BIOL 320 Lecture Exam 2

What is the size and location of the heart?

Size - about the shape of a fist

Location - mediastinum, base sits along the diaphragm, apex sits left of the midline, posterior to the sternum

What are the “great vessels”?

Aorta, superior vena cava, inferior vena cava, pulmonary arteries, pulmonary veins

What are the layers of the pericardium?

1. Fibrous pericardium: dense connective tissue that anchors the heart

2. Parietal pericardium:

   1. Serous: epithelium

   2. Visceral/epicardium: lines the heart

What is pericarditis?

Inflammation/irritation of the pericardial cavity, which separates the serous and visceral layers of the pericardium

What is the function of heart valves in a relaxed heart?

Use gravity to drain blood from veins into the atria and ventricles. The cusps of SL valves catch blood and close under its weight.

What do the valves do when the atria contract?

Squeeze remaining blood from atria into ventricles

What do the valves do when the ventricles contract?

1. Pressure pushes AV valve flaps up

2. Papillary muscle contracts, keeping AV valves closed

3. Blood has to find alternate path through the SL valves

What are the “lub” and “dub” sounds of the heart?

Lub = AV valves closing

Dub = SL valves closing

What is occurring if a heart murmur is heard?

Turbulent blood flow through valves, delayed closing of the valves

Valve stenosis

Narrowing of the atrial semilunar valve that reduces blood flow from left ventricle through the aorta. Causes the heart to have to pump extra hard.

What are the branches of the left coronary artery?

1. Anterior interventricular artery

2. Left marginal artery

3. Circumflex artery

What are the branches of the right coronary artery?

1. Right marginal artery

2. Posterior interventricular artery

What three veins drain the heart?

1. Great cardiac vein: empties left side of the heart

2. Middle cardiac vein: empties from the back/both ventricles of the heart

3. Small cardiac vein: empties right side of the heart

Coronary sinus

Collects blood from the great, middle, and small cardiac veins and empties them into the right atrium

Anastomosis

Connection between 2 arteries that allows blood to continue flowing without passing through capillary beds

What does the intercalated disk structure of cardiac muscle allow for?

The desmosomes and gap junctions between the intercalated disks allows for the quick transmission of electrical signals between the cells

Functional synctium

Electrically, atria and ventricles act as a single unit

How does the sympathetic nervous system regulate heart rate?

contains the cardioacceleratory center (CAC)

• innervation point: all cardiac muscle, SA and AV nodes

• neurotransmitter: norepinephrine

How does the parasympathetic nervous system regulate heart rate?

contains cardioinhibitory center (CIC)

• innervation point: SA and AV node

• cranial nerve: vagus nerve

• neurotransmiter: acetylcholine

What is the Bainbridge reflex?

Baroreceptors in the atria are constantly measuring pressure and send that information to the cardioacceleratory center

• if BP is too low, the CAC will cause SA node to fire more and cause an increase in pressure

Endocrine regulation

Epinephrine: rapid, brief increase in heart rate

Thyroxine: causes a gradual, long-term increase in heart rate

Electrocardiography

P wave: atrial depolarization

QRS complex: ventricular depolarization

T wave: ventricular repolarization

Arrhythmia

Characteristics: irregular, uncoordinated heartbeat

Common causes: nicotine, caffeine

Fibrillation

Characteristics: rapid, irregular, uncoordinated contraction; no blood movement

Defibrillation: Resets the conduction system

AFib vs VFib

Ventricular fibrillation is significantly more dangerous

Ectopic focus

A pacemaker forms at a location other than the SA node. May be caused by irregular function of SA node or blockage in conductivity system

Bradycardia

Characteristics: very low HR, <60 bpm

Common causes: drugs, athlete, used as warning sign of brain edema after head trauma

Tachycardia

Common characteristics: rapid HR >100bpm, may lead to VFib

Common causes: high temperature, stress, drugs, heart disease

What is the preload?

Length of the myocytes of the ventricles stretch before contraction

Frank Starling Law of the Heart

Stroke volume increases in proportion to an increase in the volume of blood filling the heart

What is afterload?

