Synapse Happens
Which neurotransmitter is most directly associated with skeletal muscle contraction at the neuromuscular junction?
Acetylcholine (ACh)
Which hormone lowers blood glucose levels by promoting glucose uptake in cells?
Insulin
What is metabolism?
The sum of all chemical reactions occurring in a living organism.
Which chamber of the heart pumps oxygenated blood to the body?
Left ventricle
Where does gas exchange occur in the lungs?
Alveoli
This neurotransmitter can be excitatory or inhibitory depending on the receptor type and is the most abundant in the CNS.
Glutamate
Name the hormone released by the adrenal medulla during the fight-or-flight response.
Epinephrine (adrenaline)
Which metabolic process breaks down glucose to release energy: anabolism or catabolism?
Catabolism
Name the blood vessels responsible for returning blood to the heart.
Veins
Which part of the brain directly controls breathing rate?
Medulla oblongata / Brain Stem
Name the neurotransmitter primarily involved in mood regulation whose imbalance is linked to depression and anxiety.
Serotonin
This hormone regulates circadian rhythms and is released in response to darkness.
Melatonin
Name the molecule that acts as the main energy currency of the cell.
ATP (adenosine triphosphate)
Which valve prevents backflow between the left ventricle and the aorta?
Aortic semilunar valve
Name the structure that prevents food from entering the trachea during swallowing.
Epiglottis
Which neurotransmitter is released by the sympathetic nervous system during stress and increases heart rate and blood pressure?
Norepinephrine (noradrenaline)
Identify the hormone that stimulates the thyroid gland and explain where it is produced.
Thyroid-stimulating hormone (TSH), produced by the anterior pituitary gland.
Explain why enzymes are essential for metabolic reactions even though they are not consumed.
Enzymes lower activation energy, allowing reactions to occur faster without being altered or used up.
Explain how the structure of arteries differs from veins and how this relates to their function.
Arteries have thicker, more muscular walls to withstand high pressure; veins have thinner walls and valves to prevent backflow.
How does the nervous system detect changes in CO₂ levels to adjust breathing rate?
Chemoreceptors detect CO₂ and pH changes and signal the medulla to adjust breathing rate.
Explain why blocking acetylcholine receptors would affect both voluntary movement and autonomic functions.
Because acetylcholine is used at neuromuscular junctions for skeletal muscle contraction and is also a key neurotransmitter in the parasympathetic autonomic nervous system. Blocking its receptors disrupts both systems.
Predict the effect on metabolism if thyroid hormones are chronically overproduced and justify your answer.
Metabolism would increase, leading to weight loss, increased heart rate, and heat intolerance because thyroid hormones raise cellular metabolic rate.
During intense exercise, which metabolic pathway becomes more dominant, and what by-product can cause muscle fatigue?
Anaerobic respiration becomes dominant, producing lactic acid, which contributes to muscle fatigue.
Predict what would happen to blood pressure if arterioles lose their ability to constrict.
Blood pressure would decrease because arterioles regulate resistance; loss of constriction reduces vascular resistance.
Explain how the respiratory and endocrine systems work together during prolonged stress.
Stress hormones increase metabolic demand and oxygen needs; the respiratory system increases breathing rate to supply more oxygen to tissues.