Homeostasis300 Biology

Ms Gibellini

Achievement StandardDemonstrate comprehensive understanding involves linking biological ideas about maintaining a stable internal environment in an animal. This includes at least one of:

a discussion of the significance of the control system in terms of its adaptive advantage

an explanation of the biochemical and/or biophysical processes underpinning the mechanism (such as equilibrium reactions, changes in membrane permeability, metabolic pathways)

an analysis of a specific example of how external and/or internal environmental influences result in a breakdown of the control system.

A control system that maintains a stable internal environment (homeostatic system) refers to those that regulate:

body temperature

blood pressure

osmotic balance

level of blood glucose

levels and balance of respiratory gases in tissues.

The biological ideas related to the control system includes the:

purpose of the system

components of the system

mechanism of the system (how it responds to the normal range of environmental fluctuations, interaction and feedback mechanisms between parts of the system)

potential effect of disruption to the system by internal or external influences.

Environmental influences that result in a breakdown of the control system may be external influences such as extreme environment conditions, disease or infection, drugs or toxins, or internal influences such as genetic conditions or metabolic disorders.

Topic Outline

There are three parts to this assessment:

1. Classroom teaching/learning – Introduction to Homeostasis

2. Student research – Completed at HOME or in STUDY using google doc template, MUST BE finished by 25/8, printed and brought into class on Monday 25/8. (you can share useful websites but MUST complete the main points on your own)

3. Report – in class under test conditions with the use of your printed out research google doc information you will write a report based on a scenario to do with thermoregulation.

NOTE:

Resubmissions are for minor omissions with no extra time for further research or teaching and for those on the boarder of grade boundaries only.

What would your body do in response to these conditions?

http://www.youtube.com/watch?v=QKT47A-LBj4

Homeostasis

Homeostasis - body’s ability to maintain a constant internal environment.

Required for proper functioning of the body because the enzymes that control all metabolic activity essential for life, are very sensitive to changes in their environment.

Thus constant state must be maintained in spite of changing the external environment.

Balancing Act I

The following factors need to be kept in balance:

Body temperature Water (osmotic pressure) Blood sugar Carbon dioxide concentration Oxygen concentration pH Mineral salts

Balancing Act II

www.youtube.com/watch?v=XZxuQo3ylII

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/responses_to_environment/homeostasisact.shtml

What do you know?

Cut and paste the worksheet provided to match up the explanation and the organ responsible

Then draw an arrow to where on the body the organs are found

Controlling Internal Body Conditions

Negative Feedback When a condition in the body changes from the norm, a message is sent to a control

center (usually the brain).  

The Control centers then instructs effectors, such as glands and muscles, to send a response that reverses the change.

Works in the opposite direction to the stimulus hence negative feedback and is process by which homeostasis takes place.

Adaptive Advantage Organisms can adapt to the changing environments and therefore occupy

new/different niches, hence reducing competition

The more advanced an animal’s regulatory systems, the greater its chance of survival with a changing environment = survival of organism

If metabolic processes can continue despite a fluctuating environment, an organism is able to inhabit a wider range of habitats and reproduce more successfully to maintain its population. = survival of species

To Do

Complete workbook pages 117-129

http://www.youtube.com/watch?v=e-3N7w2sWps

Example 1: Regulation of Blood Sugar LevelsPurpose of the system

Ensures body has sufficient energy (glucose is turned into energy via respiration)

The amount of ATP demanded will fluctuate, and therefore the body regulates the availability of glucose to maximise its energy making potential.

Too much or too little glucose can damage the retina and brain cells

Components of the system Pancreas

Islets of Langerhans (pancreatic tissue) contain alpha and beta cells, which secrete the hormones glucagon and insulin

Adrenal Gland Secretes adrenalin and cortisol

Liver

Cell membranes

http://ats.doit.wisc.edu/biology/ap/ho/t3.htm?

Mechanism of the system (how it responds to the normal range of environmental fluctuations, interaction and feedback mechanisms between parts of the system)

Normally:

When you eat, glucose goes into your bloodstream and signals the pancreas to release insulin. This helps the glucose move into the cells and gives them needed energy.

Low Blood Sugar:

Alpha cells detect low blood glucose and respond by secreting the hormone glucagon.

