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Biology 315 > C7 Organisms > Flashcards

C7 Organisms Flashcards

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1
Q

multicellular

A

organisms with multiple cells
- have levels of organisation (cells, tissues, organs, organ systems)
- cells are specialised to perform specific funtions that sustain life + maintain homeostasis

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2
Q

unicellular

A

organisms that are only one cell
- includes bacteria and protozoa
- must perform all necessary functions within one cell
- are very adapted to suit their environment (relies on and is vulnerable to it)

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3
Q

levels of organisation

A
  • cell: basic unit of life
  • tissue: a group of specialised cells that work to serve a specific function
  • organ: structure made up of different tissues that have a specific function
  • system: a collection of organs that perform a function in the body
  • organism: entire being
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4
Q

Outline the advantages of multicellularity.

A

increased efficiency
- ‘division of labour’ - the functions of an organism are distributed amongst specialised cells, which perform a specific function = efficient

longer life spans
- death of some cells does not kill the organism
- more cells = less stress and vulnerability
- the immune systems protects the body and fights infection

dead cells can have function
- surface cells on organisms are mostly dead
- they provide support, protection and tools to body (horns, hooves, nails, xylem in plants)

evolution and intelligence
- greater genetic diversity within species - sexual reproduction, bringing more adaptations and resistance to change
- the organisms can develop a higher level of learning

size
- organisms can grow large
- larger brain = increased intelligence
- increased mobility
- reduce chance of being prey

smaller cell size
- tend to have smaller cells compared to unicellular organisms
- due to SA:V ratio, this provides them with greater efficiency (energy, nutrients etc)

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5
Q

Outline the disadvantages of being multicellular.

A

energy use and waste
- more energy is required to supply to all cells
- increased energy consumption = more waste
- waste may be difficult to eliminate and cause toxicity
- organisms spend more time eating/searching for food for energy

maturity and reproduction
- a more complex structure means organisms take longer to reach maturity
- offspring development takes longer due to the complex genetic makeup

infection
- the more complex/significant the cells of an organism are, the more likely to be attacked by pathogens
- the organism is ideal to be used for food, habitat, energy

systems
- if one organ system fails, they potentially all can = failure of entire body

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6
Q

ingestion

A

food is taken in through the mouth

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7
Q

digestion

A

food molecules are broken down (mouth, stomach, small intestine)

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8
Q

absorption

A

the products of digestion are absorbed across the gut wall (into the bloodstream)

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9
Q

egestion

A

unwanted material is eliminated (defecation)

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10
Q

alimentary canal

A
  • human gut
  • includes ALL the organs that the food passes through (esophagus, stomach, intestines etc)
  • 9m long
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11
Q

accessory organs

A

organs not part of the alimentary canal but play a key role in digestion (gall bladder, pancreas, liver, salivary glands)

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12
Q

mechanical digestion

A

the breakdown of food via mechanical processes
- chewing, churning, contractions

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13
Q

chemical digestion

A

the breakdown of food via chemical processes
- stomach acids, bile, enzymes

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14
Q

mouth

A
  • mechanical digestion
  • tongue: moves food around in mouth
  • teeth: breaks down food
  • work to turn food into a bolus
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15
Q

bolus

A

mushed up ball of food created by mouth (tongue + teeth)

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16
Q

salivary glands

A
  • chemical digestion
  • produce saliva
  • has enzymes that break down food (amylase)
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17
Q

epiglottis

A

flap at top of larynx to prevent food entering the lungs

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18
Q

oesophagus

A
  • mechanical digestion
  • food pushed down into the stomach via muscular contractions (contract/relax), forces bolus down (peristalis)
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19
Q

peristalis

A

the contractions that force a bolus down the oesophagus

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20
Q

stomach

A
  • muscular bag with a valve at each end (cardiac sphincter: top, pyloric sphincter: bottom)

Mechanical
- churning turns bolus into chyme (slurry)
Chemical
- secretes pepsin for protein digestion
- secretes HCl (kills bacteria: immune system, provides optimum pH for pepsin)

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21
Q

HCl

A
  • hydrochloric acid is produced by the stomach
  • chemical defense in the immune system as it kills bacteria
  • provides an optimum (acidic -pH2) for pepsin
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22
Q

chyme

A

mushed up food slurry produced by the stomach

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23
Q

gastric glands

A
  • glands in stomach lining
  • have mucus-secreting cells
  • mucus protects from the acidity of the stomach HCl
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24
Q

cardiac sphincter

A

valve at the top of the stomach
- cardiac = closer to heart
- allows entry of food

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25
Q

pyloric sphincter

A

valve at bottom of stomach
- allows exit of food

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26
Q

accessory organ

A

organs that are not part of the actual digestive tract, but play an important role in digestion

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27
Q

liver

A
  • accessory organ
  • secretes bile (basic/alkali)
  • this neutralises the acidic chyme from the stomach (HCl) before it enters the small intestine
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28
Q

bile

A

fluid secreted by the liver
- basic/alkali
- neutralises the acidic chyme before it moves into the small intestine

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29
Q

emulsification

A

a process in which bile breaks down lipids into smaller droplets
- allows a larger surface area for lipids so that enzymes can break them down

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30
Q

gall bladder

A
  • accessory organ
  • stores bile and releases it when needed
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31
Q

pancreas

A
  • accessory organ
  • produces and releases digestive enzymes into the intestines (lipase, phospholipase, esterase)
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32
Q

small intestine

A

functions to absorb nutrients from chyme
- secretes enzymes from intestinal wall
- receives enzymes from pancreas
- food molecules are absorbed through intestinal wall

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33
Q

Describe how the small intestine’s structure aids its function.

