mid session exam Flashcards
define anatomy
the scientific discipline that investigates the body’s structure
define physciology
scientific investigation of the processes or functions of living things
define the body’s levels of organisation
chemical level: interaction of atoms
cell level: functional unit of life
tissue level: group of similar cells and the materials surrounding them
organ level: one or more tissues functioning together
organ system level: group of organs functioning together
list the organs systems and give a brief description of their functions
cell physiology: examines processes in cells
systemic physiology: function of organ systems
neurophysiology: focuses on the nervous system
cardiovascular: the heart and blood vessels
define homeostasis and explain its importance, as well a variable and set point
homeostasis: the existence and maintenance of a relatively constant environment within the body
importance: maintains optimal conditions for enzyme action throughout the body and all cell functions.
values/variables fluctuate around the set point to establish a normal range of values
set point: the ideal normal value of a variable
in the context of homeostasis, explain negative and positive feedback
negative feedback: any deviation from the set point is made smaller (resisted), e.g. regulation of blood pressure, body temperature, blood sugar levels
positive feedback: when a deviation occurs, the response is to make the deviation greater, e.g. childbirth
describe the anatomical position and use correct anatomical terminology to describe body directions, regions, sections/planes, body cavities and associated membranes
anatomical position: body erect, face forward, feet together, palms face forward
supine: lying face upward
prone: lying face downward
directional terms:
- superior (cephalic) vs inferior (caudal)
- medial vs lateral relative to the midline
- proximal vs distal used to describe linear structures
- superficial vs deep relative to the surface of the body
- anterior (ventral) vs posterior (dorsal), anterior is forward and posterior is toward the back
body planes:
- median (through the midline) and sagittal (same plane, but to the left or right of median)
- frontal or coronal divides the body into anterior and posterior sections
transverse/cross divides body into superior and inferior sections
- oblique: other than at a right angle
planes of section through an organ:
- longitudinal: cut along the length of an organ
- cross/transverse: cut at right angle to length of the organ
- oblique: cut at any but a right angle
trunk cavities:
- diaphragm: divides the body cavity into thoracic and abdominopelvic cavities
- mediastinum: contains all structures of the thoracic cavity except the lungs
serous membrane:
- cover the organs of trunk cavities and line the cavity
- fist represents an organ
- inner balloon wall represents visceral serous membrane
- outer balloon wall represents parietal serous membrane
- cavity between two membranes filled with lubricating serous fluid that is produced by the membranes
- pericardium refers to the heart
- pleura refers to lungs and thoracic cavity
- peritoneum refers to abdominopelvic cavity
define matter, mass, element and atom
matter: anything that occupies space and has mass
mass: the amount of matter in an object
element: the simplest type of matter with unique chemical properties; composed of atoms of only one kind
atom: smallest particle of an element that has chemical characteristics of that element
describe atomic structure in terms of the three main subatomic particles and determine atomic number and mass number
atoms composed of subatomic particles
- neutrons no electrical charge
- protons one positive charge
electrons one negative charge
atomic number: equal to number of protons in each atom, which is equal to the number of electrons
mass number: number of protons plus number of neutrons
define isotope, atomic mass, describe Avogadros number and define mole and molar mass
isotope: two or more forms of same element with same number of protons and electrons but different neutron number
atomic mass: average mass of naturally occurring isotopes
Avogadros number: displays number of units in one mole solution, 6.022 x 10^23
mole: Avogadros number of atoms, ions, molecules
molar mass: mass of one mole of a substance in grams, which is equal to its atomic mass units
describe ionic and covalent bonding and hydrogen bonds
ionic bonding: atoms exchange electrons, are formed when a valence outer shell electron is transferred from one atom to another - much weaker
covalent bonding: two or more atoms share electron pairs, is stronger because the 2 atoms involved share 2 or more outer shell electrons
hydrogen bonds: occur when the positively charged H of one molecule is attracted to the negatively charged O, N or F of another molecule.