Glucagon tells the body and liver cells to break down glycogen to glucose (glycogenolysis)

Glucose is then released into the blood stream and transported around the body to where it is required.

A process called gluconeogenesis also takes place in the liver and this makes new glucose molecules from molecules other than carbohydrates, for use in the body.

Lipolysis also contributes to increasing the blood glucose level. By the breakdown of fat (adipose tissue) from body stores into glucose.

High Blood Glucose:

Beta cells detect high blood glucose levels and secrete the hormone insulin.

Cell membranes respond to insulin by becoming more permeable to glucose, thus glucose is absorbed into the body cells.

The liver also converts glucose to glycogen (glycogenesis).

Insulin stimulates the conversion of glucose to fat in adipose tissue (lipogenesis).

Insulin also converts excess glucose into protein via protein synthesis.

Low Sugar

High Sugar

High Sugar

Potential effect of disruption to the system by internal or external influences.

Factors that Affect Glucose Levels: Alcohol - prevents your body from being able to control your blood sugar

as well as it should. When you drink your liver, pancreas and kidneys are inhibited from processing blood sugar properly.

Exercise – lowers blood sugars Diet – increased carbohydrates increases levels of glucose in the body Time of day – glucose levels increase prior to waking – dawn effect Sickness and Ill health – increases glucose levels BMI – body mass index – heavier you are the slower the body processes

glucose Diabetes – pancreas doesn’t make insulin or body doesn’t process insulin

sufficiently to reduce glucose levels in the blood

Effects of disruption to Glucose Levels:

Hyperglycemia

Higher than the normal blood Glucose eg above 110 mg/dL

Overly or excessively thirsty.

urinating more often than usual.

tired, and losing weight without trying.

yeast or fungal infections.

Late symptoms of prolonged, elevated blood sugar levels are blurred vision and possibly numbness in your fingers and toes.

Severely high levels of blood sugar may cause confusion or a coma

Hyperglycemia

glucose falls below 72 mg/dl

Shakiness, anxiety, nervousness

Palpitations, tachycardia

Sweating, feeling of warmth

Pallor, coldness, clamminess

Dilated pupils (mydriasis)

•.

Adaptive advantage of being able to regulate glucose levels:

Increases animals chances of survival as more efficient bodies and more energy results in a fitter organism

Our body’s primary source of energy is glucose. All of our cells use it, and when there is not enough glucose available, our body shuts down in a similar way that a car engine stops when the gasoline tank is empty.

When glucose is properly utilized, our cells produce energy efficiently and our bodies work like a well oiled machine!

Enables animals to maintain bodies during feast and famine situations

Excess glucose can be stored as fat for later use

Fat can be turned into glucose for use when food is scarce

To do

Workbook pages 138-151

Example 2: OsmoregulationWater is continually being lost from the body in a variety of ways, sweat and urine. When water is lost from any of the body fluids, dissolved solutes become more concentrated and water is less concentrated - this creates high osmotic pressure. When water content increases and solutes are less concentrated this creates low osmotic pressure.

Changes in osmotic pressure will stimulate responses in the body to ensure water levels are maintained in optimum amounts.

Purpose of the system

Body relies upon a constant fluid level to ensure metabolic reactions within cells can proceed

Gases, nutrients, ions, hormones and wastes are carried in body fluids

Components of the system

Hypothalamus

Kidneys

Nerves

Pituitary Gland

Mechanism of the system (how it responds to the normal range of environmental fluctuations, interaction and feedback mechanisms between parts of the system)

Potential effect of disruption to the system by internal or external influences.

Hyponatremia

too much water

potentially fatal disturbance in brain functions

Marathon runners are susceptible to water intoxication if they drink too much while running.

Dehydration

People who ignore thirst during exercise, or who do not drink fluids properly while working out, often become dehydrated because of a physical lack of replacement fluids.

