Homeostasis Flashcards

Question

types of physical defence mechanisms (passive)

Answer 1

Thick barriers (e.g., bark); resistant to pathogens Leaf hairs (often containing chemicals), spines or prickles; defence against herbivores Waxy cuticles; prevents formation of moisture to inhibit bacterial infection Stoma size; small = less pathogens can enter

Answer 2

Plants produce toxic chemicals in response to pathogens (caffeine, morphine, etc.,) Some produce defensins – proteins that inhibit development of pathogens

Answer 3

they are physical barriers to reduce pathogen invasion

Answer 4

-phagocytosis -inflammatory response -fever

Answer 5

Phagocytosis is when Phagocytic leukocytes migrate to infection sites and engulf foreign bodies to kill it " eats cells that shouldn't be there"

Answer 6

the inflammatory response Increases capillary permeability at infected sites, recruiting leukocytes (leads to localised swelling) to kill the pathogen/bacteria

Answer 7

Increase body temp to activate heat-shock proteins and support microbial growth

Answer 8

in the blood, tissue and lymphatic system

Answer 9

* Neutrophils * Basophils * Eosinophils * Monocytes * Lymphocytes (3rd line of defence)

Answer 10

-most abundant type -first responder to infection -Die after phagocytosing a few pathogens

Answer 11

o Circulate in bloodstream o Responsible for initiating inflammatory responses by releasing chemicals (histamine)

Answer 12

o Prominent at sites of allergic reaction and parasite infections o Rare in blood, common at mucous membranes

Answer 13

o Share phagocytosis with neutrophils o Longer lasting o Differentiate into two types of cells Macrophages (phagocytose) Dendrite cells

Answer 14

o Responsible for production of antibodies Antibodies; target specific antigens on pathogens o Include B and T cells o Involved in destruction of virus-infected body-cells o Slowest to respond (require antigen presentation)

Answer 15

* The way the body reacts when pathogens damage cells * Damaged cells release prostaglandins (chemical that directs blood flow to an injured area) which work like histamine (causes vasodilation to recruit leukocytes to area) * Damaged cells also release chemokines that recruit phagocytes to site of damage to fight infection

Answer 16

* Works in conjunction with innate immune system * Where your body produces proteins that can trigger phagocytosis (usually from liver)

Answer 17

*Responds to specific antigens by creating antibodies and memory cells *Relies on the clonal expansion of plasma cells to produce large numbers of antibodies thus there is a delay between initial exposure to pathogen and production of large quantities of antibodies *Distinguishes self-cells from antigens via lymphocytes that enter the blood from the bone marrow or thymus and become either T lymphocytes (thymus) or B lymphocytes (bone marrow)

Answer 18

*From serum antibodies (produced by plasma cells) *Refers to bodily fluids where free-floating serum antibodies bind to antigens and assist in elimination *When they encounter pathogen, produce antibodies that complimentarily fit antigen *B-cells divide rapidly to produce cells with replicates of the antibodies or cells that remain long after in case of reinfection (memory cells)

Answer 19

*Response carried out by T-cells *Helper T-cells activate other immune cells *Cytotoxic T-cells assist with elimination of pathogens and infected host cells

Answer 20

1. Attract and activate phagocytes 2. Localise pathogen to prevent locomotion 3. Rupture pathogen membrane and destroy it 4. Can also become memory cells

Answer 21

Active: - The production of antibodies by the body itself - Longer-lasting *Creates memory cells Types of active - NATURAL; infection -ARTIFICIAL; vaccination Passive: -The acquisition of antibodies from another source -short-lived *No memory cells developed Types of passive NATURAL; maternal antibodies ARTIFICIAL; monoclonal antibodies

Answer 22

*Persistence of pathogens within host *Transmission mechanism *Proportion of the population that is immune/has be immunised *Mobility of individuals in the affected population

Answer 23

*chemical reactions occurring in the cells = metabolism o these metabolic processes process in small steps, the sum of which is called a metabolic pathway o all the anabolic and catabolic reactions happening in an organisms metabolism as a whole  CATABOLIC REACTIONS BREAK DOWN (e.g., C6H12O6(glucose) to CO2 and H2O)  ANABOLIC REACTIONS BUILD COMPLEX MOLECULES (E.G., from H2O and CO2 to C6H12O6(glucose) in photosynthesis) - Require energy

Answer 24

-Each step of metabolic pathways requires a specific enzyme (THE 5 FACTORS THAT AFFECT ENZYME ACTIVITY)

Answer 25

-The range of particular environment (eg. light, temperature, availability of water) or physiological (particular chemical concentrations) factor within which an organism can survive.

Answer 26

o Causes a response that brings the body back to normal E.g., FEVER: High temp detected by sensors Relayed to temp-regulatory control centre in brain Control centre processes info and activates effectors (e.g., sweat glands)

Answer 27

o Involves an increase in function away from normal E.g., CHILDBIRTH:  Head presses on cervix Pressure activates a signal Oxytocin gets released from pituitary gland Oxytocin increases contractions

Answer 28

Structures that detect changes in the external of internal environment

Answer 29

Input -> receptor ->regulator -> effector ->output

Answer 30

*NOCICEPTOR o Responds to damaging or potentially damaging stimuli by sending signals to spinal cord and brain *THERMORECEPTOR o Detects differences in temp *CHEMORECEPTOR o Detects chemical composition of blood levels (CO2, O2, ion conc.) *MECHANOCEPTOR o Detect touch, pressure, vibration and sound from ex. And int. environments *PHOTORECEPTOR o Detects changes in light (RETINA)

Answer 31

: a detectable change in internal or external environment (INPUT). Can be physical or chemical

