Unit 2 Flashcards
Explain basic homeostatic model
- Receptor detects stimuli (change in internal or external environment)
- Sends signal to Control Centre (brain/spinal cord - processes info and coordinates response - sends output msg to effector)
- Effector (muscle or gland) responds to output signal (sent via hormones or nerves)
- Produces Response
Describe/draw negative feedback diagram (homeostasis)
(basically sin graph)
- internal environment moves away from optimum point, corrective mechanism activates, returns to optimum point
- moves away (other way) from opt. point, corrective mechanism activates, return to opt. point
Define metabolism, incl. catabolic and anabolic
Metabolism - all chemical processes needed to maintain life (catalysed by enzymes)
Anabolic - synthesise complex molecules from simpler molecules using energy
Catabolic - break down large molecules, releasing energy
Explain tolerance levels (graph)
Tolerance is ability to survive when exposed to abiotic and biotic factors
- bell curve
- optimum range/preferred niche
- zone of physiological stress/marginal niche
- zone of intolerance/unavailable niche
- large number of organisms in optimum range
- tolerance range is in the first 2 sections
Identify neural homeostatic control pathway (types of neurons and cells)
stimulus detected by RECEPTOR CELL –{sensory neuron}–> CNS –{relay neuron}–> CNS –{motor neuron}–> EFFECTOR produces response
Explain transmission of action potential/nerve impulses with and between neurons
- Action potential generated by stimulus
- membrane depolarised (inside becomes slightly less negative), if reaches threshold potential, Na+ channels open and flood into cell
- this initiates action potential
- Conduction
- action potential rapidly passes along axon, briefly reversing distribution of charges
- (refractory period - time required for ions to return to normal distribution, cannot conduct another action potential)
- Transmission across Synapse
- action potential causes neurotransmitters to be secreted and diffused into synaptic cleft, which are taken up by dendrites of post-synaptic neuron
Explain hormonal homeostatic control pathways
Endocrine system:
- hormones (produced in small amounts, have significant effects) are chemical messengers that bind to specific receptors on cells
- part of negative feedback
- responses include: change in metabolism, gene expression (produce specific proteins), membrane permeability
Explain Primary and Secondary messengers in Endocrine Signaling
Primary messengers - hormones act directly on cell, pass into cell, bind to receptor in cytoplasm or nucleus
Secondary messengers - hormone binds to receptor on membrane, triggers biochemical reactions (cascade), lead to particular response
Explain Upregulation and Downregulation in endocrine system
- cells change in response to chronic lack or chronic abundance of hormones
Upregulation:
- in response to chronic lack of hormone
- target cell increases concentration of receptors, therefore greater response to the low number of hormones
Downregulation:
- in response to chronic abundance of hormone
- target cell reduces concentration of receptors, decreasing sensitivity and response to the high number of hormones
Define Thermoregulation, Endotherm and Ectotherm
Thermoregulation - organism’s maintenance of constant internal body temp
Endotherm - organism that can maintain body temp, independent of external environment (energy consuming, but wider tolerance range)
Ectotherm - body temp is dependent on external environment
Identify examples of Thermoregulation
Structural features: SA:V ratio (high to lose heat, low to maintain heat), slim bodies (lose heat), thin vascularized ears (lose heat), fur/feathers/insulation (maintain heat), more mitochondria in cells (produce heat energy)
Behavioural: nocturnal/diurnal, hibernation (long state of inactivity, decreased metabolism), torpor (short term state of decreased physiological activity, body temp and metabolism), aestivation (prolonged torpor becomes of high temps and low water availability), kleptothermy (shared metabolic thermogenesis/penguins huddling)
Physiological Features: vasodilation (lose heat) or vasoconstriction (maintain heat), sweating (remove heat through evaporation), increased metabolism
Define Osmoregulation, Osmoregulators, and Osmoconformers
Osmoregulation - organism’s regulation of salt and water concentrations
Osmoregulator - organism that actively controls salt concentration, independent of environment
Osmoconformer - marine organisms that have internal environment isotonic with external environment
Identify examples of Osmoregulation
Land animals:
- insulated body (decrease evaporation), using metabolic H2O (metabolising fat yields more H2O than carbs), behavioural changes (seeking shade), EXCRETORY SYSTEM (increase ADH hormone when low H2O, causes increased permeability in kidneys, therefore greater reabsorbed H2O)
Plants:
- depends on environment
- dry environment (small leaves, hard thick cuticle, sunken stoma, fine hair trap air, deep root system, low SA:V)
- humid, well-watered soil (large root masses, broad thin leaves, not many adaptations needed)
- aquatic (reduced root system, few stomata because gas exchange directly through water, cuticle to repel water not prevent drying)
Define disease
abnormal condition of organism which interrupts normal bodily functions
define infectious vs non-infectious diseases
infectious - passed from one to another, cellular or non-cellular pathogen
non-infectious - cannot be transmitted, malfunctioning body systems/structures, genetic diseases, or environmental conditions and lifestyle
Define pathogen
