Frog Systems – Class Amphibia
1. Be able to trace these from start to finish from memory
2. read lab manual on vertebrate evolution
3. read section on phylogeny and be able to produce tree of 13-1 from memory
4. Read classification schema as well
 

I. External Anatomy of Frog
1.  Rana pipens is Genus species name
2. More than half the respiration goes through the frog’s skin
3. Thus, skin must be moist (remember, oxygen must dissolve into water (or some fluid) before it can go to circ. systems)
4. Specialized glands to help keep it moist
5. Dorsal side dark and ventral side light (to evade predators from above and below)
6. Segmented body into: head & trunk
7. Eyes
8. Nostrils
9. Tympanic membranes – spans a canal for hearing. The membrane vibrates. First time we see hearing (acoustic) as a sense function
10.  Paired appendages: one set anterior (arms) and one set posterior (legs)

Internal Anatomy
II. Skeletal System of Frog
1. Skeleton is internal framework
2. Two divisions of a skeleton system (not just in frogs)
a. Axial – runs in one straight line from the skull downward
b. Appendicular – runs away from the axial
3. Axial – contains the skull and vertebra
4. Appendicular – includes all the bones that make up the limbs (both fore and hind) and the two structures that attach the limbs to the axial skeleton.
a. Pectoral Girdle – attaches the forelimbs to the axial skeleton
b. Pelvic Girdle – attaches the hind-limbs to the axial skeleton
5. 9 vertebrae plus 1 urostyle makes up the frogs vertebral column
6. A specialized vertebrae articulates (articulates means a place where of two bones connect) the skull to the column.  It is called an “atlas”.  To remember this think of the Greek God who held up the world.
7. No ribs coming off the vertebra as we see in mammals
8. Urostyle – part of the pelvic girdle and probably a fusion of vertebra
9. The Pectoral Girdles articulates the forelimbs to the vertebral column (VC) and has two sides.
a. dorsal – scapulas and suprascapulas
b. ventral – clavicles (i.e., collarbones)
10. The Pelvic Girdle articulates the hindlimbs to the VC.
11. Pelvis consists of three bones (usually same for mammals as well)
a. pubis
b. ischium
c. ilium
12. ischium and ilium are fused together
 

III. Muscular System of Frog
1. muscles of the frog used in all types of movements (from movement of frog to movement of food down the digestive tract)
2. three types of muscles here
a. skeletal (aka, striated) – moves the endoskeleton, under voluntary control
b. smooth – usually found in viscera (i.e., the inside muscles of the major systems) and under involuntary control
c. heart (cardiac) – specialized involuntary muscles type only found in heart
 

IV. Digestive System of Frog
1. Mouth is opening to DS
2. Buccal Cavity is a cavity found after the mouth
3. Two openings to Pharynx
a. Esophagus – opening to the digestive system
b. Glottis – opening to respiratory system (also contains larynx, or voice box)
4. Esophagus goes directly to the stomach
5.  The stomach has two valves that prevents all the food from rushing through it
a. cardiac valve – where the esophagus meets the stomach
b. pyloric valve – where the end of the stomach meets the duodenum
6. The Bile duct shoots off the posterior end of the stomach (before the pyloric valve) and is a passageway that goes to the gall bladder.
7. The liver does a number of things (mainly detoxify foods) but also produces a substance known as bile.  Bile acts to emulsify fats, that is, wraps the fats produced from digestion into a coating.  The liver makes this bile and then holds it in the gall bladder until it’s needed during digestion.
8. Another gland secretes materials into the bile duct and hence into the stomach. It’s called the pancreas.
9.  After the stomach is the small intestines
10. Small intestines has two divisions, in order:
a. duodenum
b. ilium
11. After the small intestines comes the Large Intestines
12. Large intestines main function is for re-absorption of water from the food products moving through the digestive system – that’s why it’s so long.
13. LI then turns into the rectum and the cloaca
14. Mesenteries (pronounced “mez-in-tare-ezes” – are clear tissues that hold the parts of the stomach together and keeps them from folding in and over its self and getting tangles up into a knot.
15. Other systems (excretory and reproductive) have ductwork that opens into the cloaca
 

V. Reproductive System of the Frog
1. Underneath the huge liver are the lungs
2. The larynx (which comes off the glottis from the mouth) divides into two branches called bronchi
3. Each bronchus leads into a lung
4. The bronchi further branches down into smaller structures such as the bronchioles and the alveoli, which are commonly know as the air sacs.
 

