Cells and Tissues Flashcards
1
Q
Intervention for Di
physiology
A
the function of living things
2
Q
homeostasis
A
maintenance of a relatively stable internal environment
3
Q
examples of what composes the external environment
A
atmosohere, air, nutrients
4
Q
examples of what composes the internal environment
A
body fluids, glucose concentrations, blood pressure
5
Q
what happens when an organism is feeding
A
nutrients are being stored for later
6
Q
what happens when an organism is fasting
A
stored ingredients are being mobilised
7
Q
what is the functional organisation of the body
A
- organism
- body system
- organ
- tissue
- cell
- subcellular
- molecular
8
Q
name the four basic tissues
A
- neurons
- muscle
- epithelial
- connective
9
Q
which two basic tissues are classed as excitable tissues
A
neurons and muscle
10
Q
what are excitable tissues
A
those which have action potentials - electrical impulses generated or conducted
11
Q
structure of epithelial tissues
A
- cells close together with minimal intercellular substance
- no nerves or blood vessels
12
Q
intercellular
A
between cells
13
Q
intracellular
A
inside a cell
14
Q
what is the general function of epithelial tissues
A
to regulate the passage of material across the epithelium
15
Q
two functional types of epithelial tissues
A
- lining: tubes, ducts, airways
- glandular - thyroid, pancreas
16
Q
exocrine
A
retains connection with suface epithelium via a duct
17
Q
example of exocrine gland and its function
A
salivary glands: secrete enzymes and mucus into mouth via salivary ducts
18
Q
endocrine
A
loses connection to surface, and secretes directly into the blood without the presence of a gland
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
20
Q
function of connective tissues
A
structural and metabolic support including repair
21
Q
structure of connective tissues
A
cells, fibres and matrix
22
Q
what does the matrix in bone contain
A
calcium hydroxyapatite
23
Q
function of bone
A
support, rigidity and transmission of forces
24
Q
what is the outside of bone made of
A
fibrous periosteum
25
what does the cavity of a bone contain
marrow for blood cell production
26
function of muscle tissues
contraction, force generation and movement
27
why does shivering occur
because muscle generates heat
28
three main types of muscle
* skeletal
* cardiac
* smooth
29
skeletal muscle - type of control
voluntary
30
what type of nerves are used by skeletal muscle
motor nerves
31
two proteins contained in muscle
myosin and actin
32
what effect do myoisin and actin have on skeletal muscle
they make it the most contractile appartatus
33
innervation for skeletal muscle
single innervation: 1 nerve ending per fibre, but 1 neuron supplies many fibres
34
what kind of contractions occur in skeletal muscle
all or none contraction
35
where is cardiac muscle found
only the heart
36
what kind of movement does the cardiac muscle do
continuous, rhythmic activity - contracting/relaxing
37
how is electrical signal propagated throughout the heart
gap junctions
38
what specialised muscle cells does cardiac muscle contain
conducting tissue
39
two types of smooth muscle
multi-unit and single-unit
40
what is a variscosity
swellings of nerve tissue on muscle
41
explain multi-unit smooth muscle
* each cell is innervated - one variscosity per cell
* variable
42
examples of multi-unit smooth muscle
airways, large arteries
43
explain single-unit smooth muscle
* one variscosity supplied multiple cells
* greater diffusion difference
* cells coupled
* syncgronous contraction
44
example of single-unit smooth muscle
gut, uterus
45
two types of nervous tissue
central and peripheral
46
central nervous tissue components
brain and spinal cord
47
peripheral nervous system components
inputs and outputs to body parts
48
function of nervous tissue
information in - integration - information out
49
neuron structure
* cell body
* nerve fibres/processes
* nerve terminals
50
example of a physiological variable
red blood cells
51
examples of physiological states that physiological variables vary by
* sex
* age
* fasted/fed
* exercise
52
what does negative feedback do?
acts to counteract the change in the controlled variable
53
five components of negative feedback
1. controlled variable
2. sensor
3. interator
4. effector
5. compensatory response
54
what occurs in the controlled variable component of negative feedback
deviation in the controlled variable occurs
55
what does the sensor component do in negative feedback
gathers information of controlled variable deviation and sends it to integration
56
what does the integrator component do in negative feedback
it's the nervous system
57
what does the effector component of negative feedback do
recieves information from nervous system and causes compensatory response
58
what does the compensatory response of negative feedback do
brings controlled variable back to normal
59
example of negative feedback
* controlled variable: body temp
* sensor: nerve cells
* integrator: temp control centre
* effector: skeletal muscle
* compensatory repsonse: heat production
60
what does positive feedback do
reinforces change in the controlled variable
61
example of positive feedback
contraction of uterus at childbirth:
* oxytocin release
* contraction of uterine smooth muscle
* moves baby lower
* pressure on cervix
* causes oxytocin release
62
what is pathophysiology
a state in which normal function at any organisational level is disrupted to the extent that normal regulatory and compensatory mechanisms cannot maintain homeostasis
63
five functions of cells
* exchange materials with surrounding environment
* perfom chemical reactions to provide energy
* synthesize cellular components
* sense and respond to changes in surrounding environment
* reproduction
64
name three types of cell
* neuron
* cardiac muscle cell
* gametes
65
one way neurons are adapted for their purpose
contain dendrites and axons
66
one way cardiac muscle cells are adapted for their function
contain gap junctions
67
name one way gametes are adapted for their function
sperm have lots of mitochondria for energy
68
three functions of plasma membrane
* acts as a barrier
* allows communication between internal and external environments
* controls passage of materials
69
what are plasma membranes made of?
phospholipid bilayer and cytocol
70
phospholipid composition
* hydrophyllic phosphate head
* hydrophobic fatty acid tail
71
nucleolus purpose
produce and assemble the cell's ribosomes
72
nucleus purpose
contains dna
73
why does the nucleus contain pores
to allow some substances in such as certain hormones
74
why is the nucleolus important
for ribosomal RNA synthesis which is a crucial stage of protein synthesis
75
what is the endoplasmic reticulum
* a membrane close to the nucleus
* encloses space (lumen)
* continuous with nuclear envelope
76
what is the rough ER
* studded with ribosomes (ie rough)
* therefore important for protein synthesis
77
what is the smooth ER
* no ribosomes (hence smooth)
* lipids
* Ca2+ store
* detox
78
what is the golgi apparatus
flattened sacs between ER and cell membrane
79
golgi apparatus function
processes and packages molecules into vesicles for transport
80
mitochondria function
generates energy (ATP) from glucose
81
what are proteins
chains of amino acids
82
roles of proteins within the cell
* enzymes
* signaling
* structure
83
roles of proteins in the cell membrane
* transport
* structure
84
roles of proteins outside cell
* digestive enzymes
* hormones
85
transcription process
* 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
86
protein syntheis pathway
* Uptake of amino acids in RER - synthesis
* Golgi - packaging
* Vacuoles - storage
* Cell membrane - release
87
cytoskeleton definition
dynamic array of filaments
88
cytoskeleton purpose
* confer shape
* allow movement
89
what is the cytoskeleton composed of
* microfilaments - 8nm
* intermediate filaments - 10nm
* microtubules -25nm
90
what are microfilaments
two helices of F-actin (fibrous)
Formed from G-actin (globular)
91
example of microfilament
actin
92
microfilament function
movement
support for microvilli
93
difference between microfilaments and intermediate filaments
intermediate are stronger and more stable
94
two examples of intermediate filaments
keratin and myosin
95
function of microtubules
* strength
* cell division
* movement
96
blood percentage of total body weight
8%
97
average volume of blood in females
5L
98
average volume of blood in men
5.5L
99
four components of blood
* erythrocytes
* leukocytes
* thrombocytes
