Lab 9: external anatomy and digestive system of fetal pig

Define these external anatomy terms:

Anterior

Posterior

Dorsal

Ventral

Medial

Lateral

Proximal

Distal

Caudal region

Cranial region

Pectoral region

Pelvic region

Anterior: front end of the pig

Posterior: back end of the pig

Dorsal: back part

Ventral: surface of the body

Medial: the midline of the body

Lateral: side of the body away from the middle

Proximal: near the center or trunk of the body, also refers to the point of origin of a part.

Distal: away from or farthest from the trunk or the point or origin of a part

Caudal region: posteriormost region from the cranial region, also referred to as the inferior or "tail" end

Cranial region: head end of the body, also referred to as the superior end

Pectoral region: anterior to the chest, breast, thorax and contains the chest muscles

Pelvic region: lower part of the torso between the abdomen and legs, contains the reproductive organs

Auricles

external portion of the ear, ear flaps

Nictitating membrane

(third eyelid) is a transparent membrane present in some animals and is used for protection and to moisten the eye while also permitting some visibility.

Tongue

surface of the tongue has Papillae - tiny projections which have the taste buds

umbilical cord function

job is to transfer nutrients and Oxygen to the fetus, and transfer Carbon Dioxide and wastes back to the mother's placenta

umbilical cord location

located on the ventral side of the animal in the abdominal region.

It contains four tubelike structures:

- allantoic stalk (1) which extends from the urinary bladder

- umbilical arteries (2) These vessels are round and contain thick walls

- umbilical vein (1). This vessel is flat and has thin walls.

mammary papillae

nipples

found in pairs in the abdominal region between the umbilicus and the urogenital opening

Male pig vs. Female pig ?

Male pigs will have their urogenital opening (or orifice) caudal to the umbilical cord, that leads to its penis housed just inside. Males will also have a scrotum sac visible as a bulge through the skin ventral to the anus. The scrotum sac protects the male reproductive glands called testes. Males do not have genital papilla.

Female pigs have their urogenital opening located ventral to the anus, also called the vagina. Females will also have genital papilla present near the urogenital opening.

Both males and females have rows of nipples (teats) and the umbilical cord will be present in both

Umbilical arteries?

These (two) arteries transport deoxygenated blood and gaseous wastes to the mother's placenta, where the blood is cleaned and replenished through diffusion.

Round vessel with thick walls

Umbilical vein

The umbilical vein transports oxygenated blood and nutrients from the mother's placenta back to the fetal pig.

flat vessels with thin walls

Allantoic duct

The Allantoic duct is an extension of the tissue that makes up the pig's bladder. It contains Nitrogenous wastes of the fetal pig.

diaphragm

divides the body cavity into the thoracic cavity and the abdominal cavity.

The two divisions of the thoracic cavity?

split into two divisions: the pleural cavity (which contains the lungs) and the pericardial cavity (which contains the heart).

What does the abdominal cavity contain?

stomach, pancreas, spleen, liver, gallbladder, and intestine.

Where is the thorax located?

is located at the anterior end of the trunk

thoracic cavity is surrounded by the rib cage and has the diaphragm on its posterior side

Where is the abdomen located?

is located at the posterior end of the trunk

abdominal cavity has the diaphragm located anterior to it

Epitrichium

the outer layer of the epidermis of the fetus of many mammals. Beneath this layer, hair develops

Where does digestion begin ?

the mouth

Esophagus

A muscular tube that connects the mouth to the stomach.

utilizes muscular contractions called peristalsis, to move food into the median side of the stomach.

runs dorsally to the trachea

Stomach function?

a large sac-like organ located posteriorly and to the left of the liver.

uses enzymes and hydrochloric acid to digest food. Inside the stomach is meconium, which is made of bile, mucous, and shed digestive lining

What are the structures of the stomach ?

Greater Curvature- the left, lateral and inferior part of the stomach

Lesser Curvature- the right, medial part of the stomach

Cardiac sphincter - is a band of smooth muscle which regulates the passage of food from the esophagus to the stomach.

Pyloric sphincter -is a band of smooth muscle which regulates the passage of food from the stomach to the duodenum

Gastric rugae - are the longitudinal folds observed in the mucosa layer of the stomach.

What are the layers in the stomach?

Inside to out

- muscosa

- submucosa

- muscle layers

- serosa

peristalsis

muscular contractions to move food into the stomach.

cardiac valve

prevents acids from rising into the esophagus.

The start of the small intestine

duodenum

Parts of the small intestine?

Duodenum, Jejunum and Ileum

Duodenum - function & the ducts that enter it?

The duodenum is the first section of the small intestine and is involved in making digestive enzymes necessary to break down food.