A

HIGH SA
- small intestine is long (6m)
- inner surface is highly folded (villi + microvilli)
= massive surface area: efficient absorption of nutrients

THIN WALL
- villi wall is only 1 cell thick
- allows efficient absorption of nutrients via diffusion

GOOD BLOOD SUPPLY
- each villus supplied with blood vessels which receive: glucose/AAs/vitamins/minerals - absorbed into blood capillaries, lipds - absorbed into lacteal (lymphatic capillary)

OTHER
- many channel/pump proteins for rapid absorption
- many mitochondria provide sufficient ATP for active transport
- blood capillaries are close to the epithelial (intestine lining) for efficient absorption via diffusion

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34
Q

villi + microvilli

A

present in small intestine
- villi: finger-like projections off intestinal cells
- microvilli: hair-like projections off villi
- increase SA

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35
Q

large intestine

A

final part of intestine (the thicker part that wraps around), functions to:
- reabsorb water + mineral ions (sodium, chlorine)
- forms + temporarily stores faeces
- maintains a pop. of good bacteria
- ferments indigestible materials

  • food then travels through the colon, then exits via anus
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36
Q

incisors
- describe the differences between carnivores, herbivores and omnivores

A

8 front teeth
- cutting/ripping off food

CARN: sharp, pointed, to cut off meat
HERB: small, chisel shaped, to cut through plants
OMNI: wide, chisel shaped, cut up variety of food

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37
Q

canines
- describe the differences between carnivores, herbivores and omnivores

A

teeth next to incisors
- sharper, pointed
- similar to incisors: ripping/tearing food

CARN: large, sharp, pointed, gripping + killing prey
HERB: none
OMNI: sharp, pointed, biting + tearing

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38
Q

molars/premolars
- describe the differences between carnivores, herbivores and omnivores

A

12 teeth at back of mouth

CARN: carnassials (specialised molars), tearing meat
HERB: broad, flat, rough, increase SA to grind plants
OMNI: broad, flat, grind variety of food

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39
Q

carnassials

A

carnivores (a defining feature)
- specialised molars
- sharp, serrated, narrow
- move like scissors, slot together
- cut/slice meat

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40
Q

diastema

A

herbivores (a defining feature)
- the gap/spacing between incisors and molars
- provides room for food to move around
- provides different angles for chewing
- temporary plant storage in cheeks

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41
Q

Describe the need for digestion within the body.

A
  • the body needs to break down food to nutrients the (useable form) that can be absorbed
  • digestion makes use of the micromolecules of food, to make macromolecules
  • plants do not need it (phs)
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42
Q

Summarise the types of digestion within the body.

A

MECHANICAL
Chewing: mouth
- teeth (grinding)
- tongue (pushing)
Churning: stomach
- muscles squeeze + mix food
- turns to chyme
- enters small intestine
- nutrients absorbed

CHEMICAL
Stomach acids
- acidic environment denatures proteins
- breaks down molecules
Bile
- released by liver, stored in gallbladder
- emulsifies lipids
Enzymes
- decrease activation energy to aid in catalysing/breaking down molecules
- most secreted by the pancreas
- have an ideal pH

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43
Q

Explain the role of enzymes in digestion.

A

work to break down large food molecules
- speed up digestion by lowering the activation energy required for reactions
- work at body temperature (37°)
- majority are secreted from the pancreas (some from liver, salivary gland, stomach, small intestine)

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44
Q

amylase (role in digestion)

A

1.
Made in: salivary glands
Works in: mouth
Role: breaks starches into disaccharides

2
Made in: pancreas
Works in: small intestine
Role: continues starch breakdown

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45
Q

proteases e.g. pepsin (role in digestion)

A

Made in: stomach
Works in: stomach
Role: breaks proteins into peptides

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46
Q

bile (role in digestion)

A

Made in: liver (stored gall bladder)
Works in: small intestine
Role: breaks fats into fatty acids

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47
Q

trypsin (role in digestion)

A

Made in: pancreas
Works in: small intestine
Role: continues protein breakdown

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48
Q

lipase (role in digestion)

A

Made in: pancreas
Works in: small intestine
Role: breaks fats into fatty acids

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49
Q

maltose, sucrose, lactase (role in digestion)

A

Made in: small intestine
Works in: small intestine
Role: breaks remaining disaccharides into monosaccharides (glucose)

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50
Q

peptidase (role in digestion)

A

Made in: small intestine
Works in: small intestine
Role: breaks dipeptides into AAs

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51
Q

Describe the role of enzymes in carb digestion.

