Anatomy of Domestic Animals: Blood, Respiratory, Cardiovascular, and Endocrine Systems

Vocabulary practice flashcards covering blood components, the respiratory system, cardiovascular structures, and endocrinology in domestic animals.

Blood

A fluid connective tissue consisting of a liquid portion called plasma (~$55\%$) and formed elements (~$45\%$) that circulates through the heart, arteries, capillaries, and veins to serve as the chief transport medium in the body.

Blood Plasma

The liquid component of blood consisting of ~$92\%$\ water and $8\%$\ solutes (including albumin, globulin, fibrinogen, glucose, and electrolytes) that serves as the internal environment for cells, obtained from blood treated with anticoagulants.

Serum

The clear fluid that separates and oozes out from blood after coagulation has occurred, defined mathematically as plasma minus clotting factors such as fibrinogen, collected without anticoagulants.

Erythrocytes

Biconcave, non-nucleated formed elements produced in the bone marrow of long bones that contain hemoglobin, survive for ~$120\text{ days}$\, and transport oxygen and carbon dioxide.

Leucocytes

Nucleated white blood cells that combat infection and initiate inflammatory responses, classified into granulocytes and agranulocytes under Wright's stain.

Granulocytes

A subcategory of white blood cells possessing prominent cytoplasmic granules, consisting of neutrophils, eosinophils, and basophils.

Agranulocytes

A subcategory of white blood cells lacking conspicuous cytoplasmic granules, comprising monocytes and lymphocytes.

Thrombocytes

Disc-shaped, non-nucleated cell fragments derived from megakaryocytes that release chemical substances to stimulate vasoconstriction and blood clotting.

Coagulation

The hemostatic process that arrests bleeding through three sequential stages: vasoconstriction, platelet plug formation, and the formation of a fibrin network.

Anticoagulants

Chemical agents that prevent blood from clotting, including heparin, warfarin (Coumadin), EDTA, citrate, and oxalate.

Paranasal Sinuses

Air-filled hollow cavities within the skull bones (maxillary, frontal, sphenoidal, and palatine) that lighten the weight of the skull and condition incoming air.

Pharynx

A shared soft tissue passage of the respiratory and digestive systems (nasopharynx) that serves as the gateway to the larynx and aids in deglutition and phonation.

Deglutition

The physiological act or process of swallowing.

Phonation

The production of vocal sounds, primarily facilitated by the larynx and respiratory airflow.

Larynx

The cartilaginous voice box composed of four cartilages that regulates the size of the airway, generates sound, and prevents foreign material from entering the lower respiratory tract.

Carina

An internal cartilaginous ridge located at the caudal termination of the trachea where it bifurcates into the right and left primary bronchi.

Accessory Bronchus

A specialized bronchus branching off the right side of the trachea cranial to the primary bifurcation, found specifically in ruminants and pigs.

Bronchioles

Small conducting air passageways approximately $1\,\text{mm}$\ thick that lack cartilage and do not participate in gas exchange, branching into terminal and respiratory bronchioles.

Alveoli

Microscopic sac-like structural chambers enveloped by capillary networks where gaseous exchange of oxygen and carbon dioxide occurs across the respiratory membrane.

Pericardium

A double-walled serous sac encasing the heart, comprising a parietal layer lining the internal fibrous pericardium and a visceral layer (epicardium) covering the heart muscle, separated by the fluid-filled pericardial cavity.

Atria

The two superior receiving chambers of the heart, each featuring an auricle; the right atrium receives blood from the venae cavae, while the left atrium receives blood from the pulmonary veins.

Ventricles

The two inferior muscular discharging chambers of the heart lined with papillary muscles; the right ventricle pumps blood into the pulmonary trunk, and the left ventricle pumps blood into the aorta.

Atrioventricular (AV) Valves

Heart valves positioned between the atria and ventricles (the tricuspid on the right and bicuspid/mitral on the left) that prevent the backflow of blood into the atria during ventricular contraction.

Chordae Tendineae

Fibrous tendon-like cords anchored to papillary muscles in the ventricles that prevent atrioventricular valve flaps from everting into the atria during ventricular systole.

Semilunar Valves

Valves featuring three half-moon cup-shaped flaps located at the base of the aorta (aortic valve) and pulmonary trunk (pulmonary valve) that close during ventricular diastole to prevent backflow into the ventricles.

Endocrine System

An integrated system of ductless glands that synthesize and secrete chemical messengers (hormones) directly into the bloodstream to elicit regulatory effects on target tissues.

Hormone

A chemical substance produced by a ductless gland and secreted into the circulatory system to produce a specific regulatory effect on distant target organs or tissues.

Hypothalamus

A neuroendocrine brain center that secretes releasing hormones (CRH, GnRH, GHRH, TRH) to stimulate the adenohypophysis, while synthesizing oxytocin and ADH for storage in the neurohypophysis.

Adenohypophysis

The anterior lobe of the pituitary gland that synthesizes and secretes ACTH, FSH, LH, GH, TSH, and PRL under hypothalamic regulation.

Neurohypophysis

The posterior lobe of the pituitary gland that stores and releases the hypothalamic peptide hormones oxytocin and antidiuretic hormone (ADH).

Calcitonin

A peptide hormone produced by the thyroid gland that acts to lower blood calcium levels by directly inhibiting osteoclasts.

Parathyroid Hormone (PTH)

A hormone produced by the two pairs of parathyroid glands that increases blood calcium and decreases blood phosphorus by stimulating bone resorption and activating vitamin D in the kidneys.

Adrenal Cortex

The outer steroid-producing region of the adrenal gland that secretes glucocorticoids (such as cortisol) and mineralocorticoids (such as aldosterone).

Adrenal Medulla

The inner core of the adrenal gland that synthesizes and secretes catecholamines (epinephrine and norepinephrine) to prepare the body for the fight-or-flight response.

Islets of Langerhans

Endocrine cell clusters dispersed within the pancreas containing beta cells that secrete insulin and alpha cells that secrete glucagon into the bloodstream.

Pinealocytes

Secretory cells of the pineal gland, derived from neuronal lineage, that convert serotonin into melatonin to regulate the sleep-wake photoperiod cycle.

Type I Diabetes Mellitus

A metabolic disorder characterized by the complete deficiency of insulin production caused by dysfunction of pancreatic beta cells.

Type II Diabetes Mellitus

A metabolic disease characterized by insulin resistance at the insulin receptor, preventing the intracellular mobilization of GLUT4 transporters for glucose uptake.