distinguish between the different types of chemical reactions and the formulae used to describe them
synthetic reactions: two or more reactants chemically combine to form a new and larger product - anabolism
decomposition reactions: a large reactant is broken down to form smaller products - catabolism
reversible reactions: chemical reactions in which the reaction can proceed with from reactants to products or from products to reactants
describe what enzymes are and how the body uses enzymes to regulate chemical reactions
enzymes (biological catalysts) proteinaceous catalysts that increase the rate of chemical reactions by lowering the activation energy necessary for reaction to begin
regulated through: temperature, concentration, catalysts
define anabolism, catabolism and metabolism
anabolism: the constructive part of metabolism concerned especially with macromolecular synthesis
catabolism: molecules break down in the body for use as energy
metabolism: a chemical reaction that occurs in the body’s cells to change food to energy
distinguish between a mixture and a solution
mixture: substances physically but not chemically combined (suspension - materials separate unless stirred, colloid - dispersal of tiny particles through a medium)
solution: mixture of liquids, gasses, or solids that are uniformly distributed and chemically combined (solvent: that which dissolved the solute, solute: that which dissolves the solvent)
explain the different ways in which solution concentration can be expressed
percent: weight of a solute in a given volume of solvent
equivalents: a measure of the concentration of an ionised substance
molarity: number of moles of solute dissolved in 1 litre of solvent
osmolarity/osmolality: molarity x number of particles into which the solute dissociates
briefly describe the role of electrolytes in the body
molecules or ions with an electrical charge
obtained by ingestion/diet
removed by kidneys, liver, skin, lungs
regulated by homeostatic mechanisms
help the body to regulate fluids and maintain the balance between fluids inside and outside cells
describe what acids, bases and buffers are, and how pH effects the human body
acid: a proton donor or any substance that releases hydrogen ions
base: a proton acceptor or any substance that binds to or accepts hydrogen ions
buffer: a solution of a conjugate acid-base pair in which acid and base components occur in similar concentrations
pH can disrupt the body’s balance, which can lead to the development of bacteria, viruses, fungi, yeasts and parasites.
describe the structure of proteins and nucleic acids and explain why they are important in the human body
proteins: composed of carbon, hydrogen, oxygen, nitrogen, sometimes iodine. functions: regulate processes, aid transport, protection, muscle contraction, structure, energy
nucleic acids: composed of carbon, hydrogen, oxygen, nitrogen, phosphorus
importance: carry the genetic blueprint of a cell and carry instructions for the functioning of the cell
describe glycolysis
anaerobic respiration, breaking down glucose into 2 ATP molecules
describe the major steps in lactic acid fermentation
where glucose is converted into cellular energy and the metabolic lactate
describe the major steps in aerobic respiration
includes citric acid cycle and electron transport chain
creates 38 ATP molecules
define glycogenesis, lipogenesis, glycogenolysis and gluconeogenesis
glycogenesis: excess glucose used to form glycogen
lipogenesis: when glycogen stores filled, glucose and amino acids used to synthesise lipids
glycogenolysis: breakdown of glycogen to glucose
gluconeogenesis: formation of glucose from amino acids and glycerol
differentiate between the absorptive and post absorptive metabolic states
absorptive state: (storage) period immediately after eating when nutrients absorbed through intestinal wall into circulatory and lymphatic systems
postabsorptive state: (breakdown) occurs late morning, afternoon, night after absorptive state concluded, blood glucose levels maintained by conversion of other molecules to glucose
define the term microbiology
is the study of microbes, either living organisms or non-living entities that cannot be seen with the naked eye
discuss some of the applications of microbiology as well as the present and future challenges in medical microbiology
applications: - food production - bioremediation - use organisms to degrade environmental waste - synthesis of numerous products - genetic engineering - introduces genes of one organism into an unrelated organism to confer new properties on the organism future challenges: - infectious disease - COVID-19 pandemic - emerging diseases - resurgence of old diseases
