Endocrine and Muscle Physiology

A comprehensive set of flashcards covering key concepts in Endocrine and Muscle Physiology.

Hormones

Chemical messengers transported in the bloodstream that stimulate physiological responses in target cells or organs.

Steroid hormones

Lipid-soluble hormones that diffuse through cell membranes.

Protein/Peptide hormones

Water-soluble hormones that bind to surface receptors.

Biogenic/Monoamines

Hormones derived from amino acids that may need carriers or membrane receptors.

TSH

Thyroid-stimulating hormone; stimulates thyroid to release T3 and T4.

ACTH

Adrenocorticotropic hormone; stimulates adrenal cortex to release cortisol.

GH

Growth hormone; stimulates tissue growth and protein synthesis.

PRL

Prolactin; stimulates milk production.

FSH

Follicle-stimulating hormone; stimulates egg maturation and sperm production.

LH

Luteinizing hormone; triggers ovulation and testosterone production.

Thymosin

Hormone secreted by the thymus that helps in the development and maturation of T-cells.

T3 and T4

Hormones secreted by follicular cells of the thyroid gland that increase metabolism and regulate appetite.

Calcitonin

Hormone secreted by C cells that lowers blood calcium levels.

Aldosterone

Hormone from the adrenal cortex that retains Na⁺, excretes K⁺, and raises blood pressure.

Cortisol

Hormone that increases glucose metabolism of fat and protein.

Androgens

Hormones that are precursors to sex hormones.

Epinephrine

Hormone from the adrenal medulla that increases heart rate, blood flow, and alertness.

Norepinephrine

Hormone that works alongside epinephrine to increase alertness and heart rate.

Insulin

Hormone secreted by beta cells that lowers blood glucose.

Glucagon

Hormone secreted by alpha cells that raises blood glucose.

Sertoli cells

Support spermatogenesis in the testes.

Leydig cells

Interstitial cells that produce testosterone.

Testosterone

Hormone that stimulates male development and sperm production.

Inhibin

Hormone that inhibits FSH to regulate sperm production.

Diabetes insipidus

ADH deficiency leading to excessive urination.

Diabetes mellitus

Condition of insulin issues leading to high blood glucose.

Polyuria

Excessive urination.

Polydipsia

Excessive thirst.

Polyphagia

Excessive hunger.

Oxytocin

Hormone that stimulates uterine contractions and milk letdown.

Prolactin

Hormone that stimulates milk production.

Estrogen

Hormone that regulates the menstrual cycle and secondary sex characteristics.

Progesterone

Hormone that maintains pregnancy.

Epimysium

Connective tissue that surrounds the entire muscle.

Perimysium

Connective tissue that surrounds a fascicle (bundle of muscle fibers).

Endomysium

Thin connective tissue that surrounds individual muscle fibers.

Fascicle

A bundle of muscle fibers.

Sarcomere

The smallest contractile unit of muscle, extending from Z-disc to Z-disc.

Z-band

The boundary of a sarcomere.

A-band

The dark band of the sarcomere containing thick myosin filaments.

I-band

The light band of the sarcomere containing thin actin filaments.

H-zone

The area in the A-band where there are only thick myosin filaments.

Actin

Thin filament involved in muscle contraction.

Myosin

Thick filament that pulls actin during muscle contraction.

Troponin

A protein that binds calcium ions to facilitate muscle contraction.

Tropomyosin

A protein that blocks binding sites on actin filaments.

Motor unit

A motor neuron and all of the muscle fibers it controls.

T-Tubule

Structure that conducts action potentials into muscle cells.

Sarcoplasmic Reticulum (SR)

Organelle that stores calcium ions in muscle cells.

Terminal Cisternae

Part of the SR that releases calcium ions during muscle contraction.

Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction to stimulate muscle contraction.

Calcium ions (Ca²⁺)

Essential for muscle contraction as they bind to troponin.

Ca²⁺ ATPase pump

Enzyme that reabsorbs calcium into the SR after contraction.

ATP

Energy molecule essential for muscle contraction and relaxation.

Sliding filament theory

Theory explaining how myosin pulls actin filaments, causing muscle contraction.

DHP receptors

Voltage sensors located in T-tubules involved in muscle contraction.

Ryanodine receptors

Receptors in the SR that release calcium ions during contraction.

AChE (Acetylcholinesterase)

Enzyme that breaks down acetylcholine to terminate muscle contraction.

Isotonic contractions

Muscle contractions that result in a change in muscle length.

Isometric contractions

Muscle contractions that do not change muscle length.

Conductive division of the respiratory system

Air passageways from the nose to bronchioles.

Respiratory division of the respiratory system

Site of gas exchange in the alveoli.

Type I alveolar cells

Cells responsible for gas exchange in the lungs.

Type II alveolar cells

Cells that secrete surfactant and repair alveoli.

Dust cells

Alveolar macrophages that help clean up debris.

Relaxed inhalation muscles

Diaphragm and external intercostals.

Forced inhalation muscles

Accessory neck muscles.

Forced exhalation muscles

Internal intercostals and abdominal muscles.

Pressure during inhalation

Increases volume and decreases pressure.

Pressure during exhalation

Decreases volume and increases pressure.

Systemic gas exchange

Gas exchange occurring at the tissues.

Pulmonary gas exchange

Gas exchange occurring in the lungs.

Red blood cells (RBCs)

Cells involved in transporting oxygen and carbon dioxide.

Carbonic anhydrase

Enzyme that catalyzes the conversion of CO₂ and H₂O into carbonic acid.

Carbonic acid

Substance that breaks down into H⁺ and bicarbonate ions.

Hypoxia

Condition of low oxygen levels in the tissues.

Hypercapnia

Condition of high carbon dioxide levels in the blood.

Central chemoreceptors

Found in the medulla, sensitive to pH changes in the CSF.

Peripheral chemoreceptors

Located in carotid and aortic bodies, sensitive to O₂, CO₂, and pH.

CO₂ loading at tissues

CO₂ enters blood and forms bicarbonate.

O₂ unloading at tissues

O₂ is released from hemoglobin to tissues.

CO₂ unloading at alveoli

CO₂ is released from blood into the lungs.

O₂ loading at alveoli

O₂ binds to hemoglobin in the lungs.

Medulla oblongata

Brain region responsible for unconscious breathing.

Obstructive disorders

Respiratory disorders characterized by narrowed airways.

Restrictive disorders

Respiratory disorders characterized by reduced lung expansion.

Spirometry volumes

Include tidal volume, inspiratory/expiratory reserve volume, residual volume, vital capacity, total lung capacity, inspiratory capacity, and functional residual capacity.

Eupnea

Normal breathing.

Dyspnea

Labored or difficult breathing.

Tachypnea

Rapid, shallow breathing.

Apnea

Absence of breathing.

Kussmaul respiration

Deep, rapid breathing typically associated