Sensory, Endocrine And Muscle Physiology

Steroid hormones are able to diffuse through membrane lipids because they are derived from cholesterol, which is a lipid. Unlike protein and peptide hormones, which are unable to cross the lipid bilayer, steroid hormones are able to easily pass through the cell membrane and bind to intracellular receptors. Once inside the cell, they can regulate gene expression and initiate various cellular responses. Therefore, the correct answer is Steroid.

The posterior pituitary gland stores and releases two hormones: oxytocin and ADH (also known as vasopressin). Oxytocin is responsible for stimulating uterine contractions during childbirth and promoting lactation, while ADH regulates water balance in the body by controlling the reabsorption of water by the kidneys. TSH (thyroid-stimulating hormone) and FSH (follicle-stimulating hormone) are not stored or released by the posterior pituitary gland, but rather by the anterior pituitary gland.

Endocrine glands are ductless glands that secrete their secretions directly into the blood or lymph stream. Unlike exocrine glands, which secrete their secretions onto a body surface or body cavity, endocrine glands release hormones that are transported through the bloodstream to target cells or organs. These hormones play a crucial role in regulating various bodily functions and maintaining homeostasis.

The pinna is the visible part of the ear that acts as a funnel, collecting sound waves from the surrounding environment. It helps to direct the sound waves into the ear canal, where they are then transmitted to the middle and inner ear for processing. By picking up sound waves, the pinna plays a crucial role in the initial stage of the hearing process.

The pinna is the external part of the ear that collects sound waves and directs them into the ear canal. It acts like a funnel, helping to amplify and localize sounds. The other options mentioned in the question, such as the tympanic membrane, stapes, and external auditory meatus, are all parts of the middle and inner ear that play a role in transmitting and amplifying sound vibrations, but they do not directly pick up sound waves like the pinna does.

Rhodopsin is not a cone in the eye. It is a light-sensitive photopigment found in the rod cells of the retina. Rod cells are responsible for vision in low light conditions and are more sensitive to light than cone cells. Rhodopsin is composed of a protein called opsin and a vitamin A derivative known as retinal. When light hits rhodopsin, it undergoes a chemical reaction that triggers a signal to the brain, allowing us to perceive visual images in dim lighting.

Hormones play a crucial role in regulating various cellular responses. They can regulate enzymes by either activating or inhibiting their activity, thereby controlling the biochemical reactions within cells. Additionally, hormones can affect protein synthesis by influencing the production of specific proteins in cells. They can also alter membrane permeability, allowing certain substances to enter or exit the cell more easily. Furthermore, hormones can stimulate secretion, triggering the release of various substances from cells or glands. However, the statement "Perceive loudness" does not fit with the topic of cellular responses of hormones and is unrelated to the other options.