B11

Nervous System vs Endocrine system

Nervous System:

• Made of brain, spinal cord, neurons

• Voluntary and involuntary responses

• Short term

• Neurons pass along fast transmission

Endocrine System:

• Made up of glands.

• Involuntary responses as chemicals released

• Target cells in specific tissues

• Hormone released in bloodstream

• Slower transmission

• Longer effect until hormone gets broken down in liver

Pituitary gland

• Releases growth hormones acting on cells to grow

• Stimulate thyroid gland to make thyroxine to control metabolism rate

• Stimulates ovaries to produce eggs and make oestrogen

• Stimulates testes to produce sperm and make testosterone

ADH

Acts on kidney to promote water reabsorption

LH/FSH

Acts on reproductive organs to release sex hormones

TSH (Thyroid stimulating hormone)

Stimulate thyroid to release thyroxine

Adrenal gland

Release adrenaline preparing for flight or fight response

Pancreas

Release insulin or glucagon for regulating blood glucose levels

Testes

Produce testosterone controlling secondary sexual characteristics in males

Ovaries

Produce oestrogen and progesterone controlling sexual characteristics in females and to maintain uterus lining.

Diabetes

Conditions where body fails to maintain a normal constant blood glucose level

Insulin

Protein that is digested in stomach

Purpose of insulin

• Cause cells to absorb glucose to carry out respiration

• Convert excess glucose to glycogen treatment

Type 1 diabetes

• Pancreas fails to produce insulin

• In young age

• Genetic

• Skinny appearance as fats and proteins are used by cells to release energy

• SOLUTION: Insulin injection and improve lifestyle

Type 2 diabetes

• Cells don’t respond to insulin

• In old age

• Causes are poor lifestyle

• Appear obese

• Improve lifestyle (Carbohydrate controlled diet)

If blood glucose levels is high

• Pancreas releases insulin

• Causing glucose to move from blood into cells

• In muscle cells and liver, glucose gets converted into glycogen

• Blood glucose levels fall to normal

If blood glucose levels is low

• Pancreas releases glucagon in the liver

• Glucagon causes muscle cells to convert glycogen into glucose via respiration

• Blood sugar levels rise back to normal

What happens if glucose isn’t converted into glycogen

Glucose gets lost in excess through urine

Importance of glucose

For cellular respiration releasing energy for the body’s metabolism. Having too much or too little glucose creates problems for the person

Glucose vs Glycogen vs Glucagon

• Glucose - Soluble carbohydrate used in respiration

• Glycogen - Insoluble storage carbohydrate found in liver and muscles

• Glucagon - Hormone stimulating liver to break down glycogen into glucose

Puberty

Time when a child develops into an adult. Sex hormones are released causing secondary sex characteristics

Changes of teen females and males

• Emotional change → Attraction to opposite sex

• Growth of hair around sex organs

• Greasy skin and hair

• Growth spurt

• Genitals grow and skin darkens

Physical changes for girls

• Breasts develop

• Hips and thighs become wider due to fat deposition

• Release 1 egg per month from ovaries

• Menstruation starts

Changes for boys

• Develop facial hair

• Deeper voice

• Testes grow and become active

• Produce sperm

• Muscle development

FSH

Matures eggs in the ovaries and stimulate oestrogen release

LH

Releases egg from ovaries

Progesterone

Maintains thickened lining in uterus and inhibits the production of LH and FSH

Oestrogen

Build up uterus lining to provide protection for embryo if pregnancy occurs and gives female secondary characteristics. Inhibits FSH release and stimulates LH release.

Length or menstrual cycle

28 days

0-5th day

• Uterus lining shed off

• Egg removed from body and isn’t fertilised (bleeding → period)

3rd day

FSH increases to mature eggs

4-15th day

FSH cause oestrogen levels to increase which builds up the uterus lining

15th day

• Rise of oestrogen levels decrease FSH

• Oestrogen cause LH to increase

• Ovulation occurs where eggs get released

• Occurs halfway through menstrual cycle

15-28th day

Progesterone from empty follicles is produced and released making levels rise which maintains uterus lining:

• If egg fertilised, progesterone levels remain high and FSH/LH levels decrease

• If egg not fertilised, progesterone levels are low so uterus starts to shed off → Period/ FSH and LH hormones increase again which repeats the cycle again

Contraception

Ways to prevent pregnancy

Types of contraception

• Hormonal

• Non hormonal

Examples of hormonal contraceptions

• Mixed pill

• Progesterone pill

• Contraceptive patch

• Contraceptive injection

• IUD

Mixed pill

• Contains oestrogen and progesterone

• Oestrogen is high which inhibits FSH release preventing maturation of eggs

• Lining stops developing and mucus in cervix thickens so sperm can’t get through

