co-ordination & control Flashcards
2.80 understand how organisms are able to respond to changes in their environment
- all living organisms need to respond to changes in environment for survival
- nervous system coordinated by brain allows body to respond to changes in environment
- organisms additionally have reflexes for fast involuntary actions that protect body from damage
2.82 understand that a coordinated response requires a stimulus, a receptor & an effector: what’s the definition of a stimulus?
change in the animal’s surroundings/the environment e.g. a ball thrown towards you
2.82 understand that a coordinated response requires a stimulus, a receptor & an effector: what’s the definition of a receptor?
specialised cells/organs that detect changes in environment e.g. your eye, or sensory neurones in finger detect heat
2.82 understand that a coordinated response requires a stimulus, a receptor & an effector: what’s the definition of an effector?
part of body (muscles) that carries out response to stimuli, e.g. hand catching ball, muscles in finger contract to pull finger away from heat
2.87 what does the central nervous system consists of, and how is it linked to sense organs (receptors)?
the brain and spinal cord, and linked to sense organs by nerves
2.88 how do reflexes work?
- stimuli detected by receptors, stimulating sensory neurones that send electrical impulses to CNS
- CNS relays impulse across the synapse to relay neurones via synaptic transmission
- relay neurones relays impulse to motor neurones in the effector, which will quickly carry out rapid response
2.89 what is the role of neurotransmitters at synapses?
chemical messengers which diffuse across the synapse & bind w receptor molecules on membrane of next neuron
2.90 describe the structure and functioning of a simple reflex arc
illustrated by the withdrawal of a finger from a hot object
- receptors detect stimulus (change in temp.) & send electrical impulse along the sensory neurone
- sensory neurone passes the impulse to the spinal chord to a relay neurone, relay neurone then passes the impulse through spinal chord & to a motor neurone
- motor neurone causes the effector (arm muscle) to contract & move arm away from stimulus (fire/hot object)
what’s definition of a synapse?
the gap between neurones
what are the 3 types of neurones?
sensory neurones, relay neurones, motor neurones
what are the functions of the structures within a motor neurone?
nucleus: contains all genetic info of cell
dendrite: tree like projections which connect to diff. neurones; 1 neurone can connect to many other neurones
cell body: main section of cell, contains nucleus
axon: the long section - electrical impulses travel long distances through the axon
myelin sheath: insulates axon & speeds up transmission of impulse
2.91 describe the structure & function of the eye as a receptor (function/description of cornea)
curved transparent disc at front of eye; does most of focusing
2.91 describe the structure & function of the eye as a receptor (function/description of pupil)
circular opening whose size is controlled by iris
2.91 describe the structure & function of the eye as a receptor (function/description of iris)
ring of muscles w hole in middle (pupil); controls how much light enters eye
2.91 describe the structure & function of the eye as a receptor (function/description of lens)
soft, flexible & transparent, its shape can be changed to fine tune focusing of light onto retina
2.91 describe the structure & function of the eye as a receptor (function/description of ciliary muscles)
ring of muscle at edge of eye which circles the lens. when it contracts lens gets fatter, when relaxes lens gets thinner
2.91 describe the structure & function of the eye as a receptor (function/description of suspensory ligament)
strong fibres which attach lens to ciliary muscle
2.91 describe the structure & function of the eye as a receptor (function/description of retina)
contains light sensitive cells called rods & cones
2.91 describe the structure & function of the eye as a receptor (function/description of optic nerve)
consists of many neurones which carry impulses from retina to brain
2.91 describe the structure & function of the eye as a receptor (function/description of fovea)
the region of the retina with the greatest no. of cones
2.91 describe the structure & function of the eye as a receptor (function/description of conjunctiva)
a mucous membrane that covers the eye to prevent infection
2.92 understand the function of the eye in responding to changes in light intensity
dim light:
- radial muscles contract and circular muscles relax
- this makes iris narrower & pupil dilates
bright light:
- circular muscles contract and radial muscles relax
- this makes iris wider & pupil constricts
2.92 what is the receptor and the effectors in the reflex arc of the eye responding to changes in light intensity?
receptor: retina (detects light intensity)
effectors: muscles of the iris
2.92 understand the function of the eye in focusing on near objects (accommodation)
light rays entering eye are spreading out (diverging) so lens needs to refract light to ensure it focusses onto retina:
- ciliary muscles contract
- meaning suspensory ligaments are therefore slack
- lens not stretched out so becomes thicker with more convex shape
- therefore more refraction of light
2.92 understand the function of the eye in focusing on distant objects (accommodation)
light rays entering eye almost parallel when they reach cornea, so lens doesn’t need to refract them much to focus light onto retina:
- ciliary muscles relax
- therefore suspensory ligaments pulled tight
- lens pulled thin & has less convex shape
- therefore less refraction of light
what’s the definition for accommodation?
the changes that take place in the eye which allow us to see objects at different distances
2.93 describe the role of the skin in temperature regulation, with references to sweating, vasoconstriction & vasodilation (too cold)
- hairs stand on end from erector muscles: hairs trap layer of air which provides insulation for conduction of heat
- less sweat released: therefore less heat loss via evaporation
- vasoconstriction: arterioles supplying capillaries near surface of skin get narrower - they constrict. less blood flows through capillaries near surface of skin, therefore less heat lost by radiation
- effect for all is less heat lost
2.93 describe the role of the skin in temperature regulation, with references to sweating, vasoconstriction & vasodilation (too hot)
- hairs lie flat: insulating layer of air not formed
- more sweat released: when it evaporates, heat energy taken away from skin as evaporation of water requires energy
- vasodilation: arterioles supplying capillaries near surface of skin widen - they dilate. more blood flows through capillaries near surface of skin, therefore more heat lost by radiation
- effects for all is more heat lost
2.94 what are the sources and functions of adrenaline?
source/gland: adrenal gland
function: increases heart & breathing rate for fight, fright or flight response
2.94 what are the sources and functions of insulin?
source/gland: pancreas
function: causes liver & muscles to take up glucose and convert it to glycogen for storage
2.94 what are the sources and functions of testosterone?
source/gland: testes
function: stimulates development of male secondary sexual characteristics
2.94 what are the sources and functions of progesterone?
source/gland: ovaries
function: maintains uterus lining and controls development of secondary female sexual characteristics
2.94 what are the sources and functions of oestrogen?
source/gland: ovaries
function: stimulates uterus lining to develop & the development of female secondary sexual characteristics
2.95B what are the sources and functions of ADH?
source/gland: pituitary gland
function: reduces amount of water lost in urine
2.95B what are the sources and functions of FSH?
source/gland: pituitary gland
function: stimulates an egg to mature in the ovary
2.95B what are the sources and functions of LH?
source/gland: pituitary gland
function: stimulates release of an egg from ovary (ovulation)
