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MB prep: Physiology > Cell physiology > Flashcards

Cell physiology Flashcards

1
Q

What is the cell membrane?

A

Also called the plasma membrane or plasmalemma, it is a semipermeable membrane that separates ECF from ICF. It is the outermost limit of the cell.

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2
Q

What is the thickness of the cell membrane?

A

75-100Ao

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3
Q

What are the composition of the cell membrane

A

Proteins (55%)
Lipids (40%)
Carbonhydrates (5%)

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4
Q

What are the 3 layers of the cell membrane

A

1 central electron lucent layer
2 electron dense areas

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5
Q

what constitutes the electron lucent layer of cell membrane?

A

proteins+electron

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6
Q

what constitutes the electron dense layer of cell membrane?

A

electrons

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7
Q

Draw a cell membrane

A

refer to drawing 8 in booklet

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8
Q

List the models of the cell membrane.

A

Danielli Davson model
Unit membrane model
Fluid mosaic model

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9
Q

Describe the Danielli Davson model

A

(1935) it is a sandwich of lipids covered at both sides

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10
Q

Describe the Unit membrane model

A

(1967) By JD Robertson on basis of electron microscopy studies

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11
Q

Describe the fluid mosaic model

A

(1972) By SJ Singer and GL Nicolhson. They said the membrane is a fluid (Lipid) with the proteins floating in and on it.

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12
Q

What are the 2 major lipids in the cell membrane

A

Cholestrol and Phospholipids

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13
Q

lList the examples of phospholipids of the cell membrane

A

Aminophospholipids, sphingomyelins, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidylinotisol.

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14
Q

Draw the arrangement of phospholipids in the cell membrane.

A

check booklet for drawing 9

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15
Q

Describe the structure of phospholipid arrangement.

A

They are arranged in 2 layers towards the middle, with the tails (Fatty acid made, hydrophobic i.e nonpolar) facing each other in dynamic movements. and the Heads(Hydrophilic i.e polar, phosphate made) facing outwards the cell, and into the cell.

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16
Q

What is the function of cholestrol in the cell membrane

A

Cholestrol helps to pack the soft phospholipids in the membrane
Cholestrol is responsible for cell integrity

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17
Q

What are the functions of the lipid layer of the cell membrane.

A

It only allows fat soluble substances like oxygen, CO2 an alcohol across, but it doesn’t allow substances like glucose or electrolytes across. (It’s selectively permeable).
They form a water barrier in the cell membrane, not allowing water outside the cell into the cell.

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18
Q

What are the functions of the protein layer of the cell membrane.

A

They protect the lipid central layers.
They are electron dense and cover both electron dense layers

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19
Q

The protein layers of the cell membrane formed by

A

glycoproteins

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20
Q

Protein molecules are classified into what categories

A

Integrated (Transmembrane proteins)
Peripheral proteins (peripheral membrane proteins)

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21
Q

What are integral proteins?

A

They’re proteins that pass through the cell membrane. They majorly function as channels and receptors. They are tightly bound to the cell.

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22
Q

List examples of integral proteins

A

Cell Adhesion Molecules (CAMs)
Cell junction proteins
Some transport proteins
Channel Proteins
Hormone receptors
Antigens
Enzymes

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23
Q

What cell adhesion molecules?

A

They are responsible for the attachment of cells to their neighbors or to basal lamina (or basal membrane). CAMs form the important structures of intercellular connections and are responsible for structural organization of tissues. They are essential in the recruitment of inflammatory cell to the epithelium for healing.

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24
Q

List types of Cell adhesion molecules

A

Cadherins: they form molecular limb junctions between neighbouring cells. They form adherens junction and desmosome.
Integrins: Form focal adhesion and hemidesmosome.
IgG super family: CAMs in the CNS
Selectins: are responsible for the attachment of cells to their neighbors or to basal lamina (or basal membrane). CAMs form the important structures of intercellular connections and are responsible for structural organization of tissues.

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25
Q

What are peripheral proteins

A

They do not run through the cell membrane, they stud on either the inner or outer wall of the cell membrane. They are loosely bound by lipids on the cell membrane and thus readily come off

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26
Q

What are examples of peripheral proteins

A

Peripheral receptors
Enzymes
Transport proteins

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27
Q

What are some peripheral proteins you know?

