Biology 5 (paper2)

define homeostasis

keeping a constant internal condition

what are the 4 main constants in an organism?

water

ions

glucose

temperature

what are the two systems in the body?

nervous

endocryotic

define hypothalamus

determines blood temperature

define vasoconstriction

when the blood is cooler restricting capillaries

what happens on a cold day?

vasoconstriction, muscle pulls hair up to block air and keep the person warm. sweating is reduced, skeletal muscles contract

define vasodilation

blood vessels dilate to cool blood

what happens on a warm day?

vasodilation, muscles pull down to create room for sweat to excrete and air to enter the muscle. vessels push against the skin

what is the brain made of?

neurones

what is the nervous system order in the brain?

receptor----- brain------ effector

what does the cerebral cortex control?

transmits information from neurons

controls higher functions (consciousness, memory, language_

what does the medulla control?

heart rate

sleep

respiration

what does the cerebellum control?

muscular activity

explain electrical stimulation

cut open skull and insert electrodes, no pain receptors. to see brain activity with differen currents

explain MRI

provides an image, sends radio waves in slices to get an image slice by slice

what are the risks and benefits of brain surgery?

risks:

brain damage

benefits:

remove tumors

what are risks and benefits of brain implants?

risks:

damage to the brain

benefits:

help early parkinsons

Define stimuli

Changes in environment

What is the central nervous system?

In vertebrates this is the brain and spinal cord in mammals, it is connected by sensory and motor neurons

Define sensory neurons

Carry information as electrical impulses from receptors

Define motor neurons

Neurons that carry information as electrical impulses from CNS to effectors

Define effectors

All muscles and glands

What do receptors detect?

Stimuli

When muscles contract what happens?

Glands release hormones

What is the order of what happens when the is a change in surrounding?

Stimulus

Receptor

Sensory neurone

CNS

Motor Neurone

Effector

Response

What is a synapses?

Something that connects neurones

How do synapses’ work?

Nerve signal is transferred by chemicals and diffuse across the gap. These chemicals then set off a new electrical signal to the next neurone

Define reflex

Rapid automatic responses to certain stimuli that doesn’t involve the conscious part of the brain to help avoid injury

What is a reflex arc?

The passage of information in a reflex

When you are hit with something what happens?

The reflex arc goes to the CNS

The neurones in the reflex arc goes through the spinal chord and unconscious part of the brain

When stimulus is detected by receptors impulses are sent to the sensory neurone to a relay neurone in the CNS

When the impulses reach a synapse they trigger chemicals

The impulses are sent along the relay neurone

Once they reach the synapse chemicals diffuse to the motor neurone

It then goes to the muscles and contracts

What is the cornea?

A layer of protection over the eye

What does the lease do?

Focuses light on the retina

What is the pupil?

A hole in the centre of the iris

What does the iris do?

Have muscles that controls the pupil size

What does the retina have?

Light sensitive receptors

What does the optic nerve do?

Send information to the brain

What do ciliary muscles do?

Change the shape of the lense to focus light

Define circular muscles

Muscles that circle around the pupil

True or false rods control light intensity

True

What do cones control?

Colour

What is the process of light entering the eye?

Cornea refracts the light a little then the lense bends it even more

It then passes through the pupil and hits the retina

What does a flat lense do?

Refract light a little

What does a round lense do?

Refract light a lot

What are the features of a thick lense?

Contracted muscles, relaxed ligament

What are the features of a thin lense?

Relaxed muscle contract ligament

What are the ciliary muscles, ligaments, shape and light rays when an object is near?

Contracted

Loose

Thick

More refraction

What are the ciliary muscles, ligament, shape and light rays like when an object is far?

Relaxed

Tight

Thin

Less refraction

What are 5 things that affect reaction time?

Drugs/alcohol

Age

Distractions

Tiredness

Hormones

What is the method of testing reaction time?

Start with a ruler 1cm above open fingers and thumb, then drop the ruler. Repeat this but with distractions

What is Myopia?

Where you can only see things that are close- short sighted. As the focus is produced too short, Thais occurs if the eyeball is too long or the lense bends too much

What is hyperopia?

Where you can only see things far away- long sighted. The image falls behind the retina, this occurs if the eyeball is too short or the light isn’t refracted enough

How can you fix myopia?

Use a conclave shaped lense

How can you fix hyperopia?

A convex shaped lense

Define endocrine system

Composed of glands that secret and produces hormone directly into the blood stream

Define target organ

The organ a particular hormone acts on

What is the pituitary gland?