Another example of dehydration can occur when temperature become too high

Blood thickens and becomes harder to pump around the body

Body over heats as cannot cool itself by sweating and heat stroke can occur

Adaptive advantage of being able to regulate water levels:

Can survive in range of temperatures and water levels increases chances of survival and niche differentiation

To Do

Workbook pages 134-137

Thermoregulation

http://www.youtube.com/watch?v=dJ8WXpsUXYQ

http://www.youtube.com/watch?v=wbWp6VgGYdE

Thermoregulation – The Basics

Temperature is regulated by the hypothalamus via the blood

Body temperature is affected by the external environment, amount of exercise (respiring muscles create more heat), BMI, illness, hydration

Changes in blood temperature result in a NEGATIVE FEEDBACK RESPONSE

Basics of Temperature Regulation

Too Hot? Nervous impulses send

messages: to the sweat glands which start

to sweat in order to lower the body temperature through evaporation,

blood vessels dilate to lose heat through conduction

breathing rate increases (brings more cooler air into body)

Muscles relax lowering skin hairs letting more air flow across skin to lose heat by convection and evaporation

No shivering

Too Hot? If this is ineffective at cooling the body goes into a HYPERTHERMIC

STATE Resulting in heat exhaustion 37’C – 39’C Resulting in heat stroke over 39’C Often dehydration also occurs at the same time

Signs: Red skin, sweating, fever, diorientation

Treatment: Cooling blood and constricting blood vessels by submersing body in ice

water Stretch body out to increase surface area in contact with cool air Move into shade Remove clothing

Too Cold? Nervous impulses send messages: to the sweat glands which stop any sweating

blood vessels constrict to prevent the loss of heat through conduction

Blood circulates near core and away from extremities

breathing rate decreases

Glands secrete adrenaline and thyroxin to increase metabolic rate

metabolic rate increases (reactions usually create heat)

Muscles shiver – respiration creates heat and friction

Muscles contract to make hairs stand up and trap warm air against the skin

Too Cold?

If this is ineffective at heating the body goes into a HYPOTHERMIC STATE When core body temperature drops below 35’C

Metabolic activity slows

Signs: Shivering, skin looks blue (especially lips)

Slowing of heart rate, breathing rate, blood pressure decreases

Confusion, difficulty walking

Frost bite, chill blains

Treatment Shelter, more dry clothing, warm drinks – not alcohol

Hot water bottle

To Do

Complete workbook pages 130-134

Internal Assessment Requirements a description of the purpose and components of this homeostatic control system,

which may include annotated diagrams or models

an explanation of the mechanism of this control system, i.e. how and why it responds to the normal range of environmental fluctuations, the interaction and feedback mechanisms between parts of the system

How they work together

an explanation of how balance is re-established following the potential effect of one specific disruption to this control system by internal or external influences in the scenario below (Student Resource A), e.g. extreme environmental conditions, disease or infection, drugs or toxins, genetic conditions, or metabolic disorders.

a discussion of the significance of this control system in terms of its adaptive advantage

an explanation of the biochemical and/or biophysical processes underpinning the mechanism of this control system, e.g. equilibrium reactions, changes in membrane permeability, metabolic pathways

an analysis of a specific example of how external and/or internal environmental influences, e.g. extreme environmental conditions, disease or infection, drugs or toxins, genetic conditions, or metabolic disorders, may result in a breakdown of this control system.

Bibliography

A bibliography is an alphabetical list of all sources

you consult or use for projects, reports, research,

etc., including– books magazines newspapers CD-ROMs websites interviews encyclopaedias video clips images (pictures)

Why do we need a bibliography?

To acknowledge our sources show where we found the informationTo give our readers information to identify and consult our sourcesTo make sure our information is accurateTo show academic honesty

Cheating

This is called plagiarism (using another person’s words, pictures or ideas without giving them credit).

To avoid plagiarism, we give credit to our sources by citing them in our bibliography.

Paraphrasing

Learn to borrow from a source without plagiarizing.

A paraphrase is... your own rendition of essential information and ideas expressed by

someone else, presented in a new form. one legitimate way (when accompanied by accurate documentation) to

borrow from a source. a more detailed restatement than a summary, which focuses concisely

on a single main idea.

Paraphrasing is a valuable skill because... it is better than quoting information from an undistinguished passage. it helps you control the temptation to quote too much. the mental process required for successful paraphrasing helps you to

grasp the full meaning of the original.

6 Steps to Effective Paraphrasing

1. Reread the original passage until you understand its full meaning.

2. Set the original aside, and write your paraphrase on a note card.

3. Jot down a few words below your paraphrase to remind you later how you envision using this material. At the top of the note card, write a key word or phrase to indicate the subject of your paraphrase.

