MODULE 1 COMMUNICATION Flashcards
DEFINE STIMULUS
change in the environment that causes a response
DEFINE RESPONSE
change in behavior or physiology as a result of a stimulus
WHAT ARE THE CONDITIONS ENZYMES NEED TO WORK EFFICIENTLY
- suitable temp
- suitable pH
- aqueos environment to keep products and substrates in solution
- free from toxins and excess inhibitors
WHAT ARE THE TWO MAJOR SYSTEMS OF COMMUNICATION AND HOW DO THEY WORK
- neuronal system; interconnected network of neurons that signal to each other across synapse junctions for quick responses
- hormonal system; signals transported in the blood released by endocrine organ and only recognised by specific target cells; long term responses
DEFINE HOMEOSTASIS
keeping internal environment constant despite external changes
DEFINE NEGATIVE FEEDBACK
process that reverses a change in conditions and ensures a constant internal environment; essential for homeostasis
WHAT ARE EFFECTOR CELLS
cells that bring about a response that reverses a change detected by receptor cells
DEFINE POSITIVE FEEDBACK
process that increases change detected by receptors which is usually harmful and not useful for homeostasis
WHAT IS A POSITIVE EXAMPLE OF POSITIVE FEEDBACK (HINT PREGNANCY)
when a woman is in labour and the cervix begins to stretch recognised by anterior pituitary gland- releases oxytocin and cervix stretches more- more oxytocin
DEFINE ECTOTHERM
organism that relies on external sources of heat to regulate its body temperature
WHAT ARE SOME ADVANTAGES TO BEING AN ECTOTHERM
- less food in respiration
- go long periods without food as they need less of it
- greater proportion of energy from food can be used to grow
WHAT ARE SOME DISADVANTAGES TO BEING AN ECTOTHERM
- less active in the cold so more risk of predation i.e lizards
- may not be active in winter so must have sufficient food stores to survive
WHAT ARE SOME ADVANTAGES TO BEING AN ENDOTHERM
- fairly constant body temp despite external temp
- activity possible during cooler weather
WHAT ARE SOME DISADVANTAGES TO BEING AN ENDOTHERM
- more energy from food used for heat
- more food
WHAT MONITORS BLOOD TEMP AND CORE TEMP
thermoregulatory centre in hypothalamus
WHAT IS AN EARLY WARNING SYSTEM FOR TEMP CHANGE
peripheral temperature receptors in the skin monitor temp in extremities send signals to hypothalamus in order to initiate behavioural mechanisms
WHAT IS A SENSORY RECEPTOR
cells that realise change in our surroundings; energy transducer converts one form on energy into another, each one adapted to detect changes in particular forms of energy
DEFINE A POLARISED MEMBRANE
one that has a potential difference across it; resting potential
DEFINE DEPOLARISATION
the loss of polarisation across a membrane; when the sodium ions are entering cell making it less negative with respect to the outside
HOW IS A NERVE IMPULSE CREATED
altering permeability of the nerve cell membrane to sodium ions; more na channels open sodium allowed to move down concentration gradient which creates a change in potential difference (depolarisation)
WHAT IS THE NORM OF SODIUM AND POTTASIUM IONS AT RESTING POTENTIAL
more na ions out than k ions in
DEFINE GENERATOR POTENTIAL
small depolarisation caused by a small amount of na ions entering the cell (depends on size of stimulus recieved by receptors)
DEFINE ACTION POTENTIAL
membrane depolarised to +40mV value ; membrane depolarises to threshold potential then loads of na ions flood in reaching an action potential
WHAT ARE THE 3 TYPES OF NEURONE AND THEIR MAIN FUNCTION
sensory- carry action potential from sensory receptor to CNS
- motor neurone; ap from cns to an effector such as muscle gland
- relay neurones-connect sensory and motor
HOW ARE NEURONES ADAPTED TO DO THEIR JOB
- long to carry ap far
- plasma membrane with many gated channels for k, na and ca
- fatty insulating layer called myelin sheath made of schwann cells providing electrical insulation
- nodes of ranvier between schwann cells
- na + k pumps using atp to actively transport na ions out and k in
- cell body that contains nucleus, many mitochondria and ribosomes
DEFINE RESTING POTENTIAL
-60mV potential difference across neurone cell membrane when at rest
DEFINE THRESHOLD POTENTIAL
potential difference across the membrane of about -50mV; if depolarisation doesnt reach -50 then no action potential is created
DEFINE ACTION POTENTIAL
when the cell is positively charged with respect to the outside with a pd of +40mV
EXPLAIN HOW AN ACTION POTENTIAL IS GENERATED
-resting potential of -60mV compared to outside
-sodium ion channels open and some na come in reaching threshold potential of -50mV
-threshold potential causes voltage gated sodium channels to open and na floods in making the cell positively charged with respect to the outside (+40mV)
sodium channels close k channels open k leaves cell
k comes in overshoots hyperpolarisation
original pd restored
DEFINE LOCAL CURRENTS
movement of ions along the neurone caused by an increase in conc at one point so ions diffuse away to area of low conc
- when ap occurs sodium ion channels open at particular point on neurone
- na ions diffuse from outside to inside lower conc
- upsets balance of ion conc obtained by na/k pumps
- na ion conc rises at point where it enters so moves along neurone aka local current
DEFINE CHOLINERGIC SYNAPSE
one that uses acetylcholine as its transmitter substance
DEFINE NEUROTRANSMITTER
chemical that diffuses across the cleft of the synapse to transmit a signal to post synaptic neurone
WHAT ARE SPECIALISED FEATURES OF THE SYNAPTIC KNOB
many mitochondria
lots of smooth endoplasmic reticulum
