Endocrine System Vocabulary

Flashcards covering vocabulary terms related to the endocrine system, including regulatory systems, hormones, glands, and their functions.

Somatic Nervous System

Voluntary system, skeletal muscle contraction

Autonomic Nervous System

Involuntary system, maintains a state of homeostasis (steady state)

Sympathetic System

Prepares the body for strenuous situations (e.g. physical activity)

Parasympathetic System = “rest and digest”

Assists during the quiet phases (e.g. digestion)

Endocrine System

Endocrine glands secrete hormones that travel in the bloodstream to target tissues

Autocrine

Secreted from an individual cell and influences the same cell it is secreted from

Paracrine

Produced by a wide variety of tissues and secreted into extracellular fluid and has a localised effect

Neurotransmitter

Produced by neurons and secreted into the synaptic cleft and travels a short distance to influence postsynaptic cells

Endocrine

Hormones secreted into the bloodstream, which travel some distance to target tissues

Chronic hormone secretion

A relatively stable concentration is maintained in the blood stream over a long time period

Acute hormone secretion

Hormone concentration alters irregularly and dramatically and changes with each stimulus

Episodic hormone secretion

Hormones are secreted at regular intervals and concentrations

Neurohormones (neuropeptides)

Chemical messengers secreted by neurons into the blood that can cause the secretion of releasing hormones, primarily from the hypothalamus

Tropic Hormones

Stimulate the secretion of other hormones from other endocrine glands or organs

Negative Feedback

Hormone secretion is inhibited by itself when there are adequate hormone levels in the blood

Positive Feedback

When a hormone stimulates its target cell and promotes the synthesis and secretion of the hormone, leading to further secretion of the hormone

Down-regulation

Decrease sensitivity to a hormone by decreasing the number of receptors

Up-regulation

Increase sensitivity to a hormone by increasing the rate of receptor synthesis

Hypothalamus

Major control site of the nervous and endocrine systems, connected to the pituitary gland by the infundibulum

Posterior Pituitary Gland (Neurohypophysis)

Extension of the hypothalamus that secretes neurohormones into the circulatory system

Anterior Pituitary Gland

Hormones are not neurohormones. Neurohormones move from a primary capillary network in the hypothalamus to the anterior pituitary gland. Hormones are produced in response and carried by a secondary capillary network. This travels through a specialized system known as the hypothalamohypophysial portal system.

Antidiuretic Hormone (ADH)

Increased water reabsorption, leading to decreased urine output and decreased blood osmolality

Somatotropin

Growth Hormone (GH)

Thyroid-Stimulating Hormone (TSH) (Thyrotropin)

Stimulates the synthesis and secretion of thyroid hormones, inhibited by thyroid hormones, and secreted in an episodic manner

Adrenocorticotropic Hormone (ACTH)

Increased secretion of glucocorticoid hormones

Thyroid Gland

Follicles filled with colloid, composed of thyroglobin which stores thyroid hormones, and parafollicular cells which secrete calcitonin

Thyroid Hormones

Regulates metabolism, affects body temperature, and promotes growth and maturation of organs

Calcitonin

Decreases osteoclast activity and lengthens the life of osteoblasts, leading to decreased Ca2+ and phosphate levels

Parathyroid Hormone (PTH)

Increases osteoclast activity and number, stimulates Ca2+ uptake within the kidneys, and increases absorption in the small intestine of Ca2+

Adrenal Glands

Inner Medulla and Outer Cortex

Adrenal Cortex Layers

Zona Glomerulosa, Zona Fasciculata, Zona Reticularis

Stimuli for Catecholamines (Epinephrine and Norepinephrine)

Emotional excitement, injury, exercise, stress, low blood glucose

Mineralocorticoids (Aldosterone)

Increases Sodium (Na+) reabsorption and causes water reabsorption

Glucocorticoid Hormones (Cortisol)

Increases protein and lipid breakdown, increases blood glucose levels, promotes tissue maturation, and decreases the intensity of the inflammatory and immune response

Androgens (Zona Reticularis)

Most androgens are derived from the reproductive system.

Islets of Langerhans (Pancreas)

Alpha cells secrete glucagon; Beta cells secrete insulin

Insulin

Increases the uptake of glucose and amino acids

Glucagon

Increases blood glucose levels