Master gland that secretes hormones into the blood

What are hormones?

Chemicals selected into the blood

What are the order of the glands and their job?

Pituitary glans- Brain, master gland

Pineal gland- brain (stimulate others)

Thyroid gland- thyroid, produces thyroxine

Thymus gland

Adrenal gland- produces Adrenalin

Pancreas- produces insulin

Ovary- produces estrogen

Testis- produces testosterone

Define glucagon

A chemical that turns glycogen into glucose

Define insulin

A chemical that changes glucose into glycogen

What is the process of glucose rising and falling

Normal blood glucose

Glucose rises

Insulin is produces by the liver and glucose to change it pinto glycogen

Normal; blood glucose

Glucose falls

Glucagon is released and glycogen is converted back into glucose

What are the features of type 1 diabetes?

Glucose too high

No insulin As body has destroyed it

Tiredness weight loss

No cure or cause

Found at childhood

What are the features of type 2 diabetes?

Glucose too high

Not enough insulin

Can be cured

Common in 40+ and overweight children

Lack of exercise

What are the 4 hormones in the menstrual cycle and their uses?

FSH (matures the egg, pituitary gland)

Oestrogen (thicken the uterus lining, ovaries)

LH(causes ovulation, pituitary gland)

Progesterone (maintain lining, ovaries)

What are days 1-6 in the menstrual cycle?

Menstruation

Uterus lining sheds, FSH

What are days 7-13 in the menstrual cycle?

Proliferation/repair

Egg matures

Oestrogen

What is day 14 in the menstrual cycle?

Ovulation

Egg is released

LH

What is day 15-28 in the menstrual cycle?

Maintaining

Progesterone

Why might there be a difficulty in getting pregnant?

Low sperm count

Diet/drugs

Eggs not maturing

Uterus lining

Blocked Fallopian tubes

What is ivf?

In vitro fertilisation, to take the eggs and fertilise them in a Petri dish

What is the process of ivf?

FSH is injected

Eggs are collected using a large needle

Sperm is collected

The eggs are fertilised in a Petri dish

The embryos are implanted in the uterus

They grow into a foetus

What are advantages of IVF?

People who can not conceive naturally can have children

If a surrogate/ donor is used homosexuals can have children

If an STD has blocked Fallopian tubes

If the person has HIV or AIDS

What are disadvantages to IVF?

Pro life supporters Disagree with destroying embryos

Only successful 22% of the time

Expensive

Embryo easy to damage

High chanced of miscarriage

What are the 7 contraceptives?

Oral (pill)

Injection/ implant/ patch

Condoms

IUD

Spermicide

Abstaining (avoiding sex during ovulation)

Sterilisation

Define tropism

Directional growth

What is the stimulus bad response to phototropism, geotropism, chemostropism, thigmotropism, and hydrotopism?

1. Ligh, no roots
2. Gravity, roots growing in different angles
3. Chemicals, roots to ions
4. Touch
5. Water, roots

Define auxin

A hormone that promotes growth when light hits auxin, auxin is inhibited. If a side doesn’t have auxin it wont grow

What do the kidneys control?

Water levels and ions

What is the process of the kidney?

Blood goes to kidney

Water, salt glucose, and urea filtered out

Salt, glucose and some water goes back into blood

Urea and extra water is filtered out

How does water leave the body?

Sweat

Urine

Exhalation

Define diuretic

Makes people urine more

What is the process when you become dehydrated?

High blood concentration

Receptors detect it

ADH realised by pituitary gland

Reabsorb more water

Concentrated urine

Normal blood levels

What is the process when you are overhydrated?

Dilute blood

Receptors detect it

Less ADH is released by pituitary gland

Less water reabsorbed

Dilute urine

Normal blood levels

Define dialysis

An external way of cleaning the blood

What is the process of dialysis?

Needle in the arm

A pump is connected and pumps the blood out

Goes to the dialysis machine, dialysis fluid is mixed with the blood and there’s a low urea CG so it diffuses out

The blood is then pumped back into the body

What are advantages and disadvantages to dialysis?

Advantages:

Toxins filtered out

Disadvantages:

Time consuming

A long time to carry out

Inconvenient

Blood clots

Infections

What does ethane control?

Fruit ripening and cell division

What does gibberillins do?

Initiating seed germentation

What are auxins used for?

Weed killer

Rooting powders

Promoting growth in tissues cultures

What are gibberllines used for?

Promote flowering

Increase fruit size

End seed dormancy