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Yr.12 Biology > homeostasis > Flashcards

homeostasis Flashcards

1
Q

Homeostasis

A

the process involved in maintaining a constant internal environment, within tolerance limits, despite changes in the internal and external environment.

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2
Q

Enzyme

A

are reusable
Speed up chemical reactions
proteins that are sensitive to temp and pH

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3
Q

Types of receptors

A

chemoreceptors - detects oxygen and ion levels (internal)
Mechanoreceptors
photoreceptors - detects lights
Thermoreceptors - changes in temp (external and internal)
pain receptors
Osmoreceptors - detect changes in osmotic pressure in blood, changes in solute conc. In the blood

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4
Q

nervous system

A

Comprises of central nervous system (CNS) and peripheral nervous system (PNS)
receive sensory information from receptors, interpret and process the sensory information, and coordinate the response.

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5
Q

Sensory and motor neurons

A

make up PNS
Responsible for transmitting info to and from the CNS

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6
Q

nerve impulse pathway

A

Sensory neutron from source of stimulation -(via PNS)-> CNS -> interconnecting neurons in CNS relay electrical impulses from sensory neurons -(to)-> motor neurons -(via PNS)-> effectors.

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7
Q

effectors

A

Muscles or glands that respond to the stimuli

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8
Q

neurons

A

Basic unit of NS
have extensions called fibres along which nerve impulses travel.
Bundle of nerve fibres comprises a nerve, and each is unwrapped in a tube of connective tissue.

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9
Q

axon

A

Tubular extension of the cell body
enclosed in fatty material, functioning as insulation (myelin sheath), assists in electrical impulses (speeds it up)

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10
Q

Neurons (types)

A

sensory neurons: from receptor to CNS (brain) via sc.
Motor neurons: from CNS (brain) to effector via sc.
Afferent: from receptor to CNS
Efferent: from CNS to effector

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11
Q

endocrine system

A

Releases hormones from endocrine glands in response to stimulus.
target tissue may be far from gland

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12
Q

Hormones

A

chemical substances, such as proteins, steroids, fatty acids and amino acids
Target and activate particular cells and organs, causing a response
only the cells in the body that have receptors for a particular hormone will respond to that hormone.

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13
Q

Pituitary gland

A

‘Master gland’ as produces many hormones that affect production by other endocrine glands.

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14
Q

hypothalamus

A

Controls the functioning of the pituitary gland in regard to water balance.
detects and coordinates many homeostatic factors.

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15
Q

Feedback mechanism

A

SisteR MERF
Stimulus, receptor, modulator, effector, response, feedback.

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16
Q

tolerance limits

A

Set ranges within which organisms can tolerate the temp, water balance and different levels of organic and inorganic materials

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17
Q

optimal range

A

Narrower range within an organism’s tolerance range

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18
Q

zone of physiological stress

A

Zone outside of optimal range but inside tolerance limits
A.K.A physiological stress

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19
Q

zone of intolerance

A

Zone that is outside the tolerance range for survival

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20
Q

Enzymes and temp

A

temp increase - increases enzyme activity -> too hot, enzymes denature (shape changes) slow metabolism
Temp decrease - decrease enzyme activity

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21
Q

Cell membrane and temp

A

hot - cell membrane becomes too fluid, allows unwanted substances into cell and wanted out.
Cold - cell membrane becomes too rigid, slowing transport of substances across them

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22
Q

nitrogenous waste

A

Produced by breakdown of proteins and nucleic acids. Highly toxic, creates ammonia
ammonia increase blood pH -> affects enzymes

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23
Q

Water

A

Higher water -> decreased ion conc -> decrease in collision rates of the reactants involved in biochemical pathways, slowing metabolism.
Hypotonic - lower ion conc outside, causes swelling, decreases ion conc inside -> decreases collision rate
Hypertonic - higher ion conc outside, causes cell shrink, plasmolysis in plants.
Isotonic - same ion conc inside and out, no net movement

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24
Q

hypertonic

A

Ions are unable to move to their reaction sites at a fast enough rate, slowing metabolic rate, cells unable to regulate conc of solutes.
wastes can’t be excreted.
Due to wastes trapped, pH increases.

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25
Q

salts (outside of cell)

A

Increase - water leaves cell, leads to cell shrinkage and dehydration
Decrease - water enters cell, cell swells, leading to weakness, fatigue, confusion.

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26
Q

gases

A

CO2 dissolves into blood, forming carbonic acid (H2CO3) and later into hydrogen and bicarbonate ions
too High CO2 - leads to inc in H+ conc. Which lowers pH, creating acidic blood.
Too Low CO2 - leads to lower ventilation rate in mammals, lower rate of photosynthesis in plants
too High O2 - can be toxic, gas can diffuse straight into cell, can cause: cell damage, nausea, dizziness and breathing problems
Too low O2 - leads to reduction in the respiration rate and thus the rate of ATP (energy) prod.

