Unit 5 - Homeostasis and Response Flashcards
What is homeostasis?
An organism’s ability to regulate its internal conditions so crucial reactions (including those involving enzymes) can happen at optimal rates
What is regulated in homeostasis?
-Blood glucose concentration
-Internal temperature
-Water levels
What does the nervous system consist of?
Central nervous system - brain and spinal chord
Peripheral nervous system - all other nerves
How does we respond to a stimulus such as something hot?
Receptor (eg skin) detects the stimulus and impulses travel to the spine via sensory and relay neurons. The signal travels along the synaptic cleft via neurotransmitters. Once at the spine, the impulse travels to the brain where a decision is made consciously. The signal then travels to the effector (eg muscle) via motor and relay neurons
What is a reflex arc?
When a signal bypasses the brain and goes straight through spine to effector, being much quicker.
What is the cerebral cortex in the brain responsible for?
Higher functions, such as memory, speech production and comprehension (Broca’s and Wernicke’s area) and problem solving
What does the cerebellum do?
Motor skills
-movement
-balance
-coordination
What is the medulla oblongata?
The area that connects the brain stem to the spinal chord. It controls unconscious actions such as:
-heart and breathing rate
-signals to adrenal glands to release adrenaline
What is accommodation in the eye?
The eye’s ability to change the shape of the lens to focus light and see objects at different distances
How do we accommodate things far away?
-Ciliary muscles relax
-Suspensory ligaments tighten
-Lens becomes thinner for less refraction of light
How do we accommodate objects close to us?
-Ciliary muscles contract
-Suspensory ligaments slacken
-Lens thickens to allow more refraction of light to focus on the retina
What are rods and cones in the eye?
Types of photoreceptor cells found in the retina with different functions. There are more rods than cones.
What is the function of rods?
Primarily responsible for scotopic vision (vision under low light conditions) and are colour-blind
What is the function of cones?
Responsible for colour vision/perception and photopic (well lit conditions)
What is the medical term for short-sightedness?
Myopia
What is the medical term for long sightedness?
Hyperopia
How can you treat myopia/hyperopia?
-Glasses
-Contact lenses
-Laser eye surgery
What is thermoregulation?
The brain detects blood temperature add sends nervous/hormonal signals to effectors
What happens if you’re too hot? (Thermoregulation)
-Sweat glands produce water which evaporates to cool the body
-Blood vessels dilate (vasodilation)
What happens if you’re too cold? (Thermoregulation)
-Hair stands up on end to trap air (layer of insulation)
-Shivering muscles to produce more heat
-Blood vessels contract (vasoconstriction)
What is the endocrine system?
A system of glands that secrete hormones to send signals to effectors, transported via blood (but is slower than nervous system)
What are the parts of the endocrine system?
Pituitary gland - ‘Master gland’ that sends signals to other glands
Adrenal glands - Releases adrenaline
Thyroid - Controls growth, metabolism and more
Pancreas - Secretes insulin and glucagon to control blood sugar
Testes - Produce sperm
Ovaries - Releases eggs and secretes hormones
What happens if blood sugar levels are too high?
-Pancreas secretes insulin
-Which causes glucose to move into cells to be used for respiration
-Excess glucose converted into glycogen as an energy store
What happens if blood sugar levels are too low?
-Pancreas secretes glucagon
-Which causes liver and muscles to convert glycogen back into glucose (example of negative feedback loop)