4. Check your rendition with the original to make sure that your version accurately expresses all the essential information in a new form.

5. Use quotation marks to identify any unique term or phraseology you have borrowed exactly from the source.

6. Record the source (including the page) on your note card so that you can credit it easily if you decide to incorporate the material into your paper.

Example of Paraphrasing The original passage:

Students frequently overuse direct quotation in taking notes, and as a result they overuse quotations in the final [research] paper. Probably only about 10% of your final manuscript should appear as directly quoted matter. Therefore, you should strive to limit the amount of exact transcribing of source materials while taking notes. Lester, James D. Writing Research Papers. 2nd ed. (1976): 46-47.

A legitimate paraphrase:

In research papers students often quote excessively, failing to keep quoted material down to a desirable level. Since the problem usually originates during note taking, it is essential to minimize the material recorded verbatim (Lester 46-47).

An acceptable summary:

Students should take just a few notes in direct quotation from sources to help minimize the amount of quoted material in a research paper (Lester 46-47).

A plagiarized version:

Students often use too many direct quotations when they take notes, resulting in too many of them in the final research paper. In fact, probably only about 10% of the final copy should consist of directly quoted material. So it is important to limit the amount of source material copied while taking notes.

ExercisesDirections: On a separate piece of paper, write a paraphrase of each of the following passages. Try not to look back at the original passage.

1. "The Antarctic is the vast source of cold on our planet, just as the sun is the source of our heat, and it exerts tremendous control on our climate," [Jacques] Cousteau told the camera. "The cold ocean water around Antarctica flows north to mix with warmer water from the tropics, and its upwellings help to cool both the surface water and our atmosphere. Yet the fragility of this regulating system is now threatened by human activity." From "Captain Cousteau," Audubon (May 1990):17.

2. The twenties were the years when drinking was against the law, and the law was a bad joke because everyone knew of a local bar where liquor could be had. They were the years when organized crime ruled the cities, and the police seemed powerless to do anything against it. Classical music was forgotten while jazz spread throughout the land, and men like Bix Beiderbecke, Louis Armstrong, and Count Basie became the heroes of the young. The flapper was born in the twenties, and with her bobbed hair and short skirts, she symbolized, perhaps more than anyone or anything else, America's break with the past. From Kathleen Yancey, English 102 Supplemental Guide (1989): 25.

3. Of the more than 1000 bicycling deaths each year, three-fourths are caused by head injuries. Half of those killed are school-age children. One study concluded that wearing a bike helmet can reduce the risk of head injury by 85 percent. In an accident, a bike helmet absorbs the shock and cushions the head. From "Bike Helmets: Unused Lifesavers," Consumer Reports (May 1990): 348.

4. Matisse is the best painter ever at putting the viewer at the scene. He's the most realistic of all modern artists, if you admit the feel of the breeze as necessary to a landscape and the smell of oranges as essential to a still life. "The Casbah Gate" depicts the well-known gateway Bab el Aassa, which pierces the southern wall of the city near the sultan's palace. With scrubby coats of ivory, aqua, blue, and rose delicately fenced by the liveliest gray outline in art history, Matisse gets the essence of a Tangier afternoon, including the subtle presence of the bowaab, the sentry who sits and surveys those who pass through the gate. From Peter Plagens, "Bright Lights." Newsweek (26 March 1990): 50.

5. While the Sears Tower is arguably the greatest achievement in skyscraper engineering so far, it's unlikely that architects and engineers have abandoned the quest for the world's tallest building. The question is: Just how high can a building go? Structural engineer William LeMessurier has designed a skyscraper nearly one-half mile high, twice as tall as the Sears Tower. And architect Robert Sobel claims that existing technology could produce a 500-story building. From Ron Bachman, "Reaching for the Sky." Dial (May 1990): 15.

Now What?

Now you have a basic understanding of Homeostasis and have seen two examples of the type of information you need to find and explain.

Next you need to go to the wiki and complete the rest of the pre learning activities, while you do these you need to be filling in the research table in google docs

Any questions not completed after completing the wiki prelearning you will need to go and find the answers to on your own

Print off the completed google table and bring it to class

Use your notes to complete the report write up based on a scenario on thermoregulation