Endocrine System Overview

Hormones that regulate water balance and blood pressure. They increase water reabsorption in the kidneys, leading to less urine production and higher blood pressure.

Hormone produced by the pancreas that lowers blood glucose levels by promoting glucose uptake into cells.

Hormone produced by the pancreas that raises blood glucose levels by stimulating glycogen breakdown in the liver.

Male sex hormone responsible for developing male secondary sexual characteristics.

Female sex hormone responsible for developing female secondary sexual characteristics.

The control center of the nervous system, composed of the brain and spinal cord.

The network of nerves extending from the CNS to the rest of the body.

Part of the PNS that carries sensory information from the body to the CNS.

Part of the PNS that carries motor commands from the CNS to the body.

Part of a neuron that carries nerve impulses away from the cell body.

A system of glands that secrete hormones directly into the bloodstream to regulate various metabolic processes.

Glands that release hormones directly into the surrounding fluid and then into the bloodstream, without using ducts or tubes.

Chemical messengers produced by endocrine glands that regulate specific cellular activities.

Hormones made up of amino acids that activate enzyme systems and require a second messenger to work.

Hormones derived from cholesterol that can directly enter cells to activate specific DNA genes for transcription and translation.

Region of the brain responsible for controlling the pituitary gland and maintaining homeostasis.

The master gland that secretes various hormones, including TSH, ACTH, FSH, LH, and growth hormone, to regulate many biological processes.

A hormone secreted by the pituitary gland that stimulates the thyroid gland to produce its own hormones.

A hormone secreted by the pituitary gland that stimulates the adrenal cortex to produce its hormones.

A hormone secreted by the pituitary gland that stimulates the development and maturation of follicles in the ovaries in females and sperm production in males.

A hormone secreted by the pituitary gland that triggers ovulation in females and testosterone production in males.

A hormone secreted by the pituitary gland that regulates growth and development of bones and muscles.

A gland located in the throat region that produces thyroxine (T4) and triiodothyronine (T3) to regulate metabolism.

A hormone produced by the thyroid gland that helps to lower blood calcium levels.

The resting membrane potential of a neuron is -70mV, meaning the inside of the cell is more negative than the outside. This charge difference is maintained by a combination of electrical potential difference and concentration gradients of ions, particularly sodium (Na+) and potassium (K+).

Depolarization is the process where the membrane potential of a neuron becomes less negative, moving closer to zero. This occurs when sodium ions (Na+) rush into the cell, causing the inside to become more positive. This is the first step in generating a nerve impulse.

Repolarization is the process that restores the neuron's membrane potential back to its resting state (-70mV). This happens when potassium ions (K+) flow out of the cell, making the inside more negative again.

Acetylcholine plays a crucial role in neuromuscular function, controlling muscle contractions. Biogenic amines, derived from amino acids, have diverse roles. These include epinephrine, norepinephrine (both involved in the "fight or flight" response), dopamine (associated with reward, motivation, and movement), serotonin (involved in mood, sleep, and memory), GABA (a major inhibitory neurotransmitter in the brain), and glycine (an inhibitory neurotransmitter outside the brain).

The corpus callosum is a band of nerve fibers connecting the left and right hemispheres of the brain. It allows communication between the two hemispheres, coordinating their functions and enabling them to work together.

The thalamus is a relay station for sensory information. All sensory pathways, except for smell, pass through the thalamus before being relayed to the cerebrum for interpretation. This ensures that sensory information is processed and integrated before reaching the higher brain areas.

The hypothalamus is responsible for regulating basic bodily functions and maintaining homeostasis. It controls hunger, thirst, body temperature, and hormone release from the pituitary gland. Key hormones regulated by the hypothalamus include ADH (antidiuretic hormone) and oxytocin.

The limbic system is often referred to as the emotional brain. It plays a crucial role in experiencing and responding to emotions, as well as in forming and retrieving memories. Key structures include the amygdala (processing emotions, especially fear) and the hippocampus (involved in memory formation).

The reticular activating system (RAS) is a network of neurons that extends from the brainstem to the entire brain. It plays a vital role in maintaining consciousness, wakefulness, and attention. The RAS filters sensory information, allowing you to focus on relevant stimuli while ignoring distracting noises.

The parasympathetic nervous system is responsible for "rest and digest" functions. It promotes relaxation, slows heart rate, stimulates digestion, and conserves energy. It also constricts the pupils, allowing less light into the eyes.

The sympathetic nervous system is responsible for the "fight or flight" response. It prepares the body for action, increasing heart rate, dilating pupils, and inhibiting digestion. It also releases adrenaline to enhance alertness.

The cornea is the transparent outer layer of the eye. It helps focus light onto the retina. It's made of tough protein, similar to the sclera.

Rods and cones are photoreceptor cells in the retina. Rods are highly sensitive to dim light and are responsible for night vision. Cones are responsible for color vision, detecting red, green, and blue light. The fovea, a small area in the center of the retina, has a high concentration of cones, providing the sharpest vision.

Myopia (nearsightedness) occurs when the eye is too long or the cornea is too curved, causing light to focus in front of the retina. Hyperopia (farsightedness) occurs when the eye is too short or the cornea is too flat, causing light to focus behind the retina. Astigmatism is caused by an irregularly shaped cornea, causing blurred vision at all distances. Cataracts are clouding of the lens, impairing light from reaching the retina. Glaucoma is caused by increased pressure inside the eye, damaging the optic nerve and potentially leading to blindness.

The cochlea is a fluid-filled chamber in the inner ear responsible for hearing. It contains the organ of Corti, which houses hair-like cells that convert sound vibrations into nerve impulses. Different frequencies of sound are detected by hair cells located in specific regions along the length of the cochlea - higher frequencies closer to the entrance and lower frequencies at the far end.