Unit 1 Objectives Flashcards
(77 cards)
1
Q
What is the role of the cell/plasma membrane?
A
- semipermeable structure that separates intracellular and extracellular components (lipid bilayer with integral and peripheral proteins) and is a barrier to water-soluble molecules
- proteins serve as receptors (hormones, growth factors, neurotransmitters), channels/carriers, enzymes, anchors (scaffolding to maintain shape), and antigens (signs/recognition)
- **cholesterol provides fluidity for proteins
2
Q
What is the role of the nucleus?
A
- the control center for the cell
- contains genetic material (DNA dispersed in nuclear matrix called chromatin)
- site for RNA synthesis
3
Q
What is the structure and function of the mitochondria?
A
- powerhouse of the cell; contains enzymes needed for capturing energy from food and converting it to cellular energy
- contains inner and outer membrane (inner membrane contains folds called cristae which allow for greater surface area)
- where vast majority of ATP production occurs
- where O2 is used and CO2 is produced
- contain their own DNA (that is distinct from chromosomal DNA found in nucleus) and ribosomes and are self-replicating
4
Q
What is the role of ribosomes?
A
- small particles of nucleoproteins (rRNA and proteins) that are held together by a strand of mRNA
- free ribosomes: involved in protein synthesis which remains in the cell as cytoplasmic structural or functional elements
- ribosomes attached to ER: translate mRNAs that code for proteins to be bound in membranes or destined for secretion
5
Q
What is the role of the endoplasmic reticulum (ER)?
A
- a tubular connection system for transporting various substances from one part of the cell to another
- large surface area and multiple enzyme systems attached to ER membranes also provides machinery for many cellular metabolic functions
- 2 types: rough and smooth ER
6
Q
What is the role of the Golgi apparatus?
A
- function in association with the ER
- modifies substances delivered from the ER via transport vesicles and packages them into secretory granules or vesicles
- produces large carbohydrate molecules that are added to proteins produced by the rough ER to form glycoproteins
7
Q
What is the role of lysosomes?
A
- “digestive organelles in the cell”
- contain hydrolytic enzymes that break down excess and worn-out cell parts as well as foreign substances that are taken into the cell
8
Q
What’s the role of proteosomes?
A
- cytoplasmic protein complexes that are not bound by membranes
- responsible for proteolysis of malformed and misfolded proteins and have roles in many cellular responses and events
9
Q
What are the components of the cytoskeleton?
A
microtubules, microfilaments, and intermediate filaments
10
Q
What’s the role of microtubules?
A
- slender and rigid tubular structures composed of globular proteins called tubulin
- development and maintenance of cell form
- participation in intracellular transport mechanisms
- formation of the basic structure for several complex cytoplasmic organelles, including cilia, flagella, and centrioles
11
Q
What are the roles of microfilaments?
A
- composed of actin, which contributes to cell motility, positioning of organelles in the cell, and cell shape and polarity
- actin microfilaments in association with thick myosin filaments contribute to muscle contraction
12
Q
What’s the role of intermediate filaments?
A
- a heterogenous group of filaments with diameter sizes between those of microtubules and actin filaments
- have structural and maintenance functions that are important in tissue, cellular, developmental, and differentiation processes
- very responsive to cellular stress, such as heat, radiation, toxins, pathogens, and oxidation
13
Q
A) Trace the pathway for cell communication beginning at the receptor and ending with the cellular response (G-PROTEIN-LINKED RECEPTORS)
B) Explain why the process is often referred to as signal transduction
A
A) G-protein linked receptor pathway (MOST COMMON):
1. Ligand (hormone/growth factor/neurotransmitter acting as the “first messenger”) that is attached to the receptor binds to guanine nucleotide/G-protein 2. Diphosphate nucleotide becomes triphosphate nucleotide when ligand binds to G-protein 3. This in turn results in activation of an intracellular enzyme, adenylate cyclase 4. The activation of adenylate cyclase catalyzes a reaction, converting ATP to cAMP (“second messenger”) 5. cAMP activates kinase (adds phosphate group/phosphorylates proteins) 6. Alterations in enzyme activity occur, ion channels open 7. TARGET CELL RESPONSE
B) An extracellular signal has to get across the membrane/is transduced to the inside of the cell in order to elicit a cellular response
14
Q
Trace the pathway for cell communication beginning at the receptor and ending with the cellular response (ENZYME LINKED)
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
15
Q
A) Trace the pathway for cell communication beginning at the receptor and ending with the cellular response (ION LINKED)
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
16
Q
Describe the function of G-proteins and second messengers in signal transduction
A
- G-proteins act as molecular switches inside cells and are involved in transmitting signals from a variety of stimuli outside a cell to its interior
- Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules (the first messengers). Second messengers are responsible for the actual cell response.
