BI102 circulatory system

what diffuses into/out of the circulatory system

O2, CO2, nutrients

How does the circulatory system affect diffusion

minimizes diffusion distance and increases surface area for diffusion

function of the circulatory system

deliver glucose and O2 to trillions of cells and to remove CO2 and urea from trillions of cells

Three basic parts of the circulatory system

1. circulatory fluid (blood)

2. set of interconnecting tubes (blood vessels)

3. muscular pump (heart)

what is a closed CS

blood is confined to vessels and is distinct from interstitial fluid (which fills space in between cells)

what is a cardiovascular system

the closed circulatory system of vertebrates

3 main types of blood vessels

1. arteries

2. capillaries

3. veins

blood flow arteries

1. carry blood away from the heart

2. branch into arterioles

3. carry blood to capillaries

blood flow veins

1. carry blood from capillaries

2. venules converge into veins

3. return blood to heart

where is the SA/V ratio highest in CS

capillaries

Four chambers of the heart and O2 level

1. Right atrium (low O2)

2. Right ventricle (low O2)

3. Left atrium (high O2)

4. Left ventricle (high O2)

pulmonary vs systemic circuit

1. pulmonary circuit picks up O2 from lungs

2. systemic circuit delivers O2 to cells in body

Blood flow pattern from right ventricle to right atrium

1. RV pumps low O2 blood to the lungs through pulmonary artery

2. in the lungs blood loads O2 and unloads CO2

3. high O2 blood travels through pulmonary veins from the lungs to the LA

4. Blood goes from LA to LV

5. Blood pumped form LV through aorta and arteries to body tissues

6. after delivering O2 to cells, blood runs back to the heart through inferior and superior vena cavas (veins)

7. vena cavas connect to the RA

8. blood goes from RA to RV and the cycle starts again

Coronary arteries

Bring O2 to the heart

Carotid arteries

Bring O2 to the brain, neck, and face

Valves of the heart

1. of them- all prevent back flow of blood

2. atrioventricular valves

3. semilunar valves

Atrioventricular valves

separates each atrium and ventricle

semilunar valves

1. between left ventricle and aorta

2. between right ventricle and pulmonary artery

Systole

contraction (pumping) phase of the cardiac cycle

Diastole

relaxation (filling) phase of the cardiac cycle

Blood pressure

systolic/diastolic

cardiac cycle

one cycle is 1 complete sequence of contraction and relaxation

form/function of arteries

1. lined with smooth epithelium to minimize flow resistance

2. surrounded by smooth muscle and connective tissue (3 layers)

3. thick elastic layers to accommodate high pressure pumped from the heart

form/function of capillaries

1. lined with smooth epithelium to minimize flow resistance

2. thin walls w 2 layers (endothelium + basal lamina) to increase diffusion

form/function of veins

1. lined with smooth epithelium to minimize flow resistance

2. surrounded by smooth muscle and connective tissue (3 layers)

3. do not have thick walls since blood is at a lower pressure

4. have valves to prevent back flow of blood

5. muscle contractions (smooth and skeletal) help get blood back to the heart

Area, blood pressure and velocity

1. flows from areas with higher pressure to areas with lower pressure

2. slows down as it moves from arteries to capillaries

3. moves slowest in capillary beds bc of high resistance and total cross sectional area (to maximize diffusion)

what moves fluid out and into capillaries

1. blood pressure moves fluid out of capillaries

2. osmotic pressure moves fluid into capillaries

3. total net fluid movement out of capillaries

lymph

fluid that leaks out from capillaries

purpose of lymphatic system

returns fluid that leaks out of capillaries

3 types of blood cells

1. erythrocytes

2. leukocytes

3. platelets

function of erythrocytes

1. RBC’s

2. contain hemoglobin (iron-containing protein) which transports O2 to cells for cell respiration

3. lack nuclei + mitochondria to make room for more hemoglobin (each molecule binds 4 O2)

4. also transport CO2 from cells to alveoli in lungs

function of leukocytes

1. WBC’s

2. function in defense

3. phagocytizing bacteria + debris

4. produce antibodies

function of platelets

1. fragments of cells

2. function in blood clotting

3. complex reactions turn platelets into fibrin which forms the blood clot

Cardiovascular disease

disorders of heart and blood vessels, accounts for over 50% of US deaths

Hypertension (high blood pressure)

1. bp consistently over 130/80 increases risk of atherosclerosis, heart attack, and stroke

2. deadly

atherosclerosis (hardening of the arteries)

buildup of cholesterol (plaque) in arteries can cause blood clots (thrombus)

Heart attack (myocardial infarction)

death of cardiac muscle resulting from blockage of 1 or more coronary arteries

stroke

death of nervous tissue in brain resulting from rupture or blockage of arteries in the head

effect of high bp on thermoregulation

1. reduce thermoregulation

2. alteration of blood flow between body core and skin

3. weakens muscles controlling vasodilation and vasoconstriction which results in a reduced ability to thermoregulate

vasodilation

1. vessel gets bigger

2. more blood flow

3. lose heat

4. muscle cells relax

vasoconstriction

1. vessels get smaller

2. less blood flow

3. don’t lose heat

4. muscle cells contract

Why does a high salt diet increase blood pressure

increased salt in the blood causes too much fluid in circulatory system (osmosis)

why can diabetes increase blood pressure

increased glucose in the blood causes too much fluid in the circulatory system (osmosis)

normal bp

less than 120/80

if high, which ratio can increase risk of cardio disease?

LDL to HDL

LDL

low-density lipoprotien, delivers cholesterol to cells for membrane protection

HDL

high-density lipoprotien, removes cholesterol for return to liver

what drugs reduce LDL levels/risk of heart attack

statins

what does PCSK9 gene mutation cause

lower LDL levels and 88% lower risk of heart attack