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7/30/2019 B3 Powerpoint

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BIOLOGY Movement of molecules

Transport systems Homeostasis

Humans and their environment


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Sports Drinks If water and ions are not replaced, the ion / water

balance of the body is disturbed and the cells donot work as efficiently.

Sports drinks contain:

- Sugars to replace the sugar used in energy releaseduring the activity.- Water and mineral ions to replace the water and

ions lost during sweating.

Most soft drinks containwater, sugar and ions.


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Exchange Surfaces

Gas and solute exchange surfaces in organisms areadapted maximise effectiveness.The effectiveness of an exchange surface is increased by:

having a large surface area being thin to provide a short diffusion path (in animals) having an efficient blood supply and

ventilation to maintain a steep concentration gradient

The size and complexity of an organism increases thedifficulty of exchanging materials.


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Exchange Systems in Plants


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Carbon dioxide enters leaves by diffusion Most of the water and mineral ions are absorbed by the roots The surface area of the roots is increased by root hairs The surface area of leaves is increased by their long and thin shape

In plants:


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Plants have stomata to obtain carbon dioxide from the atmosphere an to removeoxygen produced in photosynthesis.

Plants mainly lose water vapour from their leaves, predominantly through thestomata.

Evaporation is more rapid in hot, dry, and windy conditions.

If plants lose water faster than its replaced by the roots, the stomata can close toprevent wilting.

Stomata


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Transport Systems in Plants Flowering plants have separate transport systems:

Phloem tissue carries dissolved sugars from the leaves to the rest of the plant,including the growing regions and storage organs

Xylem tissue transports water and mineral ions, from the roots to the stem andleaves

The movement of water from the roots through the xylem and out of the leaves iscalled the transpiration streams


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The Lungs


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The Lungs

The lungs are in the upper part of thebody (thorax), protected by the ribcageand separated from the lower part of the body (abdomen) by the diaphragm/The breathing system takes air into andout of the body so that oxygen fromthe can diffuse into the bloodstreamand carbon dioxide can diffuse out of

the bloodstream into the air.

GaseousExchange Inhalation Exhalation


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Artificial BreathingAids

Positive and NegativeBreathing Pressure

The Iron Lung: Negative Breathing Pressure

Created originally for polio suffers would were paralysed and unable to breath Patients lay in a metallic cylinder which covers their whole body other than their head, with a tight seal around the neck Air is pumped out of the chamber , lowering the pressure inside creating a vacuum like atmosphere This causes the patients chest wall to move up, this increases the volume and decreases the pressure inside the chest The vacuum then switches off automatically meaning air moves back inside the chamber, increasing the pressure The ribs move down, lowering the volume and increasing the pressure inside the chest (Thorax) This forces the air out the lungs

Positive Breathing Pressure A ventilator forces a carefully measured breath of air into your lungs under a positive pressure Once the lungs have been inflated the air pressure stops The lungs deflate and the ribs move down forcing air out the lungs It can be administered by a simple face masks or a tube going into the trachea In emergency, it is a bag held and squeezed by doctor/nurse

Benefits Positive pressure aids keep patients alive during major surgery Both can keep paralysed people alive for years Positive pressure aids have been simplified for use at home Positive pressure aids allow movement Positive pressure aids can be operated by hand in an emergency Negative pressure aids are non intrusive Negative pressure aids are more like normal breathing

TheLungs


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Body Adaptations forExchanging

Substances In humans:- the surface area of the lungs

is increased by the alveoli- the surface area of the small intestine

is increased by villi. The villi provide a:

- large surface area , through folds and microvilli - an extensive network of capillaries to

absorb the products of digestion bydiffusion and active transport .

- short diffusion path as microvilli are onecell thick .


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The Heart BloodBlood is a tissue and consists of a fluid called plasma in which red blood cells , white blood cells ,and platelets are suspended.

Blood plasma transports: Carbon dioxide from the organs to the lungs Soluble products of digestion from the small intestine to other organs Urea from the liver to the kidneys

Red blood cells transport oxygen from the lungs to the organs. have no nucleus are bioconcave contain a red pigment called haemoglobin

White blood cells have a nucleus form part of the bodys defence system againstmicroorganisms

Platelets have no nucleus are small fragments of cells

have proteinous threads that help blood to clot


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The Heart Blood


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The Heart Blood


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The Heart Blood

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The Heart The HeartThe heart is a muscular organ that pumps blood around the body.

The Passage of Blood around the Body Blood enters the atria of the heart. The atria contract and force blood into the ventricles. The ventricles contract and force blood out of the heart Valves in the heart ensure that blood flows in the correct

direction. Blood flows from the heart to the organs through arteries

and returns through veins. There are two separate circulation systems One for the lungs, and one for all other organs of the body.