define the living organisms that exist in the microbial world
prokaryotes are unicellular, simple cells, dont have a nucleus
eukaryotes are multicellular, contain organelles, have a membrane-bound nucleus
name the three domains of all living organism and the properties that distinguish them from one another
three domains: organisms in each domain share certain disgusting properties
- bacteria
- archaea
- eucarya
describe the classification and structure of the algae, protozoa and fungi
algae: a diverse group of eukaryotic organisms, use light to convert carbon dioxide and water to carbohydrates, includes both microscopic unicellular and macroscopic multicellular organisms
protozoa: microscopic unicellular organisms, lack photosynthetic capability, usually motile, usually transmitted by ingesting contaminated food or water, can be difficult to treat
fungi: eukaryotes with a cell wall, yeast - unicellular, moulds - multicellular, cells organised into string, some fungi can exist as yeast or mould
define taxonomy and describe how microorganisms are classified
is the science of naming, describing and classifying organisms
identification: process of characterising in order to group them -microscopy, culture characteristics and other tests
classification: arranging organisms into smaller or related groups
nomenclature: system of assigning names
describe the 3 types of infectious agents
vector: a living organism that transmits an infectious agent
direct: spread when disease-causing microorganisms pass from the infected person to healthy person via direct physical contact
indirect: spread when an infected person sneezes or coughs, sending infectious droplets in the air
distinguish between viruses, viroid and prions and discuss the reasons why they are not organisms
viruses: non-living entities that can infect organisms of every domain. commonly referred to by organism they infect
prions: are non-cellular infectious particles, appear to consist of miss-folded protein
viroids: are infectious pieces of nucleic acid that infect plants
not living entities
what does the term ‘normal flora’ mean?
defined as populations of microorganisms routinely found growing on the body of healthy individual
describe the types of relationships that exist between microorganisms and their hosts
mutualism: association in which both partners benefit
commensalism: association in which one partner benefits and other is unharmed
parasitism: association in which the microbe benefits at expense of the host
explain the difference between resident flora and temporary flora
resident flora: typically inhabits body sites for extended periods
temporary flora: transient, they form associations for a short time and are replaced
describe the functions of normal flora and how they are influenced
protection against potentially harmful organisms - normal flora competitively excludes pathogens through covering binding sites used for pathogenic attachment, consume available nutrients, produce toxic compounds such as antibodies
stimulate immune system: response mounted against normal flora that breaches bodys anatomical barriers, may cross-react with pathogen encountered later
list the locations of the body where you would find high populations of normal flora
GI tract
Genitourinary system
respiratory system
skin
what are pathogens and opportunistic pathogens?
pathogens are organisms that can cause disease in otherwise healthy people
opportunistic pathogens are microbes that cause disease when the bodys defences are down
define virulence and infectious dose
virulence is a quantitative term referring to a pathogen disease-causing the ability
infectious dose is the number of organisms required to establish infection
describe the course of infectious disease
incubation: the time between the introduction of an organism to the onset of symptoms, the incubation period depends on numerous factors
illness: follows incubation, individual experiences signs and symptoms of the disease
convalescence: period of recuperation and recovery, infectious agents may still be spread
what does the suffic -anemia mean
blood
briefly describe the mechanisms of pathogenesis that microbes utilise
production of toxins that are ingested
the colonisation of the surface of the host followed by toxin production
invasion of host tissue
invasion of host tissues followed by toxin production
what are the 3 steps that are necessary for the establishment of infection?
adherence
colonisation
delivery of effector molecules to host cells
how do microbes breach anatomical barriers?