17
Q
Describe mechanism of membrane transport associated with 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
18
Q
Describe mechanism of membrane transport associated with 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.
19
Q
Describe mechanism of membrane transport associated with endocytosis
A
Type of vesicular transport; 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
20
Q
Describe mechanism of membrane transport associated with 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)
21
Q
Describe mechanism of membrane transport associated with faciltated 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.
22
Q
Describe 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
23
Q
Describe 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)
24
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+)
25
Describe the function of ion channels
Definition: protein molecules that span across the cell membrane allowing the passage of ions from one side of the membrane to the other
Process:
cell membrane at its resting potential
- depolarization is initiated by a stimulus, which makes the membrane potential more positive
- causes the opening of Na+ channels results in 3 Na+ entering the cell—> reduction of resting potential = “depolarization” (makes inside positive, outside negative)
-simultaneously, opening of K+ channels results in 2 K+ exiting—> increase in membrane potential= “repolarization” (going back to normal resting potential state)
- Na+ activation gates close
-reestablish the resting membrane potential (negative inside, positive outside)
26
Describe the resting membrane potential state
- 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
27
Relate the function of ATP to cell metabolism
Function: usable energy in phosphate bonds in cellular respiration
Formed in three major pathways:
-Glycolysis: results in 2 total pyruvate, 2 total NADH, and (net) 2 ATP for each pyruvate molecule (4 total ATP)
- Citric Acid: results in 4 NADH, 1 FADH2, and 1 ATP per pyruvate
- ETC: flow of protons across membrane into matrix drives ADP phosphorylation—> 32 ATP; H+ protons combine with O2 to form water as the product
28
Describe action potential
- 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 3 Na+ entry—> reduction of resting potential = “depolarization”
- opening of K+ channels results in 2 K+ exit—> increase in membrane potential = “repolarization” back to the resting state
29
What does an action potential result in?
The sweeping of depolarization to a threshold down a cell membrane results in nerve impulse in neurons and contraction in muscle (action potential)
30
Compare the processes involved in aerobic and anaerobic metabolism
Glycolysis: anerobic process and occurs in the cytoplasm
Citric Acid Cycle: aerobic conditions; occurs in the mitochondrial matrix
ETC: aerobic, occurs on the inner mitochondrial membrane
31
Describe the first process involved in cellular respiration
Glycolysis:
- 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
32
Describe the second process involved in cellular respiration
Citric acid cycles:
- 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
33
Describe the third process involved in cellular respiration
ETC/oxidative phosphorylation:
- 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 acceptor; protons H+ combine with O2 to form water as the product
34
Describe the basis for membrane potentials and an action potential
- 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.
35
What are the four types of tissues?
Epithelium, connective, muscle, and nervous
36
State the characteristics of epithelium tissue
- Covers body surfaces and linings of cavities/ hollow organs
- 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
Classification:
- always has exposed apical surfaces and presence of layers
- shapes include squamous, cuboidal, columnar, and transitional
- layers include simple, stratified, pseudo-stratified
37
State the characteristics of connective tissue
- 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
Examples: connective tissue proper, fluid connective tissues, and supporting connective tissues
38
State the characteristics of muscle tissue
- 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
- smooth muscle also lacks striations
39
What is the process for muscle contraction?
Steps:
40
State the characteristics of nervous tissue
- 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!!
41
Define symptoms
patient’s subjective observations/descriptions, usually not quantifiable
42
Define signs
abnormalities on physical exam, usually quantifiable; what you detect on physical exam
43
Define syndrome
cluster of related symptoms and signs typically due to a single cause in an individual patient
44
Define etiology
the "cause” of a disease; overly simplistic to think that a disease can have one single cause;
example: measles-> several causes such as lack of immunizations, poverty, the disease itself, etc.
45
Define pathogensis
sequence of events by which the disease develops
46
Define pathognomonic
a particular sign/abnormality is found only in one condition or disease; example: forme fruste- very mild variant of a more serious disease
Example: Gilbert's disease
47
Define incidence
number of new cases per unit time; usually expressed as "new cases per 100,000 people per year“
48
Define prevalence
number of cases at any one time; usually expressed as "cases per 100,000 people"
49
Define risk
how much your particular situation increases your chance of getting a disease compared with everyone else
50
Define diagnosis
name given to the particular disease once identified
51
Define prognosis
expected outcome for a particular case of a disease;
| Influenced by diagnosis, the age and general health of the patient, available treatments.
