Homeostasis300 Biology

2015

Ms Gibellini

Introduction Videos

http://www.johnwiley.net.au/highered/interactions/media/Energy/content/Energy/met6a/frameset.htm

http://www.physiologycentre.com/thermoregulation-student.html

Homeostasis

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

Required for proper functioning of the body because the ______________ 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 ____________________________.

Balancing Act

The following factors need to be kept in balance:

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

Negative Feedback When a condition in the body changes from the norm, a

__________is sent to a control center (usually the _____________ in the brain).

The control center then instructs _____________ (_________________) to respond and _____________ the change.

The control center then _________________ a change in temperature as a result of the ________________, it then sends a message to _______________ the response or stop it all together if temperatures have returned to ______________

Works in the ______________ direction to the stimulus hence _________________,

eg you are hot from running, so brain tells your body to sweat to cool you down. Once you are cool your brain tells your body to stop or slow down sweating.

Negative Feedback Loop

Adaptive Advantage

Organisms can _________to the changing environments and therefore occupy ___________________, hence reducing ______________

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

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

Why Regulate Heat?

Chemical reactions occurring in cells are very ___________

_____________ that control cellular activity are heat-sensitive

Many _________________can only function properly if they float freely in the lipid bilayer, which is only possible if it is liquid; at low temperature the bilayer ___________.

At around 85ºC, the ________________holding the two strands of __________ together break, causing it to become single stranded.

Why Regulate Heat

Enables mammals to successfully live in a wider variety of habitats – reduces ______________________

Always ready for _____________; can be active at a variety of times of day and night

  Their __________ capacity is many times that of

cold blooded animals

Not greatly affected by __________temperatures.

  Muscles provide ___________ power; capable of

sustained high activity.

How We Lose and Gain Heat

Body temperature is affected by the ____________, amount of _________ (____________________________), BMI, illness, hydration, ______________

Heat can be gained or lost from any place where the body is in ______________ with the environment (skin and lungs)

Heat can be gained or lost by: Conduction Convection Radiation Evaporation

How is Temperature Monitored?

The _______________ in the brain monitors the temperature of the __________ flowing through it

This is called the _____________________as it is sensing temperature at the _______ of the body.

The hypothalamus receives information regarding changes in external temperature from __________________

There are two types of receptors, hot and cold.

______________relay the messages to and from receptors and the hypothalamus and effector cells

Too Hot?

Nervous impulses send messages:to the _____________ glands which start to sweat in

order to lower the body temperature through evaporation,

______________to lose heat through conduction breathing rate ____________(brings more cooler air

into body) ____________lowering skin hairs letting more air flow

across skin to lose heat by convection and evaporation -

No ___________Behavioral responsesMetabolic rate __________

SweatingWhen you are hot, ________________are stimulated to

release sweat.

Heat energy from your skin is used to turn the liquid sweat into gas - sweat ______________

Because heat is lost, your___________ cools down as does the _________ flowing past

Deep in the dermis are supplied by sympathetic nerve fibres.

In humans most sweat glands are eccrine glands and secrete a dilute salt solution.

Sweat doesn’t work in a humid environmentEnvironmental temperature > body temp for sweating to be

effective

Vasodilation Your blood carries most of the heat energy in your body.

There are small blood vessels called ___________ just underneath your skin.

When you are hot, these capillaries get___________(dilate) so more blood comes close to the surface of the skin and heat is lost.

This is why some people go _________when they are hot!

If the temperature rises, the blood vessel dilates (gets bigger).

This means more heat is lost from the surface of the skin

Metabolic Rate

The ___________________changes through a reduction in the secretion of thyroxine

This results in a ____________ in metabolic rate The decrease in metabolic rate causes _____________to be

produced in the body

Behavioural Responses

We change our behavioural responses by:

_____________(decreasing activity)staying in the shade_______________________wearing less clothing________________Submerging body in cold water_____________________Fanning ourselves

Chicks seek shade.

When the system fails… If the body cannot lower its temperature it goes into a _____________

STATE Resulting in heat exhaustion ______________ Resulting in heat stroke over _____________ Often dehydration also occurs at the same time

________________Red skin, no sweating, fever, disorientation, pinpoint pupils,

shallow breathing

_______________ 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 Give cold fluids Ice packs/wet towels

Fever

This is usually associated with _______________. The immune system produces fever-inducing chemicals

called _____________, which travel through the blood to the hypothalamus, where they trick it into raising the body temperature.

________________________lower temperature by blocking the production of pyrogens.

Apply cold wet clothes Remove clothing Seek medical care to treat infection – antibiotics for

bacterial infections

If left un treated person can have ___________________________.

High Temp

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Thermoregulation in endotherms

Endotherms generate most of their heat metabolically. As they are warmer than their environment they tend to lose body heat to their surroundings.