penetration of skin
penetration of mucous membranes
describe how microbes avoid host defences
hide within host - become out of reach of phagocytosis, avoid killing by complement proteins, avoid destruction by phagocytosis
what is an exotoxin and what are the three types of exotoxin
most potent toxics known, are secreted by a bacterium or leak into surrounding fluids following cell lysis, made of protein
- neurotoxins: cause damage to the nervous system, the major symptom is paralysis
- entertoxins: damage to intestines and tissues of the digestive tract, major symptom is vomiting and diarrhea
- cytotoxins - damage to a variety of cells, damage caused by interference with cell function or cell lysis
how do viruses avoid the immune response
hide within cell, move from cell to cell
what is selective toxicity
antibiotics cause greater harm to bacteria than human
doesnt kill everything, just bacteria
explain the difference between bactericidal and bacteriostatic drugs
bacteriostatic are useful in situations when host defences cannot be relied upon to control pathogen
bacteriocidal are useful in situations when host defences cannot be relied upon to control pathogen
distinguish between narrow spectrum and broad spectrum drugs
narrow spectrum: work on a narrow range of organisms, gram-positive only or gram-negative only
broad-spectrum: work on a broad range of organisms, gram-positive and gram-negative
list the possible adverse effects of antimicrobial drugs
allergic reactions
toxic effects
suppression of normal flora
antimicrobial resistance
list the possible mechanisms of action of antimicrobial drugs
inhibition of cell wall synthesis inhibition of protein synthesis inhibition of nucleic acid synthesis inhibition of metabolic pathways interference with cell membrane integrity
explain why the inhibition of cell wall synthesis is an effective mechanisms for an antibiotic
antimicrobials that interfere with the synthesis of cell walls do not interfere with eukaryotic cell, due to the lack of cell walls in animal cells in plant cells
briefly discuss antimicrobial resistance
the microbes being targeted are no longer sensitive to the drug
define communicable and non communicable disease?
communicable - disease transmitted from one host to another
non-communicable - diseases that do not spread from host to another
define the following: morbidity, incidence, prevalence, endemic, epidemic, pandemic, outbreak
morbidity - the number of cases of illness in a given time period divided by population at risk
incidence: reflects the number of new cases in a specific time period
prevalence: reflects the total number of existing cases
endemic: diseases that are constantly present
epidemic: unusually large number of cases in a population
pandemic - when epidemics spread worldwide
outbreak - refers to a cluster of cases in a brief time affecting a specific population
list the 3 reservoirs of disease
human
non-human animal
environmental
what do the terms symptomatic/asymptomatic mean?
symptomatic - obvious source of infectious agents, ideally infected individuals understand the importance of precaustions
asymptomatic - individual harbours pathogen with no ill effects
what is a zoonoses and coliforms?
zoonoses - disease transmitted by non-human animal reservoirs
coliforms - present in the environment and faeces, used to monitor H2O for faecal contamination
describe the portals of entry and exit
portals of entry - pathogen must enter and colonize new host, route by which pathogen enters is the portal of entry, e.g. eyes
portals of exit - microbes must leave one host in order to be transmitted to another
what is the difference between horizontal/vertical transmission
horizontal transmission - transmission of the pathogen via contact with food, water or a living agent
vertical transmission - transmission via transfer of the pathogen from mother to foetus or child through breast feeding
discuss the different modes of contact with infectious agents or pathogens
direct contact transmission - occurs when one person physically touches another
indirect contact transmission - involves transmission of pathogens by inanimate objects or fomites
food and water (common vehicle transmission) - pathogens can be transmitted through contaminated food and water
food and water - waterborne disease outbreaks can involve large numbers of people due to the fact that municipal water is distributed to large areas
airborne (vehicle transmission) - respiratory droplets can be transmitted through the air
vectors - any living organism that can carry a disease causing microbe
describe the factors that influence the epidemiology of disease
dose - -minimum number of bacteria required to establish disease
incubation period - disease with long incubation period can spread extensively before first case appears
population characteristics - cerain population are more susceptible than others to certain pathogens
describe population characteristics that influence occurrence of disease
immunity to pathogen - previous exposure or immunisation of population decreases susceptibility of population to organism
general health - stresses such as malnutrition or overcrowing increases the susceptibility of population
age - very young or very old to be at greater risk
sex - influences disease distribution often due to anatomical differences
religious and cultural practices - cultures that routinely breastfeed babies see less infectious disease in children
genetic background - natural immunity can vary with genetic background
how are diseases eradicated
improving sanitation
reservoir and vector control
vaccination
antibiotic treatment
what is nosocomial infection
hospital acquired infections (HAI), infections may range from mild to fatal
list the common organisms that cause nosocomial infections
normal intestinal flora
pneumonia and urinary tract and burn infections
normal skin flora
