Cardiovascular Anatomy Quiz

Heart Location and Orientation

• Located between the lungs in the thoracic cavity
• Apex (bottom) of the heart points towards the left side

Pericardium

• Double-layered sac that anchors and protects the heart
• Parietal pericardium: membrane surrounding the heart's cavity
• Visceral pericardium: membrane on the heart's surface
• Pericardial Cavity: space around the heart

Heart External Anatomy

• Coronary sulcus divides the atria from the ventricles
• Anterior interventricular sulcus extends inferiorly from the coronary sulcus on the heart's anterior surface
• Posterior interventricular sulcus extends inferiorly from the coronary sulcus on the heart's posterior surface
• Superior vena cava and inferior vena cava carry blood from the body to the right atrium
• Four pulmonary veins carry blood from the lungs to the left atrium
• Two great arteries (aorta and pulmonary trunk) carry blood away from the heart's ventricles

Cardiac Skeleton

• Provides structural support and electrical insulation between the atria and ventricles
• Made of dense connective tissue

Blood Flow Through Heart

• Blood flow through the heart is a unidirectional cycle
• 1. Right atrium (RA)
• 2. Tricuspid valve
• 3. Right ventricle (RV)
• 4. Pulmonary semilunar valve
• 5. Pulmonary trunk
• 6. Pulmonary arteries
• 7. Lungs
• 8. Pulmonary veins
• 9. Left atrium (LA)
• 10. Bicuspid valve
• 11. Left ventricle (LV)
• 12. Aortic semilunar valve
• 13. Aorta
• 14. Body

Blood Supply to the Heart

• Coronary arteries supply blood to the heart wall
• Originate from the base of the aorta
• Left coronary artery:
  • Has three branches
  • Supplies blood to the anterior heart wall and left ventricle
• Right coronary artery:
  • Originates on the right side of the aorta
  • Supplies blood to the right ventricle
• Cardiac veins drain blood from the cardiac muscle
• Parallel to the coronary arteries
• Most drain into the coronary sinus, which empties into the right atrium

Heart Wall

• Three layers:
  • Epicardium: outer layer
  • Myocardium: middle layer, composed of cardiac muscle
  • Endocardium: inner, smooth layer

Cardiac Muscle

• Contains one centrally located nucleus
• Branching cells
• Rich in mitochondria
• Striated due to actin and myosin
• Uses calcium and ATP for contractions
• Intercalated disks connect cells

Cardiac Muscle Action Potentials

• Responsible for producing action potentials
• Three phases:
  • Depolarization: Na+ channels open, then Ca2+ channels open
  • Plateau phase: Na+ channels close, some K+ channels open, Ca2+ channels remain open
  • Repolarization: K+ channels open, Ca2+ channels close
• Plateau phase prolongs action potentials by keeping Ca2+ channels open

Conduction System of Heart

• Specialized cardiac muscle cells coordinate atrial and ventricular contractions
• All cells in the system can produce spontaneous action potentials
• Conduction system includes:
  • Sinoatrial (SA) node: pacemaker of heart
  • Atrioventricular (AV) node: delays signal to allow ventricles to fill
  • Atrioventricular bundle: conducts signal to ventricles
  • Right and left bundle branches: conduct signal to specific ventricular areas
  • Purkinje fibers: rapidly distribute signal throughout ventricular walls

Electrocardiogram (ECG/EKG)

• Records electrical events in the heart
• Used to diagnose cardiac abnormalities
• Uses electrodes to measure electrical activity
• Components:
  • P wave: atrial depolarization
  • QRS complex: ventricular depolarization (includes Q, R, and S waves)
  • T wave: ventricular repolarization

Cardiac Cycle

• Includes all events during one heartbeat
• Heart is a two-sided pump:
  • Atria are primer pumps
  • Ventricles are main pumps

Heart Chamber Contractions

• Pressure changes within heart chambers drive blood movement
• Blood moves from high pressure to low pressure

Events of the Cardiac Cycle

• Atrial systole (contraction of atria)
• Ventricular systole (contraction of ventricles)
• Atrial diastole (relaxation of atria)
• Ventricular diastole (relaxation of ventricles)

Heart Sounds

• Produced by the closure of heart valves
• First heart sound ('lubb'): closure of atrioventricular valves
• Second heart sound ('dupp'): closure of semilunar valves

Regulation of Heart Function

• Stroke volume: volume of blood pumped per ventricle per contraction (average 70 milliliters/beat)
• Heart rate: number of heart beats in 1 minute (average 72 beats/min)
• Cardiac output: volume of blood pumped by a ventricle in 1 minute (average 5 liters/min)

Endocrine System

• The endocrine system is composed of endocrine glands and cells that secrete hormones directly into the bloodstream.
• Hormones are chemical messengers that stimulate specific target cells containing receptors for that hormone.
• Hormones have varied effects on the body, influencing metabolism, tissue development, ion regulation, and reproductive functions.

Cellular Secretion Types

• Autocrine: Cells secrete substances that affect the same cell type.
• Paracrine: Cells secrete substances to affect nearby cells of a different type.
• Neurotransmitter and neuromodulators: Secreted by nerve cells influencing nervous system function.
• Hormones and neurohormones: Secreted into the bloodstream to bind to receptor sites.

Characteristics of the Endocrine System

• The endocrine system helps control and regulate various bodily functions.
• Hormones are regulated by feedback mechanisms, either positive or negative.
• Positive Feedback: The response amplifies the initial stimulus, as seen in tropic hormones.
• Negative Feedback: The response opposes the initial stimulus, maintaining a steady state.

Types of Hormone Receptors

• Lipid-soluble hormones: Binds to nuclear receptors due to their ability to pass through the cell and nuclear membrane.
• Water-soluble hormones: Bind to membrane-bound receptors as they cannot pass through the cell membrane.

Signal Amplification

• A single hormone can activate multiple second messengers, triggering a cascade effect, leading to the production of large amounts of final product. This is highly efficient.

Pituitary Gland

• The pituitary gland is located in the brain.
• It is divided into anterior and posterior regions, each responsible for distinct hormone secretion.
• The anterior pituitary is regulated by the hypothalamus and produces several hormones.
• The posterior pituitary stores and releases two hormones, antidiuretic hormone (ADH) and oxytocin.

Hormones & Their Functions

• Antidiuretic Hormone (ADH): Conserves water in the kidneys, released from the posterior pituitary.
• Oxytocin: Stimulates uterine contractions during labor, also released from the posterior pituitary.
• Thyroid Gland: Produces thyroid hormone and calcitonin.
• Thyroid Hormone: Regulates metabolic rates and is needed for growth.
• Calcitonin: Reduces blood calcium levels.
• Pancreas: Houses pancreatic islets responsible for hormone secretion.
• Insulin: Regulates blood glucose levels, secreted by beta cells.
• Glucagon: Regulates blood glucose levels, secreted by alpha cells.
• Somatostatin: Secreted by delta cells in the pancreas.
• Testosterone: Supports sperm and reproductive organ development and function, secreted by the testes.
• Estrogen and Progesterone: Involved in uterine and mammary gland development and the menstrual cycle, secreted by the ovaries.
• Thymosin: Promotes immune system development and function, secreted by the thymus.
• Melatonin: Regulates circadian rhythms, secreted by the pineal gland.

Test your knowledge on the structure and orientation of the heart, including its external anatomy and protective coverings. This quiz will cover key components like the pericardium, major vessels, and the cardiac skeleton. Perfect for students of anatomy and physiology.