Scientific Communication Assignment | Online Homework Help

Describe heat production changes during exercise.

Scientific Communication Task 3
Relating evidence to ideas – background knowledge
Background
In the process of energy production by cells, glucose (or sugar) is broken down. Approximately 40% of the energy from the breakdown of glucose is used to power the functions carried out by cells, tissues and organs, including the contraction of skeletal muscles during exercise. The remaining 60% of energy released is given off as heat. During exercise, the rapid and frequent contraction of skeletal muscles can increase heat production 20 times more than resting levels.
It is well known that intense exercise causes heart rate to increase. Part of the increase in heart rate is due to the role played by the cardiovascular system in a negative feedback mechanism used to remove the extra heat generated during exercise. The hypothalamus sends a signal via the sympathetic nervous system that stimulates blood vessels in the skin to dilate, so heat can be more easily lost to the external environment. But the dilation of blood vessels in the skin reduces the amount of blood returning to the heart. Since less blood is returning to the heart, the heart pumps out less blood with each heartbeat causing blood pressure to drop. As blood pressure drops, the amount of blood reaching the skin decreases, compromising the effectiveness of this heat loss mechanism. To compensate for the drop in blood pressure, a second negative feedback mechanism comes into play: the medulla oblongata (part of the brain stem) senses the drop in blood pressure and sends a signal to the heart via the sympathetic nervous system to increase the speed at which it beats. By increasing heart rate, the body is able to maintain a constant blood pressure and ensures a sufficient flow of blood to the skin so the extra heat generated during exercise can be lost from the body.
Section 1 – Describe the accepted scientific explanation behind the concept being tested
Heat production during exercise
Metabolic heat production increases many-fold during exercise. Heat production by dynamically contracting human skeletal muscle increases abruptly and markedly at the onset of dynamic exercise, increases further at a lower rate during the early stages of exercise and eventually plateaus if exercise is of a steady-state nature. When exercise is intense, however, heat production does not level off.
From the journal article: Human thermoregulation and the cardiovascular system, by González-Alonso, (2012), p.340.
Integumentary system and thermoregulation
If the body becomes excessively warm due to high temperatures, vigorous activity, or a combination of the two, sweat glands will be stimulated by the sympathetic nervous system to produce large amounts of sweat. When the sweat evaporates from the skin surface, the body is cooled as body heat is dissipated.
In addition to sweating, arterioles in the dermis dilate so that excess heat carried by the blood can dissipate through the skin and into the surrounding environment. This accounts for the skin redness that many people experience when exercising.
Modified from the eBook: Anatomy and Physiology, by Openstax (2017), pp.198-199.
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Process of thermoregulation
Figure A. Integrated model of thermoregulation (modified from Kuht and Farmery, 2018, fig. 2, p.508).
Modified from the journal article: Body temperature and its regulation, by Kuht and Farmery (2018), p.508.
A list of ‘Key Terms’ and their meanings have been provided on page 4 to assist you with your paraphrasing for Section 1.
NOTE: The ‘Key Terms’ do not have to be put into your own words.
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Section 3 – Explain the results given in Figure 1 on page 1 of this assignment
Why sweating cools us down
Have you ever wondered why we sweat when our environment is hot or when we exercise? Sweating is a life-saving strategy that cools the body down and maintains its temperature. Without sweating, the body cannot regulate its temperature, which can lead to overheating or even heatstroke. But why does sweating have a cooling effect? The answer is evaporative cooling. Turning a liquid such as sweat from its liquid state into a gas requires energy. This energy is taken from our body, or sweat, in the form of heat. The resulting heat transfer leads to the desired cooling effect.
The process of changing a liquid into its gaseous state is called evaporation. Every liquid can be turned into a gas if enough energy is added to the liquid in the form of heat. The energy needed for the transformation is known as the heat of evaporation. How much energy you need depends on factors such as the type of liquid or the surrounding temperature. If it is already very hot outside, you will need less energy to vaporize a liquid; if it is very cold, you will need more.
From the web page: Chilling science: evaporative cooling with liquids, by Lohner (2017).