In addition to the enzymes that it synthesizes, it also receives secretions from the gall bladder and pancreas through ducts

The common bile duct

- hepatic duct from the liver

- cystic duct from the gall bladder

The pancreatic duct

- from the pancreas

jejunum-ileum function?

long and highly convoluted and have an inner surface consisting of villi and microvilli, designed to increase the surface area so that more nutrients get absorbed.

Messentary

holds intestines together

visceral peritoneum that suspends both the jejunum and ileum from the abdominal wall and it is designed to hold the intestine in a coiled manner

gall bladder?

a small thin-walled sac located on the posterior portion of the liver (median lobe). It stores and concentrates bile produced by the liver.

Bile contains bile salts that help promote the breakdown of fats along with lipase

Spleen

a flap like organ located posteriorly to the stomach on the left side of the abdominal cavity. It is involved in RBC destruction and filtering blood- removing microbes (part of the lymphatic system)

Liver

a large brown organ located posteriorly to the diaphragm. It is involved in filtering harmful substances from the blood, producing bile...

Pancreas

an organ that is glandular in appearance and is located on the loop of the duodenum. It produces hormones (insulin and glucagon)

Large intestine

aka colon

located posteriorly to the spleen on the left side of the abdominal cavity. Similar to the small intestine it is kept in a folded manner by mesenteries

begins with cecum and ends with rectum

- The cecum is the beginning part of the large intestine. It consists of a blind pouch that receives waste material from the illeum of the small intestine and passes it to the colon. It plays a role in increasing the amount of time for food digestion and absorption

- The rectum is the last portion of the colon. It functions in storing solid waste until it exits the body via the anus

Peritoneum and its other layers?

a layer made up of simple squamous epithelia, which forms the lining of the abdominal cavity

The outer layer- parietal peritoneum, lines the internal body wall- the abdominal wall and pelvic cavity

The inner layer- visceral peritoneum, covers the internal organs that are in the intraperitoneal cavity.

What is the pharynx?

structure found in the neck and throat region that is shared between the respiratory and the digestive system. It is situated posterior to the mouth and nasal chamber, and superior, to the esophagus, larynx, and trachea. It has 4 openings.

What are the openings into the pharynx?

Digestive System:

> Mouth- is the anterior opening

> Esophagus- is the posterior opening

Respiratory System:

>Nasal Chamber- is the anterior opening

>Glottis - is the posterior opening into the larynx

Thyroid gland

has a dark red color and is half pea sized.

It is located between the two lobes of the thymus gland, and is ventral to the trachea and posterior to the larynx.

The thyroid is involved in producing thyroid hormones which play a role in regulating the rate of metabolism

Thymus gland

There are two large masses of glandular tissue located on the sides of the trachea.

There is also another glandular mass in the thoracic cavity anterior to the heart.

This gland plays a role in immunity.

Glottis

Posterior opening of the pharynx and is the passageway for the larynx

Larynx (voice box)

the respiratory passageway located immediately posterior to the pharynx. Its opening is the Glottis.

Air passes through the larynx, past an opening called the glottis, and into the trachea.

Trachea

respiratory tube reinforced with cartilage (Cs to maintain it open) located posteriorly to the larynx

sternum

flat bone to which ribs attached.

Serosa

the outermost layer of the GI tract. It consists of a layer of simple squamous epithelium. The serosa comprises the visceral peritoneum of the intestine.

The esophagus and pyloric sphincter perform similar roles in their respective locations within the digestive system. What are their differences?

The esophagus is a tube which carries the food from the mouth to the stomach. Muscle contractions push the food toward the stomach. Swallowing is the first of these contractions. The pyloric sphincter serves as a kind of gateway between the stomach and the small intestine. It allows the contents of the stomach to pass into the small intestine. It also prevents partially digested food and digestive juices from reentering the stomach.

Microscopy of the Jejunum-ileum

Lumen - refers to the central cavity of the gut

Villi are finger-like projections that protrude from the wall of the small intestine into the lumen

Mucosa innermost layer of the GI tract- consists of an epithelium layer(columnar epithelium), which function in absorption and secretion.

Microvilli - are microscopic hair-like projections. These hair like structures consist of foldings of the cell membrane of the mucosa epithelial cells

Lymph nodules consist of groups of lymphocytes located in the submucosa

What are the two smooth muscles of the Jejunum-ileum

There are two smooth muscle layers, consisting of circular and longitudinal muscles:

An inner layer of thick circular muscle is located between the submucosa layer and the layer of longitudinal muscle

An outer layer of longitudinal muscle (thinner)

Epiglottis

a flap of cartilage that covers the windpipe while swallowing

glottis

Opening between vocal cords

Bronchi

Two short branches located at the lower end of the trachea that carry air into the lungs.

Lungs

Two spongy organs, located in the thoracic cavity enclosed by the diaphragm and rib cage, are responsible for respiration

Bronchioles

Airways in the lungs that lead from the bronchi to the alveoli.

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood