we have

encountered life-threatening events. Also, and important to share with the students,

the human brain is so complex that we turn on the same stress response purely

psychologically. Help students to recognize that although there is no saber-tooth tiger

chasing us today, adrenalin can be released by just our state of mind. For instance,

think about the “nerves” one feels before a performance of giving a speech. The

“butterflies” one feels before a game. The “anxiety” before a first date.

Homework and Assessments Informally assess student learning by observing and questioning how they develop their models.

Student sheets from Checkpoints A, B and C.

Students or student groups should have completed worksheets. Depending on your grading policy you may choose to grade for accuracy or completion.

Final Adrenalin Model

Students should have a completed an adrenalin model that includes all the points asked for in the U7_L3_AdrenalinModelChecklist.

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Additional Information:

Teacher Content Knowledge The fight-or-flight response is mediated by the sympathetic nervous system and the

endocrine system. It is important to understand how these two systems work together.

When a person encounters a dangerous situation, his/her brain will release signals (via

the sympathetic nervous system) to the heart, lungs, adrenal gland, digestive system,

eyes, etc. instantaneously. The body is ready to expend large amounts of energy very

quickly. It is as if a person immediately shifts into “second gear.”

This response is vital for the immediate threat, but chances are, if a human encountered

a fight or a bear in the evolutionary past, he or she would need to deal with this threat

for more than just a few moments. The human body now needs to shift to a “third

gear.” This is where the endocrine system comes in. The same sympathetic nerve

signals that travel to the heart and lungs also travel to the adrenal gland. Adrenalin in

the bloodstream may take a few seconds or about a minute to act everywhere in the

body, but it provides the necessary boost to augment the nerve signals from the

sympathetic nervous system. This augmentation is possible because adrenalin acts on

the same receptors that the sympathetic nervous system acts on via the

neurotransmitter epinephrine (or norepinephrine). In addition, adrenalin also activates

cascade reactions in muscle and liver cells to increase glucose availability.

Adrenalin from the bloodstream augments nervous signals from the brain and increases

glucose availability in the body giving the boost and stamina an organism needs to react

in a fight-or-flight situation.