Veins
Veins carry blood back to the heart. Since the pressure in the veins is lower, muscle movements and venous valves, among other factors, help return the blood to the heart.
The Cardiovascular System: Structure and Function
The cardiovascular system supplies the entire body with oxygen and nutrients. At its center is the heart: a powerful muscle that continuously pumps blood through a vast network of blood vessels.
The heart, blood, and blood vessels work closely together in this process. They supply organs, muscles, and tissues with blood, transport hormones, and remove metabolic waste products. The circulatory system also helps regulate body temperature and fluid balance.
What is part of the cardiovascular system?
The cardiovascular system includes:
- the heart
- the blood
- the arteries
- the veins
- the capillaries
Through its pumping action, the heart generates the pressure needed to allow blood to flow through the blood vessels. The blood vessels form the transport system that reaches every part of the body.
The Heart: The Engine of the Circulatory System
The heart is protected behind the breastbone, slightly to the left of the body's midline. It consists mainly of heart muscle tissue and works day and night without us having to consciously control its activity.
Inside, the heart is divided into four chambers:
- right atrium
- right ventricle
- left atrium
- left ventricle
The atria receive the blood flowing back to the heart. The ventricles then pump it on to the lungs or into the systemic circulation.
Four heart valves ensure that blood flows in the right direction. They open and close in time with the heartbeat, functioning like valves.
This Is How the Heartbeat Is Formed
Every heartbeat is triggered by an electrical impulse. The heart's natural pacemaker is the sinus node, located in the right atrium.
From there, the electrical signal spreads throughout the heart. It ensures that the atria and ventricles contract in a coordinated sequence.
The heart functions largely on its own. However, its rhythm is influenced by the autonomic nervous system and various hormones. That is why the heart rate changes depending on the situation:
- At rest, the heart beats more slowly.
- When you exercise, your heart rate increases.
- Stress, excitement, or anxiety can cause your pulse to quicken.
- Heart rate normally decreases during sleep.
The heart's electrical activity can be recorded using an electrocardiogram, or ECG for short.
Systole and Diastole
A heartbeat consists of two repeating phases:
Systemic Circulation and Pulmonary Circulation
Blood circulates through the body in two interconnected systems.
The Pulmonary Circulation
The right side of the heart pumps oxygen-poor blood into the lungs. There, the blood releases carbon dioxide and takes in fresh oxygen. It then flows back to the left side of the heart.
The Body's Circulatory System
The left side of the heart pumps oxygen-rich blood through the aorta into the body. Organs and tissues absorb oxygen and nutrients. The blood, now lower in oxygen, then flows back through the veins to the right side of the heart.
Both circuits operate simultaneously and together form a closed system.
What are the functions of blood vessels?
Capillaries
Capillaries are the smallest blood vessels. Their exceptionally thin walls allow for the exchange of oxygen, nutrients, and metabolic byproducts between the blood and tissues.
Arteries
Arteries carry blood away from the heart. Their walls are strong and elastic so that they can withstand the pressure generated with every heartbeat.
The largest artery is the aorta. It carries blood from the left ventricle to the rest of the body.
Blood vessels carry blood throughout the body. Depending on their structure and function, they are classified as arteries, veins, and capillaries.
What is blood pressure?
In order for blood to flow through the blood vessels to organs and tissues, it must be under pressure. This blood pressure results from the interaction of:
- The heart's pumping power
- Diameter and Elasticity of Blood Vessels
- Blood volume
When measuring blood pressure, two numbers are given.
The upper, systolic value occurs when the heart contracts and pumps blood into the arteries.
The lower, diastolic value is measured when the heart muscle relaxes and refills with blood.
Blood pressure is not always the same. It changes in response to factors such as exercise, rest, stress, sleep, and temperature fluctuations.
What is a pulse?
The pulse is the pressure wave that travels through the arteries with each heartbeat. It can be felt, for example, at the wrist or on the side of the neck.
