B5: Homeostasis & Response

• What does the term homeostasis refer to in biology?

  Regulating internal conditions
• Homeostasis is important because it ensures crucial chemical reactions involving enzymes happen at an optimum rate.
• What are three examples of conditions regulated by homeostasis in the human body?

  Blood glucose, temperature, water levels
• The nervous system is one way our body achieves homeostasis by responding to stimuli.
• Match the part of the nervous system with its function:

  CNS ↔️ Brain and spinal cord

  PNS ↔️ Nerves outside the CNS
• In the nervous system, signals cross the gap between neurons called a synapse using neurotransmitter chemicals.
• What is the difference between a reflex arc and a conscious decision in the nervous system?

  Reflex arc bypasses the brain
• Glands can act as effectors in the nervous system by producing chemicals needed by the body.
• What type of chemical do salivary glands produce when you eat food?

  Saliva
• When investigating reaction times, introducing a stimulant like coffee will typically decrease reaction time.
• When the body is too cold, it shivers to produce heat through muscle contraction.
• What is the master gland of the endocrine system?

  Pituitary gland
• Match the gland with its hormone:

  Pancreas ↔️ Insulin

  Thyroid ↔️ Thyroxin

  Adrenal glands ↔️ Adrenaline
• What happens to blood glucose levels when insulin is secreted?

  They decrease
• Excess glucose in the blood is converted into glycogen for storage in the liver.
• Glucagon is secreted when blood glucose levels are too low.
• What is the main symptom of type 1 diabetes?

  Insufficient insulin production
• Type 2 diabetes is often associated with obesity and poor diet.
• Menstruation begins after puberty in females.
• FSH, produced by the pituitary gland, causes an egg to mature in the ovary.
• Steps in the menstrual cycle triggered by FSH:

  1️⃣ Egg matures in the ovary

  2️⃣ Ovaries produce estrogen

  3️⃣ Uterus lining thickens

  4️⃣ LH is released by the pituitary gland
• What hormone maintains the uterus lining during pregnancy?

  Progesterone
• Contraceptive pills often inhibit the production of FSH to prevent egg maturation.
• What is the function of a diaphragm in contraception?

  Barrier to prevent sperm meeting egg
• An IUD prevents a fertilized egg from implanting in the uterus lining.
• What is the term for surgically clamping the sperm ducts to prevent reproduction?

  Vasectomy
• Infertility can be treated with FSH or LH injections to stimulate egg release.
• What is the term for fertilizing an egg with sperm in a laboratory?

  IVF
• Adrenaline increases heart and breathing rate in stressful situations.
• Which hormone controls metabolic rate?

  Thyroxin
• Negative feedback in thyroxin levels involves TRH from the hypothalamus and TSH from the pituitary gland.