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Physiology > Cells and Tissues > Flashcards

Cells and Tissues Flashcards

1
Q

physiology

A

the function of living things

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2
Q

homeostasis

A

maintenance of a relatively stable internal environment

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3
Q

examples of what composes the external environment

A

atmosohere, air, nutrients

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4
Q

examples of what composes the internal environment

A

body fluids, glucose concentrations, blood pressure

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5
Q

what happens when an organism is feeding

A

nutrients are being stored for later

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6
Q

what happens when an organism is fasting

A

stored ingredients are being mobilised

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7
Q

what is the functional organisation of the body

A
  • organism
  • body system
  • organ
  • tissue
  • cell
  • subcellular
  • molecular
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8
Q

name the four basic tissues

A
  • neurons
  • muscle
  • epithelial
  • connective
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9
Q

which two basic tissues are classed as excitable tissues

A

neurons and muscle

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10
Q

what are excitable tissues

A

those which have action potentials - electrical impulses generated or conducted

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11
Q

structure of epithelial tissues

A
  • cells close together with minimal intercellular substance
  • no nerves or blood vessels
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12
Q

intercellular

A

between cells

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13
Q

intracellular

A

inside a cell

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14
Q

what is the general function of epithelial tissues

A

to regulate the passage of material across the epithelium

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15
Q

two functional types of epithelial tissues

A
  • lining: tubes, ducts, airways
  • glandular - thyroid, pancreas
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16
Q

exocrine

A

retains connection with suface epithelium via a duct

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17
Q

example of exocrine gland and its function

A

salivary glands: secrete enzymes and mucus into mouth via salivary ducts

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18
Q

endocrine

A

loses connection to surface, and secretes directly into the blood without the presence of a gland

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19
Q

example of an endocrine gland and its function

A

thyroid gland: secretes thyroid hormone into the blood, acts on most cells to regulate metabolism

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20
Q

function of connective tissues

A

structural and metabolic support including repair

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21
Q

structure of connective tissues

A

cells, fibres and matrix

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22
Q

what does the matrix in bone contain

A

calcium hydroxyapatite

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23
Q

function of bone

A

support, rigidity and transmission of forces

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24
Q

what is the outside of bone made of

A

fibrous periosteum

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25
Q

what does the cavity of a bone contain

A

marrow for blood cell production

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26
Q

function of muscle tissues

A

contraction, force generation and movement

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27
Q

why does shivering occur

A

because muscle generates heat

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28
Q

three main types of muscle

A
  • skeletal
  • cardiac
  • smooth
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29
Q

skeletal muscle - type of control

A

voluntary

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30
Q

what type of nerves are used by skeletal muscle

A

motor nerves

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31
Q

two proteins contained in muscle

A

myosin and actin

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32
Q

what effect do myoisin and actin have on skeletal muscle

A

they make it the most contractile appartatus

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33
Q

innervation for skeletal muscle

A

single innervation: 1 nerve ending per fibre, but 1 neuron supplies many fibres

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34
Q

what kind of contractions occur in skeletal muscle

A

all or none contraction

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35
Q

where is cardiac muscle found

A

only the heart

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36
Q

what kind of movement does the cardiac muscle do

A

continuous, rhythmic activity - contracting/relaxing

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37
Q

how is electrical signal propagated throughout the heart

A

gap junctions

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38
Q

what specialised muscle cells does cardiac muscle contain

A

conducting tissue

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39
Q

two types of smooth muscle

A

multi-unit and single-unit

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40
Q

what is a variscosity

A

swellings of nerve tissue on muscle

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41
Q

explain multi-unit smooth muscle

A
  • each cell is innervated - one variscosity per cell
  • variable
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42
Q

examples of multi-unit smooth muscle

A

airways, large arteries

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43
Q

explain single-unit smooth muscle

A
  • one variscosity supplied multiple cells
  • greater diffusion difference
  • cells coupled
  • syncgronous contraction
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44
Q