The resistance that ventricles must overcome to open the semilunar valves during contraction

• If someone has chronically high BP, the left ventricle will get worn out over time working against the high blood volume of the aorta

Ventricular septal defect

1 in 500 births

Superior interventricular septum fails to form, blood mixes between two ventricles, more blood is shunted form left to right because left ventricle is stronger

Coarctation of the aorta

1 in 1500 births

Part of aorta is narrowed, increasing workload of left ventricle

Tetralogy of Fallot

1 in 2000 births

1. Pulmonary trunk too narrow

2. Hypertrophied right ventricle

3. Ventricular septal defect

4. Aorta opens from both ventricles

Sclerosis & thickening of valve flaps

Common site: mitral valve

Result: heart murmur

Cardiac reserve decline

Less able to respond to sudden and prolonged stresses that increase cardiac output

sympathetic control: more variable

heart rate: declines

Fibrosis of cardiac muscle

cardiac cells die

stroke volume: reduced

fibrosis of nodes → increased arrhythmias

Atherosclerosis

Buildup of plaque in artery walls

Factors: inactivity, smoking, stress, high cholesterol

Consequences: hypertensive heat disease, coronary artery occlusion

Risks: heart attack, stroke

Arteriosclerosis

Any hardening/stiffening of the arteries

What is the purpose of the physical characteristics of elastic arteries?

Decrease shock and smooth outflow of blood; aorta, pulmonary arteries

Do elastic arteries vasoconstrict?

No

Precapillary sphincters

Adjust blood flow into the capillaries in response to blood content levels

Thoroughfare channels

Low-resistance route through capillary bed that connects venous side to arterial side, allowing blood to bypass capillary bed

Pericytes

Smooth, muscle-like cells that stabilize the walls of capillaries

What tissues don’t have capillariy beds?

Tendons and ligaments are poorly supplied, eyeballs and cartilage lack them entirely

What are the three types of capillary wall structures?

1. Continuous: clefts between cells, most abundant, used to transport solutes

2. Fenestrated: small gaps b/w cells, pores allow movement of macromolecules in and out

3. Sinusoidal: big gaps b/w cells, found in tissues involved in blood development, transport solutes, fluid, cells, are loose and leaky

What does it mean when you say arteries can’t have their “faucet wide open”?

There’s not enough blood to cover the entire body equally, so arteries “time-share” blood

What are arterioles?

Small, muscular arteries that connect to capillary networks

Why are varicose veins and hemorrhoids similar?

Both involve pooling of blood due to the weakening or rupture of venous valves

What is vascular anastomosis?

A surgery that connects two blood vessels together

Blood flow definition

volume of blood moving through a defined area

Blood pressure definition

The force exerted on a vessel wall

Resistance definition

Opposition to blood flow

What are the three factors that impact resistance?

1. Viscosity: thickness; higher thickness = higher resistance

2. Blood vessel length: longer = higher resistance

3. Blood vessel diameter: wider = lower resistance

What is laminar flow?

An even flow, blood concentrated in the center of the vessel

What is turbulent flow?

Blood flows in several directions, closer to vessel walls, increasing resistance; this is the reason we can hear heart valves closing

Name the mechanisms that regulate blood pressure long-term

1. Renin-angiotensin-aldosterone mechanism

2. Vasopressin (ADH) mechanism

3. Atrial natriuretic mechanism

4. Fluid shift mechanism

5. Stress-relaxation response

What is Poiseuille’s Law?

The speed of a liquid flowing through a tube depends on the liquid’s viscosity, the size of the tube, and the pressure behind the liquid

Laplace’s Law and critical closing pressure

Laplace’s Law describes the wall tension and pressure needed to keep a tube from collapsing; critical closing pressure is the blood pressure needed to keep vessels from collapsing

What is the percent distribution of blood in each systemic vessel type?

Systemic arteries: 15%

Systemic veins: 60%

What is the relationship between cross-sectional area of blood vessels and the rate of blood flow?

The more cross-sectional areas there are, the lower the velocity of blood flow.