Your pulse indicates how often your heart beats per minute and whether the rhythm appears regular. It is influenced by, among other things:
- physical activity
- Fitness Level
- Age
- Excitement and Stress
- Body temperature
- Fluid Supply
- Medications
- Diseases
Heart rate and blood pressure are not the same thing. A fast heart rate does not automatically mean that blood pressure is also elevated.
How does the circulatory system adapt?
The cardiovascular system constantly responds to the body's needs. During exercise, muscles need more oxygen. As a result, the heart beats faster and pumps more blood through the body.
When standing up, the circulatory system must quickly adapt to the change in body position. In warm conditions, the blood vessels in the skin dilate so that the body can release heat. In cold conditions, they tend to constrict.
The following entities, among others, are involved in this regulation:
- autonomic nervous system
- Hormones
- Kidneys
- Vascular Muscles
- Cardiac output
- Fluid and Electrolyte Balance
Mild, short-term fluctuations are normal. However, recurring symptoms such as dizziness, fainting, severe palpitations, or marked fatigue should be evaluated by a doctor.
What can put a strain on the cardiovascular system?
Various diseases and risk factors can interfere with the interaction between the heart, the circulatory system, and the blood vessels.
These include, among other things:
- chronically elevated blood pressure
- Changes in the blood vessel walls
- abnormal blood lipid levels
- Diabetes
- Smoking
- Lack of exercise
- Overweight
- prolonged stress
- Heart Rhythm Disorders
- Heart Valve Diseases
- decreasing pumping power of the heart
High or Low Blood Pressure
Persistently high blood pressure can put a strain on the heart and blood vessels. Low blood pressure generally does not cause comparable vascular damage, but it can be associated with symptoms such as dizziness, fatigue, or circulatory problems.
Changes in the Blood Vessels
Changes and deposits in the arteries can restrict blood flow. Important modifiable risk factors include, among others, smoking, high blood pressure, lack of physical activity, and abnormal metabolic levels.
Decreasing cardiac output
If the heart can no longer pump enough blood throughout the body, physical performance declines. Shortness of breath, unusual fatigue, or fluid retention may be signs of this condition and should be evaluated by a doctor.
What supports the cardiovascular system?
A heart-healthy lifestyle not only supports the heart, but also helps maintain healthy blood pressure, blood vessels, and metabolism.
Key fundamentals include:
- regular exercise
- a balanced, plant-based diet
- No smoking
- get enough sleep
- Balancing Stress and Relaxation
- healthy body weight
- Consume Alcohol Responsibly
- Have your blood pressure and key metabolic values checked
Plant Facts: Hawthorn
Hawthorn (Crataegus monogyna and Crataegus laevigata) has traditionally been closely associated with heart and circulatory health. Depending on the preparation, the leaves, flowers, or fruits are used. In the plant encyclopedia, you can learn more about the botany, active ingredients, history, and traditional uses of hawthorn.
When should symptoms be evaluated by a doctor?
Heart and circulatory problems can have various causes. Prompt medical evaluation is especially important in the following cases:
- Chest pain, pressure, or tightness
- Shortness of breath
- Fainting or Loss of Consciousness
- sudden, severe dizziness
- new or severe palpitations
- Irregular heartbeat accompanied by symptoms
- a sudden sharp drop in performance
- Pain that radiates to the arm, shoulder, back, jaw, or upper abdomen
- Water retention in the legs or feet
- Symptoms that occur during physical exertion
If you experience sudden, severe, or life-threatening symptoms, seek medical help immediately.
In-Depth Topics:
Heart Health
What exercise, nutrition, sleep, stress management, and preventive care mean for heart health.
Circulation & Blood Pressure
What high and low blood pressure mean and how circulatory problems can manifest themselves.
Vascular Health
How blood vessels are structured, what puts a strain on them, and what a lifestyle that’s good for your blood vessels might look like.