A

Glycosyc phosphatidylinotisol & Alkaline phosphatiso

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28
Q

List the functions of proteins in cell membranes

A

Structural proteins(lipoproteins and glycoproteins)
Transport proteins
Pumps(For transporting ions across the membrane)
Receptor proteins(serve as receptor sites for NTs and hormones)
Enzymes control metabolic actions
Antigens (antibody functions)
Ion channels (esp. peripheral proteins)
CAMs (attachment of cells to basal lamina)

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29
Q

What is the name of the loose carbohydrate coat over the cell?

A

glycocalyx

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30
Q

What are the functions of carbonhydrates in the cell membrane.

A

They act as receptors to some hormones.
They are negatively charged and thus do not allow negatively charged particles in or out of the cell.
The glycocalyx of neighbouring cells helps in the tight fixation of cells.

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31
Q

What are functions of the cell membrane?

A

Provide anchoring sites for filaments of the cytoskeleton.
Cell recognition
Protection of the cell cytoplasm and organelles
Selective permeability
Absorbic function
Excretory function
Exchange of gases
Maintainance of the cell shape &size.

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32
Q

Describe the cytoplasm

A

The cytoplasm is a jelly-like substance with 90-95% water. It gives a medium for chemical reactions. It has 2 parts: Ectoplasm and Endoplasm

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33
Q

The clear liquid portion of the cytoplasm is called what

A

Cytosol

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34
Q

What is the ectoplasm

A

Peripheral part of the cytoplasm, in close proximity to the cell membrane

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35
Q

What is the endoplasm

A

Inner part of the cytoplasm, between nucleus and ectoplasm.

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36
Q

What is the endoplasmic reticulum

A

It’s is a network of interconnected membranes that form flattened sacs, canals and fluid filled vessicles.

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37
Q

What is the E.R covered with

A

by a limiting membrane made of proteins and bi-layered lipids.

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38
Q

What connects the nucleus to the cell membrane

A

The lumen of the E.R

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39
Q

What organelles lumen is scattered in the cytoplasm and acts as a tubular lumen that connects two organelles in the cell.

A

E.R

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40
Q

What is the diameter of the ER lumen

A

400-700Ao

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41
Q

Describe the rough endoplasmic reticulum

A

AKA granular endoplasmic reticulum, it earns it’s name due to it’s rough or beady appearance (due to the attachment of granular ribosomes). It is vesicular or tubular in structure.

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42
Q

explain the protein synthesis function of the rough endoplasmic reticulum

A

Synthesis of proteins: Ribosomes first arrange the proteins and send them to the rough ER where carbohydrates are added to form glycoproteins and glycosylated proteins and arranged as reticular vesicles,. Most of these vesicles are then transported to the golgi body for further processing. Only few of the vesicles are sent to other cytoplasmic bodies.

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43
Q

What are the functions of the rough ER

A

Synthesis of proteins
Degradation of worn out organelles

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44
Q

Explain the ‘degradation of worn out organelles’ function of rough ER

A

It wraps itself around the wornout organelles and forms a vacuole which is often called the autophagosome. Autophagosome is digested by lysosomal enzymes.

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45
Q

Describe the smooth ER

A

AKA agranular reticulum. It is not attached to any ribosomes. It is formed by many interconnected tubules. So, it is also called tubular endoplasmic reticulum.

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46
Q

List the functions of the smooth ER

A

Synthesis of lipids and steroids
Role in cellular metabolism
Storage and metabolism of calcium
Catabolism and detoxification of toxic substances

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47
Q

Explain the ‘synthesis of lipids and steroids function’ of smooth ER

A

it’s responsible for synthesis of non-protein substances such as cholesterol and steroid. This type of endoplasmic reticulum is abundant in cells that are involved in the synthesis of lipids, phospholipids, lipoprotein substances, steroid
hormones, sebum.

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48
Q

Explain the ‘Role in cellular metabolism’ function of smooth ER

A

The outer surface of the smooth endoplasmic reticulum contains many enzymes which are involved in various metabolic processes of the cell

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49
Q

Explain the ‘storage and metabolism of calcium’ function of smooth ER

A

it’s the major site of storage and metabolism of calcium. In skeletal muscle fibers, it releases calcium which is necessary to trigger the muscle contraction.

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50
Q

Explain the ‘catabolism and detoxification’ function of smooth ER

A

it’s concerned with catabolism and detoxification of toxic substances like some drugs and carcinogens (cancer-producing substances) in the liver.