example of single-unit smooth muscle

A

gut, uterus

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45
Q

two types of nervous tissue

A

central and peripheral

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46
Q

central nervous tissue components

A

brain and spinal cord

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47
Q

peripheral nervous system components

A

inputs and outputs to body parts

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48
Q

function of nervous tissue

A

information in - integration - information out

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49
Q

neuron structure

A
  • cell body
  • nerve fibres/processes
  • nerve terminals
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50
Q

example of a physiological variable

A

red blood cells

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51
Q

examples of physiological states that physiological variables vary by

A
  • sex
  • age
  • fasted/fed
  • exercise
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52
Q

what does negative feedback do?

A

acts to counteract the change in the controlled variable

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53
Q

five components of negative feedback

A
  1. controlled variable
  2. sensor
  3. interator
  4. effector
  5. compensatory response
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54
Q

what occurs in the controlled variable component of negative feedback

A

deviation in the controlled variable occurs

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55
Q

what does the sensor component do in negative feedback

A

gathers information of controlled variable deviation and sends it to integration

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56
Q

what does the integrator component do in negative feedback

A

it’s the nervous system

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57
Q

what does the effector component of negative feedback do

A

recieves information from nervous system and causes compensatory response

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58
Q

what does the compensatory response of negative feedback do

A

brings controlled variable back to normal

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59
Q

example of negative feedback

A
  • controlled variable: body temp
  • sensor: nerve cells
  • integrator: temp control centre
  • effector: skeletal muscle
  • compensatory repsonse: heat production
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60
Q

what does positive feedback do

A

reinforces change in the controlled variable

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61
Q

example of positive feedback

A

contraction of uterus at childbirth:
* oxytocin release
* contraction of uterine smooth muscle
* moves baby lower
* pressure on cervix
* causes oxytocin release

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62
Q

what is pathophysiology

A

a state in which normal function at any organisational level is disrupted to the extent that normal regulatory and compensatory mechanisms cannot maintain homeostasis

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63
Q

five functions of cells

A
  • exchange materials with surrounding environment
  • perfom chemical reactions to provide energy
  • synthesize cellular components
  • sense and respond to changes in surrounding environment
  • reproduction
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64
Q

name three types of cell

A
  • neuron
  • cardiac muscle cell
  • gametes
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65
Q

one way neurons are adapted for their purpose

A

contain dendrites and axons

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66
Q

one way cardiac muscle cells are adapted for their function

A

contain gap junctions

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67
Q

name one way gametes are adapted for their function

A

sperm have lots of mitochondria for energy

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68
Q

three functions of plasma membrane

A
  • acts as a barrier
  • allows communication between internal and external environments
  • controls passage of materials
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69
Q

what are plasma membranes made of?

A

phospholipid bilayer and cytocol

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70
Q

phospholipid composition

A
  • hydrophyllic phosphate head
  • hydrophobic fatty acid tail
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71
Q

nucleolus purpose

A

produce and assemble the cell’s ribosomes

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72
Q

nucleus purpose

A

contains dna

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73
Q

why does the nucleus contain pores

A

to allow some substances in such as certain hormones

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74
Q

why is the nucleolus important

A

for ribosomal RNA synthesis which is a crucial stage of protein synthesis

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75
Q

what is the endoplasmic reticulum

A
  • a membrane close to the nucleus
  • encloses space (lumen)
  • continuous with nuclear envelope
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76
Q

what is the rough ER

A
  • studded with ribosomes (ie rough)
  • therefore important for protein synthesis
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77
Q

what is the smooth ER

A
  • no ribosomes (hence smooth)
  • lipids
  • Ca2+ store
  • detox
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78
Q

what is the golgi apparatus

A

flattened sacs between ER and cell membrane

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79
Q

golgi apparatus function

A

processes and packages molecules into vesicles for transport

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80
Q

mitochondria function

A

generates energy (ATP) from glucose

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81
Q

what are proteins

A

chains of amino acids

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82
Q

roles of proteins within the cell

A
  • enzymes
  • signaling
  • structure
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83
Q

