Science Nct 4

8/8/2019 Science Nct 4

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TransportationTransportation

ofofsubstancessubstances

ininanimalsanimalsandand

plantsplants


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heartheart

Theheart is a myogenic muscular organ found in all animals wit

hT

heheart is a myogenic muscular organ found in all animals wit

ha circulatory system (including all vertebrates), that is responsiblea circulatory system (including all vertebrates), that is responsible

for pumping blood throughout the blood vessels by repeated,for pumping blood throughout the blood vessels by repeated,rhythmic contractions.rhythmic contractions.

The vertebrate heart is composed of cardiac muscle, which is anThe vertebrate heart is composed of cardiac muscle, which is aninvoluntary striated muscle tissue found only in this organ, andinvoluntary striated muscle tissue found only in this organ, andconnective tissue. The average human heart, beating at 72 beatsconnective tissue. The average human heart, beating at 72 beats

per minute, will beat approximately 2.5 billion times during anper minute, will beat approximately 2.5 billion times during anaverage 66 year lifespan, and weighs approximately 250 to 300average 66 year lifespan, and weighs approximately 250 to 300grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz)grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz)in males.[1]in males.[1]

In invertebrates that possess a circulatory system, the heart isIn invertebrates that possess a circulatory system, the heart istypically a tube or small sac and pumps fluid that contains watertypically a tube or small sac and pumps fluid that contains waterand nutrients such as proteins, fats, and sugars.and nutrients such as proteins, fats, and sugars.


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ArteriesArteries


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AboutArteriesAboutArteries

THEY CARRY BLOOD AWAY FROM THETHEY CARRY BLOOD AWAY FROM THEHEARTHEART

THEYARE THICKTHEYARE THICK WALLED TUBESWALLED TUBES THEYARE DEEPLY PLACED UNDER THETHEYARE DEEPLY PLACED UNDER THE

SKIN AND BLOOD MOVES UNDER HIGHSKIN AND BLOOD MOVES UNDER HIGHPRESSUREPRESSURE

THERE ARE NO VALVES INSIDE ARTRIESTHERE ARE NO VALVES INSIDE ARTRIES


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VEINSVEINS


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ABOUT VEINSABOUT VEINS

Arteries are tough, elastic tubes that carryArteries are tough, elastic tubes that carryblood away from the heart. As the arteriesblood away from the heart. As the arteriesmove away from the heart, they dividemove away from the heart, they divide

into smaller vessels. The largest arteriesinto smaller vessels. The largest arteriesare about as thick as a thumb. Theare about as thick as a thumb. Thesmallest arteries are thinner than hair.smallest arteries are thinner than hair.These thinner arteries are calledThese thinner arteries are calledarterioles. Arteries carry bright red blood!arterioles. Arteries carry bright red blood!The color comes from theThe color comes from the oxygenoxygen that itthat itcarries.carries.


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EXCRETRY SYSTEMEXCRETRY SYSTEM


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ABOUT EXCRETRY SYSTEMABOUT EXCRETRY SYSTEM

TheThe excretory systemexcretory system is a passive biological systemis a passive biological systemthat removes excess, unnecessary or dangerousthat removes excess, unnecessary or dangerousmaterials from an organism, so as to help maintainmaterials from an organism, so as to help maintainhomeostasishomeostasis within the organism and prevent damage towithin the organism and prevent damage to

the body. It is responsible for the elimination of thethe body. It is responsible for the elimination of thewaste productswaste products ofofmetabolismmetabolism as well as other liquid andas well as other liquid andgaseous wastes. As mosthealthy functioninggaseous wastes. As mosthealthy functioning organsorgansproduce metabolic and other wastes, the entireproduce metabolic and other wastes, the entire organismorganismdepends on the function of the system; however, onlydepends on the function of the system; however, only

the organs specifically for the excretion process arethe organs specifically for the excretion process areconsidered a part of the excretory system.considered a part of the excretory system.

