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Biology > B2.2 The challenges of size > Flashcards

B2.2 The challenges of size Flashcards

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1
Q

What is a surface area to volume ratio?

A

The surface area per unit volume of an object - calculated as a ratio

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2
Q

Why is surface area to volume ratio important?

A

The smaller the organism the larger the SA:V ratio is, nutrients can diffuse directly into the organism quickly enough to sustain life as diffusion distances are small
- larger organism has lower SA:V ratio - most multicellular organisms cant use simple diffusion to survive, as diffusion over a greater distance ant occur fast enough to meet cells demands

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3
Q

Exchange surfaces in larger organisms

A

Larger organisms have developed exchange surfaces, which increase SA:V ratio - e.g. alveoli on lungs, villi of small intestine

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4
Q

What features make an efficient exchange surface?

A
  • large SA - so diffusion happens faster
  • good blood supply - to maintain a steep concentration gradient so molecules can diffuse quicker
  • thin walls - short diffusion distance
  • moist - gases can only diffuse dissolved in solution
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5
Q

Why do we need a transport system?

A
  • once substance have diffused into the body they must be transported to the cells that need them
  • our circulatory system allows materials to travel around our bodies quickly
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6
Q

What is the circulatory system made of?

A

Heart, blood and blood vessels

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7
Q

Is the circulatory system open or closed, and why?

A

Closed - as blood remains within the structures

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8
Q

What does the circulatory system transport, and where?

A
  • oxygen & glucose to the cells that need it

- Carbon dioxide and urea (waste products) away from cells

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9
Q

What is the heart?

A

A pump which circulates blood

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10
Q

What does blood flow away from the heart in?

A

Arteries

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11
Q

What does blood flow towards the heart in?

A

Vein

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12
Q

Where are valves and what do they do?

A

They are in the veins, and prevent back-flow of blood, TMT the blood flow is one-way

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13
Q

is our circulatory system double or single?

A

double - blood flows at low pressure from right side (to lungs) & high pressure from left side (to body)

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14
Q

is the heart a single or double pump?

A

double pump

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15
Q

describe the flow of blood throughout the body (oxygenated / deoxygenated blood - simple)

A
  • deoxygenated pumped from heart to lungs
  • blood receive oxygen - oxygenated blood pumped back to heart to rest of body
  • oxygen leaves blood (for respiration in body) + blood goes back to heart
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16
Q

what is meant by a closed system?

A

blood stays inside blood vessels

17
Q

what is the heart made up of?

A

cardiac tissue

18
Q

what is special about the cardiac muscle?

A

can contract without receiving a nerve impulse from brain and don’t get tired easily (like other muscles

19
Q

what are the two top chambers of the heart called?

A

atria (sing. atrium)

smaller

20
Q

what are the two bottom chambers of the heart called?

A

ventricles

larger

21
Q

label a heart diagram

A
22
Q

describe the flow of blood through the heart - for oxygenated blood

A

PV,LA,BV,LV,AO,Body

23
Q

describe the flow of blood through the heart - for deoxygenated blood

A

VC,RA,TV,RVPA,Lungs

24
Q

characteristics of arteries

A
  • thick walls
  • small lumen
  • high pressure
  • away from heart - oxygenated blood
25
Q

characteristics of veins

A
  • thin walls
  • large lumen
  • low pressure
  • into heart - deoxygenated blood
26
Q

characteristics of capillaries

A
  • very thin walls - one cell thick- - quicker diffusion for gaseous exchange
  • very small lumen
  • connected arteries to veins
27
Q

what is blood made of?

A

platelets
plasma
red & white blood cells

28
Q

what is plasma?

A
  • pale yellow liquid
  • makes 55% volume of blood
  • over 90% water containing dissolved substances such as - food (glucose +amino acids), wastes (urea +CO2), hormones and antibodies
29
Q

where are red blood cells made?

A

in bone marrow + live for about 4 months

30
Q

what is the role of red blood cells?

A

carry O2 from lungs to organs

31
Q

what are adaptations of red blood cells?

A
  • biconcave disks - larger SA:V ratio - quicker diffusion of O2
  • have lots haemoglobin which carry O2
  • no nucleus - more space for haemoglobin + can carry more O2
32
Q

what are platelets?

A

small fragments of cells - no nucleus - help blood clot at wounds

33
Q

what are white blood cells?

A
  • part of body defence system against pathogens

- have nucleus

34
Q

what are coronary arteries

A
  • supply blood to heart muscle

- wrap around outside of heart - small branches dive into blood

35
Q

what is most of the heart made up of?

A
  • cardiac muscle / tissue

Biology (12 decks)

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