any agent causing disease, capable of producing infection
define prion and give example
- non-living, abnormal/mutated forms of normally harmless proteins in brain
- cause neurodegenerative diseases
- spread by eating contaminated meat or surgical instruments
eg. mad cow disease
define viruse and give examples
- non-living, infectious
- attack host cell, inject virus’ nucleic acid (genetic code), replicates in cell, new viruses produced, host cell bursts to release virus
- ACUTE (reproduce quickly, cells die suddenly), CHRONIC (reproduce slowly, slow cell death, can last years) and DORMANT (persists in cell without reproducing until becoming active years later) INFECTIONS
eg. COVID-19, hepatitis, influenza
define bacteria and give pathogenic examples
- pathogenic bacteria cause disease, produce toxins
- spread through food, water, air, direct contact
eg. Cholera, tuberculosis, pneumonia
define fungi and give pathogenic examples
- penetrate host cell, secrete enzymes to digest cell until small enough for fungi to absorb
- spread by spores
eg. ringworm, athlete’s foot
define protists and give examples
- mostly unicellular eukaryotes in moist environments
- lifecycles involve several hosts and several life stages
eg. malaria, sleeping sickness
define parasite and give examples
- live in (endoparasites) or outside (ectoparasites) host’s body
- derive nourishment from host
eg. mosquitoes, fleas, tapeworm
define pathogen virulence
- ability of pathogen to cause disease
- measured by number of infections, how quickly it spreads through body, and number of host deaths
define and identify the virulence factors
virulence factors - contribute to survival of
pathogen
1. ADHESION- stick to host
2. COLONISATION- protein that allows colonisation (eg. produce enzymes to survive stomach acid)
3. INVASION- protein allows entry
4. IMMUNE RESPONSE BLOCKERS - switch off host immune system
identify modes of disease transmission
- direct contact (skin or body fluids)
- indirect contact (surfaces)
- airborne
- fecal-oral (contaminated food/water)
define innate vs acquired immune responses
innate - born with, non-specific
acquired - specialised/specific, developed throughout life
explain 1st line of defence in immune system
- physical and chemical barriers
- skin (physical barrier, dry outer layer inhibits bacterial growth, oil and sweat glands produce anti-bacterial and -fungal substances, beneficial bacteria live on skin)
- mucus membranes (catch pathogen to be coughed or swallowed, contain antibodies to prevent attachment)
- cilia (move pathogen out of lungs)
Explain 2nd line of defence in immune system
Inflammatory response:
- arterioles dilate
- phagocytes move to pathogen, release histamine to attract more phagocytes
- phagocytes engulf and destroy pathogens
- prostaglandins released -> vasodilators and vasorestrictors
- platelets form clots (prevent spread)
- pus produced (dead phagocytes)
Complement System:
- proteins activated by antigen presence
- produce chemicals to inactivate foreign matter
- can trigger: phagocytosis, inflammation, agglutination, precipitation, neutralisation, lysis)
Explain the recognition of ‘self’ and ‘non-self’
Proteins (MHC markers) are on surface of cells, and these proteins are built by the specific genetic code of the cell. Therefore, the MHC markers of the ‘self’ are specific to the host, and foreign cells (eg. viruses) will have different MHC markers (antigens) that can be detected.
Identify the main cells in the 3rd line of defence of the immune system
B Lymphocytes (B cells) - anti-body mediated or humoral response - mature in bone marrow T Lymphocytes (T cells) - cell-mediated response - leave bone marrow when immature, and mature in the thymus gland
Explain the immune response of B Cells
- immunoglobulins are antibodies (which B cells produce)
- B cell have immunoglobulins on their membrane that is specific to a particular antigen (specific pathogen)
- when antigen is detected, B cells are stimulated, rapidly reproducing into either Plasma cells or Memory B cells
- Plasma cells secrete their specific antibody, which binds to the antigen, causing agglutination, precipitation, neutralisation or lysis
- Memory B cells hold the ‘memory’ of the antigen encountered, so can now produce specific antibodies, making a faster, more effective immune response of Plasma B cells on 2nd infection of same pathogen
Explain the immune response of T Cells
- non-specific –> can recognise many antigens
- when pathogen is identified, T Cells rapidly reproduce, differentiating into Helper T Cells, Killer T Cells, or Memory T Cells
- Helper T Cells - recognise antigens on phagocytes that have injested pathogen, then stimulate B Cells to secrete antibodies
- Killer T Cells (cytotoxic T Cells) - produce chemicals to destroy infected host cells (phagocytes that have injested pathogen)
- Memory T Cells - have ‘memory’ of antigen, meaning faster, more efficient response on 2nd infection
define NATURALLY acquired active vs passive immunity, and give examples
Naturally acquired - born with or developed naturally throughout life
- naturally acquired PASSIVE - antibodies pass to fetus via placenta or to infant in breast milk
- naturally acquired ACTIVE - pathogen and antigens naturally enter body, specialised cells produce antibodies
define ARTIFICIALLY acquired active vs passive immunity, and give examples
Artificially acquired - immunity gained by antigen entering body unnaturally
artificially acquired PASSIVE - preformed antibodies in immune serum introduced by injection (antibiotics)
artificially acquired ACTIVE - antigen introduced in vaccines, then specialised cells produce antibodies
