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Pathophysiology (Kelsey Williams PA School) > Cell Biology > Flashcards

Cell Biology Flashcards

1
Q

What is a cell and its characteristics?

A
  • smallest functional unit of organization
  • 35-40 trillion on average
  • types: eukaryotic (humans) and prokaryotic (bacteria)
  • many types of cells; combine to form tissues
  • structure and organelle composition suit cell function
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2
Q

Name the cell components

A
  • Plasma membrane
  • Nucleus (for eukaryotes)
  • Mitochondria
  • Ribosomes
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes/ peroxisomes/proteasomes
  • Cytoskeletal components
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3
Q

Difference between eukaryotes and prokaryotes

A

Eukaryotic cells contain membrane bound organelles, including a nucleus

Prokaryotic cells do not contain a nucleus or any other membrane-bound organelles. Example: bacteria

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4
Q

What makes up the intracellular compartment?

A
  • inside the plasma membrane

- 2/3 body water (most water is inside the cells; intracellular fluid)

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5
Q

What makes up the extracellular compartment?

A
  • outside the plasma membrane

- 1/3 body water (3/4 outside blood vessels—interstitial; 1/4 inside blood vessels—plasma)

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6
Q

Intracellular fluid

A

Higher in proteins and potassium; lower in sodium

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7
Q

Extracellular fluid

A

Lower in proteins and potassium; higher in sodium

Mostly consists of ISF and plasma

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8
Q

Interstitial fluid

A
  • Main component of extracellular fluid
  • It is the body fluid between the blood vessels and cells containing nutrients from capillary by diffusion and holding waste products discharged out by the cells due to metabolism
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9
Q

What is the plasma membrane and it’s characteristics?

A
  • Aka the cell membrane, which acts as a semipermeable structure that separates the intracellular and extracellular environments
  • Phospholipid bilayer with integral and peripheral proteins
  • Barrier for water soluble molecules
  • hydrophilic (water soluble) head and a hydrophobic (water insoluble) tail
  • selectively permeable meaning that materials move from ICF to ECF
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10
Q

What are the functions of proteins?

A

They are receptors, channels/carriers, enzymes (catalyze metabolic reactions), anchors, and recognition of antigens

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11
Q

Cholesterol provides ______ for proteins

A

Fluidity in the membrane

Allows the proteins to move along the membrane to get to the correct position

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12
Q

Plasma membrane receptors

A

Hormones, growth factors, neurotransmitters (messages), and other chemical messengers

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13
Q

What are the three major classes of cell surface receptor proteins?

A

G-protein linked receptors, enzyme linked receptors, and ion channel-linked receptors

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14
Q

Plasma membrane receptors elicit changes in cell activity via _______ ________ _________.

A

Signal transduction pathways

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15
Q

G-Protein linked receptor process

A
  • First messenger binds to guanine nucleotides, such as guanine diphosphate (GDP) and guanine triphosphate (GTP)
  • they all have a ligand-binding extracellular receptor component, which recognizes a specific ligand or first messenger (converts an extracellular signal to internal response)
  • undergo conformational changes with receptor binding that activates the G protein
  • activation of G protein leads to increase in an intracellular “second messenger”
  • G protein activates and interacts with the membrane protein adenyl catalase to catalyze the conversion of ATP and cAMP
  • second messenger leads to cell response
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16
Q

What is the most common signal transduction pathway?

A

G- protein linked receptors process

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17
Q

Enzyme-Linked Receptors Process

A
  • Enzyme-linked receptors are transmembrane proteins with their ligand binding site on the outer surface of the cell membrane
  • this receptor has intrinsic activity/linked to an enzyme
  • converts an extracellular signal to an internal response
  • tyrosine kinase: most frequent enzyme, which phosphorylates intracellular proteins and changes the action of the cells
  • utilized by many growth factors
  • important in some tumorigenesis mechanisms
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18
Q

What enzyme is involved with multiple myeloma?

