Homeostasis

Tolerance limits

Specific ranges of variable factors in the internal environment that organisms must maintain for survival and optimal functioning.

Homeostasis

The ability of organisms to maintain internal stability by adjusting to changes in the external environment.

Stimulus

A variable factor in the internal or external environment that can be detected by an organism.

Receptor

Cells or tissues that detect changes in the environment and transmit this information to the central nervous system.

Effector

Glands or muscles that bring about a response to a stimulus received from the central nervous system.

Response

An action that occurs due to the initial stimulus.

Feedback

The impact of the response on the initial stimulus, which can be positive or negative.

Negative feedback

A mechanism where the response diminishes or reverses the original stimulus to maintain homeostasis.

Positive feedback

A mechanism where the response reinforces or increases the initial stimulus.

Central Nervous System

Consists of the brain and spinal cord, responsible for processing information and sending nerve impulses to tissues and organs.

Peripheral Nervous System

Includes all nerves outside the central nervous system, connecting the CNS to the rest of the body.

Reflex

An automatic response to a stimulus that does not involve conscious control.

Reflex arc

The pathway along which nerve impulses travel during a reflex action.

Endocrine System

A system of glands that secrete hormones to regulate various bodily functions.

Hormones

Chemical messengers produced by endocrine glands that regulate specific physiological activities in the body.

Glucagon

A polypeptide hormone secreted by the pancreas that stimulates the breakdown of glycogen to glucose, increasing blood sugar levels.

Insulin

A protein hormone secreted by the pancreas that acts on the liver and muscles cells, lowering blood sugar levels and increasing glycogen storage.

Thyroid Stimulating Hormone (TSH)

A glycoprotein hormone secreted by the anterior pituitary that acts on the thyroid gland to stimulate the production of thyroxine.

Aldosterone

A steroid hormone secreted by the adrenal cortex that acts on the kidneys to increase sodium and water reabsorption, thereby increasing blood pressure.

Hormones in the Bloodstream

Hormones are secreted by endocrine glands into the blood, travel to target sites, and interact with specific receptors on target cells to elicit responses.

Control of Metabolism

Hormones can alter the metabolism of target cells by binding to specific receptors, triggering responses in target tissues and organs.

Blood Glucose and Insulin

After eating, glucose levels rise, leading to insulin release, which promotes glucose uptake by cells and conversion to glycogen, lowering blood sugar levels.

Diabetes Mellitus

A metabolic disorder characterized by insufficient insulin production or ineffective insulin response, resulting in high blood sugar levels if untreated.

Thyroxine

A hormone produced by the thyroid gland that regulates metabolism by increasing the basal metabolic rate and promoting heat generation.

Osmoregulation

The maintenance of osmotic pressure in an organism's fluids by controlling water and salt concentrations, primarily regulated by the kidneys.

Adrenaline

A hormone released in response to stress or danger that increases heart rate, redirects blood flow, and stimulates glucose release for energy.

Nervous vs

The nervous system transmits messages quickly via nerves and neurotransmitters, while the endocrine system uses hormones and acts more slowly but has longer-lasting effects.

Temperature Regulation

The body responds to changes in temperature by activating mechanisms such as shivering, vasoconstriction, and hormone release to maintain homeostasis.