16. notes

The endocrine system consists of various organs that synthesize and secrete __________, which are chemical messengers that regulate bodily functions.

Hormones

Hormones play a crucial role in maintaining __________, influencing fluid, electrolyte, and acid-base balance.

homeostasis

Unlike the nervous system, which uses __________ for immediate effects, the endocrine system relies on hormones that travel through the bloodstream.

neurotransmitters

The nervous system operates through neurons that directly affect target cells, leading to rapid but __________ responses.

short-lived

The endocrine system releases hormones into the bloodstream, resulting in __________ but longer-lasting effects on target cells.

slower

The three basic types of chemical signals in the body are __________, paracrine, and autocrine signals.

endocrine

Endocrine signals are hormones released into the __________, affecting distant target cells.

bloodstream

The major endocrine organs include the anterior pituitary, thyroid gland, parathyroid glands, adrenal cortices, pancreas, and __________.

thymus

Endocrine glands are __________ and secrete hormones directly into the extracellular fluid for transport by the bloodstream.

ductless

Amino-acid hormones are classified as __________ and bind to plasma membrane receptors.

hydrophilic

Steroid hormones are classified as __________ and can cross the plasma membrane to bind to intracellular receptors.

hydrophobic

Antidiuretic hormone (ADH) regulates __________ retention in the kidneys by promoting the insertion of aquaporins in kidney tubule cells.

water

Oxytocin is involved in __________ and lactation, stimulating uterine contractions and milk ejection.

childbirth

ADH increases __________ reabsorption in the kidneys, reducing urine output and conserving body water.

water

A deficiency in ADH leads to excessive urination and extreme thirst, a condition known as __________.

diabetes insipidus

Oxytocin plays a crucial role in the milk __________ reflex, stimulated by suckling during nursing.

let-down

The hypothalamus regulates the anterior pituitary through releasing and __________ hormones, maintaining hormonal balance in the body.

inhibiting

Negative feedback loops are essential for regulating __________ levels, ensuring homeostasis in the endocrine system.

hormone

TSH stimulates __________ hormone production, essential for metabolism and growth.

thyroid

ACTH promotes adrenal gland function, influencing __________ response and metabolism.

stress

Prolactin is vital for milk production and __________ gland development post-childbirth.

mammary

The thyroid gland produces thyroid hormones and __________, crucial for metabolic regulation.

calcitonin

The parathyroid glands secrete parathyroid hormone (PTH), which increases blood __________ levels.

calcium

Thyroid hormones (T3 and T4) increase the basal metabolic rate, promoting __________ expenditure and thermoregulation.

energy

Iodide uptake and conversion processes within the thyroid follicles are essential for the synthesis of __________ hormones.

thyroid

Hyperthyroidism is characterized by excessive production of __________ hormones, leading to symptoms such as weight loss and anxiety.

thyroid

PTH is secreted by chief cells in the parathyroid gland in response to low blood __________ levels.

calcium

Calcitonin lowers blood calcium levels by inhibiting __________ activity and promoting osteoblast activity.

osteoclast

The adrenal glands consist of an outer cortex and an inner __________, each producing different hormones.

medulla

Mineralocorticoids regulate electrolyte balance and blood pressure through the __________ system.

renin-angiotensin-aldosterone

Glucocorticoids, such as cortisol, are involved in __________ response and regulating metabolism.

stress

The pancreas serves both endocrine and __________ functions, with pancreatic islets being the endocrine component.

exocrine

Alpha cells in the pancreas produce glucagon, while beta cells produce __________.

insulin

Insulin lowers blood glucose levels by facilitating __________ uptake.

cellular

When blood glucose levels rise, beta cells increase insulin secretion while alpha cells decrease __________ secretion.

glucagon

The pineal gland secretes __________, which regulates sleep-wake cycles and increases in darkness.

melatonin

The thymus produces thymosin and thymopoietin, which are crucial for T-lymphocyte __________, essential for immune response.

maturation

Testosterone promotes male secondary sex characteristics and muscle growth, regulated by a feedback loop involving the __________ and pituitary.

hypothalamus

Ovaries produce estrogen and __________, which regulate the menstrual cycle and prepare the body for pregnancy.

progesterone

Fluid homeostasis regulation involves hormones such as ADH, aldosterone, and __________.

ANP

Thyroid hormones control __________ metabolic rate, while insulin and catecholamines adjust metabolic rates during feeding and exercise.

basal