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27
Q

plasmolysis

A

Occurs in plants
cell membrane of a plant has pulled away from the cell wall due to water moving out of cell

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28
Q

Physiological processes

A

functional processes performed by organisms

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29
Q

Structural features

A

physical features that have a function

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30
Q

Behavioural adaptations

A

action performed in response to a stimulus

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31
Q

Thermoreg plants mechanisms

A

cold climate - thick, waxy leaves reduce heat loss by providing insulation against the cold climate
Hot climate - its narrow, vertical leaves minimise the amount of direct sunlight hitting them and thus minimise heat absorption during hot desert days.

32
Q

endotherms

A

Animals that use metabolic processes to generate their own heat to maintain their internal temp within tolerance range
Body generates heat loss and gain.

33
Q

ectotherm

A

Animal whose body temp is determined by the external enviro
body temp fluctuates wt external enviro
No physiological adaptations

34
Q

Methods of heat transfer

A

conduction - transfer of heat from a hotter object to a cooler object by direct contact
Convection - transfer heat when hot air/liquid rises and is replaced by cooler air/liquid
evaporation - occurs when liquid turns to vapour, cooling the skin
Radiation - transfer of heat by infrared waves.

35
Q

thermo reg in plants

A

In cool of night plant increases its metabolic heat prod, and in heat of day, evaporative cooling is used

36
Q

hot enviro structural features

A

High surface-area-to-volume ratio of bv close to surface to facilitate conduction
sweat glands for evaporation
Increased blood flow to skin
Fur can reflect heat from radiation
ectotherms - adjusts skin colour, temp rises, colour becomes lighter

37
Q

hot enviro behavioural responses

A

Shelter from high temps
reduce physical activity
Licking body parts
emerge in water
Open mouths
burrow into ground

38
Q

Hot enviro physiological adaptations

A

vasodilation
sweating
panting
Decrease metabolic activity
pilorelaxation - muscle attached to follicle relax to flatten hair, and decrease layer of air acting as an insulator

39
Q

Cold enviro structural features

A

Insulation (fur, feathers, blubber)
piloerection - muscle attached to follicle contracts so that hairs stand up
Darker shading (fur/scales)
aquatic animals - countercurrent heat exchange
Larger size

40
Q

countercurrent heat exchange

A

The exchange of heat between two fluids flowing in opposite directions in vessels that are in close proximity
heat in the blood travelling in the arteries to the foot or fin warms the blood returning to the body in the adjacent veins
Traps heat in the body core, reducing heat loss in the extremities

41
Q

cold enviro behavioural responses

A

Minimising amount of surface area exposed to the surroundings
basking in the sun
Lay on hot surface (rock)

42
Q

Cold enviro physiological adaptations

A

Vasoconstriction
inc. metabolic rate
Shivering
torpor
Hibernate
aestivation

43
Q

Torpor

A

physiological state of decreased metabolic rate and physical activity
Reduces energy and water costs

44
Q

hibernation

A

Spending a long period of time in Torpor
the metabolic rate falls to a level that just sustains life

45
Q

Aestivation

A

seasonal dormancy
Done in dry conditions

46
Q

osmoregulation

A

Active regulation of the organism’s water content

47
Q

Turgid

A

a cell into which water was diffused so that the walls are stretched and the cell is fairly rigid.

48
Q

Osmosis

A

the passive diffusion of water across a membrane in response to a concentration gradient caused by an imbalance of molecules on either side of the membrane

49
Q

Kidneys functions

A

1. Removal of nitrogenous wastes
2. Regulation of water conc in the blood
3. Maintaining ion levels in the blood

50
Q

Nephrons

A

individual filtering units
Filter blood in order to regulate chemical concentrations and produce urine

51
Q

Bowman’s capsule

A

Surrounds glomerulus
cup-shaped structures

52
Q

Glomerulus

A

a group of capillaries
Plasma is forced out through the walls of the glomerulus, then in the outer layers of the Bowman’s capsule to its interior, being filtered in the process.
Where filtration occurs

53
Q

filtrate pathway

A

Glomerulus -> bowman’s capsule -> proximal convoluted tubules -> loop of henle -> distal convoluted tubules -> collecting ducts -> ureter

54
Q

reabsorption

A

Occurs at proximal/distal tubules, loop of hence and collecting ducts
process of water, ions and other substances in the filtrate being absorbed back into the blood.

55
Q

Excretion

A

the removal of nitrogenous wastes
In mammals, urea removed as part of urine

56
Q

ammonia

A

Extremely toxic
affects pH, can denature enzymes - slow metabolic rate
Excretion: directly, diluted into water (freshwater fish), or converted to urea or uric acid (requires energy).

