Exam #2 BIOL 1015

Exam Objectives
· Major functions of the heart

· Size, shape and location of the heart

· Location of the heart
· Why is this important?
· Describe the structure of the pericardium
The pericardium is a protective sac around the heart made up of two main layers:
Fibrous Pericardium: The tough outer layer that anchors the heart and prevents it from over-
expanding.
Serous Pericardium: The inner layer, which has two parts:
Parietal Layer: Lines the inside of the fibrous layer.
Visceral Layer (Epicardium): Covers the heart itself.
Between these layers is the pericardial cavity, filled with a small amount of fluid that helps reduce
friction as the heart beats.
· What are the layers of the heart wall
Epicardium: The outer layer that protects the heart.
Myocardium: The middle layer made of muscle, responsible for pumping blood.
Endocardium: The inner layer that lines the heart chambers and valves, providing a smooth surface.
Reduces friction for smooth blood flow.
· How are the visceral and parietal pericardium different?
Visceral Pericardium: Also called the epicardium; it covers the heart directly.
Parietal Pericardium: Lines the outer sac around the heart.
· Describe the location and blood flow through the coronary arteries.
The coronary arteries are located on the surface of the heart and branch off from the aorta, just above
the aortic valve. There are two main arteries:
Left Coronary Artery (LCA): Divides into:
Left Anterior Descending (LAD) Artery: Supplies the front of the heart.
Circumflex Artery (LCx): Supplies the side and back of the heart.
Right Coronary Artery (RCA): Supplies the right side of the heart.
Starts at the Aorta: Blood is pumped from the heart into the aorta.
Enters Coronary Arteries: Blood flows into the left and right coronary arteries.
Distributes Blood:
The LCA supplies the left side of the heart.
The RCA supplies the right side.
Capillary Exchange: Blood reaches small vessels (capillaries) where oxygen and nutrients are delivered
to the heart muscle.
Returns via Veins: Used blood returns through cardiac veins to the coronary sinus and into the right
atrium.
This process keeps the heart muscle well-supplied with oxygen and nutrients.
· Review the structure and functions of the chambers of the heart.
· Name the valves of the heart and state their locations and functions.
· Relate the flow of blood through the heart, naming the chambers, valves, and vessels in
the correct order.
· Describe the structure and functions of the heart skeleton.

Structure:

The heart skeleton is made of dense connective tissue.

It consists of four fibrous rings around the heart valves:

Aortic Ring: Around the aortic valve.

Pulmonary Ring: Around the pulmonary valve.

Right Atrioventricular Ring: Around the tricuspid valve.

Left Atrioventricular Ring: Around the mitral valve.

Functions:

Support: Keeps the heart's shape and prevents overexpansion.

Anchoring Valves: Holds heart valves in place for proper function.

Electrical Insulation: Separates the atria from the ventricles, ensuring coordinated contractions.

Attachment Point: Provides a site for heart muscle to attach.

· Relate the structural and functional characteristics of cardiac muscle cells.

Structure:

Striated: Cardiac muscle cells have a striped appearance due to organized fibers.

Intercalated Discs: Connect cells to each other, allowing for synchronized contractions.

Single Nucleus: Typically have one nucleus per cell.

Branching: Cells are branched to form a network.

Functions:

Involuntary Contraction: Contracts automatically without conscious control.

Pacemaker Activity: Some cells can generate electrical impulses, starting heartbeats.

Efficient Contraction: Rapid transmission of signals ensures all heart parts contract together.

Fatigue Resistance: Rich in mitochondria, allowing sustained contractions for continuous heart
function.

Together, the heart skeleton and cardiac muscle cells ensure the heart pumps blood effectively.

· Compare and contrast cardiac muscle and skeletal muscle.

Similarities: Both types of muscle are striated and help with movement (pumping blood for cardiac
muscle, moving limbs for skeletal muscle).

Differences: Cardiac muscle works automatically and has special structures for coordination, while
skeletal muscle is controlled by your brain and can tire more easily.

· How is muscle contraction initiation different for each?

Cardiac muscle contracts automatically; skeletal muscle needs nerve signals to contract.

· Explain what is meant by the auto rhythmicity of cardiac muscle and relate it to the pacemaker
potential.
Auto rhythmicity allows the heart to beat automatically. This happens through pacemaker potential,
where specific cells create signals that lead to heart contractions.

· What are the steps for action potentials in cardiac muscle?

Action potentials in cardiac muscle involve a rapid depolarization due to sodium influx, a plateau
phase from calcium influx, and repolarization from potassium efflux, allowing the heart to contract
and reset for the next beat.

· What are the steps for action potential initiation for the Pacemaker?

Pacemaker cells initiate action potentials through a gradual depolarization, reaching a threshold that
triggers rapid calcium influx, followed by repolarization through potassium efflux, setting the stage for
the next heartbeat.

· Explain the importance of a long refractory period in cardiac muscle.