Adaptations for heat conservation include:

Insulation – insulating layers of fat, fur or feathers to prevent heat loss.

Metabolism – metabolic rate can be varied to generate more or less heat.

Endotherms also use their skin to vary their rate of heat loss and maintain a constant core body temperature.

Too Cold?

Nervous impulses send messages:to the sweat glands which stop any

_______________ blood vessels _____________ to prevent

the loss of heat through ______________Blood circulates _____________and away

from extremitiesbreathing rate ______________Glands secrete adrenaline and thyroxin

to ____________ metabolic ratemetabolic rate increases (reactions

usually ________________)Muscles _______________ – respiration

creates heat and frictionMuscles contract to make _____________

stand up and trap warm air against the skin

Vasoconstriction This is basically the opposite of ____________________

When you are cold, the capillaries near the surface of your skin get _______________(constrict) and some shut off.

This means _____________comes near the surface of the skin and less heat is lost.

This is why your fingers and toes might go ____________ when they are cold! is controlled by the sympathetic nervous system decreases blood flow to the skin from internal organs, which

decreases the transfer of heat from the internal body organs to the skin

allows less heat to be lost from the body surface

cools the skin

VasodilationVasoconstrictionCold day Hot day

Frostbite The blood vessels in the skin _____________in very cold conditions to

preserve heat. If this is prolonged it ____________the cells peripheral tissue of nutrient

and heat. When nerve cells stop working no signals get sent to the brain, the fingers and toes go numb.

If this happens for a short time it can be reversed. If it happens for longer the ___________________i.e. frostbite

Metabolism The _____________________stimulates the adrenal medulla via

sympathetic nerves The ____________ secretes adrenaline and noradrenaline into the blood This increases ________________, increasing heat production This process helps maintain internal body temperature

Shivering

Shivering is actually __________________________occurring at a rate of around ten to twenty per second

The ______________________ stimulates parts of the brain that increase skeletal muscle tone

This increases body _________________________

Piloerection

When you are cold, small muscles in the skin are activated making the_____________on your skin stand up.

The hairs trap a layer of air next to the skin, which is warmed by body heat and becomes an ______________________preventing air flow to the skin and slows heat loss

This is sometimes called ‘_______________or ‘ piloerection’

Skin

Hairs

Trapped air forms insulation

hair lies flat on the skin

the muscle is relaxed

hair stands up and a goose bump appears

the muscle contracts

body temperature normal

body temperature falls

Behavioural Responses

We change our behavioural responses by: __________________ curling into a ball putting on more ____________ using a heating device Eating/drinking ____________________ Exercising to create heat Moving out of cold – __________________

Conserving heat

When the system fails… If this is ineffective at heating the body goes into a

________________________ When core body temperature drops below __________ Metabolic activity ______________

_______________ Shivering, skin looks blue (especially lips) Slowing of heart rate, breathing rate, blood pressure

decreases Confusion, difficulty walking Frost bite, chill blains

_________________ Shelter, more dry clothing, warm drinks – not alcohol Hot water bottle, foil blanket, hot bath It is important that the return to normal temperature occurs

slowly and from the core out If left untreated ______________ occurs

Basics of Temperature Regulation

Effector Response to low temperature Response to high temperatureSmooth muscles in peripheral arterioles in the skin.

Muscles contract causing vasoconstriction. Less heat is carried from the core to the surface of the body, maintaining core temperature. Extremities can turn blue and feel cold and can even be damaged (frostbite).

 

Muscles relax causing vasodilation. More heat is carried from the core to the surface, where it is lost by convection and radiation. Skin turns red.

Sweat glands No sweat produced. Glands secrete sweat onto surface of skin, where it evaporates. This is an endothermic process and water has a high latent heat of evaporation, so it takes heat from the body.

 

Erector pili muscles in skin(attached to skin hairs)

Muscles contract, raising skin hairs and trapping an insulating layer of still, warm air next to the skin. Not very effective in humans, just causing “goosebumps”.

 

Muscles relax, lowering the skin hairs and allowing air to circulate over the skin, encouraging convection and evaporation.

 

Skeletal muscles Muscles contract and relax repeatedly, generating heat by friction and from metabolic reactions.

 

No shivering.

Adrenal and thyroid glands

Glands secrete adrenaline and thyroxine respectively, which increase the metabolic rate in different tissues, especially the liver, so generating heat.

 

Glands stop releasing adrenaline and thyroxine.

Behaviour Curling up, huddling, finding shelter, putting on more clothes.

 

Stretching out, finding shade, swimming, removing clothes.

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Physiological thermoregulation

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.

Now What? Now you have a basic understanding of thermoregulation

Next you need to go to the moodle 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 moodle 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

Make a bibliography of your references, print it off along with any diagrams you want to use and bring them to class

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