roles of proteins in the cell membrane

A
  • transport
  • structure
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84
Q

roles of proteins outside cell

A
  • digestive enzymes
  • hormones
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85
Q

transcription process

A
  • A triplet codes for one amino acid
  • Other triplets code for start/stop of amino acid sequence
  • Bases (GTCA) are complementary
  • Forms mRNA (messenger RNA)
  • mRNA to cytoplasm
  • Translation by ribosomes (using rRna or ribosomal RNA)
  • Additions of amino acids make a peptide
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86
Q

protein syntheis pathway

A
  • Uptake of amino acids in RER - synthesis
  • Golgi - packaging
  • Vacuoles - storage
  • Cell membrane - release
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87
Q

cytoskeleton definition

A

dynamic array of filaments

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88
Q

cytoskeleton purpose

A
  • confer shape
  • allow movement
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89
Q

what is the cytoskeleton composed of

A
  • microfilaments - 8nm
  • intermediate filaments - 10nm
  • microtubules -25nm
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90
Q

what are microfilaments

A

two helices of F-actin (fibrous)
Formed from G-actin (globular)

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91
Q

example of microfilament

A

actin

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92
Q

microfilament function

A

movement
support for microvilli

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93
Q

difference between microfilaments and intermediate filaments

A

intermediate are stronger and more stable

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94
Q

two examples of intermediate filaments

A

keratin and myosin

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95
Q

function of microtubules

A
  • strength
  • cell division
  • movement
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96
Q

blood percentage of total body weight

A

8%

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97
Q

average volume of blood in females

A

5L

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98
Q

average volume of blood in men

A

5.5L

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99
Q

four components of blood

A
  • erythrocytes
  • leukocytes
  • thrombocytes
  • plasma
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100
Q

components centrifgued blood divides into

A
  • red layer - 45%
  • buffy coat (platelets & leukocytes) - <1%
  • plasma - 55%
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101
Q

four constituents of plasma

A
  • water
  • electrolytes
  • nutrients, wastes, gases & hormones
  • plasma proteins
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102
Q

function of water in plasma

A

transport medium, carries heat

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103
Q

functions of electrolytes in plasma

A
  • membrane excitability
  • osmotic distribution of fluid between ECF and ICF
  • buffer pH changes
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104
Q

function of nutrients, wastes, gases and hormones in plasma

A

Blood CO2 plays role in acid-base balance

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105
Q

what percent of plasma is made up of plasma proteins

A

6-8%

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106
Q

blood pH

A

7.35-7.45

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107
Q

serum

A

plasma from which fibriogen and other clotting proteins have been removed

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108
Q

three main plasma proteins

A
  • albumins
  • globulins
  • fibrinogens
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109
Q

which is the most abundant clotting protein

A

albumins

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110
Q

two functions of albumins

A
  • contribute to colloid osmotic pressure by virtue of their abundance
  • transport molecules that are poorly soluble in plasma - bilirubin, salts drugs
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111
Q

3 subclasses of globulins

A

α, β and γ

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112
Q

what are α and β plasma proteins produced by

A

the liver

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113
Q

what are γ globulins produced by

A

lymphocytes

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114
Q

function of α/β subclasses

A

transport molecules (high specificity) also clotting factors

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115
Q

functions of α subclass of globulins

A

Inactive precursors proteins e.g. Angiotensinogen: Converted to angiotensin

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116
Q

function of γ subclass of globulins

A

immunoglobulins - ie antibodies

117
Q

what is fibrinogen

A

clotting factor

118
Q

what is fibrinogen converted to

A

fibrin

119
Q

how many erythrocytes per cubic mililitre

A

5 million

120
Q

what do erythrocytes lack

A

nuclei, mitochondria, ribosomes

121
Q

structure of erythrocytes

A

7µm diameter, 2µm thickness, biconcave

122
Q

function of erythrocytes

A

transport O2 and CO2

123
Q

how does haemoglobin work

A
  • four haem groups
  • each can bind to one O2 molecule
124
Q

erythrocyte life cycle

A

120 days

125
Q

what is erythropoieten (EPO)

A

chemical produced by kidney wich increases RBC production

126
Q

how many new erythrocytes do we make a day?