A
  • amylase, in mouth (from salivary glands) breaks starches into disaccharides
  • amylase, in small intestine (from pancreas) breaks starches into disaccharides
  • maltose, sucrose, lactase, in small intestine (from small intestine) breaks disaccharides into monosaccharides (glucose)
  • in humans: cellulose passes through undigested (no cellulase enzyme present)
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52
Q

Explain why there needs to be two regions that produce amylase.

A
  • produced in salivary glands to break down carbs
  • once the food enters the stomach, HCl (very acidic, low pH) causes the enzyme to denature
  • therefore amylase must be produced again by pancreas + released into small intestine, in order to continue carb breakdown
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53
Q

Describe the role of enzymes in lipid digestion.

A
  • bile, in intestines (from liver/gall bladder) emulsifies fat, breaks down to smaller droplets
  • lipase, in intestines (from pancreas) in small intestine breaks down fat to fatty acid chains and glycerol
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54
Q

Describe the role of enzymes in protein digestion.

A
  • proteases (e.g. pepsin), in stomach (from stomach) break proteins into polypeptide chains
  • trypsin, in small intestine (from pancreas) in neutral pH 7 environment, breaks PP chains to dipeptides
  • peptidase, in small intestine (from small intestine) breaks dipeptides into AAs
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55
Q

Describe the general trend of digestive systems within vertebrates.

A

the more complex the diet, the more complex the digestive system (more breaking down required)

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56
Q

Describe the role of enzymes in nucleic acid digestion.

A
  • nucleases in intestines (from pancreas) digest nucleic acids into nucleotides
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57
Q

State the 3 ‘points of comparison/difference’ between the types of digestive systems in vertebrates.

A
  1. stomach(s)
  2. system length/size
  3. caecum (size/present/absent)
58
Q

Describe the elements of monogastric digestive system.

A
  • single chambered stomach
  • enzymes, bile and gastric juices break down food
  • carnivores + scavengers, most omnivores, some herbivores
59
Q

Describe the structure of a carnivore’s digestive system and how it relates to it’s function.

A
  • monogastric

short, simple digestive tract
- digestion of meat (protein) is easy and fast
- scavengers: tract even shorter to avoid a bacterial infection from meat

no or very small caecum
- in carnivores it is used for the breakdown of mineral salts/water
- not used for plant matter breakdown, therefore they don’t need to have many bacteria/a large caecum

60
Q

Provide some examples of animals that have a monogastric digestive system.

A

Carnivores, humans, horses, rabbits and pigs

61
Q

Describe the elements of a ruminant digestive system.

A
  • foregut fermenters
  • 4 chambered stomach: very large, 70% of tract volume
  • cows, sheep, goats, kangaroos

Rumen
- first, large, stomach chamber
- contains bacteria to break down plant cellulose

Massive stomach size + length
- a high SA increases time that bacteria can break down dense, cellulose-rich food

62
Q

Describe the elements of a avian digestive system.

A
  • 2-chambered stomach
  • no teeth but a beak

specialised bird organs
- crop: an organ for food storage
- gizzard: an organ for breakdown of seeds, grains etc

63
Q

Birds have which type of digestive system, which special organs to aid digestion, with how many stomachs?

A

avian system, with two stomachs
- crop, for storing food
- gizzard, for breakdown of grainy foods

64
Q

foregut fermenter

A
  • ruminant herbivores
  • digestion mainly occurs in the first part of the digestive tract
65
Q

Carnivores, humans, horses, rabbits and pigs all have which type of digestive system with how many stomachs?

A

monogastric system, with one stomach

66
Q

Cows, sheep, goats and kangaroos have which type of digestive system, with how many stomachs?

A

ruminant system, with 4 stomachs

67
Q

Describe the elements of a non-ruminant herbivore digestive system.

A
  • hindgut fermenters
  • monogastric (1 stomach)

Caecum
- VERY large, at start of large intestine
- contains many bacteria to ferment dense, cellulose-rich food

Large digestive tract
- increases SA, increasing time that bacteria can break down and absorb plant cellulose

68
Q

hindgut fermenters

A
  • non-ruminant herbivores
  • digestion mainly occurs in the last part of the digestive tract
69
Q

Describe the elements of a pseudo-ruminant digestive system.

A
  • 3 chambered stomach
  • large caecum
70
Q

Rabbits, koalas and horses have which type of digestive system, with how many stomachs?

A

non-ruminant herbivore system (hindgut fermenters), with monogastric (1 chamber) stomach

71
Q

Why is gas exchange in organisms important?

A
  • cellular respiration
  • input of O2 in to cells, and output of CO2 out of cells
  • this constant demand for cellular respiration requires gas exchange
72
Q

gas exchange

A

the movement of gases from a high to low concentration (diffusion)

73
Q

Outline the factors affecting gas exchange and their relationship.

