IS2 Circulation PPT

Why do we need a transport system?

IS2

Functions

• Transport nutrients, hormones and oxygen throughout the body

• Carry waste away from cells (ex. CO2, urea)• Protect body from infection (it transports

antibodies and white blood cells)

Parts of Cardiovascular System

• Heart• Blood• Blood Vessels– Arteries– Capillaries– Veins

Heart

• muscular pump located between your lungs.

• a sac called pericardium encloses the heart.

• 4 chambers:– the two upper chambers,

which receive blood returning to the heart, are called atria (singular, atrium).

– the two lower chambers are called ventricles, which pump blood out of the heart.

Valves

• flaps of tissue that prevent blood from flowing backwards

• located between the atria and ventricles and between the ventricles and the arteries leading from the heart

• the opening and closing of the valves cause the “bump bump” sound of the heart.

Blood Flow: 2 circuits/loops Pulmonary Circuit carries

oxygen-depleted blood from the heart to the lungs and oxygen-rich blood back to the heart. Heart → Lungs → Heart

Systemic Circuit carries oxygen-rich blood from the heart to the rest of the body and oxygen-depleted blood back to the heart. Heart → Body → Heart

Blood Vessels• Arteries: take blood (with high pressure)

Away from the heart =– thick walls: help withstand high pressure– more smooth muscle: help pump blood, make

the vessel more elastic– small space inside (increases pressure)

• Veins: take blood (with low pressure) back to the heart– thinner walls compared to arteries: less

smooth muscle– have valves to prevent backflow of blood– large space inside (decreases pressure)

• Capillaries: connect arteries and veins/allow exchange of substances between blood and tissues– microscopic: only one cell at a time can go

through them– single-celled wall: allows easy diffusion of

substances– reach every cell in the body

Diffusion between cells and vessels

Pacemaker

Group of cells in the right atrium that can produce a contraction

Contraction stimulus is picked up by nerve cells and spread to the rest of the heart

Nerves and Hormones• The pacemaker is controlled by:

– nervous system• opposing nerves control the

pacemaker by speeding it up and by slowing it down.

– endocrine system• hormones secreted into the

blood also control the pacemaker.

• hormone epinephrine, also called adrenaline, increases heart rate when the body is under stress.

Blood

• connective tissue made up of cells and liquid.

• blood is pumped through the body by the heart

• you have about 4-6 liters of blood

• it takes about 1 min for blood to make a complete circuit through the body.

Blood Composition• Plasma is 90% water.

– The other 10% contains: dissolved salts, proteins, hormones, CO2, antibodies, urea, sugar, etc...

• Red Blood Cells– Carry oxygen to the cells– Contain hemoglobin, a protein that stores oxygen

(hemoglobin contains IRON)

• White Blood Cells– Produce antibodies + destroy pathogens = fight

infections

• Platelets– Small fragments of cells that help stop cuts from

bleeding– Release clotting factors that help form protein

threads called fibrin– Fibrin threads trap platelets and blood cells to

make a blood clot.

Blood Pressure

• consists of two numbers Systolic Pressure– produced when the

ventricles contract Diastolic Pressure– produced when the heart

relaxes

• average blood pressure for healthy adults– 120/80 (120 over 80)

• average heart rate is about 70 beats per minute

Atherosclerosis• slow build up of plaque (lipids,

cholesterol) inside vessels• arteries become harder, less

flexible• less space for blood• if coronary arteries are affected:

heart attack might happen = heart cells die

• Factors affecting coronary heart disease (CHD):– Age, race, heredity, gender,

cholesterol levels, blood pressure, obesity, diabetes, smoking, sedentary lifestyle, stress

Health• Cholesterol /fats might clog arteries

= pressure inside vessel increases = hypertension/even heart attack

• Salt also promotes hypertension

• Regular exercise makes the heart stronger

• Smoking increases blood pressure (nicotine is a stimulant = increases heart rate/tar accumulates all over lungs = make gas exchange more difficult/CO stick to red blood cells permanently)