B1a Revision JW

7/31/2019 B1a Revision JW

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2/33J Wilkinson Page 2

Responding to Change

Stimulus a change your body reacts to

e.g. bright light (stimulus) close eyes (reaction)

Hormones and the central nervous system control your bodys processes.

Hormones

Chemical

messengers

Made in

glands

Carried by

blood to

organs

Control

processes in

your body



Central Nervous System

The central nervous system coordinates your responses (reactions) to stimuli

Brain

Spinal cord

Central

nervous

system



Nervous System continued

Uses electrical impulses as messengers.

Neurones long cells that carry electrical impulses.

Receptors Cells in sense organs that detect a stimulus.

Sense organ full of receptors.

Sense organ Stimulus it detects

Eye Light

Ear Sound,

Position

Skin Touch,Pressure,

Pain,

Temperature

Nose and tongue Chemicals

Sensory neurone Takes electrical impulses to the central nervous system.

Motor neurone Takes electrical impulses from the central nervous system to the

effector organ.

Effector organ Muscle or gland that does something to respond to a stimulus.



Example You see a cup and pick it up

Light from

cup

Eye sees cup Electrical

impulse goes

to CNS

Brain

coordinates

response

Electrical

impulse goes

from CNS to

effector

organ

Muscle

moves so

you can pick

up cup

Stimulus Receptor Sensory

neurone

Central

nervous

system

(CNS)

Motor

neurone

Effector

organ

(muscle)



Example TV is too loud so you turn it down

Sound from

TV

Ear Electrical

impulse goes

to CNS

Brain

coordinates

response

Electrical

impulse goes

from CNS to

effector

organ

Muscle

contracts so

you can

press

remote

control

button.

Stimulus Receptor Sensory

neurone

Central

nervous

system

(CNS)

Motor

neurone

Effector

organ

(muscle)



Reflex Actions

Automatic

Dont need to think about them

The brain is not involved

Reflex Arc

Receptor Sensory

neurone

Relay

neurone

Motor

neurone

Effector

organ

Detects

stimulus

Sends

impulse to

spinal

cord

In spinal

cord

sends

impulse to

motor

neurone

Sends

impulse to

effector

organ

Responds

(reacts)



Example of a reflex action

Pulling your hand away from a hot pan without thinking about it.

1) StimulusHeat from

pan

2) Receptor

Skin

3) Sensory neurone

Impulse from receptor to

relay neurone

4) Relay

neurone in

spinal cord

5) Motor neurone

Impulse from relay neurone to

effector organ

6) Effector organ

muscle pulls hand away.


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A synapse a junction between neurones

= chemicals cross the gap

to set up an electrical

impulse in the next

neurone.



The Menstrual Cycle

28 day cycle in women.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

The cycle is controlled by hormones called, FSH, Oestrogen and LH.

Hormones are released by the pituitary gland (in the brain) and the ovaries.

Hormone Released from What it does..

FSH Pituitary gland Makes an egg mature in the

ovary.Causes ovaries to produce

oestrogen

Oestrogen Ovaries Makes womb lining thicken

Makes pituitary gland make

LH instead of FSH

LH Pituitary gland Releases mature egg from

ovary

Day

Old egg and

womb lining

leave body as a

period.

New egg

released

from

ovary

If egg is not

fertilised

new period

starts

Womb lining thickens



Controlling Fertility

Contraceptive Pill

Fertile

Can have babies

Infertile

Cant have babies

Prevents pregnancy

Contains oestrogen

Stops FSH production so

.. no mature eggs

Contraceptive pill



Controlling Fertility (continued)

FSH as a drug

FSH is given to a woman who doesnt produce mature eggs She can then produce mature

eggs.

IVF Treatment

FSH

Mature eggs

The Woman is

given FSH

Mature eggsSperm

Eggs and sperm mixed in a dish

Fertilised eggs become embryos

Embryos put in womans uterus (womb)

to grow.



Controlling Conditions

Internal Environment The conditions in your body

Homeostasis Keeping conditions inside you stable (unchanging)

What must be kept stable?

Temperature

Salt content =ion content

Watercontent

Sugar content



Keeping Your Water Content Stable

Keeping Your Ion (Salt) Content Stable

Urine - Produced by the kidneys

- Kidneys control how much salt and water is lost.

Water in Water out

Drinks

Food

Breathing out

Sweat

Urine

Ions in Ions out

Drinks

Food

Sweat

Urine



Keeping Your Temperature Stable

Body temperature = 37oC

If your temperature is too high or too low enzymes in your body wont work properly.

Warm Up

Cool Down

Keeping Your Blood Sugar Constant

You need sugar (glucose) for energy all the time.

Hormones from the pancreas stop the blood sugar getting too high or too low.