57
Q

antidiuretic hormone (ADH)

A

Controls maintenance of water balance in mammals
reduces urine output
Prod. by hypo stored in pit gland
acts on collecting ducts of nephrons
Increases reabsorption of water in the collecting ducts

58
Q

decreased H2O feedback loop

A

Stimulus: decrease in blood water content below optimal range
Receptor: osmoreceptor cells in Hypo detect the change in the blood water content and send a message to coordinator centre.
Coordinator centre (modulator): hypothalamus receives a msg from a receptor, coordinates a response and sends a msg to effector.
Effector: Pit. gland releases ADH, which travels through the blood to kidney nephrons, increasing the permeability of the collecting duct wall, which increases water absorption.

59
Q

Osmoconformers

A

an organism in which the internal solute conc. Changes wt the conc of solutes in external enviro
Able to concentrate urea in their bodies to maintain a high soluble concentration, thus matching the ocean’s high conc of solutes

60
Q

osmoregulators

A

Organism that has specialised mechanisms for regulating internal water and solute conc, despite conc changes in external enviro.
Have physiological adaptations

61
Q

osmoregulator adaptaitons

A

Structural features: waterproof/impermeable outer layer
physiological processes: reabsorb water from their cloaca, Excrete nitrogenous wastes as uric acid, retain urine in bladder for use.
behavioural adaptation: aestivation and burrowing

62
Q

Aestivation

A

used by desert frogs
Fills its bladder and pockets under the skin wt water and tucks itself into a water-conserving cocoon created from mucus and sloughed skin.
metabolic rate slows down
Can survive in cocoon for many months

63
Q

xylem

A

Carries water

64
Q

Phloem

A

caries the products of photosynthesis (eg. Glucose)

65
Q

Transpiration pull

A

set of forces that pull water up Xylem
Cohesion: attractive force that occurs between water molecules. As water evaporates from leaves, columns of water are drawn up through the xylem vessels.
Adhesion: attractive force operating between water molecules and inner walls of the Xylem vessels

66
Q

Capillary action

A

formed by the combined forces of cohesion and adhesion
Drawing up of water creates conc gradient between inside and outside of root hairs
active transport of salt ions into the roots can cause osmotic water movement into the root hairs, causes root pressure

67
Q

Root pressure

A

force pushing on the water in the Xylem
Pushes water upwards

68
Q

transpiration stream

A

The continuous flow of water from the roots to the leaves via Xylem vessels due to the forces of cohesion, adhesion and root pressure.

69
Q

transpiration

A

The evaporative loss of water from plants, usually through stomata
occurs because of the conc gradient of water vapour between the inside and outside of the leaf.
The transport of water through the plant results in water loss.

70
Q

importance of transpiration

A

1. Transpiration supplies photosynthesis wt the water it needs
2. The evaporation of water from mesophyll cells in the leaves that accompanies transpiration requires energy therefore cools the leaves in the same way that sweating cools the skin of some mammals. Heat energy is drawn out of the plant, into the water, then out into the external environment.
3. The transpiration stream is also necessary for distributing mineral salts throughout the plant.

71
Q

Guard cells opening/closing

A

light in comb wt CO2 conc and sufficient humidity opens stomata.
Using active transport, K+ are purposely moved into guard cells, creating conc gradient.
guard cells then take up water and become turgid.
Because inner walls are rigid, they are pulled apart, opening the pore.
in darkness, water lost, guard cells become flaccid, and their inner walls move together, closing the pore.
Stomata opening/closing depends on the changes in the turgor of guard cells.

72
Q

turgor and guard cells

A

Increases - guard cell expands. Due to relatively inelastic inner walls of guard cells, they bend and draw away from each other, so the pore opens.
decreases - guard cell shrinks. Guard cells lower their water potential to draw in water from the surrounding epidermal cells actively accumulating potassium ions. This requires ATP, which is supplied by chloroplasts in guard cells.

73
Q

Xerophytes

A

live in dry environment. Evap exceeds precipitation.
Adaptations: reduction in leaf surface area
sunken stomata
Deep roots
rolled leaves
Thick, waxy leaf cuticle
stomata opening at night
Shallow, spreading roots

74
Q

Halophytes

A

plants that liv in enviro of high soil salinity
Adaptations: filtration at the roots - regulates amount of salt entering, impermeable to salt prevents salt to enter.
vacuoles in root cells - stores salts, which increases the salt conc of the roots so it is greater than that in the soil.
Accumulation of salts - in older leaves, salt bladders or bark, which can later be discarded.
secretion of slat by special glands on leaves
Succulence - development of water storage structures in the leaves and other parts of the plant, dilutes the salt content of the cells.

75
Q

salt accumulators

A

Gather and store excess salt in their slat glands or in their central vacuoles

76
Q

salt excluders

A

Remove salt by ultrafiltration through cell membrane

Yr.12 Biology (6 decks)

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