A

about 1 trillion

127
Q

haemopoiesis

A

production of blood cells

128
Q

how does haemopoiesis work

A

progressive differentiation:
* begin with undifferentiated pluripotent stem cell
* graducal acquisition of specific characteristics of end cells

129
Q

anemia

A

below normal oxygen carrying capacity of blood

130
Q

two main causes of anemia

A

reduced haemoglobin content of red blood cells
reduced blood cell number

131
Q

how can reduced haemoglobin content occur

A

iron deficiency

132
Q

how can reduced blood cell number occur

A
  • reduced cell production
  • increased cell loss - haemolysis ie. too much water in membranes
133
Q

six other causes of anemia

A
  • nutritional anemia
  • pernicious anemia
  • aplastic anemia
  • renal anemia
  • hemorrgagic anemia
  • hemolytic anemia
134
Q

how does nutritional anemia occur

A

iron deficiency - can’t make sufficient haemoglobin

135
Q

how does pernicious anemia occur

A

inability to absorb vitamin B12 from gastrointestinal tract due to deficiency of an intrinsic factor

136
Q

how does aplastic anemia occur

A

failure of the bone marrow to produce enough red blood cells even though all ingredients necessary for erythropoiesis are present eg. chemo

137
Q

how does renal anemia occur

A

reduced red blood cell production due to impaired EPO synthesis due to kidney disease

138
Q

how does haemorrhagic anemia occur

A

blood loss

139
Q

how does haemolytic anemia occur

A

rupture of RBCs:
* malaria invades RBCs and ruptures them
* sickle cell diease - genetic mutation in β-chain of haemoglobin)

140
Q

what do thrombocytes lack

A

a nucleus

141
Q

what are thrombocytes made from

A

fragments of megakarocytes

142
Q

how do thrombocytes work (brief)

A
  • release serotonon to vasoconstrict and reduce blood flow to clot area
  • secrete growth factors to maintain integrity of blood vessel wall
143
Q

thrombocyte life cycle

A

survive 5-9 days and are removed from circulation by tissue macrophages

144
Q

thrombopoietin

A

hormone produced by the liver, increasesnumber of megakarocytes and therefore increases platelet production

145
Q

haemostasis

A

process of keeping blood within a damaged vessel

146
Q

what are the two steps of platelet production

A

formation of platelet plug and blood clotting

147
Q

formation of platelet plug steps

A
  • platelets aggregate on contact with exposed collagen in damaged wall of vessel
  • platelets release ADP which causes surface of nearby circulating platelets to become sticky and adhere to first layer of aggregated platelets
148
Q

blood clotting steps

A
  • reinforces platelet plug
  • converts vlood in vicinity of vessel injusry into a nonflowing gel
  • clotting facors always present in blood plasma in inactive precursor from
  • vessel damage that exposes collagen initiates blood clotting cascade
149
Q

what is the blood clotting cascade

A
  • a series of steps requiring 12 clotting factors
150
Q

two pathways of blood clotting cascade

A

extrinsic and intrinsic

151
Q

difference between intrinsic and extrinsic pathways og blood clotting cascade

A
  • extrinsic: shorter and faster
  • intrinsic: requires more upstream factors
152
Q

chemicals required at several points of blood clotting cascade

A

Ca2+/PF3

153
Q

what does the final common pathway of the blood clotting cascade involve

A
  • activation of factor X
  • conversion of prothrombin to thrombin
  • ceaves fibringoen to form fibrin
154
Q

what happens if endothelium is intact (blood clotting)

