CIRCULATORY SYSTEM
-
A fluid-filled network of tubes or vessels through which material/blood is transported between cells in an animal.
-
Transports nutrients and waste products:
-
Oxygen
-
Nutrients
-
Hormones
-
Antibodies
-
Heat (temperature regulation)
-
Carbon dioxide
-
Urea
-
WASTE PRODUCTS
COMPONENTS OF BLOOD
​
-
PLASMA – Dissolves and carries all other components of blood, waste, nutrients.
-
ERYTHROCYTES – RBCs transport oxygen and carbon dioxide using hemoglobin.
-
LEUCOCYTES – Immune response.
Phagocytes – ‘eat up’ pathogens and dead cells
Lymphocytes – Produce antibodies [B-cells/T-cells] for immune response
-
PLATELETS – Clotting of blood following damage to cells or erythrocytes.
VEINS
​
-
Large lumen
-
Inelastic (don’t deal with high blood pressure)
-
Have semi-lunar valves to prevent backflow of blood
-
Thin muscular wall and fibrous outer layer
CAPILLARIES
​
-
Single cell thick
-
Organ and blood diffusion take place
-
Low blood pressure; increased SA:V, high diffusion
ARTERIES
​
-
Small lumen
-
Elastic, muscular walls
-
Thick muscular wall (tunica media) and fibrous outer layer
VASOCONSTRICTION &
VASOLIDILATION
Controlled by nerves (stretch receptors) and hormones
Temperature regulation
NET HYDROSTATIC PRESSURE – NET OSMOTIC PRESSURE = NET FILTRATION PRESSURE
VEINS AND ARTERIES
​
PULMONARY ARTERY – Blood from heart to lungs (deoxygenated)
PULMONARY VEIN – Blood from lungs to heart (oxygenated)
UMBILICAL ARTERY – Blood from fetus to mother (deoxygenated)
UMBILICAL VEIN – Blood from mother’s placenta to fetus (oxygenated)
AORTIC ARCH AND TRUNK – Main arteries from the heart
COMMON CARATOID ARTERY – Blood to brain
RENAL VEIN AND ARTERY – Connects the kidneys
HEPATIC PORTAL VEIN – Blood from gastrointestinal tract to liver
MESSENTRIC VEINS – Connects to the small intestine (drains into hepatic)
Heart is a myogenic muscle (not fatigable; doesn’t cramp up; no buildup of lactic acid)
Sinoatrial (SA) node and atrioventricular (AV) node are stretch receptors
SA and AV nodes control the rate of heartbeat
-
A wave of excitation is sent from the SA node, causing atria to contract.
-
This excitation is conducted to the AV node, where it passes through nerves to muscle of ventricles, causing them to contract (PURKINJE FIBRES)
-
Slightly slower, allowing atria to fully contract and ventricle to fill up.
-
Electrical signals in nerves are action potential
​
CONTROL OF HEART BEAT
-
Carbon dioxide concentrations regulate the heart beat
-
Chemoreceptors in MEDULLA OBLANGATA detect the amounts of carbon dioxide in the blood. When carbon dioxide levels fall, the Vagus nerve reduces the heart rate
-
Connects medulla oblongata to heart
-
ADRENALIN: Causes rapid increase in heart rate, preparing body for action
​
Average adult blood pressure = 80/120 (diastole/systole)
Atherosclerosis
Atheromas are fatty deposits caused by high blood concentrations of low density lipoprotein (LDL) in the arterial walls next to the endothelial cells. LDL consists of cholesterol and fats.
If the artery that is blocked happens to be a coronary artery (an artery supplying the heart with oxygen and nutrients), the cells in that part of the heart will die, and the result is a myocardial infarction (heart attack).
There are several causes of plaque formation (building up of fatty deposits in arteries) leading to atherosclerosis and the increase in cardiovascular disease:
-
High blood concentrations of LDL
-
Diabetes causing high blood glucose concentrations
-
Smoking and stress causing high blood pressure
-
Diets containing high levels of trans fats
-
Recent research indicates that certain infections with bacteria, such as Chlamydia pneumoniae, can also play a role.