what are the reservoirs of infectious agents in hospitals
other patients
hospital environment
health care workers
patients own normal flora
how are nosocomial infections prevented
through development
- infection control committee
- infection control practitioner
how can cross contamination be prevented
hand washing protective clothing universal precautions risk assessment waste management
when should hands be washed and list the different types of handwashing
when to wash:
- entering and leaving clinical areas
- before contact with client
- after contact with client
- between procedures on same client
- after going to toilet, blowing nose, touching own body or someone elses
- after handling footwear
types of handwashing:
- household handwash
- clinical handwash
- procedures handwash
- surgical scrub
describe the use of soap in handwashing
surfactants in soap life soil and microorganisms from hands
what are the universal precaustions
treat all patients as potentially infectious
wear gloves whenever likely to contact with bodily fluids
use protective barriers whenever splashing of body fluids is possible
wash hands
take steps to prevent sharps injuries
what is clinical and infectious waste
clinical waste - material not contaminated with body fluids, paper hand towels, disposed of as garbage
infectious waste - material contaminated with body fluids, faeces, yellow contaminated waster containers
how are shaprs/needles/scalpels disposed
sharps - disposed in rigid-walled, speciallt labelled sharps containers
needle - not to be re-sheathed, not be bent, do not remove syringe
scalpel - do not remove scalple blade
how are sharp injuries managed
dont panic encourage bleeding flush wound with disinfectant and copious amounts of water dress wound report to clinician complete sharps injury assessment form report to hospital for risk assessment take along sharp in sealed rigid-walled container
how are blood spills managed
wear disposable gloves and plastic apron
wear eyewear if risk of splashing
mop up blood with disposable towels
place all contaminated items in contaminated waste
poor diluted sodium hypochlorite over area
leave a few minutes and mop up
place everything into contaminated waste container
wash hands
document incident
what areas of the hospital have a requirement for very low numbers of microorganisms
operating theatres burns unit intensive care units transplant/oncology wards maternity wards paediatric wards
define decontamination
the removal of possible harmful microorganisms from an object by cleaning or disinfecting
define antiseptic
a type of chemical disinfectant, suitable for use on skin or living tissue, to kill or remove harmful microorganisms without damaging the tissue
define disinfection
the destruction, removal or reduction in numbers of harmful microorganisms to an acceptable level
define sterilisation
the complete destruction or removal of all microorganisms, including endospores
define pasteurisation
a method of preserving milk and other liquids without altering their taste or quality. destroys bacteria responsible for spoilage and some pathogens, but not all microorganisms
what is a germicide
any agent capable of killing microorganisms
what is sanitation
thorough cleaning of an object or utensil to remove most microorganisms
describe the structure of the plasma membrane
separation of intracellular and extracellular materials
production of charge difference (membrane potential) across the membrane by regulation of intracellular and extracellular ion concentrations
fluid mosaic model
contain phospholipids, heads (hydrophilic) face outside and tails (hydrophobic) face inwards
describe the functions of the lipids in plasma membrane
phospholipids - form a bilayer. polar heads facing water in the interior and exterior of the cell (hydrophilic); nonpolar tails facing each other on the interior of the membrane (hydrophobic)
cholesterol - interspersed among phospholipids. amount determines fluid nature of the membrane
fluid nature provides/allows - the distribution of molecules within the membrane, phospholipids automatically reassemble, if membrane is damaged, membranes can fuse with each other
glycolipids - carbohydrate chains on the plasma membrane that allow cells to identify one anther or other molecules, used in: immunity, recognition of oocyte by sperm cell, intracellular communication
describe the functions of the proteins in plasma membrane
membrane proteins - can be markers, attachment sites, channels, receptors, enzymes and carriers. intergral or intrinsic (extend deeply into membrane, often extending from one surface to the other. can form channels through the membrane), peripheral or extrinsic (attahced to intergral proteins at either the inner or outer surfaced of the lipid bilayer), function depends on 3D shape and chemical characteristics
glycoprotiens - same as glycolipids
channel proteins (integral) - a hydrophilic region faces inward and charge determines which molecules can pass through, non-gated ion channels are always open (responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest), gated ion channels can be open or closed (ligand gated ion channel: open when there is a change in charge across the plasma membrane, voltage-gated ion channel: open when there is a change in charge across the plasma membrane
receptors - are proteins in membranes with an exposed binding site that can attach to specific molecules and act as an intracellular communication system
enzymes - some act to catalyze reactions at outer/inner surface of plasma membrane
carrier proteins - integral proteins move solutes from one side of membrane to the other, have specific binding sites, protein change shape to transport ions or molecules, are a type of transport protein
cellular organelles and their functions
cytosol - fluid portion, dissolved molecules (ions in water) and colloid (proteins in water).