A

SURFACE AREA
- larger SA = higher rate of GE (proportional)
- with a larger SA, there is more area for particles to diffuse through = faster movement

TEMP
- higher temp = higher rate of GE (proportional)
- with a higher temp there is more KE = faster particle movement

CONC GRADIENT
- larger conc gradient = higher rate of GE (proportional)
- diffusion occurs down a conc gradient (high to low), therefore the greater the diff between concs = higher rate of GE

DIFFUSION DISTANCE
- larger diffusion distance = lower rate of GE (inverse)
- larger distance means slower movement of particles to diffuse through cells

74
Q

Outline the common features of gas exchange surfaces in different organisms.

A
  • high SA
  • diffusion distance is thin (approx 1 cell thick)
  • highly vascularised (lots of blood vessels to carry O2)
  • moist (gases must dissolve into H2O to diffuse across the membrane)
75
Q

Outline the three elements that the structure/type of an vertebrate’s gas exchange surface depends on.

A
  • metabolic demand (less demand = smaller/ less complex system)
  • size of organism (smaller/less complex = smaller system)
  • external enviro (live in water/air - will need a specific system)
76
Q

State the 4 types of gas exchange surface in vertebrates, providing examples.

A
  • across membrane/skin/outer surface (protists, amphibians, aquatic species)
  • tracheae (insects, arthropods)
  • gills (fish, sharks, rays)
  • lungs/alveoli (birds, reptiles, mammals - humans)
77
Q

Describe the gas exchange structure of through a skin/membrane.

A

no specialised structures for gas exchange, gases are exchanged across the skin/outer/membrane surface

78
Q

Describe the gas exchange structure of tracheae.

A
  • openings/holes in skin
  • tracheae tubes lead inwards, extending into the circulatory system
  • they distribute gases throughout the body (a network of tubes)
79
Q

Describe the gas exchange structure of gills (structure to function)

A

HIGH SA
- thin feather like projections, with further projections (lamellae)
- need to spread out to work, this occurs when in water
= greater area for diffusion to occur

GOOD BLOOD SUPPLY
- there are dense capillary beds on the lamellae
- allow efficient exchange of substances between water and blood

COUNTERCURRENT FLOW
- blood flows in the opposite direction to the water
- this maintains a favourable conc gradient (there is more O2 in the water and it moves in, more CO2 in the blood moves out)
= constant diffusion

80
Q

Describe the gas exchange structure of lungs/alveoli.

A
  • air is taken in via breathing and goes to alveoli in the lungs
  • these tiny air sacs exchange O2 and CO2 with the bloodstream
81
Q

Describe the advantages and disadvantages of gas exchange using air.

A

PROS
- air has a higher concentration of oxygen than water
- O2 and CO2 diffuse faster = resp systems exposed to air are not required to have as much ventilation
- air is lighter = easier ventilation
= more efficient to sustain GE

CONS
- there is high water loss in order to keep the resp system moist

82
Q

Describe the structure of the lungs (how gas exchange occurs).

A
  • air enters via nose/mouth: moistens and warms air, nose filters

passes through:

TRACHEA
- cilia capture dust and pathogens
- C rings hold structure of the trachea and prevent crushing

BRONCHUS
- the two divisions from the trachea

BRONCHIOLES
- further divisions

ALVEOLI
- site of GE
- tiny air sacs at ends of bronchioles

= these structures increase surface area of the lungs for efficient gas exchange

83
Q

Describe the structure of an alveoli and how it relates to its function.

A

O2 IN: (air goes to lungs, to alveoli, and is diffused to the blood)
CO2 OUT: (is a product of CR, goes from cells to alveoli, is breathed out)

STRUCTURE
- good blood supply (dense capillary bed, allows efficient exchange of gases between blood
- very thin, 1 cell thick (short diffusion distance for gases, which maintains a constant conc gradient)
- high SA:V (millions of microscopic alveoli, allowing larger surface for GE to occur)

84
Q

Outline how the concentrations of gases change from when air is taken in to when it is taken out.

A

air breathed out has:
- more CO2
- less O2
- equal N
- more water vapour and is warmer (moist from the lungs)

85
Q

Outline the needs of a plant for survival (4) and how these enter, exit and move around the organism.

A

H2O
- absorbed (with minerals) from roots
- transported to leaves for Phs
- lost through evapotranspiration

SUGAR
- produced via Phs
- transported and used around the plant and it’s roots

O2
- absorbed from soil via roots
- used for CR
- released as Phs waste via leaves (stomata)

CO2
- absorbed via leaves (stomata)
- used for Phs
- released via roots

86
Q

vascular tissues/bundles

A

specialised for transporting substances to all areas of a plant. They contain:
- Xylem (transport water and nutrients)
- Phloem (transport sugars)

87
Q

Describe the structure of xylem and how it relates to its function.

