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B5 - Homeostasis
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B5 – HomeostasisDef: Homeostasis####regulation of internal environment between set limits
3 Egs of what control systems control####body temp, blood glucose, water levels
Def: negative feedback####response of the body if levels gets too high or low to return it to normal
What is the process of a response coordinated by the CNS?####stimuli → receptor → coordination
centre → effector → response
Def: stimuli####a factor that causes a response from the body
Eg: stimuli####bee sting
Def: Receptor####detects a stimulus
Eg: Receptor####skin
Def: Coordination Centre####receives and processes information then organises a response
Eg: Coordination Centre####Brain
Def: Effector####produces a response
Eg: Effector####muscle
Def: Response####act of restoring optimum level
Eg: Response####sweating lowers temperature
Def: Nervous system####allows humans to react to their surroundings and coordinate their
behaviour
What is the the Nervous system made up of####CNS, sensory neurones, motor neurones, effectors
Def: CNS####Central Nervous System - brain and spinal cord
Def: sensory neurone####carry information via electrical impulses from receptors to CNS
Def: motor neurone####carry information via electrical impulses from CNS to effectorsa
Def: Reflex action####automatic and rapid response to a stimuli
What is the process of a reflex arc?####stimuli → stimulus → sensory neurone → relay neurone →
motor neurone → effector response
What is the difference between a reaction coordinated by CNS and a reflex action?####doesn’t
involve conscious part of the brain
Why do reflex arcs not involve conscious part of the brain?####to prevent injury by acting rapidly
What is the required practical on reaction times?####how long it takes to react to the dropping of a
ruler (with and without caffeine)
What does the cerebral cortex do?####responsible for consciousness, intelligence, memory and
language
What does the medulla do?####unconscious activities
, What does the cerebellum do?####muscle coordination
What are the methods for studying the brain?####studying patients with brain damageelectrically
stimulating the brainMRI scans
What does the iris do when exposed to light?####circular muscles contract, radial muscles relax →
pupil shrinks → reduces amount of light enter the eye
What does the iris do in dim light?####circular muscles relax, radial muscles contract → pupil widens
→ reduces amount of light enter the eye
Def: accommodation####the changing shape of the lens to focus on an object
How does the lens change in shape to see short distance?####ciliary muscles contract, suspensory
ligaments slacken → lens becomes thicker and more curved → light refracted more
How does the lens change in shape to see long distance?####ciliary muscles relax, suspensory
ligaments contract → lens thins and flattens → light refracted less
Def: myopia####short sightedness - light focuses in front of the retina
Def: hyperopia####long sightedness - light focuses ‘behind’ retina
What type of lens would a myopia suffer’s glasses have?####concave
What type of lens would a hyperopia suffer’s glasses have?####convex
What are the treatments for vision defects?####glassescontact lenseslaser eye surgeryreplacement
lens surgery
What is optimum human body temp?####37°C
What is the coordination centre for temperature control?####thermoregulatory centre
What does the body do to cool down?####sweatvasodilation
Why does sweating cool you down?####transfers energy to the environment
Why does vasodilation cool you down?####blood flow is closer to the skin and helps transfer energy
to the environment
What does the body do to warm up?####hairs stand upvasoconstrictionshiver
Why does hairs standing up help warm you up?####creates an insulating layer
Why does vasoconstriction help warm you up?####closes of skin’s blood supply so energy doesn’t
transfer away from the body
Why does shivering help warm you up?####muscles contract → cells respire → transfers energy
Def: endocrine system####system of glands that release hormones
Def: hormone####chemical messenger sent in the blood
What does the pituitary gland do?####releases many hormones that regulate body conditions
including other glands
What does the thyroid produce?####thyroxine
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