Answer 32

*sensory RECEPTORs detect the stimuli *A chemical message is then transmitted to the coordinating centre (REGULATOR) that determines if a change is required *Another chemical messenger brings about a response (OUTPUT) within a cell or EFFECTOR organ

Answer 33

*Sensory neurons: o Convert external stimuli from organism’s environment into internal electrical impulses *Motor neurons: o Form the pathway which impulses pass from brain/spinal cord to effectors

Answer 34

* ACTION POTENTIAL (when nerve impulse passes through) o Occurs when resting potential across membrane has high stimulis (ex. Mechanical) o AXON becomes depolarised (inside becomes less negative) o 35mV o Then returns to resting potential (REPOLARISATION)

Answer 35

* Neurons convey info via nerve impulses (electrical signal) * RESTING POTENTIAL o When a nerve is not sending a nerve impulse it has a resting potential of -70mV  Inside of neuron is negative relative to outside  INSIDE; lots of large negative ions  OUTSIDE; lots of Na, Cl and Ca ions

Answer 36

* VOLTAGE-gated ion channels (closed during resting potential) open allowing sodium ions to move in (makes inside more positive) AT PEAK OF ACTION POTENTIAL; Na channels close K channels open  K leaves  inside becomes negative again

Answer 37

* Impulse forms because action potential causes a small current to flow in cytoplasm and in extracellular fluid which stimulates depolarisation of the next part of the nerve membrane

Answer 38

* The junction between a neuron and another neuron or effector by passage of a nerve impulse or of a chemical called a neurotransmitter

Answer 39

* the conversion of chemical signals that are transmitted from outside the cell to a functional change or response within the cell

Answer 40

Received by receptors on cell membrane 1. signal molecules binds to specific receptors outside of cell membrane. When combined the receptor changes shape or activates an internal response 2. activation inside the cell causes a signal transduction cascade creating effector protein 3. the resulting effector protein results in * changes to cellular metabolism/function/movement * gene expression change 4. sometimes there is no transduction cascade and the effector protein is produced from the change in receptor shape 5. receptor can be ‘reset’ and release the signal molecule

Answer 41

animal that produces it's own heat

Answer 42

* Brown Adipose Tissue o Specialised for rapid heat production o Stores lipids (lots of energy) o Contains more mitochondria than white fat o Provides insulation o Skin, feathers, fur and blubber provide insulation  Reduce heat flow between animals and environment

Answer 43

* Kleptothermy o The sharing of heat amongst animals * Hibernation o Prolonged, usually seasonal state (colder months) of reduced activity and metabolic depression o Body temp drops o Reduced energy expenditure o Can also delay reproduction * Torpor o Reduction of metabolic activity daily (or usually nightly) o Period of torpor depends on air temp (colder means greater days in torpor) * Aestivation o Form of hibernation/torpor that occurs during warmer months o Usually in response to a lack of food in arid environments

Answer 44

* Construction of the capillaries restricts blood flow in the skin, lowering heat loss * Vasodilation allows blood to flow through the skin capillaries and transport heat from the body to the skin facilitating heat loss

Answer 45

* Panting increases the cooling effects in birds and many mammals * Sweating moistens the skin, helping to cool an animal down

Answer 46

* The arrangement of blood vessels in many marine animals and birds allows for counter current heat exchange * Transfer of heat between fluids flowing in opposite direction and reduce heat loss

Answer 47

The hypothalamus has a central role in thermoregulation – it registers core body temp and coordinates nervous and hormonal responses to restore normal body temps

Answer 48

* Insulin signals cells to take up glucose from the blood -> increasing metabolic activity

Answer 49

Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body.

Answer 50

* Filters blood * Reabsorbs nutrients * Secretes excess waste molecules * Water is absorbed from o Collecting duct o Distal convoluted tubule

Answer 51

* Anti-diuretic hormone (ADH) o Produced in hypothalamus o Increases permeability of the distal convoluted tubules and collecting ducts to water o This results in more water being reabsorbed from the glomerular filtrate back into the blood o Thus less concentrated urine is excreted o Restores normal water balance (negative feedback loop)

Answer 52

if osmoreceptors detect higher water content -> less ADH released -> decreases permeability and so forth

Answer 53

* High blood concentration * Low blood volume * Low blood pressure

Answer 54

o Cannot regulate o Match their body’s salt levels/osmolarity of body fluids to their environment o Make substances to keep external and internal molarity equal o No energy used e.g. some marine animals

Answer 55

2) OSMOREGULATORS o Actively control internal salt and water balance/keeps osmolarity of body fluids constant o Need to be able to get rid of excess salts or actively promote uptake of salts from environment o Use energy to maintain the osmatic gradients via active transport (e.g., most land animals & fish)

Answer 56

- Any plant adapted to grow wholly or partly submerged in water or wet habitats

Answer 57

o A plant adapted to growing in well-watered soil.

Answer 58

o A plant that has adaptations to survive in an environment with little liquid water.

Answer 59

o A plant that grown in waters of high salinity.

Answer 60

o Openings on the underside of leaves o When the plant has enough water, stomata open. Oxygen and water vapor can exit. o When plant is low on water stomata to close. This reduces water loss through transpiration, helping the plant conserve water and maintain its internal balance.

Answer 61

o Vacuoles regulate the turgidity by regulating the amount of water present inside the cell. o cell has excessive water: vacuole usually absorbs the water and then diffuses it out of the cell o cell lacks water: water from the vacuole tends to revert into the cell thereby maintaining turgidity

Answer 62

o prevents evaporation of water from the epidermal surface (DRY/HOT ENVIRONMENT) o can also prevents external water and solutes from entering the tissues (WET/HUMID ENVIRONMENT)