A

FUNCTION: transpiration - transport of water (+ nutrients), upwards to sites of Phs (leaves/shoots)

water movement: UNI-DIRECTIONAL (one way)
- H2O movement from roots-leaves
- water evaporates, creating an evaporative pull, pulling H2O molecules up, creating a transpiration stream (regulated by guard cells and stomata)

STRUCTURE
- xylem cells are dead, made from lignin (cellulose)
- have a strong structure
- they are hollow with no plate/sieve between cells
- narrow + small to maintain adhesion/cohesion forces

88
Q

State the factors affecting transpiration (4) and their relationship.

A

TEMP: proportional (increase in temp = increase in transpiration)

LIGHT INTENSITY: proportional (increase in light = increase in transpiration)

AIR FLOW: proportional (increase in air flow = increase in transpiration)

HUMIDITY: inverse (increase in humidity = decrease in transpiration)
- this is due to the conc gradient of water inside vs outside the leaf

89
Q

Describe the structure of phloem and how it relates to its function.

A

FUNCTION: translocation, transport of sugars to all parts of a plant

movement: SOURCE-SINK (not one way)
- sugars move from source (where it is made) to sink (where sugar is needed)
- driven by ATP

STRUCTURE
- sieve plates: end walls of cell have pores, allow for flow of sugars between cells and maintain correct pressure to assist with transport from high-low pressure of the sugar
- companion cells: provide the energy needed for sieve cells
- filled with cytoplasm, a small + large vacuole: for transport of sugars, no other organelles

  • through sieve cells, the concentration gradient is mantained for facilitated diffusion
  • in leaves, the sucrose mixes with water to form sap, which is driven by osmosis
90
Q

Describe how sugar moves through a plant

A

from source to sink
- source: leaves, where it is made via Phs
- sink: storage (roots), or used (for growth)

91
Q

Describe the structure of a leaf in relation to it’s function in gas exchange.

A

FUNCTION
- perform Phs to produce glucose needed for CR (needs O2)

STRUCTURE: stomata
Function: open/close for gas exchange (CO2 in, O2 out)

Structure:
- guard cells respond based on water availability
- if water abundant: vacuoles fill, cell will swell (turgid), stomata will open
- if water limited: vacuoles empty, cell will shrivel (flaccid), stomata will close

  • guard cells are sensitive to light: will close at night when no light to drive Phs
  • they are only present on the underneath of leaves: reducing water loss as is more shaded
92
Q

Describe the two types of water absorption that occur via the roots.

A

ACTIVE (symplastic pathway)
- water moves between cytoplasm/vacuoles of adjacent cells

PASSIVE (apoplastic pathway)
- water moves from cell wall to cell wall of adjacent cells, does not enter the cytoplasm

93
Q

Why do we need a transport system?

A
  • O2, H2O, glucose, and nutrients are needed for metabolic processes
  • diffusion is too slow for multicellular organisms to transport these to all cells in their body
  • a transport system is fast, increases SA, and carries to all cells
  • the complexity of the system depends on the complexity and SA of the organism (smaller size = less energy demand)
94
Q

Outline the 7 major functions of blood as a medium.

A

MAIN FUNCTION: blood provides transport and is a link between cells and body systems
- transports O2 and nutrients to all cells
- transport CO2 and waste products out of cells and the body
- transports hormones (chemical messengers) to cells
- maintains the pH of bodily fluids (many reactions occuring in the body must be stabilised)
- distributes heat and maintains body temp (contraction/expansion of vessels)
- maintains water balance and ion conc in body fluids
- protects against disease/pathogens (white blood cells)

95
Q

Describe the structural components of of blood.

A
  • just over half is comprised of plasma (liquid part)
  • rest is formed elements (suspended in plasma): erthrocytes (red blood cells), leurocytes (white blood cells), thrombocytes (platelets)
96
Q

Describe the function of plasma within the blood.

A
  • a yellowy fluid, blood components are suspended within it
  • responsible for the transport of: CO2, glucose, AAs, vitamins, minerals, hormones, waste materials
97
Q

Describe the structure of a red blood cell and how it relates to its function.

A
  • erthrocytes
  • bi concave disc: increases SA for O2, thicker edges store more haemoglobin
  • no nucleus: more room for haemoglobin
  • flexible: to squeeze through small capillaries without breaking
98
Q

Describe how O2 is transported within the body.

A
  • not very soluable in water: majority of it is carried within haemoglobin, not water
  • haemoglobin and oxygen bond to form oxyhaemglobin: this bond is weak and easily reversible, allowing O2 to release when needed
99
Q

Describe how CO2 is transported within the body.

A
  • small amount dissolved in plasma and carried as a solution
  • some combined with the globin part of haemoglobin
  • majority is carried in plasma as bicarbonate ions
100
Q

Describe how nutrients and waste are transported within the body.

A

NUTRIENTS
- inorganic: carried as ions (e.g. Na, Cl)
- organic: dissolved into plasma

WASTES
- metabolic wastes (produced by cells, harmful if accumulated: urea, uric acid, CO2)
- dissolved into plasma

101
Q

Outline the overall structure of the heart.

A
  • a double pump
  • 4 chambers, each pump has 1 atria (top chamber) and 1 ventricle (bottom chamber)
102
Q

Describe the structure of the atria and how it relates to its function.