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51
Q

Describe the Golgi apparatus

A

is a membrane-bound organelle, involved in the processing of proteins. It is present in all the cells except red blood cells. Usually, each cell has one Golgi apparatus. Some of the cells may have more than one Golgi apparatus.

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52
Q

The golgi body was named after whom?

A

It is named after the discoverer Camillo Golgi

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53
Q

Each golgi body has 5 to 8 flattened membranous sacs called what?

A

cisternae.

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54
Q

What are the 2 faces of the golgi body?

A

Cis- face & Trans-face

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55
Q

The reticular vesicles enter through which face of the golgi body

A

The Cis-face because it faces the ER.

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56
Q

The processed materials exit through which face of the golgi apparatus?

A

The trans face, because it faces the cell membrane

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57
Q

List the functions of the golgi body.

A

> Processing,
packaging,
labelling and delivery,
of proteins and lipids. [PPLD]

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58
Q

Explain the ‘processing of materials’ function of golgi body

A

Vesicles containing glycoproteins and lipids are
transported into Golgi apparatus. Here, the glycoproteins and lipids are modified and processed

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59
Q

Explain the ‘packaging of materials’ function of golgi body

A

This part is AKA the post office of the cell. Here the processed materials are packed in the form of
secretory granules, secretory vesicles and lysosomes,which are transported either out of the cell or to another part of the cell.

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60
Q

Explain the ‘Labeling and delivery’ part of the golgi body.

A

It is AKA the shipping department of the cell. The Golgi apparatus sorts out the processed and
packed materials and labels them (such as phosphate group), depending upon the chemical content for delivery (distribution) to their proper destinations.

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61
Q

Describe Lysosomes

A

AKA the garbage system of the cell, their main function is their degradation activity. About 50 different hydrolytic enzymes, known as acid hydroxylases are present in the lysosomes. They have thick membranes(bilayered lipids) to contain those enzymes.

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62
Q

What are the types of lysosomes?

A

Primary and Secondary

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63
Q

What are primary lysosomes

A

Lysosomes that contain hydrolytic enzymes but remain inactive.

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64
Q

What are secondary lysosomes

A

Lysosomes that are now active, fused with endosome or phagosome.

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65
Q

What does Ribonuclease digest

A

RNA

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66
Q

What does deoxyribonuclease digest

A

DNA

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67
Q

What does protease digest

A

proteins into amino acids

68
Q

What do lipases digest

A

lipids into fatty acids and glycerides

69
Q

What do amylases digest

A

hydrolyze polysaccharides into glucose

70
Q

What do nucleases digest

A

nucleic acids into mononucleotides

71
Q

What do Collagenase digest

A

Collagen

72
Q

What do glycocydease digest

A

complex carbs

73
Q

What do Phosphatease digest

A

phosphate

74
Q

What do gangliosidases digest

A

Gangliosides

75
Q

list all 10 examples of lysosomal enzymes

A

ribonuclease
deoxyribonuclease
gangliosidase
glycocydease
phosphatase
lipases
amylases
nucleases
collagenases

76
Q

List the lysosome storage diseases

A

Tay sachs
Fabry

77
Q

What causes Tay sachs

A

Hexoamimidate deficiency

78
Q

what causes Fabry

A

alpha tellanocytose A deficiency

79
Q

List functions of the lysosomes

A

Degradation of macromolecules
Degradation of worn­out organelles
Removal of excess secretory products
Secretion of perforin, granzymes, melanin and serotonin

80
Q

Explain the ‘Degradation of macromolecules’ part of lysosomal function

A

Macromolecules are engulfed by the cell by means of endocytosis. The primary lysosome fuses with the phagosome or endosome to form the secondary lysosome. The pH in the secondary lysosome becomes acidic and the lysosomal
enzymes are activated. The bacteria and the other
macromolecules are digested and degraded by these enzymes. The secondary lysosome containing these degraded waste products moves through cytoplasm and fuses with cell membrane. Now the waste products are eliminated by exocytosis.

81
Q

Explain the ‘Degradation of worn-out organelles’ part of lysosomal function

A

The rough endoplasmic reticulum wraps itself around the worn-out organelles like mitochondria and form the vacuoles called autophagosomes. One primary lysosome fuses with one autophagosome to form the secondary lysosome. The enzymes in the secondary lysosome are activated. Now, these enzymes digest the contents of autophagosome.

