PRE-LAB
Student Name: Charlotte Powley

Date: 20^th January 2023

In this lab you will have to find and identify the structures from the following systems in a mouse.
Write a brief description of the structure and the function that it has.

Digestive System
Liver	4 lobes- right, left, caudate, quadrate, liver is in contact with the diaphragm but the rest is covered by visceral peritoneum. The left and right love are divided by the falciform ligament connecting it to the abdominal wall. Function is to process blood and create nutrients from the break down of food to convert into energy
Stomach	J shaped organ which has 5 distinct sections: the cardia (top part), fundus (rounded section), body/ corpus (largest section), antrum (below the body), pylorus (bottom part). Several layers of muscle and tissues make up the rest of the stomach for example mucosa. Function is to store food but not permanently, mix food and break it down using enzymes that are also produced by the stomach itself.
Intestines	Long tube which leads from the stomach to the anus. The main components include the small intestine, large intestine and the rectum. The small intestine is made up of the duodenum, jejunum and ileum. The large intestine is made up of the caecum, colon and the rectum which leads onto the anus. Main purpose of the intestines is to digest food whilst also absorbing the nutrients. Water can be extracted from the food as well as the movement of food.
Colon	Entry point is the cecum and then the colon is divided into segments known as the ascending colon, transverse colon, descending and the sigmoid colon going in order food moves along. The colon is able to remove water and some nutrients from the digested food- wastage is then transported through the colon where it can be stored in the rectum until it can leave the system.
Esophagus	Main function is to carry food and liquid to the stomach after being consumed in the mouth. Therefore it is muscular and hollow and has two sphincters controlling the opening and closing.
Pancreas	Elongated organ which is behind the stomach. 95% is made up of exocrine tissue producing enzymes. The rest of the tissue is made up of the islets of Langerhans which is where blood sugar is regulated with the production of insulin.
Cecum	Function is to absorb fluids and salts after digestion in order to create mucus. Internal wall made up of thick mucous membrane which absorbs. There is also a lining of deep muscle.
Circulatory System
Diaphragm	Three muscular parts which are the sternal, costal and lumbar which all insert into central tendon. Its shape is dome where one side is slightly higher than the other Contracts and flattens chest cavity increases in size which creates a vacuum pulling air towards lungs
Heart	4 chambers- left and right ventricle, left and right atrium- left ventricle more muscular as it needs to contract harder to pump oxygenated blood around the body. There is the aorta which carries blood away from heart and vena cava which carries blood from the rest of the body back to the heart so it can be oxygenated.
Lungs	Function of the lungs is to diffuse oxygen into the capillaries surrounding the alveoli so the exchange of gases can take place. There are two lungs and within each one there are bronchi which branch off into smaller branches called bronchioles.
Trachea	Made up of 16 to 20 cartilage rings which are flexible so is a type of connective tissue- each lined with mucosa which is a moist tissue Function is to carry air in to lungs and then out again.
General Terminology
Anterior	Before or towards more to the front
Posterior	Position is further back so nearer to behind
Ventral	Lower surface such as abdominal and is located near the anterior
Dorsal	Back section of body or upper side

TICKET OUT THE DOOR Student Name: Charlotte Powley

- We identified the lungs, trachea, diaphragm, bronchi from respiratory system.

- From the digestive system we could see the liver, esophagus, stomach, small and large intestine, rectum, spleen and cecum.

- The circulatory system was harder to see and identify the vasculature so only the heart was really identifiable during this lab.

- From the excretory and reproductive system only kidneys could be identified. No reproductive organs were found.

Questions for OneNote

What is the purpose of the lab?

The purpose was to carry out a dissection in order to identify the gross anatomy of a mouse such as looking at the different organs and thinking how their structure would relate to their function.

What is the largest organ in the mouse’s anatomy? Why?

Intestine including the large and small as well as a the cecum leading to the colon. This is so when the mouse ingests food, nutrients can be absorbed as it is digested as well as any water can be extracted.

Why is the gallbladder absent in rats – but present in mice?

There is a continuous supply of bile being produced in the rats which will have a larger liver due to their larger size. However, mice are smaller and therefore have a smaller liver so need a higher production of bile produced. In rats the concentration of bile in the liver is a lot higher than those in mice. It could also be due to their diet so rats may have a less fatty diet so don’t need to break down as many lipids.

Describe the way in which blood travels in the mammalian circulatory system.

It is a closed, double system. The heart is separated into the left and right ventricles and atriums. Oxygenated blood, from the lungs, goes to the left ventricle where it is then forced with pressure to the aorta to the systemic circulatory system (takes blood to tissues). Deoxygenated blood returns to the right atrium through the vena cava and is pumped to the pulmonary artery. The right side of the heart pumps deoxygenated blood back to the lungs in order for it to become oxygenated through gas exchange in the respiratory system.

Describe three adaptive advantages of the mammalian anatomy.- no eggs so offspring are birthed directly allowing them to develop properly and be safer. Most mammals such as mice have fur which can protect them from more harsher environments so increases likelihood of survival. Four legs giving them speed and stability

Describe 3 ways in which the organs of the circulatory system and respiratory system are protected. Protected by ribcage and also helps with motility and breathing due to its shape skin provides physical and immune protection and also prevents against water loss by being a barrier muscles- protect the bones and internal organs by surrounding each one as well as absorbing shock and reduce the friction on joints making it easier for movement.
Draw a neatly labeled diagram of your dissected mouse’s internal organs.

Include the respiratory, circulatory and digestive system (do not include the urogenital system).

The organs you are to include are the ones written on the ticket out the door.

Dissection lab This page is part of the collection 'Animal anatomy and histology'.

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