* plasma
100
components centrifgued blood divides into
* red layer - 45%
* buffy coat (platelets & leukocytes) - <1%
* plasma - 55%
101
four constituents of plasma
* water
* electrolytes
* nutrients, wastes, gases & hormones
* plasma proteins
102
function of water in plasma
transport medium, carries heat
103
functions of electrolytes in plasma
* membrane excitability
* osmotic distribution of fluid between ECF and ICF
* buffer pH changes
104
function of nutrients, wastes, gases and hormones in plasma
Blood CO2 plays role in acid-base balance
105
what percent of plasma is made up of plasma proteins
6-8%
106
blood pH
7.35-7.45
107
serum
plasma from which fibriogen and other clotting proteins have been removed
108
three main plasma proteins
* albumins
* globulins
* fibrinogens
109
which is the most abundant clotting protein
albumins
110
two functions of albumins
* contribute to colloid osmotic pressure by virtue of their abundance
* transport molecules that are poorly soluble in plasma - bilirubin, salts drugs
111
3 subclasses of globulins
α, β and γ
112
what are α and β plasma proteins produced by
the liver
113
what are γ globulins produced by
lymphocytes
114
function of α/β subclasses
transport molecules (high specificity) also clotting factors
115
functions of α subclass of globulins
Inactive precursors proteins e.g. Angiotensinogen: Converted to angiotensin
116
function of γ subclass of globulins
immunoglobulins - ie antibodies
117
what is fibrinogen
clotting factor
118
what is fibrinogen converted to
fibrin
119
how many erythrocytes per cubic mililitre
5 million
120
what do erythrocytes lack
nuclei, mitochondria, ribosomes
121
structure of erythrocytes
7µm diameter, 2µm thickness, biconcave
122
function of erythrocytes
transport O2 and CO2
123
how does haemoglobin work
* four haem groups
* each can bind to one O2 molecule
124
erythrocyte life cycle
120 days
125
what is erythropoieten (EPO)
chemical produced by kidney wich increases RBC production
126
how many new erythrocytes do we make a day?
about 1 trillion
127
haemopoiesis
production of blood cells
128
how does haemopoiesis work
progressive differentiation:
* begin with undifferentiated pluripotent stem cell
* graducal acquisition of specific characteristics of end cells
129
anemia
below normal oxygen carrying capacity of blood
130
two main causes of anemia
reduced haemoglobin content of red blood cells
reduced blood cell number
131
how can reduced haemoglobin content occur
iron deficiency
132
how can reduced blood cell number occur
* reduced cell production
* increased cell loss - haemolysis ie. too much water in membranes
133
six other causes of anemia
* nutritional anemia
* pernicious anemia
* aplastic anemia
* renal anemia
* hemorrgagic anemia
* hemolytic anemia
134
how does nutritional anemia occur
iron deficiency - can't make sufficient haemoglobin
135
how does pernicious anemia occur
inability to absorb vitamin B12 from gastrointestinal tract due to deficiency of an intrinsic factor
136
how does aplastic anemia occur
failure of the bone marrow to produce enough red blood cells even though all ingredients necessary for erythropoiesis are present eg. chemo
137
how does renal anemia occur
reduced red blood cell production due to impaired EPO synthesis due to kidney disease
138
how does haemorrhagic anemia occur
blood loss
139
how does haemolytic anemia occur
rupture of RBCs:
* malaria invades RBCs and ruptures them
* sickle cell diease - genetic mutation in β-chain of haemoglobin)
140
what do thrombocytes lack
a nucleus
141
what are thrombocytes made from
fragments of megakarocytes
142
how do thrombocytes work (brief)
* release serotonon to vasoconstrict and reduce blood flow to clot area
* secrete growth factors to maintain integrity of blood vessel wall
143
thrombocyte life cycle
survive 5-9 days and are removed from circulation by tissue macrophages
144
thrombopoietin
hormone produced by the liver, increasesnumber of megakarocytes and therefore increases platelet production
145
haemostasis
process of keeping blood within a damaged vessel
146
what are the two steps of platelet production
formation of platelet plug and blood clotting
147
formation of platelet plug steps
* 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
blood clotting steps
* 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
what is the blood clotting cascade
* a series of steps requiring 12 clotting factors
150