82
Q

Explain the ‘Removal of excess secretory products in the cells’ part of lysosomal function

A

Lysosomes in the cells of the secretory glands remove the excess secretory products by degrading the secretory granules.

83
Q

Explain the ‘Secretion of perforin, granzymes, melanin and serotonin’ part of lysosomal function

A

lysosomes having secretory function called secretory lysosomes are found in some of the
cells, particularly in the cells of immune system.

84
Q

What is the function of perforin.

A

Lysosomes in the cytotoxic T lymphocytes and
natural killer (NK) cells secrete perforin and
granzymes, which destroy both viral-infected
cells and tumor cells. Perforin is a pore-forming
protein that initiates cell death.

85
Q

What is the function of granzymes

A

Granzymes belongto the family of serine proteases (enzymes that dislodge the peptide bonds of the proteins) and cause the cell death by apoptosis

86
Q

What is the function of Melanin

A

Secretory lysosomes of melanocytes secrete
melanin

87
Q

What is the function of serotonin

A

secretory lysosomes of mast cells secrete
serotonin, which is a vasoconstrictor substance
and inflammatory mediator.

88
Q

Describe peroxidases

A

are the membrane limited vesicles like the lysosomes. Unlike lysosomes, peroxisomes are pinched off from endoplasmic reticulum and not from the Golgi apparatus. Peroxisomes contain
some oxidative enzymes.

89
Q

What are some of the oxidative enzymes in peroxidases

A

catalase, urate oxidase and D-­amino acid oxidase

90
Q

List the functions of peroxisomes

A

.Breakdown the fatty acids by means of a process
called beta­oxidation: This is the major function
of peroxisomes
.Degrade the toxic substances such as hydrogen
peroxide and other metabolic products by means
of detoxification. A large number of peroxisomes
are present in the cells of liver, which is the major
organ for detoxification
.Form the major site of oxygen utilization in the
cells
.Accelerate gluconeogenesis from fats
.Degrade purine to uric acid
.Participate in the formation of myelin
.Play a role in the formation of bile acids.

91
Q

Describe CENTROSOME AND CENTRIOLES

A

Centrosome is the membrane-bound cellular organelle situated almost in the center of cell, close to nucleus. It consists of two cylindrical structures called centrioles which are made up of proteins. Centrioles are responsible for the movement of chromosomes during cell division and the formation of cilia and flagella.

92
Q

Draw a mitochondria

A

CHECK BOOKLET FOR DRAWING 10

93
Q

Describe the mitochondria

A

It is a rod shaped membrane bound organelle with a diameter of 0.5-1m(mew). The permeable outer cell membrane encloses the organelle and has enzymes like acetyl-COA synthase, glycerol phosphate and acetyl transferase. The semi-permeable inner cell membrane has folded membranes called cristae.

94
Q

What is the the significance of the cristae in mitochondria

A

It contains enzymes for respiration. Oxidative phosphorylation occurs here.

95
Q

Explain oxidative phosphorylation.

A

Oxidative phosphorylation is a metabolic process that occurs in mitochondria where energy is generated from the electron transport chain and used to produce ATP from ADP.

96
Q

Where does the mitochondria originate from embryologically

A

ovum

97
Q

Functions of the mitochondria are?

A

Generation of energy
Detoxification
Neutralization of free radicals
Apoptosis
Synthesis of ATP

98
Q

Explain the ‘Generation of energy’ function of mitochondria

A

The energy is produced during the oxidation of digested food particles like proteins, carbohydrates and lipids by the oxidative enzymes in cristae.

99
Q

Explain the ‘Detoxification’ function of mitochondria

A

enzymes in the mitochondria cytochrom oxidase system (P240 oxidase system) such as superoxide dismutase, glutathione peroxidase, and catalase detoxify toxins and free radicals

100
Q

explain the ‘neutralization of free radicals’ function of mitochondria

A

NAD PRODUCED BY THE MITOCHONDRIA functions to mop off free radicals, NAD+FREE RADICAL=NADH

101
Q

Explain the “Apoptosis” function of mitochondria

A

Cytochrome C and second mitochondria-derived activator
of caspases (SMAC)/diablo secreted in mitochondria are
involved in apoptosis ( cell death)

102
Q

explain the ‘synthesis of ATP’ function of mitochondria

A

Through oxidative phosphorylation, ATP is synthesized from ADP

103
Q

Describe cytoskeletons

A

it’s the cellular organelle present throughout the cytoplasm. It determines the shape of the cell and gives support to the cell. It is a complex network of structures with varying sizes. In addition to determining the shape of
the cell, it is also essential for cellular movements and the response of the cell to external stimuli.