52
Causes of cell injury
-Poor nutrition (lack of nutritious substrates)
-Infectious agents: several mechanisms depending on agent; viruses multiple in host cell and cause cell to explode
-Immune injury (overly responds)
4-5 types, antibody- or T cell-mediated
-Chemical agents (poisons, toxins, too much water, too much salt)
-Physical agents: trauma, radiation, etc.
53
Ischemia (ischemic hypoxia)
Involves lack of arterial blood flow to the cells/tissues (arterial occlusion, venous occlusion); Pump failure
* Lack of oxygen due to a clot or blockage; shunts
* reversible, fixable*
54
Hypoxemia (hypoxic hypoxia)
Low oxygen in the blood
- Failure to ventilate or perfuse the lungs
- Failure of lungs to oxygenate blood
- Inadequate RBC mass
- Inability of hemoglobin to carry or release oxygen
* reversible, fixable*
55
Histotoxic hypoxia
the inability of cells to take up or use oxygen from the bloodstream, despite physiologically normal delivery of oxygen to such cells and tissues.
Examples: cyanide, carbon monoxide, and dinitrophenol
**irreversible**
56
What is the mechanism for hypoxic injury?
1) Lack of oxygen stops oxidative phosphorylation/ETC; the sodium/potassium pump fails
2) Na+ and H20 enter the cell, which leads to acute cellular edema (early sign of cell injurt)
3) anaerobic metabolism leads to lactic acid accumulation and drop in pH (denatures proteins)
* pyruvate can't enter the cell at these conditions
4) Ca2+ ATPase fails; calcium enters the cytoplasm from ECF and ER. This is the point of no return; transition from reversible to irreversible.
57
Ca+2 entry is key step leading to ____ ____.
Cell death
58
What transpires after Ca+2 entry?
-Activates enzymes that damage membranes, proteins, and DNA.
-Opens pores in outer mitochondrial membrane (shuts down oxidative phosphorylation,
mitochondria release free radicals, and mitochondria release caspases that induce apoptosis)
-Rigor mortis due to Ca+2 -induced sarcomere shortening of muscle
59
What is the mechanism of free radical injury?
- Common mechanism of cell injury (radiation, poisons, normal metabolism)
- Unpaired electron in outer (valence) orbital, typically O2 derivatives. Examples: Superoxide (O2-), hydroxyl (.OH), hydrogen peroxide (H2O2)
- Having an unpaired electron can damage other molecules that try to pair to the lonely electron
- Damage cell membranes, cause DNA mutations, aging?
- Limited ability to dispose of free radicals
60
What is chemical injury and list examples
-Depends on nature of poison (acids/alkalis destroy membranes, formaldehyde crosslinks proteins and DNA)
Other poisons:
- Cyanide-blocks ETC
- Mushrooms (toadstools)-destroy ribosomes
- Chemotherapy-damages DNA to disrupt cell replication (cancer cells)
- Strychnine-motor neuron synapses
- Carbon monoxide-replaces O2 on hemoglobin, blocks ETC
61
What are the four sources of intracellular accumulations?
- Triglycerides (fatty change, steatosis)
- Glycogen/complex lipids or carbohydrates
- Pigments
- Calcium
62
Describe fatty change/steatosis
- Involves liver or heart
- Marker for cell injury; it is *reversible*
- closely linked to heavy drinking, obesity, and metabolic syndrome
ex. non-alcoholic steatohepatitis (NASH)
- Malnutrition
- Outdated tetracycline and Ileal bypass for weight reduction can cause this
Mechanisms:
- too much free fat coming to the liver, too much fatty acid synthesis by the liver, impaired fatty acid oxidation by the liver, too little apoprotein synthesis by the liver, failure of lipoprotein secretion by the liver *all contribute to alcoholic steatohepatitis; reversible with abstinence*
63
Describe glycogen/complex lipids or carbohydrates
- infusions of glucose (dextrose)
- occurs in glycogen storage diseases-inborn errors of metabolism
- multiple storage diseases of pediatric populations
example: Tay-Sach's-ganglioside (lysosomal storage disease
64
Name and describe pigment disorders
MELANIN: present in melanocytes and their tumors (melanomas)
- Eumelanin: protects from UV light
- Pheomelanin: generates free radicals on UV exposure (redheads)
- Albinos make no melanin
- Hyperpigmentation
BILIRUBIN: a chemical compound
- yellow-orange
- product of hemoglobin breakdown
- conjugated by the liver & excreted in bile
- elevated levels produce jaundice
- multiple causes
JAUNDICE:
- too many red blood cells being broken down (occurring in hemolytic processes like sickle cell, thalassemias, pernicious anemia)
- liver can't conjugate bilirubin fast enough (liver disease, newborn jaundice, breast feeding first few weeks, etc).