VI. Circulatory System of the Frog
1. function of the CS is to provide an efficient means of distribution for exchange of products (wastes, oxygen, nitrogen, etc)
2. Closed network of vessels with a pump to keep fluid in motion.
3. Arteries – carry fluid away from heart (most terms for this function will look similar to this word. I.e., Aorta is major artery)
4. Veins - carry fluid towards the heart (most terms for this function will look similar to this word. I.e., Vena Cava is major vein)
5. Arteries and veins meet in a area known as capillaries (aka, a capillary bed)
6. Diffusion of cellular products from the CS are exchanges in the cap beds since the walls of the arteries and veins are too thick
7. Heart has 3 main divisions.
a. Right Atrium
b. Left Atrium
c. Ventricle
8. Note the number of divisions of heart is dependent on the Class you look at.  For example, mammals have 4 divisions of the heart.

VII. Lymphatic System of the Frog
1. Cellular products of the circulatory system diffuse through the walls of the capillaries.
2. However, these products can sometimes collect into the capillary beds causing swelling (called edema) or low blood pressure.
3. The lymphatic system is a system of ducts that function to drain these cap beds of products
4. This system then returns the products to the veins of the circulatory system.
5. The lymphatic system contains its own type of moving fluid called lymph
6. Think: “lymph is to the lymphatic system as blood is to the circulatory system)
7. Two pairs of lymph hearts control movement of the lymph.
a. one pair by the 3rd vertebra – pumps lymph into jugular vein
b. second pair at end of VC – pumps lymph into iliac vein in the legs

VIII. Excretory System of the Frog
1. The kidneys are the main units of the excretory system
2. Kidneys lie dorsal to the coelomic cavity
3. They filter nitrogenous waste from the blood and maintain water/osmotic balance of the body
4. The two kidneys lie on either side of the dorsal aorta. It serves as a cap bed and as such has its own arteries and veins from the aorta.  Known as renal arteries to the kidneys and renal veins away from the kidneys
5. Urine is a product made in thew kidneys and consists of nitrogenous wastes among other things
6. The ureter is a thin walled tube that runs posteriorly off the kidneys and into the cloaca
7. After urine is released into the cloaca it is held temporarily in a bladder
8. The bladder further re-absorbs water from the urine
9. Urine is then released again into the cloaca after concentration in the bladder back into the cloaca for release into the environment
10. Fat Bodies – attached to the anterior portion of the kidneys and are used as a food source during winter
11. A ventral gland next to the kidney are the adrenal glands
12. These adrenals don’t function in excretory but rather in the endocrine system and synthesize hormones such as epinephrine, norepinephrine, and corticosterone.
 

IX. Reproductive System of the Frog
Male
1. Testes are small structures ventral to the kidney and connect to the ureter by small ducts
2. These ducts carry the sperm made into the testes
3. Sperm is released with urine from the cloaca
4. Another name for the ureter is the mesonephric duct
5. Notice that in the male the reproductive and the excretory system share the same tubules
Female
1. The female has ovaries and own passageway into the cloaca called the oviduct
2. The ovaries are attached to the body wall and not the kidneys as are the testes are
3. The anterior end of the oviduct is an opening called an ostium
4. The oviduct runs posteriorly and becomes the uterus before attachment to the cloaca
5. The ovaries produces eggs into the coelomic fluid and these eggs are pulled into the ostium and down the oviduct to the uterus where they are stored for release in external fertilization
6. Notice then that unlike the males, the female system uses its own duct work to empty its gametes into the environment

X. Nervous System of the Frog
1. Read through his information in the text, but no dissection info over this on the test
2. It is a fascinating read