A

Tyrosine kinase
- there is a mutation of the enzyme, it’s turned on, tyrosine kinase is still active and causes overgrowth of the B cells

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19
Q

Ion-channel-linked receptors

A
  • Receptor acts as a gated channel for ion flow across the membrane (involved in the rapid synaptic signaling between electrically excitable cells- many neurotransmitters mediate this type of signaling)
  • ligand binding transiently opens channel allowing ion flow
  • convert extracellular signal to internal response
  • involved in neuron conduction & muscle contraction
  • side note: ions are hydrophilic; they do not cross the plasma membrane due to their charged nature
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20
Q

What type of molecules can freely pass through the membrane?

A
  • lipid soluble molecules, hydrophobic molecule, and small polar molecules can diffuse through the lipid layer
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21
Q

What molecules can not pass through the membrane?

A

Ions and large polar molecules can’t pass through the membrane without assistance from integral membrane proteins

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22
Q

What molecules require special mechanisms to pass through the membrane?

A

Water soluble molecules (larger ones)

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23
Q

Passive transport and its examples

A

Rely on gradients (difference in concentration); don’t require energy

Examples: osmosis, diffusion, and facilitated diffusion

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24
Q

Active transport

A

Transport molecules are going against electrical, chemical, or electrochemical gradients; requires ATP to move substrates against a gradient

** low concentration to high concentration—> requires ATP

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25
Q

Vesicular transport

A

A mechanism in which a cell encloses material in a small spherical membraneous sac, or vesicle, formed from the plasma membrane
- this membrane coated vesicle moves into the cell via endocytosis and out of the cell via exocytosis

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26
Q

Diffusion

A
  • a type of passive transport
  • movement of molecules cross membrane from high concentration to low concentration (always requires a gradient)
  • used for lipid soluble molecules (steroids, thyroid hormones, gases, and alcohol)
  • uncharged small water- soluble molecules via nonspecific protein channels can diffuse through the membrane
  • larger gradients & heat accelerate diffusion
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27
Q

True or False: facilitated diffusion (a type of passive transport) requires the use of a transport protein, but not ATP

A

TRUE

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28
Q

Diffusion stops when the concentration on both sides are _____.

A

Equal

  • no net movement with = concentrations
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29
Q

Osmosis

A
  • Diffusion of water toward higher solute concentration
  • solutes create an osmotic force that attracts water
  • osmolarity of extracellular fluids has great impact on cells

** REMEMBER: water always follows sodium (Na+), glucose, urea (large and polar), and proteins!!! These are the main determinants of osmosis.

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30
Q

Water always follows _____, _____, _____, and ______.

A

Sodium (Na+), glucose, urea, and proteins

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31
Q

Isotonic

A
  • Contains the same amount of sodium as ICF

- does not cause osmotic flow of water into or out of the cell

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32
Q

Hypotonic

A
  • Less sodium compared to ICF

- Less solutes causes osmotic flow of water into the cell

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33
Q

Hypertonic

A
  • contains more sodium
  • more solutes causes osmotic flow of water out of the cell
  • water follows the sodium out of the cell, which causes the cell to shrivel up
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34
Q

Facilitated diffusion

A
  • carrier proteins transport molecules too large to fit through channel proteins (glucose, amino acids)
  • similar to simple diffusion with using a concentration gradient without energy but it requires a carrier protein
  • molecule binds to receptor site on carrier protein
  • protein changes shape, molecule passes through
  • receptor sites are highly specific to certain molecules and saturable
  • Example: for diabetics, if insulin isn’t bound to this transporter, it doesn’t work. It needs insulin to move glucose into the cell.
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35
Q

Types of carrier mediated transport and its characteristics

A
  • facilitated diffusion and active transport—>transports ions and organic substances
  • characteristics: specific (single and similar substrates), saturable (rate of transport depends on number of transport proteins), and regulated (sometimes), which depends on cofactors such as hormones
36
Q

What does saturable mean?

