Endocrine system I

Endocrine system

Initiates responses slowly, Long duration responses, Acts via hormones released into the blood, Acts at diffuse locations targets can be anywhere blood reaches, Hormones act over long distances.

Nervous system

Initiates responses rapidly, Short duration responses, Acts via action potentials and neurotransmitters, Acts at specific locations determined by axon pathways, Neurotransmitters act over very short distances.

Homeostasis

Maintains and regulates internal balance of water and nutrient levels, metabolism, immune response, growth and development, and reproduction.

Endocrine glands

Ductless glands that release secretions (hormones) into surrounding body fluids (interstitial fluid, lymph system, and blood stream).

Hormones

Chemical signals released by endocrine cells that act on target cells through hormone receptors, influencing various physiological processes.

Hormone receptors

Expressed by target cells, they act via intracellular second-messenger pathways to transmit the hormonal signal and initiate a cellular response.

Second-messenger pathways

Amplify the initial hormonal signal by multiplying the response at each stage of subsequent activation and control, allowing for temporal, spatial, quantitative, and qualitative regulation.

Adrenaline

Stress hormone and neurotransmitter acting on various organ systems.

Serotonin

Hormone and neurotransmitter that affects the cardiovascular system and is often referred to as the "happiness" transmitter.

Melatonin

Hormone and neurotransmitter that helps regulate our circadian "inner" clock.

Growth hormone

Controls growth and development.

Antidiuretic hormone (ADH)

Regulates water reabsorption by the kidneys.

Insulin

Lowers blood sugar level.

Glucagon

Increases blood sugar level.

Steroid hormones

Lipid-soluble hormones synthesized from cholesterol that can enter the cell and act on intracellular receptors to directly activate genes.

Negative feedback

Regulatory mechanism that brings an internal condition or signal back to homeostasis by stimulating a physiological response.

Humoral stimuli

Change of ions or nutrients in the body fluids detected by receptors of endocrine cells, triggering the release of appropriate hormones.

Neural stimuli

Stimulation of endocrine cells by neurons, such as the release of adrenaline in response to stress.

Hormonal stimuli

Endocrine cells responding to hormones released by other endocrine cells.

Cell-specific response

Binding of a hormone triggers a cellular response that is specific to the target cell, influenced by hormone concentration, density of receptors, and receptor affinity.

Permissiveness

One hormone requires the presence of another hormone to exert its full effect, allowing for fine-scale temporal and spatial control.

Synergism

More than one hormone produces the same effect in a target cell, amplifying the overall effect.

Antagonism

Different hormones oppose each other's actions, resulting in a response from the target cell that depends on the hormone-hormone interaction.