Week 2, 3

  1. Circulatory system: Structure and function of the heart and blood vessels. Elements of Blood (composition of plasma, erythrocytes, leukocytes, and platelets), ABO blood typing system, including Rh factor.

Functions of the Cardiovascular System
Your cardiovascular system has many jobs. At times the cardiovascular system can work like a pump, a heating system,orevenapostalcarrier. Todothesetasks,yourcardiovascularsystemworkswithotherorgansystems,such as the respiratory, endocrine, and nervous systems. The cardiovascularsystem (Figure 1.38) is made up of the heart, the blood vessels, and the blood. It moves nutrients,gases(likeoxygen),andwastestoandfromyourcells. Everycellinyourbodydependsonyourcardiovascular system. If your cells don’t receive nutrients, they cannot survive. The main function of the cardiovascular system is to deliver oxygen to each of your cells. Blood receives oxygen in your lungs and then is pumped, by your heart, throughout your body. The oxygen then diffuses into your cells, and carbon dioxide, a waste product of cellular respiration, moves from your cells into your blood to be deliveredback to your lungs andexhaled. Eachcell in your body needs oxygen, as oxygen is used in cellular respiration to produce energy in the form of ATP. The cardiovascular system also plays a role in maintaining body temperature. It helps to keep you warm by moving warm blood around your body. Your blood vessels also control your body temperature to keep you from getting too hot or too cold. When your brain senses that your body temperature is increasing, it sends messages to the blood vesselsintheskintoincreaseindiameter. Increasingthediameterofthebloodvesselsincreasestheamountofblood andheatthatmovesneartheskin’ssurface. Theheatisthenreleasedfromtheskin. Thishelpsyoucooldown. What do you think your blood vessels do when your body temperature is decreasing?

Vocabulary
• cardiovascularsystem: Organ system made up of the heart, blood, and blood vessels. • cells: Basic unit of structure and function of a living organism; the basic unit of life. • connectivetissue: Groupofcellsthatareallinvolvedinsupportingandbindingothertissuesofthebody; i.e. tendon, cartilage, bone, and blood. • epithelialtissue: Layers of tightly packed cells that line the surfaces of the body. • muscletissue: Bands of cells that contract and allow movement. • nervous tissue: Group of nerve cells that sense stimuli and transmit signals; found in brain, spinal cord, and nerves. • organ: Structure made of two or more tissues that work together. • organsystem: Organs that work together to serve a common purpose. • tissue: Group of similar cells working together.
Summary
• The levels of organization in the human body include: cells, tissues, organs, and organ systems. • There are four tissue types in the body: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.