Cardiovasc system Flashcards
Arteries
-Carry blood away from heart under high pressure
-Transport oxygenated blood (except pulmonary)
-No valves
-Reddish colour
-Thicker walls than veins
Veins
-Carry blood towards heart under low pressure
-Transport deoxygenated blood (except pulmonary)
-May contain valves to prevent backflow
-Blueish colour
-Thinner walls than arteries
Capillaries
-Between arterioles and venules
-Only 1 layer (tunica intima)
Vein and artery walls
Tunica intima, Tunica media and tunica adventitia are the 3 layers
Blood composition
Plasma - contains nutrients/waste/antibodies
Plasma proteins - Albumin maintains osmotic concentration and fibrinogen and prothrombin form blood clots.
Blood functions
- Transport gases to/from body and lungs
- Transport nutrients
- Transport waste products to liver/kidney
- Regulates body fluid volume
- Defends against infection
- Regulates body temperature by conducting heat
How are erythrocytes formed
Formed by erythropoiesis in bone marrow, which takes 4-7 days. Production is controlled by Erythropoietin.
Erythrocyte function
Transports oxygen and some CO2
Leucocytes function
-Defend the body against infections
-Have nuclei
Granulocytes types (leucocytes)
-Basophils secrete histamine
-Neutrophils phagocytose bacteria
-Eosinophils are involved in allergic responses
Agranulocyte types (leucocytes)
-Lymphocytes produce antibodies (B)
-Monocytes transform into macrophages
How are thrombocytes/platelets formed
-Formed from megakaryocytes in bone marrow
Thrombocytes function
-Blood clotting
How does blood clotting work?
- Platelets stick to damaged blood vessel and release THROMBOPLASTIN.
- This converts PROTHROMBIN TO THROMBIN
- THROMBIN converts FIBRINOGEN to FIBRIN to make a clot.
-Clotting time is increased by lack of vit K and decreased by raised temperatures.
What is a thrombus
A blood clot blocking a vein/artery.
What artery and vein is in the forelimbs
Brachial
what is a hepatic portal system
A circulation system that directs blood from the digestive tract to the liver
Where would you take blood from a cat
External jugular vein, Cephalic vein and femoral vein.
Where would you take blood from a dog
External jugular vein, Cephalic vein and Saphenous vein.
Where would you find a cows pulse
Facial artery near the jaw, or Coccygeal artery at the tail base.
What is the Mediastinum
The central compartment of the thoracic cavity where the heart is located.
What is pericardium
Double layered (parietal and viscous layers) sac that encloses the heart
What are the three heart muscle layers
- Endocardium - inner layer
- Myocardium - middle composed of cardiac muscle
- Epicardium - outer layer that forms inner pericardium layer.
What is so good about cardiac muscle
It can continuously contract with minimal fatigue.
What do valves do in the heart
They prevent backflow
-Atrioventricular close during ventricular contraction
-Semilunar close after ventricular contraction.
Explain the steps of the Cardiac cycle
- Atrial Diastole (relaxation): blood fills atria and is passed to ventricles
- Atrial Systole (contraction): blood is forced into ventricles by contractions.
- Ventricular Diastole: Ventricles fill slowly and AV valves close.
- Ventricular Systole: Blood is ejected into the aorta and pulmonary trunk and SL valves close.
What is blood pressure
The force of blood against artery walls. (systolic or diastolic when heart contracts or relaxes)
What are some features of the Immune system
-Skin is a physical barrier against pathogens
-Spleen is involved in filtering blood
-Sweat inhibits bacterial growth
What is the innate immune system
-Fast non specific responses to organisms
-present at birth
What is the Adaptive immune system
-Slower responses to specific organisms
-Uses antibodies and memory cells
Conduction System
- SA node initiates contraction which spreads across both the atria (ATRIAL SYSTOLE)
- The nerve impulse must pass through the AV node at the top of the septum.
- The AV node sends impulses to the Bundle of His, which runs down the intraventricular septum.
- The Bundle of His divides into branches in the ventricles, and these connect with neurons called Purkinje fibres (in ventricular muscle)
- A wave of contraction starts in the myocardium at the apex, and spreads up through ventricular muscles, pushing blood to the oulmonary artery and aorta.