Pulse pressure definition

Systolic - Diastolic BP

What areas of the body can pulse be detected?

1. Temporal

2. Carotid

3. Apical (chest)

4. Brachial

5. Radial

6. Femoral

7. Popliteal

8. Posterior tibial

9. Dorsalis pedis

How does preload affect cardiac output?

Preload generally increases CO because it increases stroke volume (CO = HR x SV)

How does venous tone affect cardiac output?

Venous tone is determined by vasoconstrictors and vasodilators; dilation/constriction of vessels affects blood pressure

How does gravity affect cardiac output?

When standing, blood pressure increases below the heart and decreases above the heart (eg orthostatic hypotension)

Hematocrit definition

Level of erythrocytes in the bloodstream

Short-term blood pressure regulation mechanisms

1. Baroreceptors: if BP is too high, baroreceptors send inhibitory signals to CAC; if BP is too low, baroreceptors stop signaling and allow CAC to work uninhibited

2. Chemoreceptors: respond to changes in oxygen, co2, pH

3. CNS ischemic response: if BP drops below 50mmHg, vasomotor in medulla activates and stimulates the sympathetic nervous system to do intense vasoconstriction

Long-term blood pressure regulation mechanisms

1. RAAS: raises BP by releasing renin → angiotensin II → kidneys reabsorb more sodium & water, increasing BP

2. ADH: raises BP by directly causing kidneys to reabsorb more water

3. ANH: atrial natriuretic hormone is released when BP is too high, causing kidneys to excrete sodium → water follows in urine

Where are lymphatic vessels NOT found?

Bone marrow, corneas, CNS, cartilage, epidermis

What function does lymphatic capillaries’ loose attachments hold?

1. Allows all interstitial fluid to permeate it

2. Overlapping cells act as valves for one-way flow

What are the primary lymphatic organs?

Red bone marrow and thymus

Where to B cells and T cells become immunocompetent?

B cells = red bone marrow

T cells = thymus

What are the secondary lymphatic organs/tissues?

Tonsils, lymph nodes, spleen

What distinguishes lymphatic tissue from a lymphatic organ?

Lymphatic organs are encapsulated, tissue are diffuse

What are the three types of tonsils?

1. Palatine: posterior oral cavity

2. Pharyngeal (adenoids when swollen): top back wall of throat

3. Lingual: base of tongue; becomes less infected/removed less often than the other 2

What fills the trabeculae compartments of the spleen?

White pulp (surrounds arteries in spleen; 1/4) and red pulp (surrounds veins in spleen; 3/4)

Splenic funtions

Destroying defective RBC, responding to foreign substances in the bloodstream, blood reservoir, stores & releases platelets

How do the splenic cords aid with circulation?

During exercise or an emergency, splenic cords eject 40-50% of blood into bloodstream

What regions are lymph nodes most concentrated in?

1. Inguinal

2. Axillary

3. Cervical

Peyer’s Patches

Group of lymphoid follicles in small intestine that destroy bacteria, prevent breach of intestinal wall, generate “memory” lymphocytes

MALT (Mucosa-associated lymphatic tissue)

Peyer’s patches, tonsils, appendix, lymphoid nodules in bronchials

Adaptive immunity

Response to foreign substances is faster and stronger after the first time

Innate immunity

Body recognizes and responds to foreign substances with the same intensity each time

1. Physical barriers (external defenses)

2. Internal defenses

What are some specific surface barriers?

Skin, stomach, vagina (all have low pH), tears, saliva, mucous

What are the types of internal innate immunity?

Phagocytes, killer cells, inflammation, antimicrobes

What must occur before phagocytosis can be done?

Phagocytes MUST adhere to the pathogen

What are the four cardinal signs of inflammation?

Redness, heat, pain, swelling

What are the benefits of inflammation?

Prevent spread of damaging agents, dispose of cell debris, enhances tissue repair

Antigen

Mobilizes adaptive defense and provokes immune response

Characteristics of complete antigens

Immunogenicity: stimulates lymphocyte proliferation

Reactivity: can react with lymphocytes and antibodies