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Unit 14: Coordination and response - Coggle Diagram
Unit 14: Coordination and response
14.1 Coordination and response
Electrical impulses travel along neurons
mammalian nervous system
Central nervous system (CNS)
brain + spinal cord
Peripheral nervous system (PNS)
everything outside brain + spinal cord
Function
body function coordination + regulation
simple reflex arc
sensory receptor (sense
stimulus
) → sensory neurone → brain → relay neurone → motor neurone → effector (response made)
Reflex action: automatically + rapidly integrating + coordinating stimuli with responses of effectors (muscles and glands)
Synapse: junction between two neurones
impulse stimulates release of neurotransmitter molecules from vesicles into synaptic gap
neurotransmitter molecules
diffuse
across gap
neurotransmitter molecules bind with receptor proteins on the next neurone
impulse stimulated in the next neurone
synapses ensure impulses travel one way
14.2 Sense organs
groups of receptor cells responding to specific stimuli (light, sound, touch, temperature, chemicals)
eye
cornea
refracts light
iris
controls amount light enter pupil
lens
focus light onto retina
retina
contains light receptors, some sensitive to light of different colours
Sensitive to light
optic nerve
carries impulses to brain
Accommodation
Focus on near objects
tired ∵ circular ciliary muscles contract
circular ciliary muscles contract → tension in suspensory ligaments reduces, slackened → > convex (fatter, thick, short) → light
refracted
more by lens → light focused on yellow spot
Focus on distant objects
muscles relax → ↑ suspensory ligaments tension → pull onto lens
circular ciliary muscles relax → tension in suspensory ligaments ↑, pulled tight → less convex (thinner, longer, wider ∵ pulled by suspensory ligaments) → light refracted a little by lens → light focused on yellow spot
colour vision
rods
black / white / grey; evenly distributed other than in blind spot; > sensitivity for night vision
cones
mainly at fovea, sensitive to R / G / B; clear detail coloured image
Fovea / yellow spot
region of the retina, lots of cones, sees good detail
Skin structure
maintenance of constant internal body temperature
Hot: ↑ temp → > sweat / production (> sweat evaporate → cooling) + ↑ blood circulation →
vasodilation
→ > blood flow to surface → hair flat → heat escape
Cold: same,
vasoconstriction
→ > blood to shunt vessel → < blood flow to capillaries skin surface → hair stand up (trap air) + shivering → > heat produced
temperature receptors (skin) detects temperature change → impulse → (brain) hypothalamus → effector
14.3 Hormones
Hormone: chemical substance, produced by gland, carried by blood, alters activity of one / > specific target organs
Adrenaline
secreted in fight or flight situations: ↑ B.R., H.R., pupil diameter
Control of metabolic activity: ↑ blood glucose conc., ↑ H.R.
nervous vs hormonal control
faster, shorter effect vs slower, longer effect
14.4 Homeostasis
Maintenance of constant internal environment
Insulin: ↓ blood glucose conc.
Control by -ve feedback
Type 1 diabetes treatment: insulin injections + management
maintenance of a constant internal
body temperature in mammals
Hot
↑ sweat production + blood circulation →
vessel dilation
→ > blood to surface → hair lie flat → heat can escape
Cold
↓ sweat production + blood circulation →
vessel constriction
→ > blood to shunt vessel → < blood to capillaries → hair stands up (trap warm air), shiver → > heat produced
14.5 Tropic response
Gravitropism: Response, parts of a plant grow towards / away from gravity
shoot: away
root: towards (∵ have water)
Phototropism: response, parts of a plant grow towards / away from the direction of the light source
shoot: towards (∵ photosynthesis)
roots: away
Auxin
Shoot
promote growth
produced here
diffuses through plant from here
unequally distributed in response to light and gravity
Less in > light areas
More at the bottom ∵ gravitational force
stimulates cell elongation
↑ elasticity → ↑ water entering
Root
inhibit growth ;(
Purpose
Growing cuttings
Cutting: part of plant removed from main shoot = no root, water, minerals
auxin containing rooting powder
Killing weeds
↓ competition for food, auxin stimulates uncontrolled growth of broad-leaves plants
Ripening fruits
making seedless fruits
controlling dormancy