· Absolute - Prevents Tetany: It ensures that the heart muscle cannot undergo
tetany (sustained contraction), which would stop the heart from pumping
effectively. Allows for Filling: The heart has enough time to relax and fill with
blood before the next contraction, ensuring efficient blood flow.

· relative - Flexibility: It allows for the possibility of increased heart rate under
certain conditions (like exercise) when a stronger stimulus is present.
Prevention of Erratic Activity: It helps to prevent arrhythmias by ensuring that
the heart does not contract too frequently or erratically.

· Describe the waves and intervals of an electrocardiogram.

The P wave shows atrial depolarization, the QRS complex indicates ventricular depolarization, and the
T wave represents ventricular repolarization. Key intervals like the PR, QT, and RR intervals help assess
heart function and rhythm.

· Describe the cardiac cycle and the relationship among the contraction of each of the chambers,
the opening and closing of valves, the pressure in each of the chambers, the phases of the
electrocardiogram, and the heart sounds.

Contraction and Relaxation: The heart chambers contract and relax in a coordinated manner to
facilitate blood flow.
Valve Opening and Closing: The opening and closing of the valves prevent backflow and ensure one-
way blood movement.

Pressure Changes: Pressure increases during contraction (systole) and decreases during relaxation
(diastole).

Electrocardiogram Phases: The electrical activity (ECG) corresponds to specific phases of the cardiac
cycle, aiding in timing the contractions.

Heart Sounds: The "lub" sound occurs with AV valve closure during ventricular systole, and the "dub"
sound occurs with semilunar valve closure during isovolumetric relaxation.

· Discuss the heart sounds and their significance.

Heart sounds provide valuable information about cardiac function and health. The first and second
sounds indicate normal valve function and the phases of the cardiac cycle, while additional sounds like
S3 and S4 can signal potential heart problems. Clinicians often listen for these sounds during a physical
examination to assess heart conditions.

· Define mean arterial pressure, cardiac output, and peripheral resistance.

Mean Arterial Pressure (MAP) reflects average arterial pressure and is crucial for organ perfusion.

Cardiac Output (CO) measures the heart's pumping efficiency and is influenced by stroke volume and
heart rate.

Peripheral Resistance (PR) indicates the resistance against blood flow in the vessels, impacting blood
pressure regulation.

· Explain the role of MAP in causing blood flow.

Mean Arterial Pressure (MAP) is essential for driving blood flow through the circulatory system. It
ensures adequate perfusion of organs by acting as the primary pressure gradient for blood flow.
Through its relationship with cardiac output and peripheral resistance, MAP helps maintain stable
blood flow under varying physiological conditions.

· Distinguish between pulmonary and systemic vessels.

Pulmonary vessels are involved in gas exchange, transporting deoxygenated blood to the lungs and
returning oxygenated blood to the heart at lower pressure. In contrast, systemic vessels distribute
oxygenated blood to the body and return deoxygenated blood to the heart at higher pressure.

· Trace the path of blood flow in pulmonary circulation.

In pulmonary circulation, deoxygenated blood flows from the body to the right atrium, then to the
right ventricle, and is pumped through the pulmonary arteries to the lungs for oxygenation. The
oxygenated blood then returns to the left atrium via the pulmonary veins, completing the cycle.

· Define blood pressure

Blood pressure is the force of blood against vessel walls, measured in mmHg, and expressed as systolic
over diastolic values. It is vital for assessing cardiovascular health and regulating blood flow.

· How is it measured?

Blood pressure is measured using a sphygmomanometer, which includes an inflatable cuff and a
pressure gauge. The cuff is inflated to stop blood flow, then gradually deflated while listening for the
first sound (systolic pressure) and when the sound disappears (diastolic pressure). Digital devices
automate this process for convenience.

· Summarize Poiseuille’s law

Poiseuille’s Law describes how blood flow through vessels is affected by radius, pressure difference,
fluid viscosity, and vessel length, highlighting the significant impact of vessel diameter on flow rate.

· Explain how blood pressure and resistance to flow change as blood flows through the
blood vessels.

Blood Pressure: High in arteries, decreases in arterioles, continues to drop in capillaries, and is lowest
in veins.

Resistance to Flow: Low in arteries, high in arterioles (where most regulation occurs), and lower in
capillaries and veins. The dynamic regulation of vessel diameter, especially in arterioles, plays a crucial
role in controlling blood pressure and flow throughout the circulatory system.

· List the functions of the circulatory system.

The circulatory system plays a vital role in transporting nutrients, gases, hormones, and waste
products, supporting immune function, regulating temperature and pH, and maintaining overall
homeostasis in the body.
 · List the types of arteries, capillaries and veins

Arteries: Elastic arteries (e.g., aorta), muscular arteries (e.g., brachial), arterioles.

Capillaries: Continuous capillaries, fenestrated capillaries, sinusoidal capillaries.

Veins: Venules, medium-sized veins (e.g., femoral vein), large veins (e.g., superior vena cava).

