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homeostasis

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Tags and Description

homeostasis, osmosis etc

105 Terms

1

homeostasis

the ability of an organism to maintain constant internal conditions despite changes in the external environment

all levers of organisation contribute to homeostasis

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2

steady state

another term for homeostasis

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3

Things to keep stable

  • body temp

  • blood pH

  • blood glucose levels

  • amount of wastes in blood

  • blood pressure

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3 step process in maintaining stable body conditions

  • change must be detected somehow

  • solution must be developed

  • adjustments must be made

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5

receptors

step 1 in maintaining stable body conditions

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6

what occurs within receptors

cells receive messages about a change which is known as the stimulus

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7

examples of receptors

sense organs:

  • eyes

  • ears

  • nose

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8

chemoreceptors

detect chemicals such as glucose levels

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9

baroreceptors

detect pressure such as full bladder

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10

control centre

involved in step 2 of maintaining stable body conditions

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11

what occurs within the control centre

received info from receptors, then sends messages back out to fix the problem

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12

effectors

step 3 in maintaining stable body conditions

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what occurs within effectors

cells, tissues and organs follow instructions from the control centre and make changes to produce a response

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14

negative feedback loop

reduces or opposes the intensity of the stimulus

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15

set point

the physiological value around which the normal range fluctuates

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16

normal range

the restricted set of values that is optimally stable and healthful

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what does homeostasis aim to reach

homeostasis aims to keep the body at the set point

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18

positive feedback

the response increases the stimulus rapidly until end point is reached

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19

components of cell membrane

has 2 layers of lipids

has a phospholipid inlayer

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20

structure of lipids

polar heads

non polar and hydrophobic tails

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21

function of phospholipid bilayer

allows water inside and outside of the cell

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22

membrane proteins

peripheral and integral proteins

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23

peripheral proteins

do not go all the way through the membrane, acts likes assistants to integral proteins

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integral proteins

goes all the way through the membrane

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3 types of integral proteins

transporter, cell surface identity maker, cell surface receptor

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26

transporter cell surface

moves things in and out of the cell

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cell surface identity maker

cell recognition eg. antigen

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28

cell surface receptor

brings a message into the cell

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29

what can cross the phospholipid bilayer

non-polar, hydrophobic molecules that have no charge

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30

polar

electrons aren’t shared evenly

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31

how do non-polar hydrophobic molecules cross through the phospholipid bilayer

dissolves in membrane and goes through

smaller molecules cross more quickly

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32

what cannot cross the phospholipid bilayer

polar hydrophilic molecules mostly cannot cross

water and ethanol are polar but small - some get through

large polar molecules eg. glucose

charged molecules

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33

2 methods of transport across the cell

active transport and passive transport

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34

active transport

the movement of substances across the membrane using energy, usually against concentration gradient

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35

passive transport

movement of substances across the membrane without the use of cellular energy, usually with the concentration gradient

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concentration gradient

occurs when a substance is more concentrated in one area than another

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37

diffusion

movement from high to low concentration

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38

passive diffusion

does not require energy

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39

movement of ions or smaller polar molecules

cannot pass through the phospholipid bilayer but there are channels made of protein

moves along the concentrated gradient through facilitated diffusion

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40

active transport requirements and method : primary

against concentration gradient and requires energy and special protein channels

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41

active transport : secondary

uses the electrochemical gradient of an ion to move something else against its gradient

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42

antiporter

membrane protein that transports two molecules at the same time in the opposite direction

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43

symporters

proteins that transports two molecules across a membrane in the same direction

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44

where do large molecules move in and out of the cell

through vesicles and vacuoles

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45

endocytosis

moves large molecules to the inside of a cell

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46

exocytosis

moves large molecules to the outside of a cell

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47

osmosis

diffusion of water through a semi-permeable membrane

from a high concentration to a low concentration

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48

hypertonic

more solutes and less water in a solution

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49

hypotonic

less solute and more water in a solution

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50

isotonic

equal in solute and water in a solution

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51

passive transport

movement of substances across the membrane without the use of cellular energy, with the concentration gradient