A

Function: collect blood, from body or lung
Structure:
- thin walled/smaller, as only required for blood collection/draining into the ventricle

103
Q

Describe the function of the ventricle and how it relates to its function.

A

Function: pump blood at higher pressure to lungs and body
Structure: thick walls (more muscular), larger, to pump blood to whole body with force

104
Q

Why are the walls of the left ventricle more muscular than the right ventricle?

A
  • the left ventricle must pump blood to the entire body, which takes a lot of force
  • the right ventricle must only pump blood to the lungs, which is not as far and requires less force
105
Q

What important feature must be noted when looking at a diagram of a heart?

A

The left side of the heart will be on the right side of the diagram (because it is the patient’s left side), and vice versa

106
Q

Describe the cardiac cycle (2 phases)

A
  • 1 cycle is one complete heartbeat (one contraction and one relaxation)

2 phases
SYSTOLE: pumping (heart contracts)
DIASTOLE: filling (heart relaxes

  • each movement out of an atrium/ventricle is a contraction
  • 1-way valves ensure blood doesn’t flow the wrong way
107
Q

Describe the flow of the blood, starting with deoxygenated blood.

A

deoxygenated blood - right atrium - right ventricle - lungs (O2 replenished) - oxygenated blood - left atrium - left ventricle - body (O2 used) - deoxygenated blood

108
Q

vessels

A

tubes for blood transport around the body, including:
- arteries
- veins
- capillaries

109
Q

Describe the structure of arteries and how it relates to their function.

A

FUNCTION
- transport high O2 blood away from the heart to body tissues/organs
- HIGH pressure

STRUCTURE
- narrow lumen (relative to wall thickness): maintains blood flow at high pressure
- thick arterial walls: outer layer contains flexible strong fibres that prevent tearing, another layer of muscle/elastic fibres, contracts/releases to maintain flow and pressure

110
Q

Describe the structure of veins and how it relates to their function.

A

FUNCTION
- transports/collects low O2 blood from body tissues and back to heart/lungs
- LOW pressure

STRUCTURE
- wide lumen (relative to wall thickness): maximises blood flow at low pressure
- thin arterial walls: contain less muscle/elastic fibres, not needed
- one-way valves: prevent backflow of blood/pooling at lower points such as feet

  • flow in veins is driven by skeletal muscle contractions (contractions compress vein, valve opens, blood moves up)
111
Q

Describe the structure of capillaries and how it relates to their function.

A

FUNCTION
- exchange (CO2, O2, nutrients, waste etc) between blood and body cells

STRUCTURE
- very thin: 1 cell thick, low pressure
- small/narrow lumen: only fit 1 red blood cell across

this means that:
- small diffusion distance between blood and capillary, allowing efficient exchange
- SA is increased, allowing longer exposure for cells to exchange substances

  • basement membrane and a permeable outer layer: allow exchange of substances in/out
112
Q

Summarise how blood flows through the body in a cycle, starting at the heart.

A
  • oxygenated, high pressure blood exits heart via aorta from left ventricle
  • arteries
  • arterioles
  • capillaries: materials are exchanged between blood and cells, O2 is used (blood becomes deoxygenated)
  • venuoles
  • veins
  • deoxygenated, low pressure blood enters heart via vena cava
  • right atrium
  • right ventricle: pumped to lungs (becomes oxygenated)
  • left atrium
  • left ventricle
  • exits again via aorta
113
Q

excretion

A

the removal of metabolic wastes from the body
- excretes CO2, ammonia, ions/salts, etc

114
Q

State the organs/components involved in excretion and what they excrete.

A
  • Lungs (breathing): CO2, water
  • Skin (sweat): H2O, ions/salts
  • Liver: converts ammonia to urea

URINARY SYSTEM
- Kidneys: nephrons (filtering + osmoregulation)
- Ureter: connection to-
- Bladder: storage
- Urethra: removal

115
Q

urea
- where is it produced
- how is it transported

A
  • produced in: liver
  • transported in: blood
116
Q

What is the origin of nitrogenous waste products in animals?

A

protein
- excess breaks down into AAs, is converted to ammonia

117
Q

Why do we have to convert ammonia to urea?

A
  • liver converts ammonia to urea using H2O
  • we cannot store proteins like we can with fats/carbs
  • excess AAs are broken down and converted to ammonia
  • it is very toxic, converted to urea which is less toxic, is then excreted from body
118
Q

Why do plants not need an excretory system?

