Unit 2 QCAA Flashcards
define disease
Any deviation from the normal structure or function of an organ/system
identify difference between infectious vs non-infectious diseases
Infectious - transmitted from one to another
Non-Infectious - caused by genetic and lifestyle factors
define pathogen
a causative agent of disease
define prion
type of protein that can trigger normal brain proteins to fold abnormally (cause neurodegenerative diseases)
define virus
- make of DNA or RNA, coated with protein shell (capsid)
- depend on other cells to reproduce (NON-LIVING)
define bacteria
prokaryotic organisms (pathogenic bacteria cause disease)
define fungi
eukaryotic organisms that secrete enzymes to externally digest before absorbing the nutrients
define protists
eukaryotic organisms, usually dont cause disease, but there are some that are pathogenic parasites that infect organisms to reproduce
define parasite
organisms that live on or in another (host) and obtain nourishment at the expense of the host
identify and describe virulence factors
Adherence factors:
- ability to adhere to host cells
- bacteria resist physical removal by producing fimbriae or pili, non-fimbrial adhesins and biofilm-producing glycocalyx
Invasion factors:
- ability of pathogen to enter host tissues, multiply and spread to other tissues
- eg. secrete enzymes to break down collagen, hyaluronic acid (‘glue’ holding cells together) to enter
Capsules:
- allow pathogens to resist host immune defence by preventing phagocytes from adhering to them
- antibodies cannot reach surface of bacteria to bind, therefore cannot initiate phagocytosis
Toxins:
- damage host tissues and be either endotoxins or exotoxins
Lifestyle Changes:
- change pathogenicity dependent on environmental changes
- eg. viruses switch between lytic and lysogenic cycles
- eg. fungal spores remain inactive until soil conditions become more favourable
identify modes of disease transmission
- direct contact
- body fluids
- contaminated food/water
- disease-specific vectors (eg. mosquitos carrying malaria)
describe recognition of self vs non-self
- MHC markers on surface of host cells label as ‘self’, no not attacked by immune system
- antigens on pathogens are recognised as ‘non-self’, because different from MHC markers on host cells
innate vs adaptive immunity
Innate: - general/non-specific Adaptive: - specific to certain antigen - developed through life - involves B and T lymphocytes
give examples of physical and chemical defences of plants against pathogens
Physical defences:
- waxy cuticle
- bark/woody stems
Chemical defences:
- production of toxins harmful to pathogen (eg. insecticide pyrethrin)
- production of defensins with antimicrobial properties
identify barriers of the innate immune response in vertebrates
- skin, mucus, cilia, saliva, tears, gastric acid
explain the inflammatory system
- immune cells go to site of infection
- vasodilation –> more cells can get to infection
- mast cells secrete histamine and prostaglandins (cause vasodilation and increase permeability of capillaries)
- phagocytes engulf pathogen and display antigens
- natural killer cells destroy infected host cells
Explain Humoral Response (B cells)
- effector B cells (plasma cells) - secrete specific antibodies to bind with antigen
- memory B cells - when activated by antigen, divide rapidly to produce plasma cells to secrete antibodies
explain the cell-mediated response (T cells)
- helper T cells - activate B cells, phagocytes and cytotoxic T cells
- Cytotoxic T cells (killer T cells) - destroy infected host cells with chemicals
- Memory T cells - survive for many ears and very quickly create cytotoxic and helper T cells when exposed to pathogen again
describe and give examples of passive and active immunity for both naturally and artificially acquired immunity
Passive - antibodies gained via placenta or breastfeeding (natural) or via antibody serum injection (artificial)
Active - natural exposure to pathogen (natural) or vaccination (artificial)
identify factors that facilitate in the transmission of disease
- local, national and global movement of humans
- natural movement of animals via migration
- via water and wind
identify factors affecting immunity (within pathogen and community)
- persistence of pathogens within host
- transmission mechanism
- proportion of populated immunised (herd immunity)
- mobility of individuals in affected population
identify strategies to control spread of disease
- personal hygiene measures (wash hands, masks) Community level: - contact tracing and quarantine - school and workplace closures - reduction of mass gatherings - temperature screening - travel restrictions
describe homeostasis and how it is maintained
- homeostasis maintained through feedback loops
- feedback loops - recognise stimulus, receptors, control centre, effector, and communication pathways (hormonal and nervous)
recognise the sensory receptors, and which type of stimuli they detect
- mechanoreceptors (tough, pressure, hearing, equilibrium, position, acceleration)
- thermoreceptors (temperature)
- chemoreceptors (taste and smell)
- nociceptors (pain, physical/chemical damage to tissues)
- osmoreceptors (water volume)
- photoreceptors (light intensity)
explain catabolism vs anabolism
catabolism - break down molecules into smaller
anabolism - build up (synthesis) smaller molecules into larger
explain why changes in metabolic activity alter optimum conditions for enzymes
- metabolic activity produces heath and CO2 - affect pH levels
- higher temps and extreme pH denature enzymes