two pathways of blood clotting cascade
extrinsic and intrinsic
151
difference between intrinsic and extrinsic pathways og blood clotting cascade
* extrinsic: shorter and faster
* intrinsic: requires more upstream factors
152
chemicals required at several points of blood clotting cascade
Ca2+/PF3
153
what does the final common pathway of the blood clotting cascade involve
* activation of factor X
* conversion of prothrombin to thrombin
* ceaves fibringoen to form fibrin
154
what happens if endothelium is intact (blood clotting)
it releases NO and prostacyclin which inhibit platelet adhesion
155
clot dissolution steps
* 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
clot prevention steps
* tissue Plasminogen Activator (tPA) converts plasminogen in plasmin and prevents inappropriate clot formation
* tPA is used clinically as a clot buster
157
what does thrombodulin do (blood clotting)
* binds thrombin - this preventing fibrinogen conversion
* activates protein C - anticoagulant which inactivates active factors V and VIII
158
what is a thrombus
abnormal intravascular clot attached to a vessel wall
159
what are emboli
freely floating clots
160
four factors that can cause thromboembolism
* 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
haemophilia
excessive bleeding caused by deficiency of one of the factors in the clotting cascade
162
haemophilia A
clotting factor XIII deficiency
163
haemophilia B
clotting factor IX deficiency
164
importance of body fluids
* primary transport system between cells
* large part of internal environment - homeostasis
* fluid composition is critical for cell function
165
three things body fluid transport between cells
* nutrition
* waste
* signals
166
what two main compartments are contained within total body water
* intracellular fluid
* extracellular fluid
167
what two fluid compartments are contained within extracellular fluid
plasma and interstitial fluid
168
total body water percentage for males
60%
169
total body water percentage for females
55%
170
why is the TBW percentage lowe for females than it is for males
females have more fat
171
what is the boundary between intracellular fluid and interstitial fluid
cell membrane
172
cell membrane permeability
| intracellular/interstitial fluids boundary
* selectively permeable
* ion pumps inside membrane to allow transport of certain ions but not others
173
boundary between interstitial fluid and plasma
capillary wall
174
capillary wall permeability
| interstitial fluid and plasma barrier
permeable to small molecules
175
composition of interstitial fluid
* high in Na+
* high in Cl-
* low in K+
176
intracellular fluid composition
* low in Na+ (pump)
* low in Cl-
* high in K+ (pump)
177
osmosis
water moves from a lower solute concentration to a higher solute concentraiton
178
how does water move in osmosis
passively - no energy required
179
what does water move across in osmosis
cell membrane - semipermeable ie. permeable to water but not to solute
180
tonicity
effect of solute concentration on cell volume
181
hypotonic solution
cell gains water and swells
182
hypertonic solution
cell looses water and shrinks
183
fluid repacement method in the case of haemorrhage
replace blood with isotonic saline (0.9% w/v NaCl) - no change in cell volume
184
fluid repacement method in case of diarrhoea
replace water and ions - rehydration salts
185
what does the lymphatic system do
* fluid (lymph) leaks out of cardiovascular system
* lymphatic system returns lymph to the cardiovascular system
186
what are systemic capillaries
capllaries which allow the axchange of materials between blood and body tissues - nutrients, gases (O2 & CO2), water
187
how does lymphatic drainage work
* 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
explanation of Starlings Law
* 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
what happens in the case of liver failure
* 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
normal daily inputs of fluid
* fluid
* food
* metabolism
191
normal daily outputs of fluid
* gut
* urine
* breahing/skin
* sweating
192
normal daily fluid input and output regulation
* fluid ingested and urine are regulated for water balance
* sweating is regulated for heat balance
193
abnormal fluid inputs
* clinical - injection/infusion
* polydipsia - excessive drinking
194
abnormal fluid outputs
* gut - vomiting, diarrhoea
* urine - diabetes insipidus
* skin - burns