65
Describe calcium accumulation
Dystrophic calcification
- normal calcium levels: pineal gland, aortic valve sinuses, airway cartilages
- abnormal calcium levels: retained abortions (lithopedion), breast cancers,, surgical scars, pancreatic necrosis
- metastatic calcification: occurs with high calcium and/or phosphate levels
- sites of pH gradients: small airway walls and renal tubular walls
66
Define necrosis and what are the three types
Definition: gross and microscopic changes that indicate cell death
Types: coagulation, liquefactive, caseous, and apoptosis
67
Describe coagulation necrosis
- Usually due to ischemic hypoxia or free radical injury
- Death of groups of cells
- Gross-soft, pale
- Micro-loss of nuclei but cytoplasm intact
- dead cells produce acute inflammatory response
- may be replaced by scar, destroyed, walled-off, infected, or even heal
68
Describe liquefaction necrosis
- Usually due to bacterial infections or poisons or ischemic hypoxia in CNS
- Death of groups of cells
- Results from hydrolysis via lysosomal or WBC enzymes (pus)
- Gross-gelantinous mass or nothing there
69
Describe caseous necrosis
* midpoint between coagulation and liquefaction necrosis*
- Usually due to immune injury in response to certain infections (TB, fungus)
- Death of group of cells
- Crumbled, friable debris, cheesy, gross-pale
70
Apoptosis
- Death of a single cell
- Programmed cell death or suicide
- usually due to immune response or in response to cellular damage
- Two main triggers: 1) mitochondria leak capases caused by Ca2+ entry
2) Death receptor- Fas (CD95) or TNF receptors bind their ligases
```
Examples:
- embryologic remodeling of hands (why we have fingers)
- breast shrinkage after
lactation
- Neurons that don't synapse
```
Overall, no inflammatory response! Remains phagocytized by macrophages
71
Compare dry, wet, and gas gangrene in regards to pathophysiology and physical outcomes
Dry: mostly due to coagulation necrosis; no infection; grossly visible; due to diabetes
Wet: mostly liquefactive necrosis, foul-smelling, infected, grossly visible; due to diabetes
Gas: called clostridial or flesh eating; produce cell membrane disruptive toxins
72
State changes in cell structure and function that occur as a result of normal adaptive processes
- changes in response to stress or injury or lack of normal stimulation
- mitigate injurious agent if effective
- cell death results if ineffective
- triggered by reversible alterations in gene activity
73
Describe cell changes that occur with atrophy
- decrease in cell size, not cell number
- typically reversible
- causes: loss of motor innervation, decrease blood supply, loss of hormonal stimulation, malnutrition
examples: loss of breast tissue from menopause; loss of muscle mass while arm in a cast
74
Describe cell changes that occur with hypertrophy
- Increase in cell size, may result in increase organ size
- causes: increase workload and hormonal stimulation
- example: increase in breast size during pregnancy, heart of obese person or hypertensive person
* heart hypertrophy can by physiologic or pathologic*
75
Describe cell changes that occur with hyperplasia
-Increase in cell number, which may result in increase organ size
- May be physiologic or pathologic
Causes: hormonal stimulation and genetic mutations (risk for cancer)
Examples: female breast in puberty and lymph nodes close to infection
*generally reversible with removal of stimulus agent, but genetic mutations will not reverse it.
76
Describe cell changes that occur with metaplasia
- Substitution of one cell type for another
- theoretically reversible
- Pseudostratified--> stratified squamous in smokers
example: Columnar to stratified squamous in cervix of women with HPV
77
Describe cell changes that occur with dysplasia
-"Bad growth"; "atypia"
- Loss of uniformity and orientation
- Resemble cancer cells but not cancer
- results from genetic mutations that create a growth advantage
- ongoing epithelial injury promotes dysplastic process
-examples: bronchi of smokers and Cervix of HPV- infected women
- If a neoplasm exhibits anaplasic, it is malignant.
Therefore, dysplastic is considered precancerous anaplastic cells confined to an epithelium and not invading.