A
  • plants do not have an excessive excretory system
  • vacuoles: store and expel wastes (e.g. contractile vacuole)
  • storage of waste in other places: bark, leaves, fruit, which can be shed/dropped
119
Q

Briefly outline the function of nephrons:
- where are they located?
- what are they for? (2)

A
  • kidneys filter blood via nephrons

FUNCTION
- Selective reabsorption (nephron to blood): needed substances are reabsorbed into the blood
- Secretion (blood to nephron): waste substances are kept in the nephron to be excreted in urine

120
Q

NEPHRONS
Describe the main function and process involved in the components of a nephron:
- bowman’s capsule
- proximal tubule
- loop of henle
- distal tubule
- collecting duct

A

BOWMAN’S CAPSULE: Filtration
- filtering of blood components at high pressure
- filters: glucose, AAs, urea, ions etc into the nephron
- does not filter: lipids, blood cells, proteins
- once filtered, substance is called filtrate

PROXIMAL TUBULE: Selective Reabsorption
- some substances that the body needs are reabsorbed
- 80% of reabsorption occurs here
- all AAs + glucose
- most H2O, ions, bicarb
- Secretion: of some harmful substances into blood (alcohol, drugs, toxins)

LOOP OF HENLE: Osmoregulation
- loop hangs into medulla (in kidneys)
Descending (down) limb:
- medulla is very salty: free water moves into it, is reabsorbed
- has a low permeability to ions
Ascending (up) limb:
- ions are reabsorbed
- low permeability to water

DISTAL TUBULE: Selective Reabsorption
- final reabsorption of substances (H2O, bicarb, ions)
- can be controlled by hormones (ADH for H2O) as needed
- filtrate changes to urine, is more concentrated
- Secretion: of some harmful substances into blood (alcohol, drugs, toxins)

COLLECTING DUCT: Osmoregulation
- is permeable to H2O, but is regulated by ADH (a hormone)
Body is dehydrated:
- hypothalamus detects this
- triggers release of ADH hormone
- permeability to H2O increases
- more H2O is absorbed out of nephron
- urine is more concentrated, has a lesser volume
Body is hydrated:
- less ADH release
- becomes less permeable to H2O
- less H2O absorbed out of nephron
- urine is more diluted, has a greater volume

121
Q

Explain why drinking alcohol results in severe dehydration.

A
  • alcohol blocks the release of ADH hormone
  • body will not reabsorb H2O
  • urine will be diluted, despite body being dehydrated
122
Q

OSMOREGULATION
- why control of water/ions is important
- how they are controlled
- ADH hormone

A

WHY
- Ions: essential, but wrong amounts = cell damage
- Water: too much = lysis, too little = cells become flaccid

CONTROLLED
- mainly controlled by kidneys (nephrons)
- some ions/water by sweat, some water by breathing

ADH
- antidiuretic hormone
- acts on nephron in the kidneys to either reabsorb more water if dehydrated, or release water if hydrated

123
Q

Describe how ammonia is excreted by different types of organisms (3):
- name of substance
- what happens
- energy requirement
- provide example of an organism

A

EXPULSION
- ammonia expelled directly into water which flushes it away
- low energy
- e.g. aquatic animals, fish

UREA
- ammonia converted to urea via the liver, expelled from bodyin urine (made in kidney nephrons)
- medium energy
- mammals, most amphibians

URIC ACID
- ammonia excreted in a white paste, requiring little water, for conservation
- high energy
- birds, some reptiles

124
Q

ammonia

A

a toxic metabolic waste produced by the breakdown of excess AAs, must be eliminated from the body

125
Q

homeostasis

A
  • maintenance of the body’s internal enviro, despite changes in the external/internal enviro
  • a state of BALANCE amongst the body’s systems, necessary for survival
126
Q

Why is homeostasis important?

A
  • must maintain body’s conditions (temp, pH) so that organism can function
  • outside the ideal range = organism/cell death
127
Q

Explain how homeostasis is a negative feedback loop.

A

NEGATIVE FEEDBACK
- a change is reversed/reduced to bring the body back to stability again
- a constant balancing of internal enviro to maintain stable levels

128
Q

stimulus-response pathway

A
  • the negative feedback loop through which homeostasis is controlled
  • each homeostatic process is controlled by a specific stimulus-response pathway

Sequence:
NORMAL LEVELS > stimulus > receptor> sensory neuron > Nervous System > motor neuron > effector > response > NORMAL LEVELS

129
Q

State the 3 main stimulus-response pathways for homeostasis.

A
  1. Blood glucose conc
  2. Osmoregulation (water balance)
  3. Thermoregulation (body temp)
130
Q

Outline what a positive feedback loop is (+ examples).

A
  • a change is amplified/continued within the body
  • childbirth, lactation, blood clotting
131
Q

Outline the main 2 body systems involved in homeostasis, and their components.

