The document discusses the circulatory and respiratory systems of sheep, highlighting their role in oxygen intake, carbon dioxide removal, and nutrient distribution. It describes the anatomy of the sheep heart, which has a four-chambered structure similar to humans, and details the components involved in blood circulation. Additionally, it differentiates between closed and open circulatory systems, focusing on the closed system present in humans and sheep.

1. Sheep Heart:
Circulatory/Respiratory Dissection Lab - Sheep Heart Circulatory and Respiratory systems are
critical adaptations that allow animals to 1) take in oxygen from the external environment to make
energy in cell respiration, 2) to get rid of carbon dioxide waste produced in cell respiration, and 3)
cycle nutrients throughout the body for use by the cells. The respiratory system allows animals to
do gas exchange, moving oxygen from the external environment into the blood and CO2 from the
blood into the external environment. The circulatory system pumps the blood throughout the body
to move oxygen, CO2, and nutrients to their final destinations. There are two types of circulatory
systems in animals: closed and open. Both types have at least one pump (i.e. heart) to push the
circulatory fluid throughout the body. In closed systems, the blood is ALWAYS contained within
blood vessels, while in open systems, the fluid -- called Ifinph -- is pumped into open sinuses
instead of blood vessels. Humans have a CLOSED circulatory system, so we will focus on that
model today. Sheep Sheep are vertebrate chordate mammals like humans, so their circulatory
anatomy is almost identical to ours. They have a 4-chambered heart and blood vessels that
contain blood.Heart Diagram - External The sheep heart has 4 chambers -- a left and right atrium
on top (the external surface of the atria is called an auricle), and a left and right ventricle on
bottom. Note that whenever we refer to anatomical positions, we refer to left and right from the
position of the organism we're looking at. So the "right" is on our left, and vice versa. You can see
the pulmonary trunk/artery in blue on top of the heart, and the aorta in red. These two arteries
carry blood away from the heart after it has been pumped out of the ventricles. The pulmonary
veins and vena cava return blood to the atria. The cells of the heart are fed oxygen via blood in the
coronary arteries, which are visible on the surface of the heart. Blockage of these arteries starves
the heart of oxygen, resulting in a heart attack.The basic layout of the mammalian heart. Find the
four chambers of the heart: the left and right atria on top, and the left and right ventricles on
bottom. Remember that the heart's purpose is to pump blood throughout the body. Which
chambers of the heart beat first? Notice the valves separating them. Which valve is on the right
side of the heart? The left? What is the purpose of these valves? Do you see any other valves in
the heart?