cytoplasm - material outside the nucleus but inside the plasma membrane, composed of: cytosol, cytoskeleton, cytoplasmic inclusion, organelles
cytoskeleton - supports the cell but has to allow for movements like changes in cell shape and movements of cilia, made from: microtubles, microfilaments, intermediate filaments
cytoplasmic inclusion: aggregates of chemicals such as lipid droplets, melanin
nucleus - membrane-bound organelle contains nucleoplasm, chromatin and a nucleolus, and is surrounded by the nuclear envelope, DNA located here
centrioles and spindle fibres - centrioles are located in the centrosome a specialised zone near the nucelus, center of microtubule formation, before cell division, centrioles divide, move to ends of cell and organise spindle fibres
ribosomes - sites of protein synthesis, composed of a large and small subunit, can be free or attached, are made of protein and rRNA
endoplasmic reticulum - rough (has attached ribosomes, proteins produced and modified here), smooth (no attached ribosomes, manufacture lipids)
golgi apparatus - modification, packaging, distribution of proteins and lipids for secretion or internal use, vesicles join and leave from opposite sides
mitochondria - major site of ATP synthesis, membranes: cristae (infoldings of inner membrane) and matrix (substance located in space formed by inner membrane), increases in number when cell energy requirements increase, contains DNA that codes for some of the proteins needed for mitochondria production.
describe the organisation of DNA into chromosomes
chromatin - dna complexed with proteins (histones), during cell division, chromatin condenses into pairs of chromatids called chromosomes. each pair of chromatids is joined but a centromere
define interphase and describe the activites in cells life cycle
G1 phase, S phase, G2 phase, PMAT
cytokinesis - division of cell cytoplasm
mitosis - series of events that leads to the production of two cells by division of a mother cell into two daughter cells, cells are genetically identical, (prophase, metaphase, anaphase and telophase)
interphase - phase between cell divison, replication of DNA, ongoing normal cell activities, growth and production of organelles
define mitosis and list the events that occur during prophase, metaphase, anaphase, telophase and cytokenesis
mitosis - processof nucleur divison in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells
prophase - chromosomes condense and centrosomes move to opposite sides of the nucleus, initiating formation of the mitotic spindle
metaphase - chromosomes line up at the metaphase plate, under tension from miotic spindle
anaphase - sister chromatids separate from each other and are pulled towards opposite ends of the cell
telophase - chromosomes arrive at cell poles, the mitotic spindle disassembles and the vesicles that contain fragments of the original nucelus membrane assemble around the two sets of chromosomes
cytokenesis - four stages (initiation, contraction, membrane insertion and completion)
describe the process of DNA replication
opening of the double helix and separation of the DNA strands (two strands of the DNA double helix uncoil at a specific origin), the priming of the template strand, and the assembly of the new DNA segment
describe the production of mRNA via transcription
a gene is copied; its DNA is used as a pattern for RNA synthesis, complementary nucleotide pairs bind to each other, the mRNA strand is synthesised one base pair at a time
after transcription mRNA molecule must be trimmed
describe translation and describe the role of mRNA, rRNA, tRNA in the production of a protein at a ribosome
synthesis of a protein at the ribosomes using mRNA, tRNA and rRNA
mRNA - carry the coding sequences for protein synthesis
rRNA - direct the catalytic steps of protein synthesis
tRNA - helps decode a messenger RNA (mRNA) sequence into a protein, carry amino acids to the ribosome
define triplets, codons, anticodons
triplets - a three-base codon of the genetic code