identify types of nerve cells
- sensory (detects stimuli, sends internal or external sensory information to CNS)
- interneuron/relay neuron (in CNS, link sensory and motor, in brain to process info)
- motor neurons (carry impulses from CNS to effectors –> muscles or glands)
differentiate between sensory and motor neuron structure
Motor:
- soma at one end
- dendrites connect directly to soma
- longer axon
- axon connects to effector
Sensory:
- soma in centre of cell
- dendrites connect to ends of axon
- shorter axon
- axon connects to receptor
explain the process of passage of nerve impulse (action potential, and synapse transmission)
Action Potential:
- resting potential at approx. -70mV, inactive and polarised (sodium on outside, potassium inside - negative inside overall)
- when stimulated, membrane increases Na+ permeability, Na+ floods into cell, neuron briefly depolarised
- if reaches threshold limit (-55mV), more Na+ enters
- once action potential reaches around +30 - +40mV, Na channels close, neuron repolarises with inside becoming more negative again
- hyperpolarisation - when repolarising, becomes slightly too negative before returning to resting potential
- refractory period - time when neuron is repolarising, cannot generate another action potential
Synaptic Transmission:
- action potential stimulates neurotransmitters contained in capsules in the synaptic knob to fuse to presynaptic membrane and diffuse across synaptic cleft through exocytosis
- neurotransmitters bind to receptors on postsynaptic neuron, triggering new action potential
describe hormones
- chemical compounds that act as intercellular messengers to regulate various metabolic functions
- relay messages to cells displaying specific receptors for each hormone
- travel through circulatory or lymphatic system
explain cell’s sensitivity to specific hormone
- cell can change the concentration of specific hormone receptors on its membrane
- upregulation - when hormone concentration in low, cell increases concentration of receptors on surface
- downregulation - when hormone concentration is high, cell decreases concentration of receptors on surface
describe signal transduction mechanism in hormonal system
- hormone binding to receptor activates signal transduction
- signal transduction alters cellular activity (change permeability of membrane, alter gene expression)
define endotherms vs exotherms
endotherms - heat produced and temp maintained internally, not reliant on external environment
exotherms - body temp dependent on external environment
identify thermoregulatory mechanisms of endotherms (structural features, behavioural responses, physiological mechanisms, homeostatic mechanisms)
Structural Features:
- brown adipose tissue (turn food into body heat by non-shivering thermogenesis)
- increased no. mitochondria per cell (release more metabolic heat)
- insulation (fur, feathers or fat layers)
Behavioural Responses:
- kleptothermy (sharing of metabolic thermogenesis with another animal - huddling)
- hibernation (slow metabolism, breathing, drop temp to conserve energy in winter)
- aestivation (state of lowered metabolism and dormancy similar to hibernation, but in summer, not winter)
- torpor (hibernation, but shorter periods, sometimes just through night or day)
Physiological Mechanisms:
- vasomotor control (vasoconstriction or vasodilation in peripheral blood vessels)
- Evaporative heat loss
- Countercurrent heat exchange (heat transferred from warmer artery blood to colder venous blood from limbs
- Thermogenesis/metabolic activity (shivering creates energy from ATP, or non-shivering with more mitochondria to create heat energy)
Homeostatic mechanisms:
- increase certain hormones to affect metabolism
- insulin increases glucose in cellular respiration, creating energy
define osmoconformers vs osmoregulators
Osmoconformers - isotonic with salinity of environment, do not regulate salt and water concentration themselves
Osmoregulators - actively regulate salt and water concentration, independent of environment
Identify osmoregulatory mechanisms (structural features, behavioural responses, physiological mechanisms, homeostatic mechanisms)
Structural features:
- animals have differing lengths of loop of Henle
Behavioural responses:
- drink more when dehydrated
- move to shade
Physiological mechanisms:
- specialised cells in gives can actively absorb or secrete salts (aid in moving between fresh and salt water)
Homeostatic mechanisms
- ADH increases reabsorption of water, making urine more concentrated (increase ADH when dehydrated, decrease ADH when too much water)
identify osmoregulatory mechanisms in plants (based on environments)
General:
- waxy cuticle on upper and lower epidermis
- abscisic acid (ABA) produced in roots when soil is dry and translocated to leaves –> close stomata to reduce water loss
Hydrophytes (aquatic):
- little need for support or transport tissue
- water absorbed through leaves
- waxy cuticle to repel excess water, not to prevent evaporation
Halophytes (salt water):
- glands to actively secrete/remove salt
- root level exclusion (roots structured to exclude 95% salt in soil)
- tissue partitioning (concentrate salts in certain leaves which then fall off)
Mesophytes (only moderate water needed):
- large root masses
- leaves - broad, thin, waxy cuticle
- most stomata on underside
- produce abscisic acid
Xerophytes (dry conditions):
- leaves - small, hard, thick cuticle, sunken stoma
- fine hairs trap humid air, decrease evaporation
- deep root system to reach water table
