Cardiovascular System

Question 1

THE BLOOD

Answer 1

• Structure: blood plasma = proteins binding lipid-soluble molecules; water (mostly); other solutes (ions, nutrients, ,gases, hormones, wastes)
blood cells = platelets (coagulation), white (immune cells), red (erythrocytes) (mainly, transports gases and contain hemoglobin)
• Functions: transport these “other solutes”; Regulates pH, body temp. and water content of cells; Protects from microbes and blood loss

Question 2

THE HEART - muscle

Answer 2

• Cardiac muscle = Cylindrical cells connected by **intercalacted discs ** with gap junctions where action potential can conduct between cells
• Responsible for pumping of heart
• Controlled by ANS (involuntary contraction and relaxation)

Question 3

THE HEART - Conduction

Answer 3

• Sinoatrial (SA) node = specialized fibers in right atrium that can generate action potentials → setting the rythm
1. SA-node sends action potentials → atrias contract → blood towards valves forcing them open
2. Action potential → antrioventricular (AV) node → holds signal for blood to flow into ventricles → signal to bundle of His → branches through septum (left/right) → apex and around ventricles
3. Contraction of ventricles (starting in apex) → blood pushed upwards → valves force open → out to the body

Question 4

ECG and CARDIAC CYCLE

Answer 4

• ECG records heart frequency shown in waves: **P-wave* = depolarization of atrium → contraction
QRS-complex = ventricular depolarization → contraction
T-wave = ventricular repolarization → befor relax
• Systole = Chambers are emptied → Blood out to body
• Diastole = relaxation of ventricles → blood fill atria and then ventricles fills up

Question 5

Cardiac output

Answer 5

• Blood volume pumped out of left ventricle per minute
• Stroke volume = blood volume per heart beat: end diastolic volume- end systolic volume (ventricles)
• Heart rate = heartbeats per minute ~ 75 at rest
Heart rate × stroke volume = cardiac output

Question 6

Regulation

Answer 6

• Input to cardiovascular center from: cerebral cortex, limbic system, and hypothalamus and receptors
• Output via vagus nerve (10) (parasympathetic) → decreases heart rate; or sympathetic nerves (cardiac accelerator nerves) → increased heartrate and force (increased stroke volume)

Question 7

BLOOD VESSELS

Answer 7

• Arteries = blood away from heart
• ArterioIs = smaller branches of arteries
• Capillaries = microscopic branches of arterioIs
• Venules = uniting capillaries
• Veins = uniting venules, blood to heart

Question 8

Circulation

Answer 8

• Pulmonary = blood to/from lungs
• Systemic = blood to/from rest of the body
• Coronary = blood supplying heart, contain vessels branch from ascending aorta

Question 9

Trans-capillary exchange

Answer 9

• Artriols regulate flow from arteries → capillaries by vasoconstriction and vasodilation
• First blood pressure bigger than osmotic pressure in capillaries → water + nutrients filtrated out → then blood’s concentration of particles get higher than in interstitial fluid → water + wastes from cells to capillaries by osmosis
• Exchange also happens through diffusion

Question 10

Venous return

Answer 10

• Blood pressure drops when passed capillaries and close to 0 when entering righ atrium
→ Atria “sucks” blood in when ventricles contract
→ Respiratory pumps: inhalation → abdominal veins compress and thoracic decompress → blood transported to right atrium
→ Skeletal muscle pumps: contraction help blood back to heart, ex. in legs → veins have valves stopping blood flow downwards → muscle help too

Question 11

Blood pressure

Answer 11

• Needed to push/transport blood throughout the body
• Created by vascular resistance: depends on size of lumen, total vessel length, and blood viscosity
• Systolic = pressure against arteries walls during systole period (contraction)
• Diastolic = pressure against arteries during diastolic periosd (relaxation)

Question 12

THE LYMPHATIC SYSTEM

Answer 12

• Drains excess interestial fluid
• Transports dietary lipids and lipid-soluble vitamines into blood
• Initiates immune responses → protects from invasion

Question 13

Blood pressure - regulation

Answer 13

• Baroreceptors detect changes in pressure → input to cardiovascular center
→ sympathetic output through = vasoconstriction increasing blood pressure
→ parasympathetic output = vasodilation decreasing blood pressure
→ RAAS: Renin from kidneys → angiotensinogen in liver turn to angiotensin 1 → angiotensin 2 in capillaries → stimulates hypothalamus → ADH + thirst → more H2O → increased blood pressure