Ch. 48 Cardiovascular System
Introduction
- The cardiovascular system is the transportation system of the body
- It is comprised of blood, heart, and blood vessels
- The system supplies nutrients to and removes waste products from various tissues of the body
- The conveying media is liquid in form of blood which flows in a closed tubular system
Function of the Cardiovascular System
- Transport nutrients, hormones
- Remove waste products
- Gaseous exchange
- Immunity
- Blood vessels transport blood
- Carries oxygen and carbon dioxide
- Also carries nutrients and wastes
- Heart pumps blood through blood vessels
Components of the Cardiovascular System
- Blood
- Heart
- Blood vessels
Blood
- Made up of blood cells and plasma
- Blood cells:
- Erythrocytes (red blood cells)
- Leukocytes
- Thrombocytes (platelets)
- Plasma is the fluid portion
Heart
- The heart is a four chambered, hollow, muscular organ approximately the size of your fist
- Location:
- Superior surface of diaphragm
- Left of the midline
- Anterior to the vertebral column, posterior to the sternum
Functions of the Heart
- Generating blood pressure
- Routing blood
- Heart separates pulmonary and systemic circulations
- Heart valves ensure one-way blood flow
- Regulating blood supply
- Changes in contraction rate and force match blood delivery to changing metabolic needs
Blood Vessels
- A closed network of tubes
- This includes:
- Arteries (Distributing Channels)
- Thick walled tubes
- Elastic fibers
- Circular smooth muscle
- Capillaries (Miscroscopic Vessels)
- One cell thick
- Serves the Respiratory System
- Veins (Draining Channel)
- General Structure:
- Tunica intima
- Tunica media
- Tunica adventitia
Classification of Blood Vessels
- Conducting Vessels
- Distributing Vessels
- Resistance Vessels
- Exchange Vessels
- Capacitance/Reservoir Vessels
Arteries
- Blood vessels that carry blood away from the heart are called arteries
- They are the thickest blood vessels and they carry blood high in oxygen known as oxygenated blood
- Lumen is small
- No valves
- Repeated branching
Classification of Arteries
- Elastic- ex. Aorta and its major branches
- Muscular- ex. Renal, Testicular, Radial, Tibial
- Arterioles (
Capillaries (5-8 micron)
- The smallest blood vessels are capillaries and they connect the arteries and veins
- This is where the exchange of nutrients and gases occurs
- Two kinds of Capillaries:
- Continuous- skin, lung, smooth muscle, connective tissues
- Fenestrated- pancreas, endocrine glands, small intestine, choroid plexus, cilliary process etc
Sinusoids
- Sinusoids- large irregular vascular space (30-40 micron) ex. liver, spleen, bone marrow, suprarental, parathroid
Veins
- Blood vessels that carry blood back to the heart are called veins
- They have one-way valves which prevent blood from flowing backwards
- They carry blood that is high in carbon dioxide known as deoxygenated blood (low oxygen blood)
- Thin walled
- Large irregular lumen
- Have valves
- Dead space around
- Types:
- Some veins don’t have valves
- Some veins don’t have muscular tissue
- Factors responsible for venous return:
- Muscle contraction
- Negative intrathoracic pressure
- Pulsation of arteries
- Gravity
- Valves
Circulation
- Coronary Circulation- the circulation of blood within the heart
- Pulmonary Circulation- the flow of blood between the heart and lungs
- Systemic Circulation- the flow of blood between the heart and the cells of the body
- Fetal Circulation
- Portal Circulation- the flow of blood between two sets of capillaries before draining in systemic veins