Homeostasis and Response Flashcards
What is homeostasis?
The maintenance of a constant internal environment to keep conditions optimal for enzyme activity and cell function.
What are the three main factors controlled by homeostasis?
- Blood glucose concentration
- Body temperature
- Water levels
What are the three main components of a control system?
- Receptors – Detect changes (stimuli) in the environment.
- Coordination centres – Process information (e.g., brain, spinal cord, pancreas).
- Effectors – Carry out a response (muscles or glands).
What is negative feedback?
A mechanism that reverses a change in a condition, bringing it back to normal levels.
What is the function of the nervous system?
Allows the body to detect and respond to stimuli.
Describe the pathway of a nervous response.
- Receptor detects stimulus.
- Sensory neuron sends impulse to CNS.
- Relay neuron in spinal cord processes information.
- Motor neuron carries impulse to effector.
- Effector (muscle or gland) carries out response.
What is a reflex?
A rapid, automatic response to prevent harm (e.g., blinking, moving away from heat).
What is the role of synapses and what are they?
Gaps between neurons where chemical signals (neurotransmitters) allow impulses to pass.
What are the main parts of the brain and their functions?
- Cerebral Cortex – Controls memory, intelligence, language.
- Cerebellum – Controls balance & coordination.
- Medulla – Controls heart rate & breathing.
How do scientists study the brain?
- Patients with brain damage – Observe changes in function.
- Electrical stimulation – Insert electrodes to see effects.
- MRI scans – Identify active brain regions.
Why is brain surgery risky?
The brain is complex, delicate, and difficult to access; damage can cause permanent loss of function.
What are the main parts of the eye and their functions?
- Cornea – Focuses light onto the retina.
- Iris – Controls pupil size (adjusts to light levels).
- Lens – Changes shape to focus light on retina.
- Retina – Contains light-sensitive receptors.
- Optic nerve – Carries impulses to the brain.
How does the eye adjust for different distances?
- Focusing on a near object:
- Ciliary muscles contract, suspensory ligaments loosen.
- Lens thickens to refract light more.
- Focusing on a distant object:
- Ciliary muscles relax, suspensory ligaments tighten.
- Lens flattens to refract light less.
What are the two main vision defects?
- Myopia (short-sightedness) – Lens too curved, image focuses in front of retina.
- Hyperopia (long-sightedness) – Lens too flat, image focuses behind retina.
How are vision defects corrected?
- Glasses or contacts:
Concave lenses correct myopia; Convex lenses correct hyperopia. - Laser surgery reshapes the cornea.
How does the body respond to overheating?
- Sweating – Evaporation removes heat.
- Vasodilation – Blood vessels widen, increasing heat loss.
How does the body respond to being too cold?
- Shivering – Muscles contract, increasing respiration & heat production.
- Vasoconstriction – Blood vessels narrow, reducing heat loss.
What is the endocrine system?
A system of glands that release hormones into the blood.
What are the main endocrine glands and their functions?
- Pituitary gland – “Master gland,” secretes hormones of its own and controls other glands.
- Thyroid – Releases thyroxine (controls metabolism).
- Adrenal glands – Releases adrenaline (fight or flight).
- Pancreas – Releases insulin & glucagon (controls blood sugar).
- Ovaries – Releases oestrogen (menstrual cycle).
- Testes – Releases testosterone (sperm production).
What hormone lowers blood sugar?
Insulin – Converts glucose into glycogen (stored in liver).
What hormone increases blood sugar?
Glucagon – Converts glycogen back into glucose.
What is diabetes?
- Type 1 Diabetes – Body does not produce insulin.
- Type 2 Diabetes – Body cells no longer respond to insulin.
How is diabetes treated?
- Type 1 – Insulin injections.
- Type 2 – Diet, exercise, medication.
What are the four main menstrual cycle hormones?
- FSH – Stimulates egg maturation.
- Oestrogen – Stimulates uterus lining growth.
- LH – Triggers ovulation.
- Progesterone – Maintains uterus lining.