codons - a sequence of 3 consecutive nucelotides that codes for a specific amino acid or signals the termination of gene translation
anticodons - a trinucleotide sequence complementary to that of a corresponding codon in a messenger RNA sequence
describe the genetic code
term used for the way the four bases of DNA are strung together in a way that the cellular machinery, the ribosome, can read them and turn them into a proteins
define integral, peripheral and transport proteins in the plasma membrane
integral - extend deeply into membrane, often extending from one surface to the other, can from channels through the membrane
peripheral - attached to integral proteins at either the inner or outer surfaces of the lipid bilayer
transport - protein that serves the function of moving other materials with an organism
define non-gated, ligand-gated and voltage-gated ion channels
non-gated - always open, responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest
ligand-gated ion channel- open in response to small molecules that bind to proteins or glycoproteins
voltage-gated ion channel - open when there is a change in charge across the plasma membrane
describe how carrier proteins and ATP-powered pumps move ions and molecules across the membrane
molecule or solute binds to site, sometimes energy source is needed to move molecule to other side of membrane, incites the carrier to alter its shape resulting in the release of the bound molecule or solute
define symport and antiport
symport - a mechanism of transport across a membrane in which two different molecules move in the same direction
antiport - membrane protein that transports two molecules at the same time in the opposite direction
explain how a chemical signal can bind to a receptor in the plasma membrane and cause a change in the activity of a cell
when a signalling molecule joins with an appropriate receptor on a cell surface, this binding triggers a chain of events that not only carriers the signal to the cell interior, but amplifies it as well
define diffusion, osmosis and osmotic pressure
diffusion - movement of solutes from an area of high concentration to lower concentration in solution
osmosis - diffusion of water (solvent) across a selectively permeable membrane
osmotic pressure - force required to prevent water from moving across a membrane by osmosis
define filtration
works like a sieve
depends on pressure difference on either side of a partition
moves from side greater pressure to lower
define mediated transport
involve carrier proteins or channels in the cell membrane
move larger, water soluble molecules or electrically charged molecules across the plasma membrane
define endocytosis, receptor-mediated endocytosis, phagocytosis and pinocytosis
endocytosis - internalization of substances by formation of a vesicle, types: phagocytosis, pinocytosis, receptor-mediated endocytosis
receptor-mediated endocytosis - cells absorb metabolites, hormones, proteins and viruses by the inward budding of the plasma membrane
phagocytosis - ingest solid particles into the cell
pinocytosis - cell takes in the fluids along with dissolved small molecules
describe exocytosus
accumulated vesicles containing products or waste are expelled from cell
describe receptor/ligand-mediated communication, specificity, up-regulation and down-regulation
portion of molecule where ligand binds is called binding site
if the molecule is a receptor the binding site is called a receptor site
ligand/receptor site is specific
the purpose of binding to target tissue is to elicit a response by the target cell
down-regulation - causes the number of receptors to decrease, can occur after cells are exposed to a ligand
up-regulation - increase in synthesis of receptors for a hormone, thus increases sensitivity to that hormone
explain mechanisms involved in receptor-mediated communication
membrane bound receptors - integral proteins with receptor site at extracellular surface, interact with ligands that cannot pass through the plasma membrane
intracellular receptors - receptors in the cytoplasm or in the nucleus