A

it releases NO and prostacyclin which inhibit platelet adhesion

155
Q

clot dissolution steps

A
  • plasmin dissolves clot
  • plasmin is produced from plasminogen by many clotting factors including XII
  • phagocytic white blood cells remove the products of clot dissolution
156
Q

clot prevention steps

A
  • tissue Plasminogen Activator (tPA) converts plasminogen in plasmin and prevents inappropriate clot formation
  • tPA is used clinically as a clot buster
157
Q

what does thrombodulin do (blood clotting)

A
  • binds thrombin - this preventing fibrinogen conversion
  • activates protein C - anticoagulant which inactivates active factors V and VIII
158
Q

what is a thrombus

A

abnormal intravascular clot attached to a vessel wall

159
Q

what are emboli

A

freely floating clots

160
Q

four factors that can cause thromboembolism

A
  • roughened vessel surfaces associated with atherosclerosis
  • imbalnaces in clotting-anticlotting system
  • slow-moving blood
  • release of thromboplastin into blood from large amounts of traumatized tissue
161
Q

haemophilia

A

excessive bleeding caused by deficiency of one of the factors in the clotting cascade

162
Q

haemophilia A

A

clotting factor XIII deficiency

163
Q

haemophilia B

A

clotting factor IX deficiency

164
Q

importance of body fluids

A
  • primary transport system between cells
  • large part of internal environment - homeostasis
  • fluid composition is critical for cell function
165
Q

three things body fluid transport between cells

A
  • nutrition
  • waste
  • signals
166
Q

what two main compartments are contained within total body water

A
  • intracellular fluid
  • extracellular fluid
167
Q

what two fluid compartments are contained within extracellular fluid

A

plasma and interstitial fluid

168
Q

total body water percentage for males

A

60%

169
Q

total body water percentage for females

A

55%

170
Q

why is the TBW percentage lowe for females than it is for males

A

females have more fat

171
Q

what is the boundary between intracellular fluid and interstitial fluid

A

cell membrane

172
Q

cell membrane permeability

intracellular/interstitial fluids boundary

A
  • selectively permeable
  • ion pumps inside membrane to allow transport of certain ions but not others
173
Q

boundary between interstitial fluid and plasma

A

capillary wall

174
Q

capillary wall permeability

interstitial fluid and plasma barrier

A

permeable to small molecules

175
Q

composition of interstitial fluid

A
  • high in Na+
  • high in Cl-
  • low in K+
176
Q

intracellular fluid composition

A
  • low in Na+ (pump)
  • low in Cl-
  • high in K+ (pump)
177
Q

osmosis

A

water moves from a lower solute concentration to a higher solute concentraiton

178
Q

how does water move in osmosis

A

passively - no energy required

179
Q

what does water move across in osmosis

A

cell membrane - semipermeable ie. permeable to water but not to solute

180
Q

tonicity

A

effect of solute concentration on cell volume

181
Q

hypotonic solution

A

cell gains water and swells

182
Q

hypertonic solution

A

cell looses water and shrinks

183
Q

fluid repacement method in the case of haemorrhage

A

replace blood with isotonic saline (0.9% w/v NaCl) - no change in cell volume

184
Q

fluid repacement method in case of diarrhoea

A

replace water and ions - rehydration salts

185
Q

what does the lymphatic system do

A
  • fluid (lymph) leaks out of cardiovascular system
  • lymphatic system returns lymph to the cardiovascular system
186
Q

what are systemic capillaries

A

capllaries which allow the axchange of materials between blood and body tissues - nutrients, gases (O2 & CO2), water

