Chapter 11, The Heart, Part B

Chapter 11
Part B: (Mostly) Blood Vessels
1. The heart
a. Cardiac output (CO) defined: amount of blood pumped by each side (ventricle) of the heart in one minute
b. Stroke volume defined: volume of blood pumped by each ventricle in one contraction (each heartbeat)
i. Remains relatively constant
ii. 70 mL of blood is pumped out of the left ventricle/heartbeat
c. Heart rate: 75 beats per minute
d. CO = HR x SV {CO = HR (75 beats/min) x SV (70 mL/beat)}
i. Volume of CO = 5250 mL/min
ii. Starling’s law of the heart—the more the cardiac muscle is stretched, the stronger the contraction
iii. Changing heart rate is the most common way to change cardiac output
2. Regulation of heart rate
a. Increased heart rate by the sympathetic nervous system
i. Crisis—more blood needed
ii. Low blood pressure
iii. Hormonal control:
1. Epinephrine = adrenaline
2. Thyroxine—thyroid gland, general metabolism
iv. Exercise
v. Low blood volume
b. Decreased heart rate by the parasympathetic nervous system
i. High blood pressure or blood volume
ii. Low venous rate
3. Blood vessels = the vascular system
a. General purpose is to transport blood to the tissues and back
b. Classified by direction
i. Carry blood away from heart
1. Arteries
2. Arterioles = small arteries
ii. Exchanges between tissues and blood:
1. Capillary beds
iii. Return blood toward heart
1. Venules
2. Veins
c. Structure of walls: three layers = tunics
i. Tunic Intima (inner)
1. Endothelium—simple squamous epithelium
ii. Tunic Media
1. Smooth muscle, connectiveTissue
2. Controlled by sympathetic nervous system (not voluntary)
iii. Tunic Externa
1. Mostly fibrous connectiveTissue
d. Differences between vessels
i. Walls of Arteries are the thickest, more elastic
ii. Lumens (opening) of Veins are larger
iii. Larger veins have valves to prevent backflow
iv. Skeletal muscle “milks” blood in veins toward the heart
v. Wall of Capillaries are only one cell layer think for diffusion
e. Movement of blood through
i. Arteries
ii. Veins
f. Capillary beds
i. Two types of vessels:
1. Vascular shunt—vessel directly connecting an arteriole to a venule.
2. True capillaries—exchange vessels:
ii. Oxygen and nutrients cross to cells
iii. Carbon dioxide and metabolic waste products cross into blood
iv. Materials exchanged due to concentration gradients:
1. Oxygen and nutrients leave the blood
2. Carbon dioxide and other wastes leave the cells
v. Exchange mechanisms: direct diffusion across plasma membranes, endocytosis or exocytosis
vi. Materials move through interstitial fluid to cells
1. Endocytosis
2. Exocytosis
3. Interstitial fluid
g. Major arteries: Aorta
i. Largest artery in the body
ii. Leaves from the left ventricle of the heart
iii. Regions:
1. Ascending aorta—leaves the left ventricle
2. Aortic Arch—180 degrees to the left
3. Thoracic aorta—travels downward through the thorax
4. Abdominal aorta—passes through the diaphragm into the abdominopelvic cavity
iv. Systemic arteries
1. Arterial Branches of the aorta
v. Pulmonary
1. Branches branches of the pulmonary arteries
2. Study figure 11.12
h. Major veins
i. Systemic circulation
1. Superior and inferior vena cava enter the Right atrium:
2. Superior vena cava drains the head and arms
3. Inferior vena cava drains the lower body
ii. Pulmonary circulation
1. Pulmonary veins enter left atrium
i. Fetal circulation
i. Fetus receives exchanges of gases, nutrients, and wastes through the placenta
ii. Umbilical cord contains three vessels:
1. Umbilical vein—carries blood rich in nutrients and oxygen to the fetus
2. Umbilical arteries (2)—carry carbon dioxide and debris-laden blood from the fetus to placenta
iii. Bypass of the (nonfunctional) lungs:
1. Blood entering right atrium is shunted directly into the left atrium through the Foramen ovale (hold in septum)
2. Blood from Pulmonary artery goes directly into aorta
j. Hepatic portal circulation
i. Portal circulation—extra set of veins and capillaries
ii. Veins of hepatic portal circulation drain:
1. Digestive organs
2. Spleen
3. Pancreas
iii. Hepatic portal vein carries blood to the liver
iv. Importance of liver for nutrients
1. Maintains proper glucose, fat, and protein concentrations in blood
4. Pulse
a. Defined—pressure wave of blood
b. Unit—beats/minutes (bpm = beats per minutes)
c. Monitored at “pressure points” in arteries where pulse is easily palpated
d. Pulse Averages 70-76 bpm at rest
5. Blood pressure
a. Measurements by health professionals are made on the pressure in large arteries
b. Measured with a Sphygmomanometer
c. Systolic—pressure at the peak of the ventricular contractions
d. Diastolic—pressure when ventricles relax
e. How to write it: systolic/diastolic (120/80 mm Hg)
f. Pressure in blood vessels decreases as distance from the heart increases
g. Effects of factors
i. Affected by age, weight, time of day, exercise, body position, emotional state, genetics
ii. CO (cardiac output)—amount of blood pumped out of the left ventricle per minute
iii. PR (peripheral resistance)—the amount of friction as blood encounters as it flows through vessels:
1. Increased by narrowing of blood vessels and increased blood volume
iv. BP = CO x PR
v. Neural
1. Autonomic
vi. Renal =
1. Regulated by
2. Rennin
vii. Temperature
1. Heat
2. Cold
viii. Chemicals
ix. Diet
x. Genetic predisposition
h. Variations
i. Normal
1. Systolic:
2. Diastolic:
ii. Hypotension
1. Low
2. Associated
iii. Hypertension
1. High
2. Can be