* sweating - hyperhydria
* haemorrhage
195
examples of a regulation failure
* polydipsia
* hyperhydria
* diabetes insipidus
196
structure of immune system
a network of cells and tissues
197
3 roles of immune system
* defends body against invading pathogens
* destroys abnormal/mutant cells within the body
* removes 'worn out' cells
198
harmful effects of the immune system
* allergies
* autoimmune dieases
* tissue rejection
199
four types of pathogen
* bacteria
* parasite
* fungus
* virus
200
bacteria example
staphylococcus aureus (causes sepsis)
201
parasite example
tapeworm
202
fungus example
epidermophyton floccosum (athlete’s foot)
203
virus example
polio
204
what tissues are part of the immune system
primary and secondary lymphoid tissues
205
what cells are part of the immune system
* lymphocytes
* granulocytes
* monocytes
* dendritic cells
* natural killer cells
206
three types of granulocytes
* neutriohils
* eosinophils
* basophils
207
what soluble mediators are part of the immune system
cytokines & chemokines
complement proteins
208
central/primary lymphoid tissues
bone marrow and thymus
209
where are B-cells devleoped
bone marrow
210
where are T-cells developed
thymus
211
what are peripheral/secondary lymphoid tissues
* spleen
* lymph nodes
* Gut associated lymphoid tissue
* adenoids
* appendix
* tonsils
212
neutrophil role (3)
* destroy bacteria by phagocytosis
* first defenders on scene of bacterial invasion
* scavenge to clean up debris
213
most abundant leukocyte
neutrophils
214
percentage of leukocytes that are neutrophils
60-70%
215
eosinophilia
increase in circulating eosinophils
216
what is eosinophilia associated with
* allergic reactions such as asthma and hay fever
* internal parasite infections such as worms
217
how do eosinophils deal with parasite infections like worms
they attach to the worm and secrete substances to kill it
218
what percentage of leukocytes is made up of eosinophils
1-4%
219
monocytes development
* 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
how long do monocytes last
can range from several months to years
221
what are dendritic cells
cells similar to monocytes but are more efficient antigen presenting cells
222
what is nonspecific or innate immunity
* phagocytosis and inflammation
* initial and immediate response against invasion by any pathogens
223
four main mechanisms of nonspecific immunity
* physical barrier: skin, mucous membranes
* inflammation and phagocytosis: by neutrophils and macrophages
* interferon
* complement
224
signs of inflammatory response
* redness
* heat
* swelling
* pain
225
3 results of inflammatory response
* destorys or inactivates invaders
* removes debris
* prepares for healing and repair
226
four stages of phagocytosus
* attachment
* internalisation
* degradation
* exocytosis
227
three types of interferon
α, β and γ
228
how does interferon work
* cytokine is realeased by virus-infected cells
* induces expression of enzymes that prevent viral replication
* thus protects other cells from the virus
229
anti-cancer effects of interferon
* slows cell division
* enhances action of NK cells and cytotoxic T cells
230
how do natural killer cells work
* they attack virus-infected cells
* cause lysis via release of perforins
231
name a major source of interferon γ
natural killer cells
232
what is the complement system made up of
over 25 proteins and protein fragments that usually circulate as inactive precursors in the blood
233
how much of the globulin fraction of plasma is made up of the complement proteins
about 5%
234
what happens when the complement cascade is activated
* 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
what is specific immunity
comes into play after nonspecific responses have begin
responds to specific pathofens on second or later exposure
236
four main components of specific immunity
* specificity
* diversity
* memory
* self-tolerance
237
how does specificity work
| specific immunity
* antigen receptors are present on B and T cells
* these bind foreign molecules known as antigens
* antibody-antigen interactions are specific
238
how does diversity work
| specific immunity
the body prossesses millions of lymphocytes that can recognise and respons to millions of antigens
239
how does memory work
| specific immunity
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
how many specific antigen receptors can the average B or T cell have
about 100,000
241