104
Q

What are the 3 components of cytoskeleton

A

Microtubule
Intermediate filaments
Microfilaments

105
Q

Describe the micotubules

A

Microtubules are the straight, hollow and tubular structures of the cytoskeleton. These organelles without the limiting membrane are arranged in different bundles. Each tubule has a diameter of 20 to 30 nm Structurally, the microtubules are formed by bundles of globular protein called TUBULIN.

106
Q

What are the functions of microtubules

A

Determine the shape of the cell
Give structural strength to the cell
Act like conveyer belts which allow the movement of granules, vesicles, protein molecules and some organelles like mitochondria to different
parts of the cell
Form the spindle fibers which separate the chromosomes during mitosis
Are responsible for the movement of centrioles and the complex cellular structures like cilia.

107
Q

Describe intermediate filaments

A

Intermediate filaments are the structures that form a network around the nucleus and extend to the periphery of the cell. Diameter of each filament is about 10 nm. The intermediate filaments are formed by rope­like polymers, which are made up of FIBROUS PROTEINS.

108
Q

What are the functions of intermediate filaments

A

Intermediate filaments help to maintain the shape of the cell.
Connect the adjacent cells through desmosomes.

109
Q

What are the subclasses of intermediate filaments

A

Keratins (in epithelial cells)
Glial filaments (in astrocytes)
Neurofilaments (in nerve cells)
Vimentin (in many types of cells)
Desmin (in muscle fibers).

110
Q

Describe microfilaments

A

Microfilaments are long and fine thread­like structures with a diameter of about 3 to 6 nm. These filaments are made up of non-tubular contractile proteins called ACTIN and MYOSIN. Actin is more abundant than myosin.
The microfilaments present in ectoplasm contain only actin molecules and those present in endoplasm contain both actin and myosin molecules.

111
Q

What are the functions of microfilaments

A

Give structural strength to the cell
Provide resistance to the cell against the pulling
forces
Are responsible for cellular movements like
contraction, gliding and cytokinesis (partition of
cytoplasm during cell division).

112
Q

Describe the nucleus

A

The nucleus is a spherical organelle that is present in eukaryotic cells with a diameter of 10-22 mew. It is surrounded by a double membrane known as the nuclear envelope, which contains nuclear pores that allow for the exchange of materials between the nucleus and the cytoplasm. The nucleus contains most of the genetic material of the cell in the form of chromatin, which is made up of DNA and associated proteins. Within the nucleus, there is a distinct region called the nucleolus, where ribosomal RNA is synthesized and assembled into ribosomes.

113
Q

What are the functions of the nucleus

A

Synthesis of RNA
Sending genetic instruction to cytoplasm for protein synthesis
Formation of subunits of ribosomes
Control of cell division
Storage of hereditary information in genes (DNA)

114
Q

What are the types of RNA

A

messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)

115
Q

Explain mRNA

A

Messenger RNA carries the genetic code of the amino acid sequence for synthesis of protein from the DNA to the cytoplasm.

116
Q

Explain tRNA

A

Transfer RNA is responsible for decoding the genetic message present in mRNA.

117
Q

Explain rRNA

A

Ribosomal RNA is present within the ribosome and forms a part of the structure of ribosome. It is responsible for the assembly of protein from amino acids in the ribosome

118
Q

Explain Transcription

A

Transcription is when RNA is synthesized from DNA by RNA polymerase, using a DNA template, producing an RNA molecule that carries the same genetic information.

119
Q

Explain translation

A

Translation is the process by which ribosomes read the genetic information in mRNA and synthesize a protein by linking amino acids together in a sequence dictated by the mRNA template.

120
Q

Differentiate between Cilia and flagella

A

Structure: Cilia are typically shorter and more numerous than flagella, and they are generally found on the surface of cells in large numbers.
Function: Cilia are involved in a variety of functions, including movement of substances across cell surfaces, sensory perception, and locomotion of certain cells. Flagella are primarily involved in cell movement, such as the movement of sperm cells.
Location: Cilia are found on the surface of a variety of cells, including those in the respiratory tract, oviducts, and fallopian tubes. Flagella are found on the surface of sperm cells and certain types of bacteria.

