B10: The Nervous System Flashcards
what is the purpose of the nervous system?
enable humans to react to their surroundings /coordinate their behaviour
adaptations of nervous system?
- neurones have a cell body
- have cytoplasmic extensions from this body called AXONS/DENTRITES
what is a reflex?
- rapid reaction - involuntary responses that dont involve the consious part of your brainas the coordinator the reaction
3 types of neurones involved in reflex arc/function?
SENSORY NEURONES : carry impulse from sense organ to CNS
MOTOR NEURONES: carry impulses from CNS—> effectors
RELAY NEURONES: - connect sensory/motot neurones in CNS
sensory neurones structure?
LONG/cell body bracnhes off middle of axon
motor neurones structure?
LONG /have large cell body at one end with DENTRITES branching off it
Relay neurones structure?
SHORT/ small cell body at one end with many dentrites braching off it
reflex arc order ?
stimulus –> recepetor –> sensory neurones —> relay neurones –> motor neurones —> effector –> response
explain
reflex arc when you touch a hot object ?
when you touch hot object, RECPEPTOR is stimulated
- elelctrical IMPULSE from receptor to sensory neurones
- at end of sensory neurone there is a SYNAPSE
- releases A CHEMICAL (neurotransmitters) /DIFFUSESto relay neurone
- this triggers electrical impulse on relay neurone and passes along to another synpase
- another chemcial released/triggers impulse in MOTOR NEURONES
- electrical impluse passes from motor neurones —> effector
- muscle contracts/pull hand away
why do drugs affect our brain fruction? (3)
- drugs can bind to neurotransmitter receptors on the postsynapitic neurone (membrane of relay/motor neurone)
- triggering impusles in different parts of the brain
- frequent drug use can lead to overstimulation of neurones/loss of function
REQUIRED PRACTICAL : REACTION TIME?
- PERSON 1 sit on chair with arm on table, with dominant hand on edge
- Person 2 hold ruler so 0 mark is level with top of thumb
- person 2 drops ruler/1 catches it as quick as possible
- record no. on ruler/REPEAT
- after 1/2 have completed ,change one factor (caffeine,alcohol,listen to music)
RECORD RESULTS - use conversion table to convert ruler measurement to reaction time
control variables of reaction time experiment?
- perosn catching ruler use DOMINANT HAND
- drop same ruler from same height
- if investigating effect of caffeine , make sure there’s no loud music/alcohol consumption before
the eye function?
sense organ containing receptors sesnitive to light intensity/color
structure of eye and function? (6)
cilrop
CORNEA : transparent lens that refract light as it enter eye
IRIS: control how much light enter pupil
LENS: transparent disc that can change shape to focus light on retina
RETINA: contains LIGHT RECPETORS/COLOR RECPETORS
OPTIC NERVE : sensory neurone that carry impuses between eye to brain
PUPIL : hole that allows light to enter eye
in dim light what happen to eye?
pupil DILATES (WIDENS)
radial muscle CONTACT
circular muscle RELAX
BRIGHT LIGHT what happens to eye?
pupil constricts
radial muscles RELAX
cirlcular muscle CONTACTS
what is accomodation?
-proccess of changing shae of lens to focus on near/far objects
what happens to eye when focusing on
near objects
-ciliary muscles CONTRACT
-suspensory ligaments LOOSEN
-lens is thicker/refracts light more
what happens to eye when focusing on
far objects ?
- ciliary muscles relax
- suspensory ligaments TIGHTEN
- Lens is THINNER/slightly refracts light
cause and solution of MYOPIA?
CAUSE -lens is too curved/thick
-image is in focus IN FRONT of retina
SOLUTION : cocave lens corrects rays so they focus on the retina
cause and solution of HYPEROPIA?
CAUSE- lens is too flat /light is focused BEHIND RETINA
SOLUTION: CONVEX LENS refracts light rays to fucs on retina
as/dis of
TREATMENTS FOR HYPEROPIA/MYOPIA?
HARD/SOFT CONTACT LENSES: sit on surface of eye
ad : ideal for sports /comfy
dis: risk of infection
LASER EYE SURGERY: change shape of cornea
dis : risk of unexpected damage
LENS REPLACEMENT SURGERY: replace lens with plastic,artifical one
dis: invasive
-risk of damage occuring to retina (complete sight loss)
fucntions of regions in brain?
CEREBRAL CORTEX: outer layer of brain divided in 2 hemispheres for INTELLIGENCE, MEMORY,CONSCIOUSNESS,
PERSONALITY
CEREBELLUM: -under cerebral cortex - BALANCE, MUSCLE COORDINATION,MOVEMENT
MEDULLA: controls unconsious activities like heart rate/breathing
why are there difficluties in understanding the brain /treatement options?
very complex /delicate organ
any potential treatemnt could elad to further damage (speech,personality changes etc)
electrical stimulation of brain process?
tiny electrodes pushed into different parts of brain
-tiny jolts of electricity stimulate regions /effects can be observed
MRI SCAN/fuctional mri scans uses?
uses magnetic fields to study brain/ the effect these have on protons in water molecules in body
- functional MRI scans produce images of different images of brain that are active during different actvities (active region shave increased blood flow)
what is homeostasis ?
regulation of internal conditions of a cell/organism to maintain optimum conditions for function in response to internal/external changes.
what does homeostasis control?
blood glucose conc
body temp
water levels
name 3 difference between nervous system and endocrine system?
endocrine system is:
- slower
- longer lasting
- via blood instead of neurones
changes to cyclist’s core body temp and skin temperature in a race?
- Skin temperature decreases (during the race)
- As a result of increased sweating
- Heat energy is lost as sweat evaporates from the skin, leading to the skin cooling
- Core body temperature increases (during the race)
- as a result of the muscles contracting more
- muscle contraction releases more energy (as heat)
controlling body temp?
1) temp increases - blood vessels dilate (vasodilation) , so sweat is produced by gland
2) sweat evaporates from skin - heat energy lost , cooling down body
3) temp decrease - blood vessels constrict (vasoconstriction), so sweating stops
4) skeletal muscles shiver - this muscle contraction increases heat released in body - increasing temp
