109 terms

Unit 14: Nervous and Immune (IGCSE Biology 0610)

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Terms in this set (...)

Pathogen
Disease causing organism
Transmissible disease
Disease caused by a pathogen that is spread from one host to another.
Direct contact
Method of transmitting a pathogen. EG: shaking hands.
Bodily fluids
Method of transmitting a pathogen. EG: Through the blood from a mother to feotus.
Airbourne droplets
Method of transmitting a pathogen. EG: Sneezing.
Contaminated surfaces
Method of transmitting an infection. EG: Doorhandles.
Contaminated food
Method of transmitting an infection. EG: Food poisoning from uncooked chicken.
Animals
Method of transmitting an infection. EG: dog bites and rabies.
Indirect contact
When the infected organism does not directly touch you.
Mechanical barrier
Barrier preventing entry into the body.
Skin
Prevents entry to the body. Largest external organ.
Cillia
Prevents pathogens entering respiratory system.
Scab
Prevents pathogens entering wounds.
Fibrinogen and platelets
The two materials in the blood needed to make a scab.
Chemical barrier
Destroys or traps pathogens.
Hydrochloric Acid
Corrosive liquid in the stomach that destroys pathogens.
Mucus
Sticky substance in the upper respiratory system destroys pathogens.
White blood cells
Destroy invading pathogens.
Lymphocytes
Create antibodies for a quick response to a specific pathogen. Lymphocyte needs to have discovered the pathogen before.
Antibody
Secreted by lymphocytes. Sticks pathogens together, marks the pathogen for phagocytes or destroys the pathogens.
Antigen
The part that the antibody sticks to on the pathogen.
Phagocytes
Engulfs all kinds of pathogens.
Active immunity
Body produces it's own lymphocytes and antibodies. Permanent.
Passive immunity
Body reliant on another source of antibodies, EG: a "booster" vaccination or breastmilk. Temporary.
Drug
Any substance taken into the body that modifies or affects chemical reactions in the body
Antibiotics
Drugs that are used to treat bacterial infections
Eg: penicillin
Bacterial cell walls
Antibiotics work by preventing these from forming (also, note, these are NOT present in viruses)
Antibiotic resistance
This is formed by artificial selection over time as some bacteria develop a mutation which allows them to survive being killed by antibiotics
MRSA
An example of a type of bacteria which are resistance to most antibiotics
Alcohol and Heroin
Powerful, addictive depressant drugs that affects the nervous system and have negative social implications
Depressant drugs
Slow down (inhibit) some parts of the nervous system
Stimulants
Speed up the action of the nervous system , they cause more neurotransmitter molecules to diffuse across the synapse Eg: Nicotine, caffeine
Cirrhosis
Permanent scarring of the liver after excessive alcohol intake
Hepatitis
Inflammation in the liver after excessive alcohol intake
Withdrawal symptoms
Occur when the drug becomes a necessity for the body to function normally. They are classified into two parts: Emotional and Physical
Emotional addiction/ physiological addiction
When you think you need to use that drug, for example, a person might think they need marijuana in order to fall asleep.
Physical addiction
When the user's body cannot function without the use of the drug.
Heroin
An addictive, illegal, depressant analgesic derived from morphine
Nicotine
The addictive part in cigarettes, a stimulant which mimics the natural neurotransmitters in the nervous system concerned with the control of heartbeat and blood pressure (narrowing of blood vessels)
Tar
Contained in cigarettes, causes cancer. It is also an irritant causing coughing.
Carbon monoxide
One of the chemicals in cigarette smoke, which reduces oxygen supply to cells by combining with hemoglobin in the place of oxygen, at the alveolar capillaries.
Chronic obstructive pulmonary disease
a group of progressive lung diseases. The most common are emphysema and chronic bronchitis. Many people with COPD have both of these conditions.
Emphysema
A disease resulting from the breakdown of the walls of the alveoli. Cigarette smoke affects white blood cells which then destroy lung tissue. This results in less SA for oxygen exchange.
Liver
The organ which breaks down alcohol and other toxins
Testosterone
A hormone used to enhance sporting performance, by stimulating male's aggressive behaviour
Anabolic steroids
Hormones used to enhance sporting performance by increasing the growth of muscle and reducing body fat. There is an increase in strength and power.
Stimulus
A change in an animal's surroundings
Response
A reaction to a change in one's surroundings
Central Nervous System (CNS)
Consists of the brain and spinal cord
Reflex action
A rapid automatic (or involuntary) action in response to a stimulus that is not started by impulses from the brain
Reflex arc
The nerve pathway of a reflex e.g. stimulus > receptor > sensory neurone > CNS > relay neurone > motor neurone > effector > response
Sensory neurone
