Transport System Flashcards
1
Q
There are 2 basic mechanisms of transport
A
Passive transport system
Active transport system
2
Q
What is passive transport system
A
Is the movement of substances along concentration gradient or electrical gradient or both (electrochemical gradient)
It is referred to as diffusion or downhill transport and doesn’t need energy
3
Q
Passive transport is the movement of substances from a region of higher concentration to a region of lower concentration T or F
A
True
4
Q
Diffusion can be divided into 3
A
-simple diffusion through lipid layer
- simple diffusion through protein layer
- facilitated or carrier mediated diffusion
5
Q
Simple diffusion through lipid layer
A
Lipid layer of cell membrane allows only lipid soluble substances to pass through it, therefore, diffusion in lipid layer is directly proportional to the solubility of substances in lipids
6
Q
Simple diffusion through protein layer
A
Protein layer is permeable to water soluble substances, mainly electrolytes diffuse through protein layer
7
Q
Explain protein channels or ion channels
A
In the central lipid layer there are some pores, then integral proteins layer come and invaginate these pores from either surface of cell membrane, this pores on central lipid layer and lined with integral protein milecules, these pores are hypothetical pores and form channel for diffusion of water, electrolytes and other substances that can’t pass through lipid layer
8
Q
Characteristics feature of protein channel is
A
Selective permeability
9
Q
Protein channels are named according to the ions that diffuse through it e.g
A
Sodium channels, potassium channels
10
Q
Continously opened protein channel are called
A
Ungated channels
11
Q
Closed protein channels that only open when necessary are called
A
Gated channel
12
Q
Gated channel is divided into 3
A
Voltage gated channel
Ligand gated channel
Mechanical gated channel
13
Q
Gated channel is divided into 3
A
Voltage gated channel
Ligand gated channel
Mechanical gated channel
14
Q
Voltage gated channels
A
Channels that open whenever there is change in electrical potential
15
Q
An example of voltage gated channel is excitation contraction coupling, explain
A
The action potential spreads through transverse tubules of sacrotubular system where action potential reaches cristernae, large number of calcium ions diffuse from cisternae into sacroplasm
16
Q
An example of ligand gated channels is the transmission of impusle through neuromuscular junctions
A
Acethylcholine is released from vesicle and passes through pre synaptic membrane to the synaptic cleft causing opening of sodium channels in the post synaptic membrane and sodium ions diffuse into neuromuscular structures from ECF
17
Q
What are mechanically gated channels
A
They are channels that open due ti mechanical factors
18
Q
An example of mechanically gated channel is that in
A
in pecinian corpuscles, haircells of organs of corti and vestibular apparatus
19
Q
Explain hair cells of organ of corti as a mechanically gated channel
A
Sound waves causes movement of cilia in hair cells which causes opening of potassium channels leading to development of receptor potassium
20
Q
Facilitated diffusion is faster than simple diffusion T or F
A
T
21
Q
Glucose and amino acids are transported through facilitated diffusion, why
A
Because the diameter of the molecules are larger than hat of the channels so they can’t transport through the channels without help
22
Q
In facilitated diffusion, some changes occur in carrier protein which results to
A
The molecule reaching the other side of cell membrane
23
Q
What are the special types of passive transport
A
Bulk flow
Filtration
Osmosis
24
Q
What is bulk flow
A
It is the movement of large molecules of substances from a region of higher pressure to a region of lower pressure
25
Examples of bulk flow and explain
Exchanged of gases within respiratory membrane of lungs
1.Partial pressure of oxygen is greater in alveolar air than in alveolar blood capillary so oxygen moves from air yo capillary
2.partial pressure in Co2 is more in blood than alveoli so Co2 moves from blood to alveoli
26
What is Filtration
It is the movement of water and solute from a region of high hydrostatic pressure to a region of low hydrostatic pressure
27
Where is Filtration process seen
At the arterial end of capillaries where movement of fluid occurs along with dissolved substances from interstitial fluid
At the glomeruli of kidney
28
What is osmosis
