circulatory system Flashcards
(14 cards)
three functions of the circulatory system?
1) Transportation of many substances in the blood, including nutrients, waste, hormones, respiratory gases, ions, etc.
2) disease-fighting
3) temperature regulation (in some animals)
components of the circulatory system: what is the vascular tissue associated with and what is the tissue its produced in called?
blood = plasma and formed elements (formed elements are cells and cell parts)
Red blood cells are associated with transport of respiratory gases, particularly oxygen. White blood cells are associated with combating diseases, parasites, and allergic reactions. Blood cells are produced in various tissues scattered through the body of vertebrates. Blood cell producing tissues are referred to as hemopoeitic tissues, such as marrow, lymph nodes, and spleen.
components of the circulatory system: what are blood vessels and how are they assembled? same for capillaries and arteries
The lumen of blood vessels is lined with a smooth, slick squamous epithelium termed an Endothelium, which reduces friction as blood with cells circulates through the vessels. One exception is that the capillaries consist only of endothelium—they are very thin with a small diameter to the lumen, about 8 to 10 microns—not much larger than a red blood cell (about 7 micron diameter). A small amount of smooth muscle, the precapillary sphincter, is present at the start of a capillary bed (where it branches from an arteriole). When closed, blood is prevented from entering a capillary bed. Many if not most precapillary sphincters are closed most of the time. Think about blushing. Blushing is caused when precapillary sphincters supplying blood to your cheeks relax so that blood enters, and the cheeks blush or turn a reddish hue. If too many precapillary sphincters open simultaneously, too little blood flows to the brain and a person will faint—rapidly. The other vessels have smooth muscles throughout their length (comparable to the muscularis externa of the gut tube). Larger arteries have a thicker layer of smooth muscle and more elastin protein fibers in their walls
components of the circulatory system: what is the pump and why do we need it?
The heart provides the major force that moves blood through the body. The need for a circulatory system arises with an increase in body bulk (not just size or length). ex:, various types of “worms” can get long and still not require a circulatory system if they are flat. The body of a jellyfish or of a flatworm is only a couple of cell layers thick, and diffusion suffices because of their gastrovascular cavity. The branches of the gastrovascular cavity carry materials to all regions of the body—without a blood supply or circulatory system. No cells are far from nutrients, and respiratory gases diffuse across their body surfaces. Roundworms also lack a circulatory system, but their intestine is surrounded by fluid and nutrients are sloshed around their body cavity. With increase in body bulk, distances from gut and nutrients become too great for diffusion to operate quickly enough to provide distant cells with nutrients; therefore, the need for vessels to transport the nutrients and a pump to generate the force to propel the fluid (blood) and its components throughout the body efficiently=a true circulatory system.
does all fluid return to the heart via blood vessels?
no, some enters the lymph vessels and is returned to the heart in that manner.
vertebrate closed system and blood flow through heart: if the animal has gills, what type of heart and system do they have?
have four chambers, all arranged in a series. The most posterior chamber that receives blood from the body is the Sinus venosus, which dumps blood into an atrium, from there into a ventricle, and from there into either a conus arteriosus (sharks) or a similar chamber that forces blood into a ventral aorta, which carries blood to the gills. After passing through gills, most blood is forced into the dorsal aorta, which distributes blood posteriorly to most organs of the body. Blood returns from the tissues, via the venous system of vessels, to the Sinus venosus of the heart and the pattern is repeated. This type of circulatory system, with blood flowing from heart to respiratory system, to body, and then back to the heart is known as a Single Circuit system. heart-gill-body-heart.
vertebrate closed system and blood flow through heart: if the animal has lungs, what type of heart and system do they have? frog specific
have a double circuit circulatory system: blood flows from heart to lungs, to heart to body, then back to heart. Two circuits of blood: pulmonary (associated with lungs) and systemic (associated with all other body systems). The heart receives blood low in O2 from body, but high in O2 from lungs, which requires that the two masses of blood be kept separated. in frogs, the atrium becomes subdivided into two chambers, but the ventricle does not. However, small muscular papillae or projections off the wall of the ventricle (Trabeculae) help limit the mixing of the O2 rich and O2 poor blood. Also, the conus arteriosus (chamber into which the ventricle pumps blood) has a spiral valve that directs blood into either the lungs or general circulation. In effect, the heart of a frog has five chambers: sinus venosus, right atrium, left atrium, ventricle, and conus arteriosus. Frogs also breath through their skin (transcutaneous or cutaneous) respiration, which helps with their relatively low O2 demands.
vertebrate closed system and blood flow through heart: if the animal has lungs, what type of heart and system do they have? bird and mammal specific
complete separation of the embryonic single atrium and single ventricle occurs. Mammals have a four chamber heart because the Sinus venosus becomes incorporated into the wall of the right atrium (it becomes the Sinus node, or sinoatrial node = the pacemaker of the heart), and the conus becomes subdivided into various blood vessels—thus two atria and two ventricles. The Sinus node is regulated by neurotransmitters released from a component of the parasympathetic nervous system (the vagus nerve, which secretes acetylcholine and slows heart rate) and of the sympathetic nervous system, which secretes epinephrine to speed the heart rate. These two neurotransmitters have antagonistic actions, but help maintain a normal heart rate appropriate for specific activities.
blood contraction and pressure: how do blood vessels and arteries and such contract or move blood?
Most blood vessels have smooth muscles throughout their length (comparable to the muscularis externa of the gut tube). Larger arteries have a thicker layer of smooth muscle and more elastin protein fibers in their walls. Elastin allows the walls of the arteries to stretch when blood is pumped into them when the heart contracts (systole). When the heart relaxes (diastole), the elastin returns the blood vessel to its normal diameter and forces blood forward (valves prevent it from flowing back into the heart).
blood contraction and pressure: what is systolic pressure?
The higher pressure reading(120/80) is the force generated on the wall of large arteries when the heart contracts
blood contraction and pressure: what is diastolic pressure?
the lower reading is the pressure caused by the vessels returning to normal when the heart relaxes
blood contraction and pressure: what is filtration pressure?
forces blood, nutrients, etc. though the walls of capillaries and into the tissues (recall the glomerulus–which is a tuft of capillaries). The further the blood travels from the heart, the more similar the two pressures become, and a drop in overall pressure occurs. For example, in capillaries, we do not detect a difference in systolic and diastolic pressures—instead, we can measure only one pressure somewhere around 40-45 mm HG pressure. =filt. press.
blood contraction and pressure: what is plasma osmotic pressure?
draws some fluid back in to the capillary, but not all of the fluid returns. The remainder of the fluid is taken back to the heart by lymph vessels, which are one-way vessels that originate in tissues and carry fluids back to heart. If they get blocked, fluid builds up in the tissues and causes swelling. elephantiasis
blood contraction and pressure: how does filtration pressure and plasma osmotic pressure work together?
Net flow of water will be out of the capillary until filtration pressure drops to below that of plasma osmotic pressure. Filtration pressure drops as fluid (and solutes) is pushed out of the capillary into extracellular spaces. When this occurs, more fluid will be brought in, rather than leave, the capillary. Not all fluid is pulled back in, which explains the purpose of the lymph vessels.