121
Q

Describe the ribosomes

A

Ribosomes are the organelles without limiting membrane. These organelles are granular and small dot-like structures with a diameter of 15 nm. Ribosomes are made up of 35% of proteins and 65% of RNA. RNA present in ribosomes is called ribosomal RNA (rRNA). Ribosomes are concerned with protein synthesis in the cell.

122
Q

What are the 2 types of ribosomes

A

Ribosomes that are attached to rough endoplasmic reticulum
Free ribosomes that are distributed in the cytoplasm.

123
Q

What are the functions of ribosomes

A

Ribosomes attached to rough endoplasmic reticulum are involved in the synthesis of proteins such as the enzymatic proteins, hormonal proteins, lysosomal proteins and the proteins of the cell membrane.
Free ribosomes are responsible for the synthesis of proteins in hemoglobin, peroxisome and mitochondria.

124
Q

Describe vacoules

A

They are sacs formed by the pinching in of the cell membrane, they are very important in phagocytosis.

125
Q

Outline the percentage chemical composition of the cell

A

Water - 70-80%
Proteins - 10-15%
Lipids - 2-5%
Carbohydrates - 1-2%
Nucleic acids - 1-2%
Inorganic ions - <1%

126
Q

What are cell junctions

A

Cell junction is the connection between the neighboring cells or the contact between the cell and extracellular matrix. It is also called membrane junction.

127
Q

What are the types of cell junction

A

Occluding junctions
Communicating junctions
Anchoring junctions.

128
Q

What are occluding cell junctions

A

Cell junctions which prevent intercellular exchange of substances are called occluding junctions, i.e. these junctions prevent the movement of ions and molecules from one cell to another cell. TIGHT JUNCTIONS belong to
this category.

129
Q

WHAT are tight junctions

A

Tight junctions consist of specialized proteins, such as claudins, cingulin, symplekin, occludins, that form strands that bind to similar proteins on neighbouring cells, effectively sealing the space between them. This creates a barrier that prevents the movement of molecules between cells, forcing them to move through the cells themselves. This selective permeability allows tight junctions to control the movement of substances such as ions, nutrients, and toxins, and maintain the integrity of the tissues they form

130
Q

Functions of Occluding (tight) junctions?

A

Strength and stability to tissues
Selective permeability
Preventing the backflow of urine in the urinary tract
Maintenance of cell polarity(keep proteins in their apical domains)
Formation of blood­brain barrier
Controlling the absorption of nutrients in the digestive system

131
Q

What are communicating junctions

A

Cell junctions which permit the intercellular exchange of substances are called communicating junctions, i.e. these junctions permit the movement of ions and molecules from one cell to another cell. GAP JUNCTION and
CHEMICAL SYNAPSE are the communicating junctions.

132
Q

What are gap junctions

A

Gap junctions are composed of connexin proteins, which form hexagonal-shaped channels called connexons that span the plasma membrane of adjacent cells. These channels allow for the passage of small molecules, such as ions, sugars, and amino acids, between cells, enabling them to exchange information and coordinate their activities. This direct communication is essential for various physiological processes, such as the synchronization of cardiac muscle contractions, the propagation of nerve impulses, and the regulation of cell growth and differentiation.

133
Q

What is the chemical synapse

A

Chemical synapse is the junction between a nerve fiber and a muscle fiber or between two nerve fibers, through which the signals are transmitted by the release of chemical transmitter

134
Q

What are anchoring junctions

A

Anchoring cell junctions are specialized protein structures that provide mechanical strength and stability to tissues by connecting adjacent cells. They are found in tissues that experience mechanical stress, such as skin, heart muscle, and uterus.

135
Q

Explain desmosomes

A

AKA macula adherens, it does cell-cell communication with spot welds. The transmembrane proteins are the CADHERIN

136
Q

Explain Hemidesmosomes

A

attachment of cells to Basal lamina,Extracellular matrix. The transmembrane protein is INTEGRIN

137
Q

state the carrier proteins of active transport

A

Uniport(1 substance, 1 direction)
Symport (2 different substance, same direction)
Antiport (2 different substances, opposite directions)

138
Q

What are the factors that affect diffusion?

A

Permeability of cell membrane(directly ppt)
Temperature(directly ppt)
concentration gradient (directly ppt)
solubility of substance(directly ppt)
thickness of cell membrane(inversely ppt)
size of molecules(inversely ppt)
size of ions(inversely ppt), Na is an exception.
charge(inversely ppt. e.g ca2+ > Na+)

139
Q

Explain passive transport

A

Passive transport: This is the movement of substances across the cell membrane without the need for energy input from the cell.