A

Rate of transport depends on number of transport proteins

37
Q

Primary active transport

A

Energy used to move substrate against gradient

Example: Na+/ K+ ATPase membrane pump (moves sodium from inside the cell to the extracellular region where its concentration is approximately 14 times greater than inside; the pump also returns potassium to the inside where its concentration is approximately 35 times greater than it is outside the cell)

Other examples: Ca 2+ ATPase, H+/K+ ATPase

38
Q

Secondary active transport

A

Gradient established from primary active transport (Na+) used to move second substrate against gradient/uphill

Indirectly requires energy (ATP)

  • this mechanism uses membrane transport proteins, and they have two binding sites: one for sodium and the other for the substance undergoing secondary transport

Examples: symport/cotransport (same direction of sodium) and antiport/countertransport (opposite direction of sodium)

39
Q

Name and describe the two types of secondary active transport systems with examples

A

1) cotransport/symport—> sodium and the solute are transported in the same direction (Example: Na+/glucose transport)

2) countertransport/antiport—> sodium and the solute are transported in opposite directions
(Example: Ca 2+/ Na 2+)

40
Q

Na+/ K+ ATPase

A
  • Type of primary active transport
  • this pump is present in all cell membranes
  • accounts for significant ATP utilization
  • Na+/; K+ moved against concentration gradients
  • asymmetric: 3 sodiums are pumped out in exchange for 2 potassium’s; more positives go out compared to those that come in.
  • Positive on outside, negative on inside (establishes the electrical gradient)
  • This binding changes the shape of the protein channel and then potassium ions are released into the cell.
  • creates/ maintains electrical gradient across cell membrane
41
Q

Endocytosis

A

Cell membrane extends around material and internalizes/ engulfs extracellular materials
Ex. White blood cells with phagocytosis (pg. 17)

Forms a vesicle, then the vesicles may fuse with a lysosome for chemical breakdown

42
Q

Exocytosis

A

The mechanism for secretion of intracellular substances into the extracellular spaces

Important in removing cellular debris and releasing substances, such as hormones, synthesized in the cell (secretion—endocrine/exocrine glands)

43
Q

What is the definition and steps for phagocytosis?

A

Def: “cell eating,” involves the engulfment and subsequent killing or degradation of microorganisms and other particulate matter

1) a phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it
2) the pseudopodia approach one another and fuse to trap the material within the vesicle (pinch it inside)
3) vesicle moves into the cytoplasm
4) lysosomes fuse with the vesicle
5) this fusion activates digestive enzymes
6) the enzymes break down the structure of the phagocytosis material
7) residue is then ejected from the cell by exocytosis

44
Q

Mitochondria and it’s characteristics

A
  • ancient bacteria
  • inner/outer membranes surround the matrix (inside)
  • inner membrane folded for greater surface; inner membrane folds= cristae
  • provide for efficient utilization of organic fuels
  • vast majority of ATP production; called the “power house”
  • where O2 is used and CO2 produced
45
Q

What is cellular respiration and its basic characteristics?

A
  • a set of metabolic reactions and processes that take place in cells of organisms to convert biochemical energy from nutrients into ATP, and then release waste products
  • converts non-usable energy in organic compounds to usable energy
  • organic compounds are oxidized to harvest compounds
  • electrons carry energy utilized to phosphorylate ADP
  • ATP represents usable energy in phosphate bonds
46
Q

ATP is formed through three major pathways: ______, ______, and _______.

A

Glycolysis, citric acid cycle, and electron transport chain (in this order)

47
Q

Where does glycolysis occur? Describe the steps of glycolysis.

A
  • glycolysis is an anerobic process and occurs in the cytoplasm (oxidation occurs)
  • glucose molecule is trapped, splitting of a 6 carbon molecule glucose molecule into two three carbon pyruvate molecules, and oxidized
  • results in 2 pyruvate, 2 NADH, and (net) 2 ATP
  • electrons carried by NADH (“the thief”); electrons are stolen by NAD+—> NADH—> ATP is formed
  • pyruvate enters the mitochondrial matrix or converted to lactic acid (occurs when oxygen is lacking)
  • each three carbon molecule is rearranged and each molecule produces 2 ATP
48
Q

Citric acid cycle and its characteristics

A
  • occurs in the mitochondrial matrix under aerobic conditions
  • each pyruvate acid molecule formed by the glycolytic is oxidized further and each combines with acetyl coenzyme to form acetyl-CoA
  • each pyruvate needs to complete 2 circuits to completely breakdown the 2 pyruvate molecules
  • removal of carbons produces CO2
  • results in 4 NADH, 1 FADH2, and 1 ATP per pyruvate
  • electrons carried by NADH and FADH2
49
Q

Electron transport chain/oxidative phosphorylation

A
  • aerobic, occurs on the inner mitochondrial membrane
  • NADH/FADH2 pass electrons to series of carriers
  • passage generates proton gradients between membranes
  • more protons are carried across the membrane
  • flow of protons into matrix drives ADP phosphorylation—> 32 ATP
  • cytochrome c oxidase complex transfer electrons from cytochrome C to oxygen the terminal electron accepter; protons H+ combine with O2 to form water as the product
50
Q

What is the net yield of molecules for ATP after the cellular respiration processes?

