Endocrine System Flash Cards.

Endocrine system

A system that helps other systems work together and maintain homeostasis through chemical messengers known as hormones.

Homeostasis

The state of steady internal conditions maintained by living organisms.

Hormones

Chemical messengers that travel through the bloodstream to regulate various processes in the body.

Glands

Ductless organs that produce and secrete hormones directly into the bloodstream.

Growth hormone

A hormone produced by the pituitary gland that stimulates growth and regulates metabolism.

Hypothalamus

A brain region that plays a crucial role in controlling the endocrine system by linking the nervous system to the endocrine system.

Pituitary gland

Known as the master gland, it controls various endocrine functions and secretes hormones that regulate other glands.

Thyroid gland

Located in the neck, it produces hormones that regulate metabolism, growth, and development.

Calcitonin

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

Parathyroid hormone (PTH)

A hormone produced by the parathyroid glands that increases blood calcium levels.

Adrenal glands

Located above the kidneys, these glands produce hormones involved in stress responses, including adrenaline.

Insulin

A hormone produced by beta cells of the pancreas that helps lower blood glucose levels.

Glucagon

A hormone produced by the pancreas that increases blood glucose levels.

Epinephrine

Also known as adrenaline, it is a hormone released during fight-or-flight response.

Negative feedback

A regulatory mechanism in which a change in a variable triggers a response that counteracts the initial change.

Half-life

The time required for the amount of a substance (such as a hormone) to reduce to half its initial value.

Synergism

An interaction between two hormones that produces a greater effect than the sum of their individual effects.

Antagonism

When two hormones have opposing effects on a target organ or system.

Diabetes mellitus

A metabolic disorder caused by high blood sugar levels due to insulin deficiency or resistance.

Thymus gland

An organ that produces hormones involved in the immune response and T-lymphocyte production.

Gonads

Sex organs (ovaries and testes) that produce sex hormones including estrogen, progesterone, and testosterone.

Pineal gland

A gland in the brain that produces the hormone melatonin, which regulates sleep-wake cycles.

Hormonal stimuli

Stimulation of glands to release hormones by other hormones, often referred to as tropins.

Location of the Pituitary Gland

Located at the base of the brain, below the hypothalamus.

Location of the Thyroid Gland

Located in the neck, just below the Adam's apple.

Location of the Parathyroid Glands

Typically located behind the thyroid gland, usually four small glands.

Location of the Adrenal Glands

Located on top of each kidney.

Location of the Pancreas

Located behind the stomach, extending across the abdomen.

Location of the Gonads

Ovaries located in the pelvic cavity for females, testes located in the scrotum for males.

Location of the Thymus Gland

Located in the upper chest, behind the sternum.

Location of the Pineal Gland

Located in the brain, near the center between the two hemispheres.

Amino acid-based hormones

Hormones made up of simple amino acids or proteins, usually hydrophilic and cannot easily cross cell membranes.

Steroid hormones

Hormones derived from cholesterol, typically lipophilic, allowing them to pass through cell membranes and influence gene expression.

Second messenger system

A mechanism in which hormones activate membrane-bound receptors, leading to the production of secondary molecules (like cAMP) that mediate cellular responses.

Direct gene activation

A mechanism by which steroid hormones pass through the cell membrane and bind to receptors inside the cell, directly influencing gene transcription.

Differences between amino acid-based hormones and steroid hormones

Amino acid-based hormones are typically hydrophilic and act via receptors on the cell surface, while steroid hormones are lipophilic and act through direct gene activation.

Differences between second messenger system and direct gene activation

The second messenger system involves external receptor binding and intracellular signaling, whereas direct gene activation involves hormone-receptor binding inside the cell and direct modification of gene expression.

Humoral stimuli

Stimulation of hormone release in response to changes in levels of certain ions or nutrients in the blood.

Hormonal stimuli

Stimulation of glands to release hormones in response to other hormones.

Nervous stimuli

Stimulation of hormone release that is initiated by the nervous system, often in response to stress.

Positive feedback

A regulatory mechanism in which a change in a variable triggers a response that enhances the initial change.

Endocrine reflexes

A series of events leading to hormone release in response to a stimulus, often involving nervous or humoral signals.

Circadian rhythms

Biological processes that follow a roughly 24-hour cycle, often influenced by external cues like light, regulating hormone release.

Pheromones

Chemical signals released outside the body that influence the behavior of other individuals of the same species.

Feedback loops

Regulatory pathways in physiology that involve receptors, integration centers, and effectors to maintain homeostasis.

Pancreas

Secretes insulin and glucagon to regulate blood glucose levels.

Adrenal Glands

Secrete adrenaline (epinephrine) and cortisol in response to stress.

Thyroid Gland

Secretes thyroid hormones (T3 and T4) that regulate metabolism.

Pituitary Gland

Secretes various hormones including growth hormone, prolactin, and thyroid-stimulating hormone (TSH).

Parathyroid Glands

Secrete parathyroid hormone (PTH) to regulate calcium levels in the blood.

Thymus Gland

Secretes thymosin, which regulates immune responses.

Gonads (Ovaries and Testes)

Secrete sex hormones: estrogen and progesterone from ovaries; testosterone from testes.

Pineal Gland

Secretes melatonin to regulate sleep-wake cycles.

Relationship between Hypothalamus and Pituitary Gland

The hypothalamus produces hormones that regulate the pituitary gland, controlling its release of various hormones to other endocrine glands.

Target Glands

Glands that respond to hormones secreted by the pituitary gland, including the adrenal glands, thyroid gland, and gonads.

Negative Feedback Mechanism

A process where rising hormone levels from a target gland signal the hypothalamus and pituitary gland to reduce hormone release, maintaining balance.

Hypothalamic-pituitary axis

A complex set of direct influences and interactions between the hypothalamus and the pituitary gland, coordinating endocrine activity.

Role of Negative Feedback in Endocrine Regulation

Negative feedback prevents overproduction of hormones by inhibiting the hypothalamus and pituitary when target gland hormones are sufficiently high.