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52

metabolism

sum of all biochemical reactions occurring in the cells

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53

2 types of metabolism

anabolic and catabolic

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54

anabolic reactions

building/making molecules

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55

catabolic reactions

breaking down molecules/breaking bonds

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56

what do biochem reactions require

most biochem reactions need enzymes to increase the speed of the reaction to sustain life

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57

methods to make particles collide

  • make particles smaller

  • add heat energy to increase movement causing more collisions

  • alter concentration/pressure

  • using catalysts

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enzymes

proteins that act as a catalyst to increase the rate of reactions

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active site

area on the enzyme where the substrate attach

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60

size of enzymes and active site

enzymes are usually very large proteins and the active site is just a small region

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function of active site

males enzymes specific to particular substrates

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pathways

metabolic reactions occur in a series of these pathway reactions

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63

3 reasons cells need energy

chemical, mechanical and electrochemical

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64

energy for chemicals

to aid the building/rearranging/breaking apart of substances

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energy for mechanicals

to aid the movement of cell structure eg.cilia

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energy for electrochemical

to aid the movement of charged particles across membranes

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how do cells get energy (1)

breaking down high energy moles in food through metabolic pathways

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68

how do cells get energy (2)

law of conservation of energy

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69

how is ATP used

  • energy in phosphate bonds

  • bonds broken = energy released

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70

cellular respiration

glucose + oxygen - water + carbon dioxide + ATP

describing the metabolism of carbohydrates

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71

metabolism of carbohydrates

over 3 metabolic pathways:

  • glycolysis

  • citric acid cycle

  • oxidative phosphorylation

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72

beta oxidation

a metabolic pathway where fatty acids are used to produce energy

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glycolysis

  • series of chemical reaction

  • occurs in cytoplasm

  • does not need oxygen

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substrate and product of glycolysis

substrate = glucose

product = pyruvate

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ATP within glycolysis

uses 2 ATP and produces 4 ATP

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TCA/Citric acid/Krebs cycle

in the presence of oxygen

pyruvate is converted to Acetyl-CoA inside the mitochondria

Acetyl-CoA enters the cycle

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77

link reactions

where pyruvate is converted to Acetyl-CoA inside the mitochondria

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78

where does oxidative phosphorylation occur

occurs in the mitochondria

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79

2 parts of oxidative phosphorylation

electron transfer chain

chemiosmosis

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80

fermentation

following glycolysis, if oxygen is absent then pyruvate is converted into lactate - lactic acid

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81

how is ATP produced

By breaking down glucose metabolic pathways

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82

breakdown of glucose (step 1 in making ATP)

begins with glycolysis which can be aerobic or anaerobic

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83

what reaction is lactate produced in

anaerobic

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84

aerobic reaction of glycolysis (step 2 in making ATP)

both glycolysis and beta oxidation feed their products into the citric acid cycle which produces carbon dioxide

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85

where does hydrogen within oxidative phosphorylation come from (step 3 in making ATP)

glycolysis and citric acid cycle strip hydrogen from carbohydrates

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86

Final step in making ATP

Oxidative phosphorylation combines the hydrogen with oxygen to make water - this process provides the energy to run ATPase which produces ATP

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87

phosphorylation

adding phosphate

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88

coordinated processes/variables

body’s internal environment

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core principles

  • feedback loops

  • structure function

  • cell-cell communication

  • gradients

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90

potential energy

energy that is stored

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91

2 basic types of passive transport

diffusion and osmosis

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92

properties of water

water absorbs heat without changing significantly in temperature itself

water carries heat with it when it changes from a liquid to a gas

water cushions and protects the body’s structure

water as a lubricant between 2 adjacent surfaces

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93

yield of glycolysis

spent 2 ATP

produces 4 ATP

produced 2 NADH

splits glucose into 2-3 carbon pyruvate

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94

which pathways produce acetyl CoA

glycolysis and beta oxidation

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95

what are the metabolic cycles used for glucose metabolism

glycolysis, citric acid cycle, oxidative phosphorylation

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96

what pathway metabolises acetyl-CoA

citric acid cycle

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97

how does water move in regards to concentration gradient

water moves down the concentration gradient

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98

what causes cells to swell

hypotonic solutions

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99

what causes cells to shrink

hypertonic solutions

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100

what reaction produces the most ATP

oxidative phosphorylation

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