Rat Anatomy

• Phylum Chordata
• bilateral symmetry
• divided longitudinally: head, trunk, tail
• homotherms: org that maintains body temp at constant lvl above environment
• Males = big visible scrotum
• Females = many nipples

where all major sense organs including brain, mouth, and associated structures are

main body of animal that terminates in region of anus or cloaca (posterior opening in birds, reptiles, amphibians)

• propulsion (eg fish, whales, crocs)
• balance
• thermoregulation and display

• 1) pharyngeal gill
• 2) notocord
• 3) single hollow, dorsal nerve cord
• 4) post anal tail

notocord absent in adults usually

• longs hairs on snout
• tactile in function
• sensitive to touch

• fleshy lips
• cheeks => cheek pouches can carry food or nesting stuff

• hardened enamel only at front
• soft dentine on backside that erodes--> self sharpening

formed by the hard palate anteriorly and boneless soft palate posteriorly

• iris pink because albinos lack pigments that color eye
• un-pigmented eye is pink b/c of presence and color of blood

flap surrounding canal

• trunk region of vertebrates constructed like double tubular system
• "inner" tube = digestive tract
• "outer" tube is body wall of organism

• divides coelom into thoracic and abdominal cavities
• contracts (- pressure/ exhale) and relaxes (+ pressure/ inhale)

• contains heart and lungs
• protected by rib cage

contains most of digestive tract and excretory system

• narrow line of white connective tissue (mid-ventral)
• extends from sternum to pelvis
• muscles attached help compress abdomen

• Parotids
• Submaxillaries

• large
• located medially on ventral surface
• two covering trachea

• not well defined
• on side of submaxillaries

• moves salivary enzymes from parotid gland to mouth
• extends from parotid gland into mouth, lying on top of jaw muscle
• visble white duct
• Watch out for white facial nerve doral of it -> will not lead to paratoid gland

can be traced by finding white parotid duct

• four small yellow-whitish spheres
• located anterior to submaxillaries
• filter lymph fluid
• part of immune system

• tear glands
• found on side of neck, anterior to parotids
• large and darkened
• connect to eye by lacrymal duct

connects Lacrymal gland to eye --> Tears

• visible white strand connected to facial muscles
• resembles parotid duct but more dorsal

Jaw muscle

• major muscle of respiration
• flap of muscle
• seperates thoracic and abdominal cavities
• contracts (inhale)/ relaxes (exhale)

Air- > Larynx -> Trachea (from laryngopharynx)---splits into two---> Bronchi --divides--> Alveoli (tiny sacs)

attaches part of liver and diaphragm to abdominal wall

• includes heart and lungs
• right atrium = dark lobe extending out
• thymus = pink mass of tissue anterior (above) heart

• lumph organ that decreases in size with age
• white/pinkish, fat-like mass anterior of heart
• makes T-cells

• where air enters
• contains vocal cords
• connects to trachea (anterior of it) from laryngopharynx
• food prevented from entering by epiglottis

• part of throat that connects inner nose to throat
• at back of mouth
• Anterior to larynx (right above it)
• 3 parts: oro/naso/laryngopharynx

mouth section

nasal section

• Throat section
• where vocal cords are
• substances passing thru go to either esophgagus or larynx

prevents food from entering larynx

present on walls of trachea -> prevents collapse

• conducts air into lungs
• pink, small, and sponge-like
• ventral/ anterior to esophagus (in front of it)

• important gland in endocrine system
• surrounds cephalic end of trachea

think outer membrane that surrounds heart

will appear small and dark in their collapsed state

make up most of heart mass

• visible anterior to heart (on top part)
• carotid arteries connected to it
• pumps out oxygenated blood

• smaller arteries branching off aorta
• carries oxygenated blood

carry deoxygenated from liver and anterior/lateral regions of body to heart

lead away from heart

Veins (deoxy blood ) -> Heart ->Vena Cava -> Right Atrium -> Tricuspid (one wave valve) -> Right Ventricle -> Semilunar valve -> Pulmonary Arteries (deoxy blood) -> Lungs

oxy blood (from Lungs) -> pulmonary veins -> Left Atrium -> biscuspid valve -> Left Ventricle ->Semilunar valve -> Aorta -> rest of Body

carries deoxygenated blood from right ventricle to lungs

carries deoxygenated blood from lung to left atrium

the tricuspid and bicuspid

measures blood pressure

• Normal = 120/80
• external pressure greater/equal to internal pressure of brachial artery = no blood flow
• measuring pressure of brachial artery!!

• sound heard due to force generated by contraction of left ventricle
• "Lub-Dub" heart as pressure on brachial artery is released and the walls expand letting blood flow

• Force generated due to the elastic walls of the brachial arteries
• when sound disappears b/c blood flow is flowing smoothly

• Lub = atrio-ventricular valves (bicuspid and tricuspid)
• Dub = semi-lunar valves closing

• pick up interstitial fluid
• return fluid to circulatory system

• big part of lymph system
• located dorsal to stomach -> bright red (same color as liver)
• blood filtered and acted upon by lymphocytes and phagocytes w/in spleen
• storage and destruction of red blood cells

Mouth-> Pharynx (throat) -> Esophagus -> Stomach -> Small Intestines (Duodenum -> Jujunum -> ileum) -> Caecum -> Colon (large intestine) -> Rectum -> Anus

• move food in mouth to stomach
• no role in digestion
• collapsed when not in use
• dorsal/posterior to trachea (right behind it)

blood vessels pass to and from organs via mesenteries

• Store food
• secretes hydrochloric acid (HCl) -> optimal for enzymes
• posterior end contains pyloric sphincter

reulates emptying of acidic chyme from stomach to small intestine

semifluid mass of partially digested food

• three regions: deodenum, jujunum, ileum
• secretes from liver and pancreas enter deodenum to aid in digestion

• irregular, pinkish/grayish gland on mesentery below stomach (looks like chewed up bubble gum)
• near first loop of stomach
• pancreatic juices contain digestive enzymes
• ->digestive enzymes that break down proteins, carbs, fats
• ->bicarbonate ions that neutralize acidic chyme
• also for endocrine system: makes hormones insulin, glucagon, etc

• absorb water
• materials not absorbed = feces
• makes ONE single loop and ends in rectum -> anus

• beginning of large intestine
• has special bacteria for herbovores to break down complex carbs like cellulose

on dorsal wall of abdominal cavity

Blood -> Kidney-> Renal Artery -> Renal Vein

some blood enter nephrons

• funcitonal unit of kidney
• forms urine, regulates ionic balance, etc

• where urine exits in kidney
• Tugging it will move both bladder and kidney

Urine -> ureter -> Urinary Bladder -> Urethra

outer section containing larger number of renal corpuscles

• inner part composed of collecting tubules
• tubles empty into ureter

• Males: urethra extends distally into penis -> common urogenital tract
• Females: seperate

• Y-shaped structure against dorsal wall of abdominal cavity
• ovaries at end of each uterine horn -> highly vascularized with bumps

• coiled white structure immediately adjecent to ovaries
• conducts egg from ovary to uterus

occurs in oviduct/ fallopian tubes

occurs in uterus

located in scrotum - pocket of skin

where sperm is produced

Seminiferous Tubules -> Epididymis (caput -> caudal) -> Vas Deferens -> Ejaculatory Duct -> Uretra -> Penis

small cartilaginous piece in lower part of sternum

Skull -> Cervical Vertebrae (neck) -> Thoracic Vertebrae (ribcage area)-> Lumbar Vertebrae (bottom rib to pelvis)-> illium (pelvis bone) -> Sacrum (pelvis to butt) -> caudal vertebrae (tail)