It is the movement of water or any other solute from a region of low conc of solute to higher concentration of solute
29
In osmosis, semi permeable membrane of water allows passage of water and other solvents but not solute T or F
T
30
Osmosis depends on
Osmotic pressure
31
What is osmotic pressure
R3ssure created by solutes in a fluid
32
During osmosis, the solute in area of higher concentration get dissolved in solvent creating a pressure called______________ which prevents
Osmotic pressure, further movement of solvent
33
What is reverse osmotic pressure
It is the process by which water or other solutes flow in reverse direction (from higher concentration to lower conc) if external pressure is applied on the High concentration
34
Oncotic pressure is also called
Colloidal osmotic pressure
35
What is oncotic pressure and what is normal oncotic pressure
Oncotic pressure is part of osmotic pressure created by larger colloidal substances esp proteins
25mmHg
36
Albumin creates _________ percent of osmotic pressure
70
37
Osmosis can be prevented by
Applying pressure to mole conc
38
Types of osmosis
Endosmosis- movement of water into cell
Exosmosis- movement of water out of cell
39
What is active transport
Is the movement of substances against chemical electrical or electrochemical gradient
40
Active transport is also called
Uphill transport
41
Active transport requires energy that is derived by
Breaking down high energy compounds such as ATP
42
Differences between passive and active transport
The definition
-Passive transport is also called downhill moment while active is called uphill movement
-passive doesn't require energy while active does
- substances transported by passive include oxygen, co2, water, and electrolytes while active is ionic substances such as sodium, potassium, hydrogen, chlorine and non ionic substances such as - glucose, amino acids, urea
43
Difference between active transport and facilitated diffusion
-carrier proteins pf active transport require energy while that of facilitated diffusion doesn't
- substances are transported against conc gradient in active while not in facilitated diffusion
44
Carrier proteins of active transport are
Uniport
Symport or antiport
45
What is a uniport
It is a carrier protein that carriers only one substance in a single direction
46
Uniport is also called
Uniport pump
47
Carrier protein that transports two or more substances in the same direction is caller
Symport pump
48
What is symport pump
It is a carrier protein that transports two or more substances in the dame direction
49
What is symport pump
It is a carrier protein that transports two or more substances in the dame direction
50
The carrier protein that transports two different substances in opposite directions is called
Antiport
51
Antiport exchange one substance for another T or F
T
52
Types of active transport
Primary and secondary
53
What is primary active transport
It is a type of transport mechanism in which energy is liberated directly from atp
Substances like sodium, potassium, calcium and hydrogen can be transported
54
Sodium potassium pump is also called
Na+-K+ ATPase pump or Na+-K+ ATPase
55
Explain primary active transport of sodium and potassium
Sodium and potassium are transported in cell membrane using sodium potassium pump
Ot transports sodium from inside to outside cell and potassium from outside to inside cell
56
The Na+-K+ pump is responsible for
Distribution of sodium and potassium ions across cell membrane and the development of resting membrane potential
57
Alpha subunit of Na-K+ pump has 6 sites
-Three sites for sodium on the inner surface (towards cytoplasm) of the protein molecule
-Two sites for potassium on the outer surface( towards cytoplasm) of the protein molecule
-One site for the enzyme adenine triphosphatase(ATPase) near the site for sodium
58
Mechanism of action of Na+-K+ pump
- three sodium ions attach to the receptor sites on the inner surface of protein molecule and two potassium attach to the receptor sites on the outer surface of protein molecule
- the binding of sodium and potassium To their receptor sites activates enzyme ATPase
- ATPase ......... ATP to ADP with the release of high energy phosphate
- then the release of this energy causes like a conformational change in the structure of carrier protein
- the outer surface faces teh inside of the cell and the inner surface faces the outside of the cell
- release takes place and sodium is released outside of cell and potassium inside of cell
59
Hydrogen is actively transported across the cell by carrier protein called
Hydrogen pump
