Kinesiology - Physiology: Cardiovascular System

Cardiovascular system

Transport system that carries nutrients, waste & other important chemicals throughout the body

Heart

A pump that has 4 chambers & 2 stroke pumps

• a hallow bag of muscle

Myocardium

Thickest part of the heart

• contracts to shrink chambers of the heart to pump blood

• Surrounds by pericardium tissue that protects and anchors the heart muscles to surrounding tissues

Right atrium

Collecting chamber that first collects blood returning from the body and pumps it to the right ventricle

Blood returns to the right atrium from these 3 vessels

Superior vena cava: upper part of the body

Inferior vena cava: lower part of the body

Cardiac sinus: coronary arteries (within the heart)

Left atrium

Collects blood returning from the lungs via pulmonary vein and pups blood to left ventricle

Right ventricle

Pumps blood to lungs via the pulmonary artery

Left ventricle

Pumps blood to the whole body through the aorta

Valves

Prevent backdown of the blood in your heart

• the valves between the atria and ventricles are the Tricuspid (right) and Bicuspid (left) mitral valves

• Valves between the ventricles and vessels are the semilunar valves (aortic and pulmonary)

Pulmonary circulation

Starts from the right side of the heart and de-oxygenated blood travels to the lungs to gain O2 & deposit CO2 and returns to the left side of the heart oxygenated

Systemic circulation

Starts on the left side and the oxygenated blood travels to the organs & returns the de-oxygenated blood to the right side of the heart

Electric control

• heartbeat is firstly controlled by brain stem

• Heart is a muscle - cells are similar to the skeletal muscle but electrically connected

  • When gets signalled to contract they all will contract(all or nothing principle)

Sino-atrial node

Bundle of nerve cells in the walls of the right atrium causing the heart to beat intrinsically @ ~75bpm

• heart’s natural pacemaker

Atrio-ventricular node

Bundle of nerve cells in the walls between the right atrium & right ventricle that are meant to delay electrical signals to ventricles by 0.1 seconds

• So everything gets into ventricle front he atria before being sent away

  • Second job is to take over for the SA node if needed

Blood Pressure

A measure of force with which blood pushes on the walls of the aorta & other arteries

• tidal measurement as pressure & flow of blood changes between contraction phase (rapid & strong flow) & relaxation phase (slower & more gentle flow) of heart muscles

• Normal/healthy BP is 120/80mm of Mercury

• High BP is expected & normal especially during exercise because the heart pumps faster & with greater force because the body is demanding more

Systole

Period of strongest contraction of ventricles - highest pressure of blood in aorta

Diastole

Period of relaxation of ventricle - lowest pressure in aorta

Blood Pressure formula

Systole/diastole

Heart rate

Average measure for how many times heart contracts/“beats” in 1 min

• avg resting HR is 75bpm

• HR increases during exercise to meet body’s demand

Stroke volume

Amount of blood pumped by each “stroke” of the left ventricle

• measured in ml/beat

• Varies per person based on their gender & size

Cardiac output

Amount of blood pumped by a ventricle in 1 minute

• CO = HR x SV

• Avg body has a total blood volume of 5L, so entire volume of blood will circulate completely around body each minute

Arteries

Transports blood away from the heart

• systemic arteries always carry oxygenated blood

• Pulmonary artery’s carry deoxygenated blood there is high pressure of blood in the arteries

• Al starts from the aorta that has the largest and greatest pressure

  • Branches & its diameter decreases until the smallest arteries (arterioles)

• Thick & have small muscles

• Muscles can change diameter of artery

  • Act as a secondary pump

Vasodilation

Blood flow increases because the diameter increases

Vasoconstriction

Blood flow decreases because diameter decreases

Capillaries

Smallest vessels in the body & could have the thickness of a RBC

• there are lots of capillaries in the body

• Very very thin walls

• Site of material exchange between the blood and the tissues

  • Forms a 3-d web of the body

• Gases and small solutes pass through the walls while the larger materials pass through the pores

Veins

Carries blood back to the heart

• mostly carries deoxygenated blood

  • Except for the pulmonary vein that carries oxygenated blood

• Has no muscles and has low pressure

• Veins have one way valves that prevent back flow

Venus return

Mechanism helping blood flow back into the heart

Muscular pump

Veins often located along the outside of muscles & when the muscle contracts it squeezes the veins resulting in the pumping action

Thoracic pump

Diaphragm moves up and down causing breathing and as it does that it creates an alternating sequence of pressure change in the body cavity & causes veins to expand & contract causing the pumping action

Blood

Main vehicle of transport in the body

Plasma

Is found within blood and is a clear fluid that is ~55% of blood volume that carries all dissolved solutes

• mostly water

• Salts, sugars, gases, various biochemicals

Blood cells

~45% blood volume

~2% of cells are either

• leukocytes: WBC

  • Immune system

• Thrombocytes: platelets

  • Clotting

99% of blood cels are

• erythrocytes: RBC

  • Round donut shaped and is flat

    • Produced in the bone marrow of long bones

    • Lives for ~120 days

Hemoglobin

Carries O2 around the body

• bodyguard

• Starts out blue/green until it binds with O2 making is oxyhemoglobin (red) and when it unbinds it becomes blue/green again

Anemia

When you don’t have enough RBC (iron)

Sickle Cell disease

Poorly shaped blood cells

Blood popping

Taking blood out & putting it back in

• erythropotin: stimulates RBC production

Carbon monoxide poisoning

CO is better 2 binding to hemoglobin than O2

CO2 transport

• 80% of CO2 is dissolved in plasma

• Reacts wth H2O to make HCO3 → bicarbonate

  • Bicarbonate solution is a buffer for blood pH (7.4)