187
Q

how does lymphatic drainage work

A
  • 3L per day is not reabsorbed in capillaries and venules
  • it enters lymph vessels instead
  • its pumped to lymph nodes
  • it re-enters circulation near the right atrium
188
Q

explanation of Starlings Law

A
  • arteries -> arterioles -> capillairies -> venules
  • blood flows from arteries to venules
  • outward pressure (12mmHg) is greater than inward pressure (8mmHg)
  • Fluid leaves the capillary and enters the interstitial fluid
189
Q

what happens in the case of liver failure

A
  • the liver synthesises most plasma proteins
  • liver failure leads to a fall in plasma proteins
  • colloid OP falls
  • Reduced inward flow
  • accumulation of fluid in tissues (oedema)
190
Q

normal daily inputs of fluid

A
  • fluid
  • food
  • metabolism
191
Q

normal daily outputs of fluid

A
  • gut
  • urine
  • breahing/skin
  • sweating
192
Q

normal daily fluid input and output regulation

A
  • fluid ingested and urine are regulated for water balance
  • sweating is regulated for heat balance
193
Q

abnormal fluid inputs

A
  • clinical - injection/infusion
  • polydipsia - excessive drinking
194
Q

abnormal fluid outputs

A
  • gut - vomiting, diarrhoea
  • urine - diabetes insipidus
  • skin - burns
  • sweating - hyperhydria
  • haemorrhage
195
Q

examples of a regulation failure

A
  • polydipsia
  • hyperhydria
  • diabetes insipidus
196
Q

structure of immune system

A

a network of cells and tissues

197
Q

3 roles of immune system

A
  • defends body against invading pathogens
  • destroys abnormal/mutant cells within the body
  • removes ‘worn out’ cells
198
Q

harmful effects of the immune system

A
  • allergies
  • autoimmune dieases
  • tissue rejection
199
Q

four types of pathogen

A
  • bacteria
  • parasite
  • fungus
  • virus
200
Q

bacteria example

A

staphylococcus aureus (causes sepsis)

201
Q

parasite example

A

tapeworm

202
Q

fungus example

A

epidermophyton floccosum (athlete’s foot)

203
Q

virus example

A

polio

204
Q

what tissues are part of the immune system

A

primary and secondary lymphoid tissues

205
Q

what cells are part of the immune system

A
  • lymphocytes
  • granulocytes
  • monocytes
  • dendritic cells
  • natural killer cells
206
Q

three types of granulocytes

A
  • neutriohils
  • eosinophils
  • basophils
207
Q

what soluble mediators are part of the immune system

A

cytokines & chemokines
complement proteins

208
Q

central/primary lymphoid tissues

A

bone marrow and thymus

209
Q

where are B-cells devleoped

A

bone marrow

210
Q

where are T-cells developed

A

thymus

211
Q

what are peripheral/secondary lymphoid tissues

A
  • spleen
  • lymph nodes
  • Gut associated lymphoid tissue
  • adenoids
  • appendix
  • tonsils
212
Q

neutrophil role (3)

A
  • destroy bacteria by phagocytosis
  • first defenders on scene of bacterial invasion
  • scavenge to clean up debris
213
Q

most abundant leukocyte

A

neutrophils

214
Q

percentage of leukocytes that are neutrophils

A

60-70%

215
Q

eosinophilia

A

increase in circulating eosinophils

216
Q

what is eosinophilia associated with

A
  • allergic reactions such as asthma and hay fever
  • internal parasite infections such as worms
217
Q

how do eosinophils deal with parasite infections like worms

A

they attach to the worm and secrete substances to kill it

218
Q

what percentage of leukocytes is made up of eosinophils

A

1-4%

219
Q

monocytes development

A
  • emerge from bone marrow immature and circulate for a day or two until settling down
  • mature and enlarge in resident tissue and become known as macrophages
  • become professional phagocytes and can act as antigen presenting cells
220
Q

how long do monocytes last

A

can range from several months to years

221
Q

what are dendritic cells

A

cells similar to monocytes but are more efficient antigen presenting cells

222
Q

what is nonspecific or innate immunity

A
  • phagocytosis and inflammation
  • initial and immediate response against invasion by any pathogens
223
Q

four main mechanisms of nonspecific immunity

A
  • physical barrier: skin, mucous membranes
  • inflammation and phagocytosis: by neutrophils and macrophages
  • interferon
  • complement
224
Q