There are four main chambers of theheart: Left Atria Right Atria

Left Ventricle Right Ventricle

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The Heart The Heart

Bl d V l


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The Heart Blood VesselsBlood is carried through one of three vessels: arteries , veins , or capillaries

Arteries Arteries have thick walls containing muscle and

elastic fibres. If arteries begin to narrow and restrict blood flow

stents are used to keep them open. They carry blood out of the heart and into the lungs. In general, arteries carry oxygenated blood.

The exception to this rule is the pulmonary artery, whichcarries deoxygenated blood from the heart to the lungs.

Veins Veins have thinner walls than arteries and often

have valves to prevent back-flow of blood. Valves can be replaced artificially. They carry blood into the heart and out of the lungs. In general, veins carry deoxygenated blood. The exception to this rule is the pulmonary vein, whichcarries oxygenated blood from the lungs to the heart.

Capillaries In the organs, blood flows through very narrow,

thin-walled blood vessels called capillaries. Substances needed by the cells in body tissues

pass out of the blood through the capillary walls. Substances produced by the cells pass into

the blood, through the walls of the capillaries.


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Temperature Control Body temperature is monitored and controlled by the thermoregulatory centre in the brain. This centre has receptors sensitive to the temperature of the blood flowing through the brain.

Temperature receptors in the skin send impulses to the thermoregulatory centre, givinginformation about skin temperature.

If the core bodytemperature is too high :

blood vessels supplyingthe skin capillariesdilate so that more bloodflows through thecapillaries and more heat islost sweat glands releasemore sweat whichcools the body as itevaporates. Hair on the skin lies flat toallow hot air to escape

If the core bodytemperature is too low :

blood vessels supplyingthe skin capillariesconstrict to reduce theflow of blood throughthe capillaries

muscles may shiver their contraction needs

respiration, whichreleases some energyto warm the body.

Hair stands on end to trap air and insulatethe skin


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Removal of Waste

Waste products that have to be removed fromthe body include:

Carbon Dioxide : produced by respiration andremoved via the lungs when we breathe out

Urea : produced in the liver by the breakdownof amino acids and removed by the kidneys inthe urine , which is temporarily stored in thebladder .


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The Kidneys If the water or ion content of the body is wrong, too much

water may move into or out of the cells and damage them . Water and ions enter the body when we eat and drink, and

leave the body through the urine produced by the kidneys.

People who suffer from kidney failure may be treated either byusing a kidney dialysis machine or by having a healthy kidney

transplanted .


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Dialysis Treatment by dialysis restores the concentrations of dissolved substances in the

blood to normal levels

Dialysis has to be carried out at regular intervals. In a dialysis machine a persons blood flows between partially permeable

membranes. The dialysis fluid contains the same concentration of useful substances as the

blood.This ensures that glucose and useful mineral ions are not lost. Urea passes outfrom the blood into the dialysis fluid.


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Kidney Transplants In kidney transplants a diseased kidney is replaced with a healthy one from

a donor. However, the donor kidney may be rejected by the immune system unless

precautions are taken. Antigens are proteins on the surface of cells. The recipients antibodies may attack the antigens on the donor organ as

they do not recognise them as part of the recipients body. To prevent rejection of the transplanted kidney:

- a donor kidney with a tissue -type similar to that of the recipient is used - the recipient is treated with drugs that suppress the immune system.


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Sugar Control The blood glucose concentration of the body is monitored and regulated by the

pancreas . The pancreas produces the hormone insulin , which allows the glucose to move from the

blood into the cells. A second hormone, glucagon, is produced in the pancreas when blood glucose levels

fall.Glucagon causes glycogen to be converted into glucose and be released into the blood.


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DiabetesDiabetes is a disease in which a persons blood glucose concentration may riseto a high level because the pancreas does not produce enough of the hormone

insulin.

Type 1 diabetes may be controlled or cured by:- pancreas transplant- transplanting pancreatic cells- injecting artificially harvested insulin.

Type 2 diabetes may becontrolled by- careful attention to diet- exercise- injecting insulin.

Treatment Advantages Disadvantages

Pancreas Transplant Permanent cureDoesnt require insulin

injections

Not always availableRequires

immunosuppressantsTransplantingpancreatic cells

Theoretical permanentcureDoesnt need insulininjections

Hasnt been successfulso far

Injecting insulin Unlimited supplyNo match needed Not a permanent cure


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Sustainable Water SourcesHumans need water to survive. Many places find themselves landlocked, with nosanitary and reliable water source.For this reason, dams are built. Dams, and the resevoirs they create, supply largepopulations with a reliable water supply.However, they can cause many problems, including:

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