Why vasodilation cools us down
Radiation. Like water flowing downhill, heat naturally moves from warm areas to cooler ones. As long as the air around you is cooler than your body, you radiate heat to the air. But this transfer stops when the air temperature approaches body temperature.
Radiation requires rerouting blood flow so more of it goes to the skin. This makes the heart beat faster and pump harder. On a hot day, it may circulate two to four times as much blood each minute as it does on a cool day.
From the blog post: Heat is hard on the heart; simple precautions can ease the strain, by Harvard Health Publishing Staff (2019). A list of ‘Key Terms’ and their meanings have been provided on page 4 to assist you with your paraphrasing for Section 3.
NOTE: The ‘Key Terms’ do not have to be put into your own words.
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Key terms
To assist you with completing Sections 1 and 3 of this assignment we have provided you with a list of scientific terms and their meanings. You will need to look up the meaning of any terms not covered here that you are unfamiliar with.
NOTE: The ‘Key Terms’ do not have to be put into your own words.
Arterioles – smallest type of artery that leads into capillary beds.
Cerebral cortex – part of the brain where thought and decision making occurs.
Circadian rhythm – 24 hour cycle the body operates to.
Core temperature – temperature of 36.5-37.5°C found in the tissues and organs of the body.
Dermis – lower layer of tissue that makes up the skin.
Dynamic exercise – exercise that involves movement of joints.
Evaporation – transfer of heat from the body by conversion of water in sweat to a gas.
Heatstroke – condition in which core temperature rises to 40°C or higher.
Hypothalamus – small region of the brain responsible for regulating body temperature.
Integumentary system – skin and associated structures such as hair and nails that protect the body.
Metabolism – the chemical reactions that take place in the body to maintain life.
Negative feedback – homeostatic control mechanism that returns a variable to its set point by cancelling out a stimulus.
Ovulation – release of an egg from the ovaries during the menstrual cycle.
Pyrogens – chemicals released by white blood cells and damaged cells during illness that cause a fever.
Radiation – transfer of heat from the body to the surrounding environment via infrared waves.
Receptors – specialised nerves that detect changes in the environment inside and outside the body.
Set point – the normal level a variable, such as core body temperature, is maintained at using negative feedback.
Skeletal muscle – one of the three types of muscle tissue found in the body which is under voluntary control.
Somatic nerves – branch or division of the motor nerves that carries signals from the brain to the skeletal muscles.
Sympathetic nerves – branch or division of the autonomic nervous system that regulates the ‘fight or flight’ response.
Sweat glands – glands in the skin that produce and secrete sweat onto the surface of the skin.
Thermoregulation – process of regulating core body temperature.
Vaporize – convert something into a vapour.
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Referencing
Using the details of the sources below, develop a correctly formatted APA-style reference list for Scientific Communication Task 3. The details below have not been formatted according to the CDU APA Referencing Style. For detailed information on referencing refer to learning materials for Week 6, Chapter 5 in your textbook for TEP022 and the CDU APA 7th Referencing Style Guide.
NOTE THAT IF YOU DO NOT INCLUDE ADEQUATE REFERENCING IN SCIENTIFIC COMMUNICATION TASK 3, BOTH IN-TEXT AND AS A REFERENCE LIST, YOU WILL BE ASKED TO RESUBMIT YOUR ASSIGNMENT AND YOUR ASSIGNMENT WILL BE MARKED ON A PASS/FAIL BASIS ONLY.
Reference type
Web page
Authors
Svenja Lohner
Year
September 14th, 2017
Article title Chilling science: evaporative cooling with liquids
Publisher
Scientific American
Where can you find this web page?
https://www.scientificamerican.com/article/chilling-science-evaporative-cooling-with-liquids/
Reference type
ebook
Authors
Openstax
Year
2017
Article title
Anatomy and physiology
Where can you find this ebook?
https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
Reference type
Journal article
Authors
Kuht, J. & Farmery, A.D.
Year
2018
Article title
Body temperature and its regulation
Pages
507-512
Journal title
Anaesthesia & Intensive Care Medicine
Issue
Vol 19, Issue 9
doi
https://doi.org/10.1016/j.mpaic.2018.06.003
Where can you find this journal article?
This journal article can be found using “Library Search” on the CDU Library website: http://cdu.edu.au/library/
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