A

36 molecules of ATP from 1 molecule of glucose (2 from glycolysis, 2 from the citric acid cycle, and 32 from the electron transport chain)

51
Q

Membrane potential overview

A
  • important in excitable tissues: muscle, heart, neurons, and some glands
  • electrical gradient (polarity) across cell membrane is “polarized” at rest
  • created by Na+/ K+ ATPase (3 sodium ions are pumped out and 2 potassium ions are pumped in) and presence of proteins in ICF
  • ICF is negatively charged relative to ECF
  • Stimulation of cells results in reversal polarity in segment of membrane—> depolarization
  • if depolarization is sufficient—> spreads along membrane
  • “action potential” leads to contraction, nerve impulses, etc.
52
Q

Resting membrane potential

A
  • expressed as ICF compared to ECF
  • excess negative charge inside the cell
  • created and maintained by the Na+/K+ ATPase pump
  • negative potential voltage inside: (-70mV)
  • membrane is polarized
53
Q

Action potential overview

A
  • Involve rapid changes in the membrane potential
  • Local changes in membrane potential result from:
  • neuron stimulation/inhibition, temperature, light, pressure, etc.
  • due to opening/closing of specific ion channels
  • opening of Na+ channels results in Na+ entry—> reduction of resting potential = “depolarization”
  • opening of K+ channels results in K+ exit—> increase in membrane potential = “repolarization” back to the resting state
54
Q

Depolarization

A
  • opening of the membrane channels for Na+ allows large amounts of the positively charged Na+ ions to diffuse to the interior of the cell causing the membrane potential to undergo _________ (rapid change to positive on the inside and negative on the outside)
55
Q

Repolarization

A
  • Na+ channels close

- K+ channels open, which leads to rapid effort of K+ from the cell and reestablishment of the RMP

56
Q

What does an action potential result in?

A

The sweeping of depolarization down a cell membrane results in nerve impulse in neurons and contraction in muscle

57
Q

Cells and extracellular matrix combine to form ______.

A

Tissues

58
Q

Tissues combine to form _____.

A

Organs

59
Q

What are the four types of tissues?

A

Epithelium, connective, muscle, and nervous

60
Q

Epithelium tissue

A
  • Covers body surfaces and linings of cavities/ hollow organs
  • always has exposed apical surfaces
  • hypercellular with little matrix (tightly packed cells with very little space in between)
  • avascular
  • high degree of regeneration (most cancers involving this tissue)
  • provides protection, permeability, and often secretes substances into exposed surfaces (glandular epithelium)
  • some possess microvilli or cilia
61
Q

Epithelium is classified by:

A

Apical cell shape and presence of layers

Shapes include squamous, cuboidal, columnar, and transitional

Layers include simple, stratified, pseudo-stratified

62
Q

What are the locations and functions of the simple squamous epithelium?

A

Locations: lining ventral cavities; lining heart and blood vessels; portions of kidney tubules (thin sections of nephron loops); inner linings of cornea; alveoli of lungs

Functions: reduces friction, controls vessel permeability, performs absorption and secretion

63
Q

What are the locations and functions of a simple cuboidal epithelium?

A

Locations: glands, ducts, portions of kidney tubules, thyroid gland

Functions: limited protection, secretion, absorption

64
Q

What are the locations and functions of simple columnar epithelium?

A

Locations: lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys

Functions: protection, secretion, absorption

65
Q

What are locations and functions of Pseudo-stratified ciliated columnar epithelium?

A

Locations: lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract

Functions: protection, secretion

66
Q

What are the locations and functions of stratified squamous epithelium?

A

Locations: surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina

Functions: provides physical protection against abrasion, pathogens, and chemical attack

67
Q

What are the locations and functions of the transitional epithelium?