As it involves several functions that are only superficiallyAs it involves several functions that are only superficiallyrelated, it is not usually used in more formalrelated, it is not usually used in more formalclassifications of anatomy or function.classifications of anatomy or function.


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CAPILLARIESCAPILLARIES


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ABOUT CAPILLARIESABOUT CAPILLARIES

Blood flows from the heart to theBlood flows from the heart to the arteriesarteries, which branch, which branchand narrow into theand narrow into the arteriolesarterioles, and then branch further, and then branch furtherstill into the capillaries. After the tissue has beenstill into the capillaries. After the tissue has beenperfused, capillaries join and widen to become venulesperfused, capillaries join and widen to become venules

and th

en widen more to becomeand th

en widen more to become veinsveins, wh

ich

return, wh

ich

returnblood to the heart.blood to the heart. Capillaries do not function on their own. The "capillaryCapillaries do not function on their own. The "capillary

bed" is an interweaving network of capillaries supplyingbed" is an interweaving network of capillaries supplyinganan organorgan. The more. The more metabolicallymetabolically active the cells, theactive the cells, themore capillaries they will require to supply nutrients andmore capillaries they will require to supply nutrients and

carry away waste products.carry away waste products. A capillary bed can consist of two types of vessels: trueA capillary bed can consist of two types of vessels: true

capillaries which branch mainly from metarterioles andcapillaries which branch mainly from metarterioles andprovide exchange between cells and the circulation.provide exchange between cells and the circulation.Secondly, capillary beds also consists of a vascular shuntSecondly, capillary beds also consists of a vascular shunt

wh

ich

is a sh

ort vessel th

at directly connects th

ewh

ich

is a sh

ort vessel th

at directly connects th

earteriole and venule at opposite ends of the bed.arteriole and venule at opposite ends of the bed.


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XYLEM AND PHLOEMXYLEM AND PHLOEM


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ABOUT XYLEMABOUT XYLEM

The xylem is responsible for the transport ofThe xylem is responsible for the transport ofwater and soluble mineral nutrients from thewater and soluble mineral nutrients from theroots throughout the plant. It is also used toroots throughout the plant. It is also used to

replace water lost during transpiration andreplace water lost during transpiration andphotosynthesis. Xylemphotosynthesis. Xylem sapsap consists mainly ofconsists mainly ofwater and inorganic ions, although it can containwater and inorganic ions, although it can containa number of organic chemicals as well. Thisa number of organic chemicals as well. Thistransport is not powered by energy spent by thetransport is not powered by energy spent by thetrachearytracheary elements themselves, which are deadelements themselves, which are deadby maturity and no longer have living contents.by maturity and no longer have living contents.Two phenomena cause xylem sap to flow:Two phenomena cause xylem sap to flow:


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ABOUT PHLOEMABOUT PHLOEM

UnlikeUnlike xylemxylem (which is composed primarily of dead(which is composed primarily of deadcells), the phloem is composed of stillcells), the phloem is composed of still--living cells thatliving cells thattransporttransportsapsap. The sap is a water. The sap is a water--based solution, butbased solution, but

rich

inrich

in sugarssugars made by the p

hotosynt

hetic areas.made by t

he p

hotosynt

hetic areas.These sugars are transported to nonThese sugars are transported to non--photosyntheticphotosynthetic

parts of the plant, such as the roots, or into storageparts of the plant, such as the roots, or into storagestructures, such asstructures, such as tuberstubers or bulbs.or bulbs.

Th

eTh

eP

ressure flow hypothesisP

ressure flow hypothesis was ah

ypoth

esiswas ah

ypoth

esisproposed byproposed by Ernst MunchErnst Munch in 1930 that explained thein 1930 that explained themechanism of phloem translocationmechanism of phloem translocation[2][2]. Ahigh. Ahighconcentration of organic substance insideconcentration of organic substance inside cellscells of theof thephloem at a source, such as aphloem at a source, such as a leafleaf, creates a, creates a diffusiondiffusion

gradientgradientthat draws water into the cellsthat draws water into the cells


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Science Nct 4

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