· Major arteries

Major arteries include the aorta, pulmonary arteries, coronary arteries, carotid arteries, subclavian
arteries, brachial artery, and others that branch out to supply various regions of the body.

· Major veins

Major veins include the superior and inferior vena cavae, coronary sinus, jugular veins, subclavian
veins, brachiocephalic veins, and various veins in the arms and legs.

· List the major veins that carry blood away from each of the body areas

Head and Neck: Internal jugular, external jugular.

Upper Limbs: Subclavian, brachial, radial, and ulnar veins.

Thorax: Brachiocephalic, hepatic veins.

Abdomen: Renal veins, inferior mesenteric, superior mesenteric veins.

Lower Limbs: Femoral, popliteal, anterior tibial, posterior tibial, great saphenous veins.

· Compare laminar and turbulent blood flow.

Laminar Flow: Smooth, efficient, and orderly; ideal for normal blood circulation.

Turbulent Flow: Chaotic and inefficient; associated with higher resistance and potential health issues.

· Relate Laplace’s law to critical closing pressure.

Laplace’s Law explains how the tension in a vessel wall relates to internal pressure and vessel radius,
while critical closing pressure indicates the minimum pressure required to keep a vessel open. The two
concepts are interconnected; as internal pressure decreases, it may fall below critical closing pressure,
especially in smaller vessels, leading to vessel collapse and impaired blood flow.
 · Define pulse pressure.

Pulse pressure is the difference between systolic and diastolic blood pressure, reflecting the health of
the cardiovascular system and providing important information about heart function and vascular
condition.

· List locations on the body where the pulse can be detected.

Wrist, on the thumb side.

Neck, beside the trachea.

Groin, where the thigh meets the pelvis.

Behind the knee.

Top of the foot, between the first and second metatarsal bones.

Inside of the ankle, just behind the medial malleolus (the bony prominence).

Side of the forehead, above the ear.

Inner side of the upper arm.

· Describe the exchange of materials across a capillary wall.

Exchange across capillary walls occurs through diffusion, filtration, reabsorption, and transcytosis,
enabling the transfer of gases, nutrients, waste, and other substances between blood and tissues.

· Define: mean arterial pressure, cardiac output, and peripheral resistance.

Mean Arterial Pressure (MAP): Average arterial pressure during the cardiac cycle; essential for organ
perfusion.

Cardiac Output (CO): Total blood pumped by the heart per minute; reflects heart efficiency.

Peripheral Resistance (PR): Resistance to blood flow in blood vessels; influenced by vessel diameter
and blood viscosity.

· Explain how preload, venous tone, and gravity affect cardiac output.

Preload: Increased venous return enhances preload, leading to higher cardiac output; decreased
venous return has the opposite effect.
Venous Tone: Greater venous constriction increases venous return and cardiac output; decreased tone
can reduce both.

Gravity: Affects blood distribution; standing can decrease venous return and cardiac output, while
lying down can enhance them.

· Explain how nervous mechanisms control blood flow.

Nervous mechanisms control blood flow through the autonomic nervous system, with the sympathetic
division primarily responsible for vasoconstriction and increased heart rate, while the parasympathetic
division promotes vasodilation and a decreased heart rate. Baroreceptors and chemoreceptors play
essential roles in maintaining blood pressure and adjusting blood flow based on the body's needs,
while local control mechanisms allow tissues to regulate their own blood supply.

· Explain how hormonal mechanisms control blood flow.

Hormonal mechanisms regulate blood flow through various hormones, including epinephrine,
norepinephrine, renin-angiotensin-aldosterone, ADH, and ANP. These hormones influence
vasoconstriction, vasodilation, and fluid balance, thereby playing critical roles in maintaining blood
pressure and ensuring adequate blood flow to tissues.

· Describe the short-term mechanisms that regulate arterial blood pressure.

· Describe the long-term mechanisms that regulate arterial blood pressure.

· Describe the functions of the lymphatic system.

· Parts of lymphatic system

· Structure of lymphatic vessels

· How lymph is formed and transported through the vessels

· Lymphatic tissues versus organs

· Structure and function of:

· Tonsils

· Lymph nodes

· Spleen
 · Thymus

· Define:

· Antigen

· Innate immunity

· Inflammation

· Antibody mediated immunity

· Cell mediated immunity

· Immunotherapy

· Describe the three components of innate immunity.

· Describe the chemical mediators and cells involved with innate immunity.

· Distinguish between the general characteristics of innate immunity and adaptive immunity.

· Types of white blood cells involved in innate immunity

· Explain the role of haptens in allergic reactions.

· Describe the origin, development, activation, proliferation, and inhibition of lymphocytes.

· Describe the function of major histocompatibility complex (MHC) molecules in immunity.

· Distinguish between MHC class I molecules and MHC class II molecules.

· Diagram the structure of an antibody.

· Describe the effects produced by antibodies.

· Discuss the primary and secondary responses to an antigen and explain the basis for long-lasting
immunity.

· Describe the types and functions of T cells.