A

Locations: urinary bladder; renal pelvis of kidneys; ureters

Functions: permits expansion and recoil after stretching

68
Q

Connective tissue characteristics

A
  • most abundant, most diverse, most complex
  • fills spaces, supports structures, provides 3D structure
  • fewer cells (hypocellular); more matrix
  • matrix comprised of ground substance (liquid, solid, gel) and protein fibers (collagen-strong, reticular, and elastic-stretchy)
  • subtypes differ based on consistency of ground substance and presence/proportion of fibers
  • few “rules” due to diverse nature
69
Q

Connective tissue proper

A

Loose (adipose and reticular tissue) and dense (regular and irregular)

70
Q

Fluid connective tissues

A

Blood (cardiovascular system) and lymph (lymphoid system)

71
Q

Supporting connective tissue

A

Cartilage and bone

72
Q

Muscle tissue types and characteristics

A
  • 3 types: skeletal, smooth, cardiac
  • all muscles contract (shorten), contraction produces movement (only similarity between them)
  • many differences between each muscle
  • contractile proteins: actin and myosin, which are arranged into sacromeres (except for smooth muscle), regulated by troponin and tropomyosin
  • complex interaction during contraction (watch video)
73
Q

Skeletal muscle locations, functions, and characteristics

A
  • Cells are long, cylindrical, appear striated, and multinucleate
  • Locations: combined with connective tissues and neural tissue
  • Functions: generally moves skeleton, moves eye/voluntary sphincters; guards entrances and exits to digestive system, respiratory, and urinary tracts; generates heat; protects internal organs
  • actin and myosin produce striations
  • stimulated by somatic motor neuron voluntary control
74
Q

Smooth muscle locations, functions, and characteristics

A
  • walls of hollow organs (except heart) and blood vessels
  • in general, produces organ movement or contraction
  • functions: moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels
  • short, spindle shaped, uninucleate cells
  • no sacromeres
  • stimulated by autonomic neurons or hormones or other
  • lacks striations that cardiac muscles have
75
Q

Cardiac muscle location, function, and characteristics

A
  • only present in the heart
  • short, branched, and uninucleate cells
  • connected by intercalated discs only found in cardiac muscles- opens pathways of cytoplasm of adjacent cells)
  • functions: circulates blood; maintains blood pressure
  • actin/myosin produce striations
  • stimulated by conduction system
  • cells are branches as opposed to being spindle shaped
76
Q

Which muscle tissue does not have sacromeres?

A

Smooth muscle

77
Q

Which muscles have actin/myosin that produce striations?

A

Cardiac muscle and skeletal muscle

78
Q

Nervous tissue

A
  • composed of neurons and neuroglia (glia)—> provides support to the neurons
  • makes up CNS and PNS
  • collects internal and external info (senses)
  • interprets information (processes)
  • initiates commands to restore aberrations (responds)
  • neurons sense, process, and respond; glia support neurons in various ways!!
79
Q

Describe a neuron and its features (cell body, dendrites, axon)

A
  • neurons conduct information via nerve impulses (action potentials)

Features:

  • cell body (soma)- contains nucleus and organelles
  • dendrites- usually multiple/branched; received incoming information
  • axon- usually single; conduct outgoing information
80
Q

Conduction towards CNS involves ______/_______.

A

Afferent/sensory

81
Q

Conduction away from CNS involves _______/_______.

A

Efferent/ motor

82
Q

Multipolar neurons

A

Consists of all somatic motor & visceral motor neurons; most CNS neurons

83
Q

Unipolar neurons

A

Consists of all somatic sensory & visceral sensory neurons

84
Q

Bipolar neurons

A

Some special sensory neurons

85
Q

CNS glia consists of:

A
  • astrocytes (involved in scar formation; part of blood brain barrier)
  • oligodendrocytes (responsible for myelination)
  • microglia (phagocytosis defense cells)
  • ependymal cells (lining of brain ventricles, and source of cerebrospinal fluid)
86
Q

PNS consists of:

A

Satellite cells (found in ganglia) and Schwann cells (responsible for myelination)

Pathophysiology (Kelsey Williams PA School) (3 decks)

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