Topic 6.2 – The blood system Essential idea: The blood system continuously transports substances to cells and simultaneously collects waste products. https://www.hhmi.org/biointeractive/heart-matter

Data practice: CPR survival rates. Get started early to save a life! These data compare compression-only CPR with conventional CPR: neurologically favorable one-month survival. Population: bystander-assisted patients, transferred to hospital by ambulance. Japan. 2005 – 2007. Compression-only n=20,707 Conventional CPR n= 19,328 Compare survival rates of compression-only CPR with conventional CPR in all cases (top graph). Describe the effect of increasing time to start CPR on survival of patients in cases of cardiac origin. Calculate the difference in survival between hands-only CPR and conventional CPR in cases of non-cardiac origin after 7-8 minutes. Compare survival rates between cases of cardiac and non-cardiac origin. Suggest a reason for the differences. Data from: http://www.bmj.com/content/342/bmj.c7106.full

Arteries convey blood at high pressures from the ventricles to the tissues of the body. This is aided by the presence of muscle cells and elastic fibers in their vessel walls. Having thick vessel walls and elastic fibers, allow our arteries to quickly respond to the heart. Our heart beats on average 70 beats per minute (bpm), but during exercise, can increase healthily to around 200 bpm. This increase in heart rate serves to fulfill the needs of our muscles as they perform contractions. These muscle walls and elastic fibers also maintain our blood pressure, even when our heart is not pumping adequately.

Blood flows through tissues in capillaries Blood flows through tissues in capillaries. Capillaries have permeable walls that allow the exchange of materials between cells in the tissue and the capillary. Notice the thin structure of the vessel wall in a capillary. This allows for quick passive transport of oxygen and nutrients into tissue, and waste and carbon dioxide out of tissue. Often, capillaries are not much larger than a single erythrocyte. This makes a burst capillary generally not a terrible thing, but also can make it difficult to get immune cells through capillaries.

Veins collect blood at low pressure from the tissues of the body and return it to the atria. Veins collect blood after it has interacted with the body. The blood within veins is deoxygenated and nutrient poor (often). The structure of veins is adapted to deal with blood flow in this low pressure environment.: Larger Lumen Valves Veins have valves that work together with the circulation of the heart to prevent the backflow of blood. Shown below: Valves from the front and side. Valves allow the veins to keep blood flow in the correct direction and prevent backflow. This ensures that blood never goes for too long without finding the heart/lungs again.

Blood flows from the heart, through arteries, then capillaries, then veins, then back to the heart. Compare the structure of arteries, capillaries and veins. How are each structured to match their function?

Familiarize yourself with the relationship between the diagram and this actual heart image. How many of the structures can you label?

RIGHT LEFT

There is a special circulation of blood for the lungs.

The coronary arteries are the arteries that supply the heart with the energy and oxygen it needs in order to continually pump. A blockage in one of the coronary arteries can result in a Heart Attack. In a heart attack, the heart is unable to beat and supply the body with blood. The blood flow to the heart is important to maintain at all times. Even limiting the blood flow to a section of the heart for a brief period of time will cause the heart muscle tissue to become damaged. Watch this short video to understand what is going on to cause a heart attack. Get the facts on heart attacks from the American Heart Association (AHA)

The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain.

The heart rate can be increased or decreased by impulses brought to the heart through two nerves from the medulla of the brain. Heart rate is increased through action of the sympathetic nervous system. Hormones involved in the increase of heart rate Epinephrine (Adrenaline) - Adrenal Thyroxin - Thyroid

Atrial Systole; Ventricular diastole The cardiac cycle is due to the pressure changes in the atria and ventricles as the heart contracts. Cardiac Diastole Atrial Systole; Ventricular diastole Atrial Diastole All chambers are relaxed Blood flows into the heart Atria Contract, pushing blood into ventricles - Ventricles Contract, pushing blood out of the heart

… But what if the signals are mixed? Arrhythmias! http://library.med.utah.edu/kw/pharm/hyper_heart1.html … But what if the signals are mixed? Arrhythmias! Cool movies on different arrhythmias http://medmovie.com/library_id/7556/topic/cvml_0004a/

Your Task – To create a life size model of the body over the course of the Human Physiology Unit Circulatory Section– Materials : Large Poster Paper Construction Paper Scissors Tape Markers Steps – Cut out and label a model heart and put it on the body in the correct positioning. Cut you must include one MAJOR artery and vein in your person, and these should connect with the heart appropriately. You should also include the capillaries that interact with the digestive system (and allow for the absorption and assimilation of nutrients from food. Place all the required parts of your person in the appropriate position.