Chapter 6a Transport in animals Flashcards
Why do multicellular organisms need a circulatory system?
Due to small SA:vol ratio, higher metabolic rate, and increased activity leading to greater demand for O2 and waste removal.
Higher metabolic rates and activity require a mass transport system for efficient nutrient and waste exchange.
What is a closed circulatory system?
A system where blood always moves within blood vessels, allowing pressure to be maintained.
This system contrasts with an open circulatory system, where blood is not always contained within vessels.
What is a double circulatory system?
A system where blood passes through the heart twice per complete circuit around the body.
This includes the pulmonary and systemic circuits.
What are the two circulatory systems in mammals?
- Pulmonary circuit (PC)
- Systemic circuit (SC)
The pulmonary circuit carries blood to the lungs, while the systemic circuit delivers blood to the body.
What are the advantages of a double circulatory system?
- Maintains blood pressure
- Prevents mixing of oxygenated and deoxygenated blood
- Increases efficiency in delivering O2 and glucose
- Allows different blood pressures in pulmonary and systemic circuits
This separation enhances the efficiency of the circulatory system.
What are the advantages of a closed circulatory system?
- Maintains blood pressure throughout the body
- Allows different blood pressures in circuits
- Matches blood supply to organ demands
- Requires lower blood volumes
This system is more efficient for transporting nutrients and wastes.
What is the role of blood circulation in tissue respiration?
Transport of oxygen to tissues and carbon dioxide back to the lungs.
This is essential for cellular respiration and energy production.
What is the primary function of arteries?
Carry blood away from the heart, generally transporting oxygenated blood.
The only exception is the pulmonary artery, which carries deoxygenated blood.
What is the structure of capillaries designed for?
Facilitating exchange between blood and tissues with a single layer of squamous endothelial cells.
This thin structure allows for efficient diffusion of gases and nutrients.
What is the primary function of veins?
Return blood to the heart, generally transporting deoxygenated blood.
The pulmonary vein is an exception, carrying oxygenated blood.
What causes blood pressure to drop in arterioles?
Increased contact with blood vessel walls and friction slows down the blood flow.
This is a significant factor in the overall regulation of blood pressure in the circulatory system.
What happens to blood pressure as blood moves through capillaries?
Blood pressure drops due to increased cross-sectional area and friction.
This lower pressure is advantageous for gas exchange.
What role do skeletal muscles play in maintaining blood pressure in veins?
They compress veins, increasing blood pressure within them to ensure blood returns to the heart.
This mechanism helps counteract gravity and prevents blood pooling.
What is hypertension?
Persistently high blood pressure, with specific clinical definitions for stages.
It is a major preventable cause of morbidity and mortality.
What are some risk factors for hypertension?
- Smoking
- Obesity
- High salt intake
- Excessive alcohol consumption
- High stress levels
- Increasing age
- Post-menopausal drop in estrogen
- Biological sex (males at higher risk)
- Sedentary lifestyle
These factors contribute to the development and exacerbation of high blood pressure.
What is hypotension?
Persistently low blood pressure that can result in weakness, dizziness, and potentially coma.
Severe hypotension can be life-threatening.
How is blood pressure measured using a sphygmomanometer?
Cuff inflates to stop blood flow, then deflates while listening for Korotkoff sounds to determine systolic and diastolic pressures.
This method provides both systolic and diastolic readings for assessing blood pressure.
What is the typical blood pressure reading in mmHg?
120/80 mmHg is considered typical.
This reading reflects normal blood pressure in a healthy adult.
What are Korotkoff sounds?
Sounds heard when measuring blood pressure that indicate the return of blood flow as the cuff is deflated.
These sounds help determine systolic and diastolic pressure.
