Biology Chapter 14 - Coordination and response

Auxin

-made in the shoot tip
-stimulates cell elongation

Hormone

Chemical substance produced by a gland, carried by blood and alters the activity of target organs

Adrenal glands

Produces adrenaline

Pancreas

Produces insulin

Pancreas

Produces glucagon

Testes

Produces testosterone

Ovaries

Produces oestrogen

Adrenaline

Hormone secreted in 'fight or flight' situations

Adrenaline

-increased breathing rate
-increased heart rate
-increased pupil diameter

Nervous response

-electrical
-through neurones
-faster transmission speed
-short effect duration

Hormonal response

-chemical
-through blood vessels
-slower transmission speed
-long effect duration

Adrenaline

-increase blood sugar concentration
-vasoconstriction in digestive track

Homeostasis

Maintenance of constant internal environment

Insulin

Deceases blood glucose concentration

Negative feedback

Ensures actual temperature is as close to pre-set value as possible; responds when value is not pre-set value

Treatment of type 1 diabetes

Regular injections of insulin shots

Control carbonhydrate intake

Monitor glucose concentration of urine

Controling of body temperature in the heat

-hypothalamus detects an increase in blood temperature
-hypothalamus sends impulses to skin to increase rating of sweating
-vasodialation on vessel near skin(more heat lost by radiation)

Controling of body temperature in the cold

-hypothalamus detects decrease in blood temperature
-hair erector muscles contract to provide insulation as hair stands up
-body start to shiver (muscles contract and release heat from respiration)
-vasoconstriction on vessel near skin

Gravitropism

Response in which parts of a plant grow towards or away from gravity

Phototropism

Response in which parts of plant grow towards or away from direction of light source

Concentration of auxin

-concentrated on shady side of shoot (grows towards light -positive phototropism)
-concentrated on lower side of shoot (grows away from ground -negative gravitropism)
-concentrated on lower side of root (prevents cell growth on lower side -positive gravitropism)

Electrical impluses

travel along neurons

Central Nervous System (CNS)

consisting of brain and spinal cord

Peripheral Nervous System (PNS)

consisting of nerves outside of brain and spinal cord

nervous system

coordination and regulation of body functions

sensory neurones

has cell body (necleus) somewhere along the axon

motor neurones

has cell body at one end of the axon

relay neurones

shorter axon

describe the path electrial impluses go through during reflex

receptor-sensory neurone- relay neurone- motor neurone - effector

reflex

rapid, automatic response to stimulus

synapse

junction between two neurones

Why do impluses only travel in one direction

due to synpase

first step of synaptic transmission

impluse stimulates the release of neurotransmitter molecules from vesicles into synaptic gap

second step of synaptic transmission

neurotransmitter molecules diffuse across the gap

third step of synaptic transmission

neurotransmitter bind to protein receptor of postsynaptic neurone

fourth step of synaptic transmission

impluse is then stimulated in the next neurone

sense organs

groups of receptor cells responding to specific stumuli

cornea

refracts light

iris

controls how much light enters the pupil

lens

focuses light onto retina

retina

contains light receptors

optic nerve

carries impulses to the brain

pupil reflex

controls the amount of light that reaches the retina, by having circular and radial muscles work in opposition(antagonistic action)

accommodation

changes that occur in the eye when focusing on far and near objects

distant object

-ciliary muscles relax

-suspensory ligaments tighten
-lens in an elliptical (thin) shape
-light rays refracted

rod cells

-found mostly at the outer part of retina, absent in blind spot and fovea
-sensitive to low intensity light, responsible for night vision

cone cells

-concentraded in the fovea, absent in blind spot and most of retina
-three different types of cones, absorbing different coloured light, for colour vision

fovea

-greatest concentration of cone cells
-allow sharp, detailed and colourful vision