A neurone conducting impulses from receptors to the brain or spinal cord
Motor neurone
A neurone transmitting impulses from the brain or spinal cord to a muscle or gland
Axon
The long threadlike part of a nerve cell that carries impulses
Myelin sheath
Fatty insulation that surrounds axons and helps to speed up the conduction of impulses
Dendrons
The fine cytoplasmic extensions of a nerve cell body
Synapse
A junction between two nerve cells
Neurotransmitter
A chemical substance released from a nerve cell, allowing an impulse to travel from a nerve cell to another nerve, muscle, organ or tissue
Cerebrum
Consisting of two hemispheres, it is the largest part of the brain and is the source of all conscious thought
Ciliary muscle
changes thickness of the lens when focusing
Choroid
full of black pigment to absorb light & stop reflection in the eye
Vitreous humour
jelly-like substance which maintains the internal pressure in the eye and its shape
Retina
inner light sensitive layer which contains rod cells & cones
Yellow spot/fovea
most sensitive part of the retina-contains mainly cones
Blind spot
point where the optic nerve attaches to the eye-no light sensitive cells here
Optic nerve
carries nerve impulses from the eye to the brain
Sclera/sclerotic
tough, white, protective layer
Suspensory ligaments
holds the lens in place
Iris
controls the intensity/amount of light entering the pupil
Lens
changes shape to focus light on the retina
Pupil
allows light to pass through the iris
Aqueous humour
watery liquid filling in the front of the eye
Cornea
refracts light when it enters the eye and protects the lens
Conjunctiva
mucous membrane that covers the front of the eye and lines the inside of the eyelids
Tapetum
reflective layer of the choroid in the eyes of many animals causing them to glow in the dark
DISTANT OBJECT- ciliary muscles,suspensory ligaments,shape of lens
relax, pull, less convex (flatter)
NEARBY OBJECT- ciliary muscles,suspensory ligaments,shape of lens
contract, slack, more convex (rounded)
Light in a fat lens
light bends more sharply- nearby object
Rods
photoreceptors on the retina that work even in dim light
What 2 types of images do rods display?
black and white & night vision
cones
photoreceptors on the retina which work in bright light
What 2 things do cones display?
Detailed & coloured vision
How many rods and cones do we have?
120 mil rods and 6-7 mil cones
What does the fovea do?
it contains the most cones and thus displays the sharpest images
What type of neurones is the optic nerve made of?
sensory neurones
Accommodation
changes that occur in the shape of the lens when focusing on far & near objects
% of refraction done by the cornea
60%
Amount of refraction depends on
the distance between the object and the eye
Do closer/distant objects need to be refracted more?
nearby objects as the light rays from them are diverging not parallel
Lysozyme
enzyme secreted by the tear glands
Pupil reflex
coordination of circular and radial muscles in the iris to control the intensity of light entering the pupil to protect the eye
BRIGHT LIGHT- circular muscles, iris, pupil,radial muscles
contract, expands, constricts, relax
DIM LIGHT- circular muscles, radial muscles, pupil
relax, contract, dilates
Example of Antagonistic muscles in the eyes
circular and radial
Doc shining a light in your eyes
testing for healthy function of two cranial nerves: the optic nerve and the oculomotor nerve
Iris reflex (arc)
1. stimulus (light intensity)
2. receptor (retina)
3. sensory neurones in optic nerve
4. coordinator (unconscious part of the brain)
5. motor neurones in nerve to iris
6. iris muscles (effector)
7. response (change in size of pupil)
Sense organs
groups of receptor cells that respond to specific stimuli
5 sense organs
eyes, nose, tongue, ears, skin
Hormone
a chemical substance produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
The endocrine consists and depends on chemicals of hormones which are released though endocrine glands name some
-Adrenal Glands
-Pancreas
-Reproductive Organs
What does the adrenal glands do?
Produces the hormone Adrenaline
Adrenaline
the hormone secreted in 'fight or flight' situations and its effects, limited to increased breathing and pulse rate and widened pupils
What does the Pancreas Gland do?
Produces/Secretes the hormone Insulin
Insulin
a hormone from the pancreas that controls glucose level in the body
what does the reproductive organs produce limited to the ovaries and testes
produces hormones and gametes, From the ovary, oestrogen is produced and from the testes testosterone
Oestrogen
a hormone from ovaries which prepares the uterus for embryo (thick)
Testosterome
The hormone is used in reproduction. dick enlargement, voice deeper body hair ect
Where would adrenaline be secreted (examples)
bungee jumping, rollercoasters and more
Nervous system vs Hormonal system
Nervous system is rapid (electrical impulses)
Endocrine can be slow (chemical messages in blood)

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