60
Hydrogen pump obtains energy from __________ by activity of _______
ATP,ATPase
61
Hydrogen pump are present in two important organs
Stomach- pumps the parietal cell of gastric glands
Kidney- pumps the epithelial cells of distal convulated tubule
62
When sodium is transported by a carrier protein, another substance us transported by that protein either in the same or difffernt direction T or F
T
63
Transport of sodium us coupled with transported of another substance T or F
T
64
Two types of secondary active transport
Cotransport
Countertransport
65
What is sodium cotransport
Sodium co transport is a process by which along with sodium, another substance ie being transported by carrier protein, symport
66
Energy needed for movement of sodium in sodium co transport is gotten from ATP, while the energy released from movement of sodium is used for ________________
Movement of another substance
67
Examples of substances transported by sodium co transport are
Glucose, amino acids, iodine, iron, chlorides, urate
68
Carrier proteins of sodium co transport
It has 2 receptor sites
One for binding of sodium and the other for binding of another substance
69
Sodium co transport of glucose occurs during
Absorption of glucose from small intestine and reabsorption of glucose from renal tubule
70
Sodium co transport of amino acids
Carrier proteins of amino acids is different from that of glucose
For amino acids, there are 5 sets of Carrier protein, each one carriers different amino acids depending on the molecular weight of the acid
71
Sodium co transport of amino acids also occurs in the
Absorption of amino acids from intestine and reabsorption from renal tubule
72
What is the carrier protein for sodium cotransport and sodium countertransport
Symport, antiport
73
What is sodium calcium counter transport
In this transport, sodium and calcium move in opposite directions with the help of a carrier protein
74
Sodium hydrogen countertransport
In this hydrogen ions are exchanged for sodium ions
It occurs in the renal tubular cells
75
In sodium hydrogen countertransport, sodium moves from _______________ to ________ while hydrogen moves from ________ to ________
Tubular lumen to tubular cells, tubular cells to tubular lumen
76
Other countertransport systems are
Sodium magnesium
Sodium potassium
Calcium magnesium
Calcium potassium
77
Special type of active transport- vesicular active transport are
Endocytosis
Exocytosis
Transcytosis
78
What is endocytosis
It is teh process by which macromolecules enter the cell
79
There are three types of endocytosus
Pinocytosis
Phagocytosis
Receptor mediated endocytosis
80
What is pinocytosis
It is the process by which macromolecules like antigens and bacteria are taken into the cell
81
Pinocytosis is also called
Cell drinking
82
The mechanism of pinocytosis
- macromolecules bind to the outer surface of cell membrane in form of droplets
- the cell membrane evaginate these droplets
-droplets are engulfed by cell membrane
-droplets are transformed to vesicles or vacoules called endosom3s
-tje primary lysosome is the cytoplasm attaches to endosome to form secondary lysosomes
- hydrolytic enzym3s in secondary lysosomes activare digestion and degradation
83
What is phagocytosis
T is the process by which particles larger than macromolecules are engulfed by the cell
84
Phagocytosis is also called
Cell eating
85
Larger bacteria, larger antigen, larger foreign body are all taken in by
Phagocytosis
86
Mechanism of phagocytosis
-once bacteria or foreign body enters the body, the phagocytic cells produce a cytoplasmic extension called pseudopodium
- then the particles are engulfed and converted to endosome like vacoule- called phagosome
- the ohagosome move to the interior of the cell
- primary lusosome fuses with phagospme to form secondary lysosome
- the hydrolytic enzymes in secondary lysosome cause degradation and digestion of phagosomal Content
87
What is Receptor mediated endocytosis
It is the transport of macromolecules with the help of receptor protein
88
The surface of cell membrane have some pits with receptor proteins called ___________, together with the receptor protein, the pits are called _________ which are involved in receptor mediated endocytosis
Clathrin, receptor coated pit
89
Receptor mediated endocytosis is induced in substances like ______
Ligands
90
Ligand molecules approach the cell and bind to lreceptor in the pit and forms____________
Ligand-receptor complex
91
Mechanism of receptor mediated endocytosis
-it is induced ins substances like ligand
