Physiology, Homeostasis, Nervous System, and Endocrine Functions Flashcards

A detailed set of vocabulary flashcards covering negative and positive feedback mechanisms, homeostasis components, thermoregulation, the nervous system, and endocrine glands with their corresponding hormones and functions.

Negative Feedback Mechanism

A self-regulating physiological process in which the body's response opposes the initial change to restore balance and return conditions to homeostasis.

Homeostasis

The body's ability to maintain a constant, relatively stable internal environment despite continuous external changes.

Positive Feedback Loop

A feedback mechanism that amplifies and reinforces a change occurring in the body until an endpoint is reached, such as in childbirth or blood clotting.

Set Point

An average target value, such as $37\,^\circ\text{C}$ for human body temperature, around which normal physiological conditions fluctuate.

Dynamic Equilibrium

A state of ever-changing balance within narrow physiological limits rather than a total lack of change.

Stimulus

A change in internal or external body conditions, such as an increase in blood pressure or body temperature, that initiates a feedback loop.

Sensor (Receptor)

A structure, such as baroreceptors or thermoreceptors, that detects a stimulus and transmits a signal to the control center.

Control Center

A component, such as the medulla oblongata or hypothalamus, that receives and analyzes information from receptors and determines the appropriate response.

Effector

An organ, gland, or muscle, such as the heart or blood vessels, that carries out the response directed by the control center to counteract a change.

Cerebrum

The region of the brain that controls voluntary actions, such as eating and walking.

Medulla Oblongata

A region of the brainstem that controls involuntary actions such as heartbeat and peristalsis, and acts as a control center in blood pressure regulation.

Spinal Cord

A major structure of the central nervous system that coordinates reflex actions, such as breathing, sneezing, or withdrawing a hand from a hot object.

Central Nervous System (CNS)

The core part of the nervous system consisting of the brain and spinal cord that interprets nerve impulses and coordinates organ functions.

Peripheral Nervous System (PNS)

The division of the nervous system comprising $12$ pairs of cranial nerves and $31$ pairs of spinal nerves.

Thermoregulatory Centre

A region in the brain containing temperature-sensitive receptors that acts as the body's thermostat to regulate blood and skin temperature around $37\,^\circ\text{C}$.

Vasodilation

The dilation of blood vessels supplying skin capillaries when the body is too hot, increasing surface blood flow to facilitate heat loss.

Vasoconstriction

The constriction of blood vessels supplying skin capillaries when the body is cold, reducing surface blood flow to conserve heat.

Shivering

Automatic muscle contractions triggered by cold conditions that increase respiration rate to generate heat.

Urea

A metabolic waste product synthesized from excess amino acids that must be excreted from the body to prevent toxicity.

Frostbite

Cell damage and tissue death resulting from prolonged exposure to extreme cold when blood flow to fingers and toes is shut off to conserve core body heat.

Hormones - Glands & Functions Overview

A reference chart outlining the major endocrine glands, their secreted hormones, and their corresponding functions in regulating growth, metabolism, and balance.

Thyroid-Releasing Hormone (TRH)

A hypothalamic hormone that stimulates the release of thyroid-stimulating hormone (TSH) from the anterior pituitary.

Corticotropin-Releasing Hormone (CRH)

A hypothalamic hormone that stimulates the anterior pituitary to secrete adrenocorticotropic hormone (ACTH).

Gonadotropin-Releasing Hormone (GnRH)

A hypothalamic hormone that stimulates the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Growth Hormone-Releasing Hormone (GHRH)

A hypothalamic hormone that stimulates the release of growth hormone (GH).

Somatostatin

A hormone produced by the hypothalamus and pancreas that inhibits growth hormone (GH), thyroid-stimulating hormone (TSH), insulin, and glucagon.

Dopamine

A neurohormone released by the hypothalamus that inhibits the secretion of prolactin.

Growth Hormone (GH)

An anterior pituitary hormone that stimulates general body growth.

Thyroid-Stimulating Hormone (TSH)

An anterior pituitary hormone that stimulates the thyroid gland to release thyroid hormones.

Adrenocorticotropic Hormone (ACTH)

An anterior pituitary hormone that stimulates secretion of hormones by the adrenal cortex.

Follicle-Stimulating Hormone (FSH)

An anterior pituitary hormone that promotes follicle growth in females and sperm production in males.

Luteinizing Hormone (LH)

An anterior pituitary hormone that triggers ovulation in females and stimulates testosterone secretion in males.

Prolactin

An anterior pituitary hormone that promotes milk production in mammary glands.

Antidiuretic Hormone (ADH)

A posterior pituitary hormone known as a 'water saver' that enhances water reabsorption in the kidneys.

Oxytocin

A posterior pituitary hormone that stimulates uterine contractions during labor and milk ejection during lactation.

Triiodothyronine ($T_3$) and Thyroxine ($T_4$)

Hormones produced by the thyroid gland that increase metabolic rate and promote growth.

Calcitonin

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

Parathyroid Hormone (PTH)

A hormone secreted by the parathyroid glands that acts to raise blood calcium levels.

Cortisol

An adrenal cortex hormone involved in the stress response that acts to increase blood glucose levels.

Aldosterone

An adrenal cortex hormone that regulates electrolyte balance by promoting sodium retention and potassium excretion.

Adrenaline and Noradrenaline

Hormones secreted by the adrenal medulla that trigger fight-or-flight responses and elevate blood pressure.

Insulin

A hormone secreted by pancreatic beta cells that lowers blood glucose by promoting cell uptake of glucose.

Glucagon

A hormone secreted by the pancreas that works to raise blood glucose levels.

Melatonin

A hormone released by the pineal gland that helps regulate sleep-wake cycles.

Thymosin

A hormone secreted by the thymus gland that facilitates T cell maturation.

Estrogen and Progesterone

Female sex hormones secreted by the ovaries; estrogen controls female secondary sexual characteristics, while progesterone maintains pregnancy.

Testosterone

A male sex hormone secreted by the testes that governs male secondary sexual characteristics and sperm formation.