signs of inflammatory response

A
  • redness
  • heat
  • swelling
  • pain
225
Q

3 results of inflammatory response

A
  • destorys or inactivates invaders
  • removes debris
  • prepares for healing and repair
226
Q

four stages of phagocytosus

A
  • attachment
  • internalisation
  • degradation
  • exocytosis
227
Q

three types of interferon

A

α, β and γ

228
Q

how does interferon work

A
  • cytokine is realeased by virus-infected cells
  • induces expression of enzymes that prevent viral replication
  • thus protects other cells from the virus
229
Q

anti-cancer effects of interferon

A
  • slows cell division
  • enhances action of NK cells and cytotoxic T cells
230
Q

how do natural killer cells work

A
  • they attack virus-infected cells
  • cause lysis via release of perforins
231
Q

name a major source of interferon γ

A

natural killer cells

232
Q

what is the complement system made up of

A

over 25 proteins and protein fragments that usually circulate as inactive precursors in the blood

233
Q

how much of the globulin fraction of plasma is made up of the complement proteins

A

about 5%

234
Q

what happens when the complement cascade is activated

A
  • results in the formation of a cell-killing membrane attack complex
  • induces lysis of invading micro-organisms
  • also complements the ability of other immune mechanisms to clear pathogens
235
Q

what is specific immunity

A

comes into play after nonspecific responses have begin
responds to specific pathofens on second or later exposure

236
Q

four main components of specific immunity

A
  • specificity
  • diversity
  • memory
  • self-tolerance
237
Q

how does specificity work

specific immunity

A
  • antigen receptors are present on B and T cells
  • these bind foreign molecules known as antigens
  • antibody-antigen interactions are specific
238
Q

how does diversity work

specific immunity

A

the body prossesses millions of lymphocytes that can recognise and respons to millions of antigens

239
Q

how does memory work

specific immunity

A

the first exposure to an antigen generates lymphocytes and long-lived emmory cells - the next exposure to the same antigen, memory cells react faster and with a stronger response

240
Q

how many specific antigen receptors can the average B or T cell have

A

about 100,000

241
Q

what are plasma cells

A

short lived cells that produce anti-bodies in blood

242
Q

what are memory cells

A

long lived cells which have antigen receptors for their specific santigen

243
Q

how does self-tolerance work

specific immunity

A
  • Lymphocytes can distinguish ‘self’ (our normal antigens) from non-self (antigens from foreign material)
  • This means B or T cells that may attack ‘self’ are usually destroyed in the bone marrrow
  • ths process fails in autoimmune diseases
244
Q

which type of lymphocyte produces antibodies

A

B-cells

245
Q

what do B-cells mainly defend against

A

bacteria, toxins and viruses presnt in body fluids

246
Q

what type of immunity are B-cells responsible for

A

antibody-mediated or humoral immunity

247
Q

what do T-cells do

A
  • directly destroy specific target cells by releasing chemicals that punch holes in the victim cell
  • target cells include body cells invaded by viruses and cancer cells
248
Q

what type of immunity are T cells responsible for

A

cell-mediated immunity

249
Q

five steps of humoral immunity

A
  1. neutralisation
  2. agglutination
  3. oposination
  4. complement activation
  5. enhanced NK cell activity
250
Q

neutralisation

humoral immunity

A

antibodies block the activity of a pathogen

251
Q

agglutination

humoral immunity

A

multiple pathogens are aggregated by antibody molecules

252
Q

opsonisation

humoral immunity

A

pathogens bound by antibodies are more efficiently engulfed by phagocytes

253
Q

complement activation

humoral immunity

A

antibodies bound to pathogens activate the complement cascade, resulting in lysis of the cell

254
Q

enhanced NK cell activity

humoral immunity

A

abnormal body cells that are bound by antibodies are recognised by NK cells are are subsequently lysed

