cardiovascular system Flashcards
function of the circulatory system
The circulatory system consists of a network of vessels carrying the blood pumped by the heart to every part of the body.
how does blood enter and leave the heart
Blood leaves the heart and travels the body through arteries, and blood returns to the heart through veins.
Heart arteries arterioles capillaries venules veins Heart lungs heart
arteries……
characteristics of the heart
The pump • Weighs 9-12 lbs • Consists of 4 chambers:
– 2 atria (receiving), 2 ventricles (ejecting)
– 100% of blood volume passes through the heart each minute
equine heart rate
The resting heart beats about 35 times per minute, a galloping horse can get up to 240 beats per minute.
• Each beat moves about a liter of blood
how much blood do horses have in their body?
Horses on average have 11 gallons or 45 liters of blood in their body
pericardium
sac encasing the heart, contains a small amount of fluid for lubrication
myocardium
specialized cardiac muscle (involuntary striated muscle) that does not fatigue.
diastole
the action of relaxing to receive blood
systole
the action of contracting to pump blood
what is the heart sound?
The heart sound is the sound made by the valves as they close.
The first sound is the sound of the mitral and tricuspid valves as they close, and the second sound is the sound of the semi-lunar valves closing (valves on the aorta and pulmonary artery).
The period of silence is when the heart is being filled again with blood.
arteries
blood is carried away from the heart in arteries. The oxygen in arterial blood (oxygenated) gives a bright red color. When arteries are cut, the blood is pumped out with each heart beat. The walls are made up of elastic collagen and smooth muscle. A small artery is an arteriole.
veins
carry blood from tissues back to the heart. Venous blood (deoxygenated) is dark red. Veins have no pulse and no muscle around walls, so it relies on valves to impede backflow of blood. A small vein is a venule.
capillaries
form a network of thread-like vessels that reach into every part of the body. Capillaries carry arterial blood into tissues, receive CO2 from tissues, and carry away venous blood. They have very thin walls (one single cell makes up the wall), this allows the diffusion of oxygen and nutrients (from food) into tissues. From capillaries cells escape to sites of injury to fight infection. The very narrow lumen slows the blood flow to allow for the delivery of oxygen and nutrients to tissues.
what does blood transport
Oxygen from lungs to cells •CO2 from cells to lungs •Nutrients and water from gut to cells •Hormones from endocrine glands to cells •Antibodies or white blood cells to site of injury or infection •Heat from center of the body or working muscles , distributed as required or dissipated •Waste products from cells to liver and kidneys for detoxification and excretion
3 parts of blood
Plasma- fluid (92% water), plus glucose, proteins, lipids, nutrients.
– Platelets- Small sticky bodies to stop bleeding
– Cells-
• Red blood cells carry
oxygen
• White blood cells defend against disease
red blood cells
The function of RBC’s is to carry oxygen from lungs to
tissues and carbon dioxide from tissues to lungs. •They live 3-4 months, and have no nucleus.
•Old RBC’s are broken down by liver and spleen. •New cells are produced by bone marrow. •RBC’s carry O2 and CO2 attached to its hemoglobin.
platelets
Very small, live 9-11 days, help in blood-clotting process.
white blood cells
The main function of white blood cells is to defend the body against disease. They have nucleus and are capable of independent movement: they cross the blood vessel walls and accumulate at sites of injury or infection.
eosinophil
type of WBC, Break down foreign proteins. Increase in response to
allergens, particularly parasitic larvae.
neutrophils
type of WBC, 60% of leukocytes. Defense against acute bacterial infection. They phagocyte invading pathogens. Once it is full, it dies and produces pus.
Basophils
type of WBC, Control inflammation by releasing histamine (can be a problem in cases of hypersensitivity – allergy). Basophils have heparin (anti-coagulant), which is released in areas of inflammation.
monocytes
type of WBC, In blood they are called monocytes, but when they leave the blood and go into tissue they become large cells called macrophages. Macrophages engulf foreign matter. They are the vacuum cleaner of infection or injury sites.
lymphocytes
Type of WBC, 35% of leukocytes. They produce antibodies specific to invading viral pathogens to protect the body against these invaders
anemia
decreased red blood cell count and concentration of hemoglobin
bacterial infection
increase in white blood cell count
dehydration
increase PCV (packed cell volume), which is the ratio between plasma and cells.
fitness level
a fit horse has a higher number of red blood cells and higher hemoglobin concentration
viral infection
reduction in total number of white blood cells. Neutrophil and lymphocyte ratio inverts from 60:40 (N:L) to 40:60.
the spleen
Horses use their spleen to increase the number of red blood cells in the blood
• Horse spleen is 3-4 feet long, 8 inches wide and 4 inches thick
• The blood in a resting horse is made up of 35% RBC, the blood in the spleen is made up of 80% RBC
lymph system
Clear, fluid that squeezes out of blood vessels to send WBC and nutrients to injured areas
• Edema or Swelling, helps promote healing and immobilizes the area, however, too much swelling can restrict blood flow, and cause increased pain
systemic circulation
The aorta branches out to supply blood to every organ and tissue of the body. The names of the arteries that branch out from the aorta correspond to which organ or tissue they supply.
coronary artery
supplies blood to heart
brachiocephalic trunk
supplies blood to forelimbs, brain, head and neck.
celiac artery
(further divides into gastric, splenic and hepatic): blood to stomach, liver and spleen.
mesenteric artery
supplies blood to intestines.
renal artery
supplies blood to the kidney
iliac artery
supplies blood to the hindquarters
