Biology - HOMEOSTASIS & RESPONSE (B5)

What is Homeostasis? -

What is homeostasis?

The regulation of internal conditions to maintain a stable interval environment in resposne to internal + external changes.

What is Homeostasis? -

What conditions in the body are controlled by homeostasis?

Blood glucose concentration, Body temperature, Water levels, Ion content.

What is Homeostasis? -

Why is homeostasis important?

To maintain optimal conditions for enzyme action + cell function.

The Nervous System -

What is the function of the nervous system?

To detect stimuli, process information, + coordinate a response using electrical impulses.

The Nervous System -

What are the three main types of neurones + their functions?

Sensory neurone: Carries impulses from receptor to CNS

Relay neurone: Connects sensory to motor neurones in the CNS

Motor neurone: Carries impulse from CNS to effector

The Nervous System -

What are receptors + effectors?

Receptors: Cells that detect stimuli

Effectors: Muscles / glands that carry out responses

The Nervous System -

What is a reflex arc + why is it important?

An automatic + rapid response to a stimulus that bypasses the brain to protect the body from harm.

The Nervous System -

Sequence the path of a reflex action.

Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.

The Nervous System -

What is a synapse + how do impulses cross it?

A gap between neurones where chemicals (neurotransmitters) are released to transmit the signal.

Nervous System Practical (Reaction Time) -

What is measured in the reaction time practical?

The time taken to respond to a stimulus, e.g. catching a ruler.

Nervous System Practical (Reaction Time) -

What variables should be controlled in this experiment?

Same ruler, same height, no distractions, same hand, rest before trial.

Nervous System Practical (Reaction Time) -

How can caffeine affect reaction time?

It can reduce reaction time (faster response), but this should be tested w/ care + under controlled conditions.

The Endocrine System -

What is the endocrine system?

A system of glands that secrete hormones into the blood to regulate body processes.

The Endocrine System -

What is hormone?

A chemical messenger secreted by glands + transported in the blood to target organs.

The Endocrine System -

Name 5 major endocrine glands + one hormone they produce.

Pituitary gland - many hormones, including FSH/LH

Pancreas - insulin + glucagon

Adrenal gland - adrenaline

Thyroid - thyroxine

Ovaries/testes - oestrogen/testosterone

Controlling Blood Glucose -

What does insulin do?

Lowers blood glucose by promoting glucose uptake + storage as glycogen in the liver.

Controlling Blood Glucose -

What does glucagon do?

Raises blood glucose by breaking down glycogen into glucose in the liver.

Controlling Blood Glucose -

What is Type 1 diabetes + how is it treated?

A disorder where the pancreas produces little / no insulin; treated w/ insulin injections.

Controlling Blood Glucose -

What is Type 2 diabetes + how is it treated?

A condition where body cells no longer respond to insulin; treated w/ diet, exercise, + sometimes medication.

Thermoregulation & Water Balance -

How does the body cool down when it’s too hot?

Sweat is produced + evaporates. Blood vessels dilate (vasodilation) to release heat.

Thermoregulation & Water Balance -

How does the body respond to being too cold?

Hairs strand up to trap air, Blood vessels constrict (vasoconstriction), Shivering generates heat from respiration.

Hormones in Human Reproduction -

What are the four key hormones in the menstrual cycle?

FSH: Stimulates egg maturation + oestrogen production

Oestrogen: Repairs uterus lining; inhibits FSH; stimulates LH

LH: Triggers ovulation

Progesterone: Maintains uterus lining + inhibits LH/FSH

Hormones in Human Reproduction -

What is ovulation + when does it occur?

The releases of an egg from the ovary, usually around day 14 of the cycle.

Contraception -

Name 3 hormonal methods of contraception.

Combined pill, Contraceptive patch, Injection / implant.

Contraception -

How do hormonal contraceptives work?

They prevent ovulation + make the uterus lining less suitable for implantation.

Contraception -

Name 3 non-hormonal methods of contraception.

Barrier methods (condoms, diaphragm)

Intrauterine device (IUD)

Surgical methods (sterilisation)

Contraception -

What are the advantages + disadvantages of hormonal contraception?

Very effective, long-term options available

May have side effects (e.g. mood changes, weight gain)

Fertility Treatments -

How can hormones be used to treat infertility?

FSH + LH can be given to stimulate egg production + ovulation.

Fertility Treatments -

What is IVF + how does it work?

In vitro fertilisation involves collecting eggs, fertilising them outside the body, + implanting embryos into the uterus.

Fertility Treatments -

What are the pros + cons of IVF?

Can help couples have children.

Expensive, low success rate, emotional stress, multiple births.

Negative Feedback -

What is negative feedback?

A control mechanism where a change is detected + responses restore conditions back to normal.

Negative Feedback -

Give two examples of negative feedback in the body.

Thryoxine regulation (controls metabolism).

Blood glucose control using insulin + glucagon.