255
Q

five classes of antibodies

A
  • IgM
  • IgD
  • IgG
  • IgE
  • IgA
256
Q

what percentage of T cells are helper T cells

A

70%

257
Q

how do helper T cells work

A

In a phagocytic immune cell, Class II MHC molecules present the antigen at cell surface so helper T cells can bind it and secrete cytokines that will amplify the immune response

258
Q

what kind of action are helper T cells involved in and how

A
  • indirect action
  • they stimulate the development of B cells into plasma cells
259
Q

what percentage of T cells are cytotoxic T cells

A

30%

260
Q

how do cytotoxic T cells work

A

in an infected cell, Class I MHC molecules present antigen at cell surface so cytotoxic T cells can kill the infected cell

261
Q

what kind of action are Cytotoxic T cells involved in and how?

A
  • direct action
  • kill infected cells by lysis
262
Q

two examples of autoimmune dieases

A

rheumatoid arthritis and multiple sclerosis

263
Q

what happens with rheumatoid arthritis

A

inflammation of cartilage and bone of joints

264
Q

what happens with multiple sclerosis

A

T cells attack myelin leading to blurred vision, muscle weakness and ataxia

265
Q

what is AIDS caused by

A

human immunodeficiency virus (HIV)

266
Q

how does AIDS work

A
  • HIV binds to surface of helper T cells and its nucleic acids enter the T cell
  • Inside the cell, HIV uses the cell to make copies of itself
  • HIV slowly destroys all helper T cells in the body
  • When T cell function is impaired, immune responses weaken and other diseases develop (opportunistic infections)
267
Q

how does passive diffusion occur

A

down a concentration gradient

268
Q

what four things is passive diffusion proportional to?

A
  • size of gradient
  • membrane surface area
  • Permeability of membrane
  • O2, CO2, fatty acids, steriods, hormones
269
Q

what is facilitated diffusion

A
  • carrier molecules are present in their resting state in membranes
  • binding leads to conformational change in shape
  • molecule passes through membrane
270
Q

what does the rate of facilitated diffusion depend on

A
  • numver of carriers in membrane (regulated)
  • affinity - same on both sides
  • concenraation of substance to be transported
271
Q

why do membranes have ion channels

A

because ions cannot pass directly through membranes

272
Q

what must occur for ions to pass through ion channels

A
  • both sides must be open
  • they are specific
  • only ositive or negative ions can pass through - never both at same time
  • some channels only open when specific binders are present
273
Q

what does flux depend on

ion channels

A

electrochemical gradient

274
Q

examples of ions that pass through ion channels

A
  • Na+
  • K+
  • Cl-
275
Q

how does active transport work

A
  • opposes electrochemical gradient
  • uses ATP
276
Q

primary active transport

A

uses energy directly

277
Q

secondary active transport

A

uses a gradient created by sodium pump

278
Q

sodium pump

A

Na+/K+/ATPase pump

279
Q

how des a sodium pump work

A
  • phosphorlyation leads to conformation change and change in affinity
  • one ATP is used per cycle
  • 3:2 ratio of Na+ out to K+ in
280
Q

Consequences of Na+/K+/ATPase pump

A
  • Membrane potential (Vm) -50-90 mV - means potential energy for secondary active transport and active potential
  • Balance between electrical and chemical (diffusional) forces - means 20% of resting (basal) resting metabolic rate is used
281
Q

contrasport

A
  • Na+ moves into cell down gradient
  • releases energy
282
Q

example of cotransport

A

glucose within the gut

283
Q

countertransport

A

Na+ and (eg.) h+ go in opposite directions

284
Q

electrical driving force of extracellular fluid

A

cations > anions
means net is positive

285
Q

electrical driving foce of intracellular fluid

A

anions > cations
meaning net is negative

286
Q

what does electrical driving force depend on

A
  • size of membrane potential
  • quantity of charge
287
Q

involuntary muscles

A

smooth and cardiac

288
Q

connective tissue examples

A

blood, bone, cartilage

289
Q

nucleus purpose

A

contains dna

Physiology (6 decks)

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