- ligand molecules move to the cell and attach to the receptor proteins in the pit to form a ligand protein complex
- ligand receptor complex get aggregated in the pit, the coated pit becomes detached from the cell membrane and becomes the coated vesicle, which forms the endosome
-the endosome moves to the interior of the cell and attaches to primary kysosome to form secondary lysosome
- hydrolytic enzymes in secondary lysosomes are activated and causes release of ligands into cytoplasm
- receptor may move to a new pit of the cell membrane
92
Caveolin coated pits are concerned with
The transport of vitamins into the cell
93
What is exocytosis
It is the process by which substances are extruded from the cell without passing through cell membrane
94
Exocytosis is involved in the release of
Secretory products of the cell
95
Mechanism of exocytosis
-It is used in the release of secretory products from the cell
- secretory products are stored in form of secretory vesicles in cytoplasm
- when needed, the secretory vesicle moves to the cell membrane and fuses with cell membrane
- later contents of vesicle are released outta cell
96
Calcium plays an important role in the release of secretory substances such as
Neurotransmitters
97
Role pf calcium in exocytosis
Calcium enters the cell and causes exocytosis, however the exact mechanism of exocytosis is unknown
98
What is transcytosis
It is a transport mechanism in which extracellular macromolecules enter the cell through one side, pass across cytoplasm and exit through the other side
99
Mechanism of transcytosis
-The cell encloses the extracellular substances ny invagination of cell membrane to form vesicle
- the vesicle moves across the cell and is thrown to opposite side of cell membrane by exocytosis
- transcytosis also requires a receptor coated pit, coated with caveolin instead of clathrin
100
Transcytosis is also called
Vesicle trafficking / cytopempsis
101
Transcytosis plays an important role in
The Selective transport of substances across two environments without any distinct change in the composition of environmemt
102
An example of transcytosis movement
Transport of proteins from capillary blood to interstitial fluid across endothelial of capillary
103
HIV is transported by transcytosis T or F
T
104
HIV is transported by transcytosis T or F
T
105
What are molecular motors
They are protein bases molecular machines that perform intracellular movement of substances in response to stimuli
106
Function of molecular motors
-Transport of synaptic vesicles containing neurotransmitters from nerve cell body to synaptic terminal
- role in cell division for moving chromosomes
- transport of viruses and toxins to the interior of cells for their own detriment
107
Types of molecular motors
Kinesis
Dynein
Myosin
108
Kinesin transports substances by moving over the
Microtubule
109
Kinesin molevule has two heads and one tail portion, one head ______________ to obtain _____________ which the other head uses to move and causes movement of the entire kinesin
Hydrolysws ATP to obtain energy
110
End portion of tail of kinesin carries
The cargo- substances to be transported
111
Kinesin is responsible for ________________ transport
Anterograde transport- transport of substances to the positive end of microtubule
112
Dynein is similar to kinesin and transports substances over microtubules T or F
T
113
Dynein is responsible for __________ transport
Retrograde transport- transport of substances t9 the negative side of mircotubule
114
Myosin transports substances by moving over
Microfilaments
115
Myosin are divided into _____ types based on amino acid sequence
18
116
Myosin II and V are functionally significant, myosin II is involved in _____________ and myosin V is involved in ___________
Muscle contraction, transport of vesicles
117
Abnormalities of sodium potassium pump can occur due to
Altered number or change in the functional status of Na+/K+ pump
118
Abnormalities of sodium potassium pump can lead to
- cardiac failure du3 to decreased number of Na+/K+ pump in the myocardium
- hypertension due to increased number of Na+/K+ pump in renal tubule, increasing the absorption of sodium causing hypertension
119
Ion channel diseases can be called
Channelopathies
120
Sodium channel diseases
Muscle spasm
Liddle's syndrome- characterised by increased osmotic pressure and hypertension due to dysfunction of sodium channels in the kidney
121
Potassium channels diseases include:
Cardiac failure
Inherited deafness
Epileptic seizures in newborns