Progesterone pill

Same as mixed pill but has less side effects

Contraceptive patch

• Contains oestrogen and progesterone

• Stuck on skin

• Lasts for a week

Contraceptive implant

• Releases continuous amount of progesterone

• Prevent ovaries from releasing eggs

• Thickens mucus in cervix to prevent sperm swimming to eggs

• Last for 3 years

Contraceptive injection

• Same function as contraceptive implant

• Last 2-3 months

IUD

• Releases progesterone

• Same effect as implant

• T shaped - inserted in uterus

Examples of non hormonal methods

Chemical:

• Spermicides

Barrier methods:

• Condom

• Diaphragm

Surgical:

• Male sterilisation

• Female sterilisation

- Copper IUD

- Abstinence

Spermicides

Kill or disable sperm and about 75% effective

Condom

• Worn over penis or under vagina

• Also prevent STD’s from being transmitted

• Can tear letting sperm get through

Diaphragms

• Plastic cup positioned above cervix

• Used alongside spermicide

Copper IUD

Kills sperm in uterus and stop any fertilised embryos implanting itself on uterus lining

Male sterilisation

Cutting sperm ducts which is permanent

Female sterilisation

Cutting fallopian tubes which is permanent

Abstaining

Not having intercourse during ovulation period

Infertility treatments

• Fertility drugs

• IVF

Fertility drugs

• Using FSH and LH to stimulate the maturation and egg release

• Woman get pregnant normally

How does IVF work

• Fertility drugs make lots of eggs mature at same time for collection

• Eggs collected and placed in petri dish

• Semen sample collected and sperm and egg mixed in petri dish

• Eggs checked to see if they fertilised and if early embryos are developing properly

• 1 or 2 tiny embryos placed in mother womb

• If successful, one baby will grow

Benefits of IVF

• Provides a way for infertile couple to have a child

• Less chance for miscarriage

Drawbacks of IVF

• Physically stressful due to hormonal reactions such as sickness

• Lead to multiple births which is risky to mother and child

• Expensive process if repeated

• Ethical concerns → if woman dies, divorce, not wanting embryos anymore

Negative Feedback

Body responds to an increase or decrease in a factor by returning it back to its original level

Thyroxine

Hormone regulating metabolic rate and is also important in growth or development

How thyroxine is produced

Thyroid gland in neck uses iodine from body to produce it

How thyroxine levels are controlled by negative feedback when it’s increased

• Brain receptors detect this

• Inhibits the release of Thyroid Stimulating Hormone

• Inhibits thyroxine release which levels fall to normal

Adrenaline

Hormone produced in times of stress preparing us for the flight or fight response

What releases adrenaline

Adrenal gland located above the kidneys

How adrenaline works during a stressful situation

• The brain detects the stimulus

• Adrenaline gets released by adrenal gland

• Body shuts down non essential functions of the body such as salivating

Effects of adrenaline

• Increased heart and breathing rate → Deliver more oxygen and glucose to brain and muscles for respiration

• Glycogen converted to glucose for respiration

• Pupils dilate to let in more light

• Blood flow to muscles increased

• Blood flow to digestive system decreased

Stimuli

Change in external environment around you

Tropisms

Responses of roots and shoots to stimuli

Two types of plant tropisms

• Phototropism

• Gravitropism

Photropism

Response of plant to light

Gravitropism

Response of plant to gravity

Auxins

• Indole Acetic Acid (IAA)

• Plant hormone

Where auxin is found

Apical meristems where there are growing roots and stems

Roots

Function to reach down to get water for nutrients and also grow down into soil when a seed germinates

Stem (Shoots)

Function to grow up to light for photosynthesis

Role of auxin

• Cell elongation

• Plant growth

Positive tropism

Growth occurs in direction to stimulus

Negative tropism

Growth occurs on the opposite direction to stimulus

Tropisms of stems

• Negative gravitropism

• Positive phototropism

Tropisms of roots

• Positive gravitropism

• Negative phototropism

How auxins work when there is no sunlight on the stems

• Auxin moves to the side of the plant with least exposure to the sun to help it grow along with the other side → Phototropism

• Makes up the lack of light on that side

• That side with the auxins would then grow more than the side receiving the most sunlight

How auxins work with roots

• Roots grow more on side with the least auxin

• Bends to force of gravity → Gravitropism

Other uses of auxins

• Kill weeds

• Rooting powder

Weeds

Broad leaves blocking sunlight from entering crops

How auxins kill weeds

Spraying auxins on weeds will making the weeds grow uncontrollably and rapidly killing them giving more land for crops to grow

How is auxins used in rooting powder

Dip the cut end of cuttings into the rooting powder containing auxins for plant growth and cell elongation

Use of Gibberellins hormone

• Seed germination by ending seed dormancy

• Speeding up germination

• Increase seedless fruit size

• Promote flowering

Germination

Seed growing

Use of ethene hormone

Helps ripen fruit

Plant hormone

Chemicals which coordinate, and control growth and development in plants helping it to respond to environmental changes