what are plasma cells
short lived cells that produce anti-bodies in blood
242
what are memory cells
long lived cells which have antigen receptors for their specific santigen
243
how does self-tolerance work
| specific immunity
* 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
which type of lymphocyte produces antibodies
B-cells
245
what do B-cells mainly defend against
bacteria, toxins and viruses presnt in body fluids
246
what type of immunity are B-cells responsible for
antibody-mediated or humoral immunity
247
what do T-cells do
* 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
what type of immunity are T cells responsible for
cell-mediated immunity
249
five steps of humoral immunity
1. neutralisation
2. agglutination
3. oposination
4. complement activation
5. enhanced NK cell activity
250
neutralisation
| humoral immunity
antibodies block the activity of a pathogen
251
agglutination
| humoral immunity
multiple pathogens are aggregated by antibody molecules
252
opsonisation
| humoral immunity
pathogens bound by antibodies are more efficiently engulfed by phagocytes
253
complement activation
| humoral immunity
antibodies bound to pathogens activate the complement cascade, resulting in lysis of the cell
254
enhanced NK cell activity
| humoral immunity
abnormal body cells that are bound by antibodies are recognised by NK cells are are subsequently lysed
255
five classes of antibodies
* IgM
* IgD
* IgG
* IgE
* IgA
256
what percentage of T cells are helper T cells
70%
257
how do helper T cells work
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
what kind of action are helper T cells involved in and how
* indirect action
* they stimulate the development of B cells into plasma cells
259
what percentage of T cells are cytotoxic T cells
30%
260
how do cytotoxic T cells work
in an infected cell, Class I MHC molecules present antigen at cell surface so cytotoxic T cells can kill the infected cell
261
what kind of action are Cytotoxic T cells involved in and how?
* direct action
* kill infected cells by lysis
262
two examples of autoimmune dieases
rheumatoid arthritis and multiple sclerosis
263
what happens with rheumatoid arthritis
inflammation of cartilage and bone of joints
264
what happens with multiple sclerosis
T cells attack myelin leading to blurred vision, muscle weakness and ataxia
265
what is AIDS caused by
human immunodeficiency virus (HIV)
266
how does AIDS work
* 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
how does passive diffusion occur
down a concentration gradient
268
what four things is passive diffusion proportional to?
* size of gradient
* membrane surface area
* Permeability of membrane
* O2, CO2, fatty acids, steriods, hormones
269
what is facilitated diffusion
* carrier molecules are present in their resting state in membranes
* binding leads to conformational change in shape
* molecule passes through membrane
270
what does the rate of facilitated diffusion depend on
* numver of carriers in membrane (regulated)
* affinity - same on both sides
* concenraation of substance to be transported
271
why do membranes have ion channels
because ions cannot pass directly through membranes
272
what must occur for ions to pass through ion channels
* 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
what does flux depend on
| ion channels
electrochemical gradient
274
examples of ions that pass through ion channels
* Na+
* K+
* Cl-
275
how does active transport work
* opposes electrochemical gradient
* uses ATP
276
primary active transport
uses energy directly
277
secondary active transport
uses a gradient created by sodium pump
278
sodium pump
Na+/K+/ATPase pump
279
how des a sodium pump work
* 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
Consequences of Na+/K+/ATPase pump
- 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
contrasport
* Na+ moves into cell down gradient
* releases energy
282
example of cotransport
glucose within the gut
283
countertransport
Na+ and (eg.) h+ go in opposite directions
284
electrical driving force of extracellular fluid
cations > anions
means net is positive
285
electrical driving foce of intracellular fluid
anions > cations
meaning net is negative
286
what does electrical driving force depend on
* size of membrane potential
* quantity of charge
287
involuntary muscles
smooth and cardiac
288
connective tissue examples
blood, bone, cartilage
289
nucleus purpose
contains dna
