Exam 3 Comparative Anatomy

Conventions for naming veins/arteries

Names reflect location or destination and sometimes characteristics, e.g., axillary in armpit, brachial in arm, renal to kidneys, pulmonary to lungs, hepatic to liver

Superficial vs deep veins

Superficial veins lie under skin and are often unpaired (cephalic, basilic, great/small saphenous); deep veins accompany arteries and share names (radial, femoral, popliteal)

Arteries vs veins overview

Arteries have thicker elastic walls and higher pressure with small round lumen and carry blood away from the heart; veins have larger flatter lumen with valves and lower pressure and carry blood toward the heart

Ancestral vertebrate heart parts

Four-part linear tube sinus venosus → atrium → ventricle → conus arteriosus forming a single circuit with no chamber separation

Teleost heart organization

Two main chambers with accessory parts and a single circuit sending deoxygenated blood to gills

Amphibian heart organization

Three chambers with two atria and one ventricle and a partial double circuit with some mixing and gas exchange via lungs and skin

Reptile heart organization

Three chambers with a partially divided ventricle and partial double circuit with improved separation and possible shunting

Bird heart organization

Four chambers with a complete double circuit enabling high metabolic efficiency

Mammal heart organization

Four chambers with a complete double circuit and independent systemic and pulmonary pressures

Single vs double circulation

Single circulation is heart → gills → body → heart once per loop; double circulation returns oxygenated blood to heart for re

Cardiac automaticity definition

The heart initiates its own impulses without external input through pacemaker cells

Cardiac conduction pathway

SA node → AV node → bundle branches → Purkinje fibers coordinate rhythmic contraction

Ancestral aortic arches

Six arches present each passing through a gill slit for oxygenation

Teleost aortic arches

Arches I and II are lost and oxygenated blood exits gills via dorsal aortae

Urodeles aortic arches

SALAMANDER Arches I and II lost and arches III to VI are modified

Anurans aortic arches

FROG AND TOAD Arches I and II lost and III forms carotids and IV forms systemic arches and VI forms pulmocutaneous arteries

Reptiles aortic arches

Arches I and II lost and III forms carotids and IV forms two systemic arches and VI forms pulmonary arteries and trunk

Birds aortic arches

Arches I II and V lost and III forms carotids and right IV forms systemic arch and VI forms pulmonary arteries and left IV disappears

Mammals aortic arches

Arches I II and V lost and III forms carotids and left IV forms systemic arch and VI forms pulmonary arteries and trunk and right IV disappears

Hepatic portal system function

Transports nutrient-rich blood from digestive organs to liver for processing before returning to the heart

Right atrium function

Receives deoxygenated blood and sends it to the right ventricle

Musculi pectinati function

Atrial wall ridges that enhance contraction efficiency

Tricuspid valve function

Prevents backflow from right ventricle to right atrium during systole

Right ventricular myocardium function

Contracts to move deoxygenated blood to lungs via the pulmonary artery

Trabeculae carneae function

Ventricular ridges that reduce suction and aid electrical conduction distribution

Left atrium function

Receives oxygenated blood and sends it to the left ventricle

Mitral valve function

Prevents backflow from left ventricle to left atrium

Chordae tendineae function

Prevent atrioventricular valve prolapse during ventricular contraction

Papillary muscles function

Stabilize atrioventricular valve leaflets during systole

Left ventricular myocardium function

Thick muscular wall that generates high-pressure output to the systemic circuit

Neonatal circulatory changes

Ductus arteriosus → ligamentum arteriosum; foramen ovale → fossa ovalis; ductus venosus → ligamentum venosum; umbilical vein → round ligament; umbilical arteries → medial umbilical ligaments

Osmoconformers vs osmoregulators

Osmoconformers match internal fluids to environment (e.g., jellyfish, hagfish); osmoregulators maintain constant internal conditions (e.g., humans, birds, crocodiles)

Non-renal water or salt regulation methods in amniotes

Keratinized skin limits water loss; mammals use sweat glands; birds use nasal salt glands; crocodiles use lingual salt glands

Urinary system overall function

Removes wastes and regulates water and electrolytes and acid-base balance and produces urine

Kidney function

Filters blood and regulates water and electrolytes and produces hormones

Ureter function

Transports urine from kidney to bladder

Urinary bladder function

Stores urine until voluntary micturition

Urethra function

Conducts urine from bladder to exterior

Embryonic urinary system development through urogenital ridge

Urogenital ridge has medial genital ridge forming gonads and lateral nephric ridge forming kidneys and ducts; primordial germ cells migrate into gonads

Pronephros summary

Earliest simplest kidney from anterior nephric ridge seen in larval hagfish

Mesonephros summary

Middle nephric ridge kidney with tubule specialization and early divergence of excretory and reproductive roles found in teleosts and amphibians and embryonic amniotes

Metanephros summary

Posterior nephric ridge definitive kidney of reptiles birds and mammals including humans

Nephron overall function

Functional unit that filters blood and forms urine through sequential tubular processing

5 Parts of the Nephron

1. Renal Corpuscle
2. Proximal Convoluted Tubule
3. Loop of Henle
4. Distal Convoluted Tubule
5. Collecting Duct

Glomerular membrane role

Size-selective filtration allowing small solutes below roughly 40 kilodaltons into filtrate

Proximal convoluted tubule role

Reabsorbs glucose and amino acids and most salts and most water and secretes hydrogen and ammonium and creatinine and drug metabolites

Loop of Henle role

Descending limb reabsorbs water and ascending limb reabsorbs sodium and chloride and potassium creating countercurrent multiplication

Distal convoluted tubule role

Fine Fine-tunes salt balance via active transport and secretes hydrogen and potassium and other ions

Collecting duct role

Regulates final water reabsorption and delivers urine to ureter

Urine concentrating ability by group

Mammals concentrate up to about 25× plasma with long loops of Henle; birds about 2-4× with shorter loops; fish amphibians reptiles near 1:1 with minimal loops

Evolution of the urinary bladder

Urine storage reduces predator detection; in many non-mammals bladder reabsorbs water; birds lack a bladder to reduce flight weight

Ueogenital system (reproductive system and urinary system) embryology link

Urinary and reproductive systems co-develop from intermediate mesoderm and initially share ducts such as the mesonephric duct before diverging into separate pathways

Intromittent organs across vertebrates

Sharks and rays have paired claspers; amphibians generally lack intromittent organs; turtles/crocodiles single penis; most birds cloacal kiss though waterfowl/ratites have phallus; mammals single penis with urethra; snakes paired hemipenes

Bird fertilization modes

Most species use a cloacal kiss to transfer semen; some such as ducks geese ostrich and emu use an eversible phallus for insemination

Mesorchium/Mesovarium Function

Mesorchium suspoends testis, mesovarium suspends ovaries

Mesoductus/Mesonephric fold

Vas defrens/oviduct

Broad ligament is made up of:

mesovarium + mesosalpinx + mesometrium

Gubernaculum function

guides testis descent in males and forms ovarian and round ligaments in females