A

NERVOUS
Central: brain, spinal cord
Peripheral: neurons (sensory/motor), sense organs

ENDOCRINE
- hormones
- glands

132
Q

STIMULUS-RESPONSE PATHWAYS:
1. blood glucose concentration
- outline the pathway

A

Stimulus
- too much/too little glucose in blood

Receptor
- chemoreceptors in pancreas detect the change in levels

Control
- Too much glucose: Beta cells in pancreas secrete insulin (hormone) into the blood
- Too little glucose: Alpha cells in pancreas secrete glucagon (hormone) into blood

Effector
- liver and skeletal muscles receive message
- Too much glucose: glucose taken out of blood, converted to glycogen for storage
- Too little glucose: glycogen broken down, glucose released into blood

Response
- levels are returned back to stability, pancreas cells stop release of hormone

133
Q

STIMULUS-RESPONSE PATHWAYS:
2. Osmoregulation
- outline the pathway

A

Stimulus
- too much/too little water in blood (over/dehydrated

Receptor
- osmoregulators in the hypothalamus detect change in H2O blood volume

Control
- hypothalamus signals pituitary gland (controls ADH release) to:
- Too much H2O: slow/stop release of ADH
- Too little H2O: increase release of ADH

Effector
- Too much H2O: kidneys stop receiving signals to keep aquaporins of collecting ducts in nephrons open, less H2O absorbed
- Too little H2O: kidneys keep receiving signal to keep aquaporins open, more H2O absorbed

Response
- urine is greater/lesser in quantity, and more dilute/concentrated
- blood h2O volume reaches stability

134
Q

STIMULUS-RESPONSE PATHWAYS:
3. Thermoregulation
- outline the pathway

A

Stimulus
- body temp decrease/increase

Receptor
- thermoreceptors (in skin + hypothalamus) detect change

Control
- hypothalamus activates mechanisms to cool/warm body

Effector
- To warm body: shivering, body hair stands up, vasoconstriction (blood vessels constrict to reduce blood flow to extremities)
- To cool body: pituitary gland signalled to trigger sweat glands to produce sweat, body hair flattens, vasodilation (blood vessels widen to increase blood flow to extremities)

Response
- body temp returns to normal/stable 37°, mechanisms stop

135
Q

Describe how fennec foxes are adapted for efficient osmoregulation and thermoregulation.

A
  • live in deserts: lack of water, hot days and cold nights. Must be adapted to cope

THERMOREGULATION
- small size: higher SA:V ratio allows faster rate of heat release
- large ears: release heat quickly through many blood vessels in ears
- fur: thick, keeps fox warm at night, light coloured, reflects the sun during hot daytime
- panting: very fast panting allows fox to release heat at a faster rate

OSMOREGULATION
- enlarged medulla in kidneys: more exposure to salty solution, more water is reabsorbed into blood, urine becomes more concentrated
- long Loop of Henle: allows more water to be reabsorbed back into blood

136
Q

Describe how polar bears are adapted for efficient thermoregulation.

A
  • live in artic: very cold. Must be adapted to cope

THERMOREGULATION
- undercoat: short hairs trap and dry air close to skin
- top layer of guard hairs: waterproof, preventing water coming in contact with skin, hollow, trap air for insulation = keep bear warm
- thick fat layer: insulation
- large and rounded: small SA:V ratio, decreases rate of heat loss as smaller area for heat to disperse
- countercurrent heat exchange: heat is transferred from warm arterial blood to cold venous blood, prevents heat loss

137
Q

Describe how mangroves are adapted for efficient osmoregulation.

A
  • live in tropic environments, in bays and estuaries: high salinity, waterlogged soil, humid. Must be adapted to cope

OSMOREGULATION
Salt-controlling processes prevent water loss via osmosis:
- removal of salt: in leaves or roots via ultrafiltration
- high water conc in leaves: salt is drawn into the leaves, balancing salt conc
- dropping of leaves: aged leaves drop from tree, removing salt from the organism
- SOME mangroves, hydrophobic barrier: located in roots, prevents majority of salt entering plant

138
Q

Describe how eucalypts are adapted for efficient thermoregulation and osmoregulation.

A
  • live in Australian climate: dry, sunny. Cannot survive in cold. Must be adapted to cope

OSMOREGULATION
- shedding: of mature leaves and twigs to reduce water loss through transpiration
- twisting of stems/leaves: hang vertically, preventing exposure to sun and therefore evaporation

THERMOREGULATION
- evaporation from leaves: cools down tree
- frost-proof sap: prevents damage to tree by frost

139
Q

Describe how desert animals are adapted for efficient homeostasis.

A
  • Large SA:V to maximise heat loss (may be smaller, have thinner features, skinner etc)
  • Blood vessels close to surface to remove excess heat, especially near ears
  • Urine highly concentrated
  • Convert fat to water from food (not much H2O available for drinking)
  • Loop of Henle is extra long to reabsorb H2O
140
Q

Describe how polar animals are adapted for efficient homeostasis.

A
  • Thick layer of insulation (e.g. blubber, penguins have
    waterproof feathers)
  • Small SA: V to reduce heat loss (rounded/compact
    shape)
  • Countercurrent heat exchange (moves heat to veins
    before it is lost to environment)
141
Q

Describe how desert plants are adapted for efficient homeostasis.

A
  • Sunken stomata
  • Thick waxy cuticle (prevents H2O loss)
  • Hairs on leaves prevent water loss from wind
  • Rolled in leaves minimises SA available for H20 loss
  • rounded, compact shape
  • cacti spines: hold stomata instead of leaves reduce H2O loss through transpiration, provide shade for plant

Biology 315 (5 decks)

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