Shiver

Warm clothes

Sweat

Cool clothes



Diet and Exercise

A healthy, balanced diet is:-

All in the right amounts

Malnourished An unbalanced diet makes you malnourished and ill.

How much energy do you need?

Need less energy Need more energy

Carbohydrates

Fat Protein

Vitamins

Minerals Fibre

+ + Energy

Water

Female Male

or

pregnant female

Little exercise Lots of exercise

Elderly Young

Hot weather Cold weather



Metabolic Rate - The rate your body uses energy to carry out chemical reactions in your cells.

- Different people have different metabolic rates.

- You could think of it as how quickly your body uses up food.



Weight Problems

Losing weight:-

Eat less food.

Exercise to use energy.

Diabetes

Obesity

Cause

Eat too much energy (food)

It is stored as fat

Very fat = obese

Health Problems

Arthritis High

blood

pressureHeart

disease


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Fast Food

Causes

high blood

pressure

Causes weight problems Causes lots of cholesterol

Fast Food

Contains lots of salt

Contains too much fat

Cooking

fat



Cholesterol

Cholesterol

Made in the

liver

LDL cholesterol = bad cholesterol

causes heart disease

from eating saturated fats

Statins are

drugs that

reduce

cholesterol

HDL cholesterol = good cholesterol

reduces heart disease

from eating polyunsaturated

fats or monounsaturated

fats



Drugs

Drugs change the way your mind or body works.

Legal drugs

o Caffeineo Alcoholo Nicotineo Medicines

Illegal drugs examples-

o Cocaineo Heroino Cannabis

Addiction Your body needs the drug more and more.

Withdrawal symptoms Addicts feel very ill if they stop taking the drug.

Medicines

From the doctor Legal Safe if used correctly

Recreational drugs

Used for pleasure Some are legal e.g. alcohol Some are illegal e.g. heroin

Drugs in sport

Used illegally e.g. to speed you up e.g. to build muscles



Alcohol

Drink a little

Drink too muchAddictive

Brain and liver

damage (cirrhosis

of the liver)

Relaxes you Makes you cheerful

Shy Confident

Slow reactions

Poisonous

coma or death

AMBULANCE RIP

Loss of self control

Do stupid

things

Violence

drink



Contains tar

smoke

Clogs

lungs

EmphysemaCoughs

Bronchitis

Causes

cancer

Miscarriage

or

low weight baby

Contains

carbon

monoxide

Legal

Feel calmAddictive

Heart

disease

Contains

nicotine

Smoking Stops blood

carrying

enough

oxygen



Pathogens or Microorganisms

Pathogens are bacteria and viruses.

Pathogens reproduce inside your body and make toxins (poisons).

The toxins make you ill.

Pathogens cause infectious diseases the pathogen can be passed onto

someone else and make them ill too.

Doctor Semmelweiss

o He realised doctors were picking up pathogens from one patient andgiving them to the next patient so ..

o Doctors must wash their hands between patients.



Defences Against Disease

Stop pathogens getting in:-

Mucus in the

breathing system

traps pathogens.

Skin stops pathogens

getting in.

Blood clots to form a

scab to stop

pathogens getting in.



Defences Against Disease

White blood cells defend against disease.

Remember toxin = poison.

White blood cells

Ingest and destroypathogens

Produce antibodies to

destroy pathogens

Produce antitoxins to neutralise

(cancel out) the toxins.

Toxin

antitoxin



Using Drugs to Treat Diseases

Painkillers

o They cant get rid of the diseaseo They stop you feeling pain, so you feel better.

Antibiotics

o Kill bacteria not viruses.o Penicillin is an antibiotic.

(viruses live inside our cells, so antibiotics cant reach them).



Resistance to Antibiotics

Natural selection

Bacteria evolve into new types by mutating.

This process is called natural selection.

Antibiotic resistance = cant be killed by the antibiotic

Example:- MRSA bacteria cant be killed by antibiotics.

Bacteria

reproduce

and some

mutate

Mutation

makes a

new type

of bacteria

New

bacteria

are not

killed

All

bacteria

are

resistant

to an

antibiotic

Take an antibiotic XX

X



Developing New Medicines

Why test new

medicines?

Are they toxic

(poisonous)?

Are they effective do

they treat the disease?

Are there side effects do

they cause other problems?



Thalidomide (a drug)

ZZZZZ

Side effects

Babies born

with short,

deformed

arms and legs.

It was a sleeping pill Then it was used

to stop morning

sickness

Now

Treats leprosy

No longer given to

pregnant women

All drugs must be fully

tested.


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Immunity

Dead or inactive

(weak) pathogen.

Inject into

blood

White blood cells make

antibodies against the

pathogen

If the full strength pathogens get into your body

the white blood cells now know how to make the

antibodies quickly.

You dont get the disease. You are immune.

Vaccine

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B1a Revision JW