Cat Dissection Lab Report

May 26, 2016

Tiffany Zheng, Michelle Wang, Partha Shah

A&P

Cat Dissection Lab Report

System Overviews:

Muscular System (author):

The biceps brachii and the triceps brachii are the two main muscles of the forearm and the fascia is the white tissue that covers all muscles. The biceps brachii are on the other side of the foream, and lie underneath the cat’s shoulder muscle, the clavobrachialis. There are four main muscles of the chest visible in the cat: Pectoantebrachialis (this muscle forms almost a straight line across the top of the chest), Pectoralis major (forms a triangle just under the pectoantebrachialis), Pectoralis minor (a secondary triangle just below the pectoralis major), and the Xiphihumeralis (extends from the armpit of the cat to the center of the chest where the xiphoid process of the sternum rests). The muscle system is used to enable mobility in animals.

Digestive System (author):

The first portion of the small intestine is called the duodenum, which receives secretions from the liver and pancreas.  The last portion of the small intestine is called the ileum, which empties into the large intestine through the ileocecal valve.  The large intestine is also divided into four regions: the colon, cecum, rectum and anal canal.  The first portion of the colon is the ascending colon. The spleen is considered part of the lymphatic system where it participates in producing lymphocytes, filtering blood and destroying old red blood cells.

Cardiovascular (author):

A cat's cardiovascular system (or circulatory system) is the system responsible for circulating blood throughout the body. It consists of the heart and blood vessels, namely arteries, veins and capillaries. The heart is located in the chest between the right and left lungs and is contained in a very thin sac called the pericardial sac. Blood vessels leave the heart and form a conduit system throughout the body that carries blood to all organs, tissues and cells. The right atrium is the collecting chamber for blood from distant parts of the body. Blood is carried back to this upper right chamber of the heart in various veins. The right ventricle is the pumping chamber of the lower right heart. Blood that is high in oxygen returns to the heart from the lungs and enters the upper left chamber of the heart, the left atrium.

Endocrine (author):

A cat's endocrine system is composed of several different types of glands and organs that produce the hormones of the body. There are two adrenal glands located in the abdominal cavity directly in front of the kidneys. The pancreas is located in the forward part of the abdominal cavity, behind the liver and stomach. The endocrine glands produce hormones, and secrete them directly into the internal environment where they are transmitted via the bloodstream. Hormones produce certain effects at different points in the body. Some endocrine glands are directly under the control of the pituitary gland. For example, the adrenal gland is controlled by the pituitary hormone, adrenocorticotropic hormone (ACTH). ACTH causes the adrenal glands to produce cortisone (cortisol), which is also a hormone.

Respiratory (author):

The respiratory system is basically composed of the nares (nostrils), nasal cavity, sinuses within the skull, pharynx (back of the mouth), larynx (voice box), trachea (windpipe), bronchi (the branches of the trachea going into the lungs), and the lungs. The cat's respiratory system serves two purposes. First, it is the exchange mechanism by which the body's carbon dioxide is replaced with oxygen. It is also a unique cooling system. The diaphragm muscle separates the chest, containing the heart and lungs, from the abdomen which holds the intestines, stomach, liver, bladder, etc. The trachea carries the air to the bronchi, which in turn supply the lungs.

Reproductive (author):

The female genital tract consists of the vulva, vagina, cervix, uterus, oviducts, and ovaries, as well as the mammary glands found on the chest and abdomen. Ovaries are female gonads that produce eggs and female sexual hormones, including estrogen and progesterone. Estrogen is necessary for the development of eggs, and progesterone prepares the uterus for pregnancy. The oviducts are small tubes that connect the ovaries to the uterus. The end of the uterus is called the cervix. It separates the uterus from the vagina and provides a barrier against infection. The vagina, a muscular tube that extends from the cervix to the outside, is connected to the vulva, which is the external opening of the female genitals.

Dissection Checklist:

Pectoralis major	Near the chest Gives movement to shoulder
Pectoralis minor	Between the chest and armpit Depresses the shoulder
xiphihumeralis	Muscle that extends to xiphoid cartilage Move humerus bone
Rectus Abdominis	Two parallel muscles in the abdominal region Flexing the spine
Clavotrapezius	Anterior trapezius muscle Clavicle dorsally goes toward the head
acromiotrapezius	Middle trapezius muscle Scapula to dorsal together
spinotrapezius	Posterior trapezius muscle Scapula to dorsal
clavobrachialis
acromiodeltoid
Latissimus Dorsi	Dorsal vertebrae Moves back
Splenius	Two muscles attached to vertebrae Moves neck
Supraspinatus
Infraspinatus
Triceps brachii
Tensor Fasciae Latae
Gluteus medius
Biceps Femoris
semitendinosus
Sartorius
Gracilis
Thyroid gland
Thymus
pancreas
Aortic arch
Right and left common carotid arteries
Renal arteries
Inferior vena cava
Renal veins
External nares
larynx
Spleen
diaphragm
Esophagus
liver
Gallbladder
stomach
pancreas
duodenum
Large intestine
Ascending colon
Transverse colon
Descending colon
rectum
Urinary Bladder
uterus
Testes
Ovaries
Uterine Tubes
Vena cava
Rectum
urethra
Left uterer
ileum
cecum
Ascending aorta
Submandibular gland
brachialis
Sartorius
peritoneum
adductors

Reflexes Lab Analysis

1. Give a recap of what you did in this lab. Relate what you learned about neurons and reflexes in lecture to the applications in this lab. For example, what is a reflex, and how does it work?

In this lab, we tested different reflexes including the photopupillary reflex, knee jerk reflex, blink reflex, plantar reflex, and reaction time. Reflex actions are involuntary—they happen before you have time to think. When they happen, a nerve signal takes a shortcut through the spinal cord, rather than involving the brain. If we touch a very hot object, a sensory neuron sends a signal shooting from the hand to the spinal cord.

1. Claims Evidence Reasoning: For each of the 5 parts, write a claim that explains what the specific reflex is.   Cite your evidence of it happening, or not, and then provide your reasoning for why that particular reflex occurred. If it didn’t, why?

In the photopupillary reflex part, a person covers his or her eyes with hands for an extended period of time and then is shined in the eye with a bright flashlight. The iris became a lot smaller, as the amount of light entering the eye triggered the reflex. The pupil contracts so that less light enters the eye.

In the knee jerk reflex/ patellar reflex portion, the spot just below my knee cap was hit with a small hammer, resulting in my leg immediately kicking out. This reflex, called a monosynaptic reflex, occurs because the knee tap causes the thigh muscle to stretch. This simultaneously sends out information to the spinal cord. When the quadriceps are fatigued, the patella reflex does not occur.

The blink reflex was tested when a clear sheet was held over my face and a cotton ball was thrown at it. Even though I understood that there was a barrier between the cotton ball and my face, I still blinked. This reflex occurred because humans instinctually will close their eyes if something is heading towards their eyes.

The plantar reflex was tested when a pen was dragged up the bottom of a foot. Naturally, the toes flexed and came closer together. This reflex occurred because the nerve system in developed humans is fully myelinated.

Lastly, we tested reaction time by dropping a ruler and measuring how far down it took for the person to close their hand and catch the ruler. I noticed that with each trial, the trial distances decreased as we got used to catching the ruler. However, when we texted, the first trial distance was more than twice the distance of the first regular trial distance. The first trial was 23 cm while the first trial with texting involved was 50 cm. However both trials decreased in distance for the next two trials.