140
Q

what are the types of passive transport?

A

Diffusion
Osmosis
Facilitated diffusion

141
Q

What is diffusion

A

The movement of substances from an area of high concentration to an area of low concentration, down their concentration gradient across the cell membrane.

142
Q

what is osmosis

A

movement of substances across a semi-permeable membrane. It moves from HIGH Concentration to a LOW concentration

143
Q

What is facilitated diffusion

A

The movement of substances across the membrane with the help of transport proteins, down their concentration gradient.

144
Q

What is active transport

A

This is the movement of substances across the cell membrane that requires energy input from the cell, usually in the form of ATP

145
Q

what are the 2 types of active transport

A

primary and secondary active transport

146
Q

explain primary active transport

A

This involves the direct use of energy by transport proteins to move substances against their concentration gradient.

147
Q

explain secondary active transport

A

This involves the use of a gradient of one substance (usually sodium ions) to transport another substance against its concentration gradient. The NA/K pump

148
Q

what is bulk transport

A

This is the movement of large molecules or groups of molecules across the cell membrane, usually through vesicles or other membranous structures

149
Q

what are the types of bulk transport

A

Endocytosis, Pinocytosis, Exocytosis

150
Q

explain pinocytosis

A

The Cell forms an invagination then materials dissolve in water to be brought into cell. AKA “Cell Drinking”

151
Q

Explain exocytosis

A

The process by which substances are secreted from the cell by fusion of a vesicle with the plasma membrane

152
Q

explain endocytosis

A

The process by which substances are taken into the cell by engulfment in a vesicle formed from the plasma membrane.

153
Q

explain receptor based endocytosis

A

Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol

154
Q

explain phagocytosis

A

Used to engulf large particles such as food, bacteria, etc. into vesicles

155
Q

what is homeostasis

A

the maintenance of constant the internal environment of the body

156
Q

State examples of homeostatic control in the body

A

The decrease in pH (acidosis) or increase in pH (alkalosis) maintain PH at 7.4. The respiratory system, blood and kidney
help in the regulation of pH.
The skin, respiratory system, digestive system, excretory system, skeletal muscles and nervous system are involved
in maintaining the temperature within normal limits(37.5)
Digestive system and circulatory system play major roles in the supply of nutrients for cell activity and tissue growth.
Kidneys and other excretory organs are involved in the excretion of waste products.
Hormones are to be synthesized and released from the endocrine glands in appropriate quantities and these hormones must act on the body cells appropriately.
Nervous system controls and coordinates bodily activities that require rapid responses and detects and initiates reactions to changes in external environment and internal environment.

157
Q

what are the components of a homeostatic system

A

The system is governed by a cycle: SENSORS and DETECTORS recognize a deviation, information of a deviation is transmitted to the CONTROL CENTER, instructions to correct the deviation are sent from the control center to the EFFECTORS either by chemical synapse or hormones to correct the deviation.

158
Q

What is negative feedback

A

Negative feedback is the one to which the system reacts in such a way as to arrest the change or reverse the direction of change. After receiving a message, effectors send negative feedback signals back to the system, which would then stabilize its own function to maintain homeostasis.

159
Q

Give examples of negative feedback

A

Negative feedback to control TSH production, Negative feedback for ADH secretion, negative feedback for GH production’s , negative feedback for Insulin production.

160
Q

What is positive feedback

A

Positive feedback is the one to which the system reacts in such a way as to increase the intensity of the change in the same direction.

161
Q

What are some examples of positive feedback

A

milk ejection reflex, parturition, Blood clotting

162
Q

List the cell organelles with limiting membrane

A

Endoplasmic reticulum
Golgi apparatus
Lysosome
Peroxisome
Centrosome and centrioles
Secretory vesicles
Mitochondria
Nucleus

163
Q

List the cell organelles without a limiting membrane

A

Ribosomes
Cytoskeleton

164
Q

what is the adherens junction

A

joins an actin bundle in one cell to a similar bundle in a neighbouring cell

165
Q

what happens to a cell in isotonic solution

A

Nonet movement

166
Q

what happens to a cell in a hypertonic solution

A

it shrinks

167
Q

what happens to a cell in a hypotonic solution

A

it bursts

MB prep: Physiology (12 decks)

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