vesicles of acetlycholine
voltage gated calcium channels
WHAT ARE SPECIALISED FEATURES OF THE POST SYNAPTIC MEMBRANE
contains sodium ion channels that have 5 polypeptide units 2 of which have receptors for acetylcholine and when they bind they open
HOW IS A SIGNAL TRANSMITTED ACROSS A SYNAPSE
- signal arrives at presynaptic knob
- calcium channels open and ca in
- cause vesicles to bind to presynaptic knob
- acetylcholine released and binds to sodium channel on post synaptic knob
- sodium diffuses in causes generator potential -> threshold potential -> action potential
WHAT IS ACETYLCHOLINESTERASE
enzyme that breaks down acetylcholine in choline and ethanoic acid which stops transmission of signals
ethanoic acid and choline recycled and recombined using ATP from mitochondria respiration
WHAT ARE THE ROLES OF SYNAPSES IN A NERVOUS SYSTEM
- many pre synaptic knobs to one post synaptic useful where several diff stimuli for one response
- one pre to many post useful in reflec arc
- pathways of synapses that enable nervous system to convey wide range of messages
- messages can only travel in one direction as only pre has acetylcholine
- low level signals amplified by process called summation
- acclimitisation getting used to smells or noises as synapse becomes fatigued so stops sending vesicles with transmitter substance; stops synapse becoming overworked
WHAT ARE THE 2 TYPES OF HORMONES
steroid
protein and peptide
WHAT IS AN ENDOCRINE GLAND
a gland that releases hormones directly into the blood stream
WHAT IS AN EXOCRINE GLAND
a gland that releases its substance into ducts so it can be carried to where it needs to be
WHAT MAKES THE ENDOCRINE SYSTEM ABLE TO SEND A MESSAGE TO MULTIPLE CELLS OR TO ONE
hormones have certains target receptors into which they will fit; it can either fit into many or into one
WHAT EFFECT DOES ADRENALINE HAVE ON A CELL
adrenaline cannot enter a cell so acts as a first messenger
it binds to the cell and activates adenyl cyclase
adenyl cyclase converts ATP into cAMP which is second messenger and causes reaction in cell
WHAT IS THE FUNCTION OF THE ADRENAL MEDULLA
releases adrenaline used in fight or flight response
- concerts glycogen into glucose
- stops saliva ducts
- speeds up heart rate
- stops digestion in order to save energy
- dilate pupils
WHAT IS THE FUNCTION OF THE ADRENAL CORTEX
makes mineral-corticoids to help control conc of na and k in bloof
makes glucocorticoids to control metabolism of carbs and protein in the liver
WHAT PART OF THE PANCREAS IS CONSIDERED EXOCRINE
cells are in tubules and release digestive enzymes; where the tubules all join together they run into the pancreatic duct where the enzymes can be carried into the first part of the small intestine
WHAT ENZYMES ARE IN THE PANCREATIC FLUID
trypsinogen; an inactive protease
amylase; a carbohydrase
lipase
and sodium hydrogen carbonate which neutralises the acidic contents in the stomach
WHAT IS THE ENDOCRINE FUNCTION OF THE PANCREAS
islets of langerhans which contain alpha cells and beta cells which can be secreted into the blood when needed
WHAT DO ALPHA CELLS MAKE AND WHAT DO BETA CELLS MAKE
alpha cells make glucagon
beta cells make insulin
WHAT HAPPENS IF BLOOD GLUCOSE LEVELS DROP TOO LOW
alpha cells in islets of langerhans realise this
make glucagon and secrete into blood
glucagon binds to target receptors on liver cells
conversion of glycogen to glucose (glycogenolysis)
conversion into glucose using fats and amino acids (glucaneogenesis) and use of more fatty acids in respiration
WHAT HAPPENS IF BLOOD GLUCOSE LEVELS TOO HIGH
beta cells in islets of langerhans realise this
secrete insulin
binds to target cells (liver muscle and some brain)
activates adenyl cyclase and converts ATP into cAMP which activates enzyme reactions in cells
more glucose channels inserted into cell
more glucose enters cell
more glucose enters cells and converted into glycogen for storage (glycogenesis)
WHAT IS THE CONTROL OF INSULIN SECRETION IN CELLS
- cells contain k and ca ion channels
- k channels usually open so k out and c channels closed so cell more negative on inside
- glucose enters cells when outside levels too high
- used in metabolism to make ATP
- ATP causes k channels to close and ca to open so ca diffuses in cell
- cause insulin vesicles to move to and fuse with the cell wall to release insulin via exocytosis
WHAT IS TYPE 1 DIABETES
bodies own immune system destroys beta cells so no insulin produced; usually occurs in childhood
WHAT IS TYPE 2 DIABETES
body becomes unresponsive to insulin produced as target cells receptors may decline and lose their ability to take up insulin, also less insulin produced
WHAT INCREASES THE RISK OF TYPE 2 DIABETES
usually occurs in old people especially if asian/afro carribean descent, family history of diabetes, diet high in sugars or obese
HOW DOES THE HEART CONTROL THE HEART RATE
- myogenic
- contains SAN in right atrium wall which can initiate a contraction which spreads down atria walls, through AVN and purkinje tissues to base of the heart and then ventricles where they contract
- medulla oblongata connected to heart via nerves and so can control rate of contractions; accelarator nerve increase and vagus nerve decrease
- heart muscles responds to adrenaline
HOW DOES THE PRESENCE OF INCREASED CO2 AFFECT HEART RATE
co2 reacts with water in the blood plasma and reduces ph
detected by chemoreceptors in carotid arteries, aorta and brain which send impulses to cardiovascular centre which increase heart rate
if co2 levels fall accelerator nerve less activated and heart rate falls
