Podcast Beta
Questions and Answers
What is the peak of the aortic pressure pulse termed as?
What happens to systolic pressure as the pressure pulse travels down the blood vessels?
What is the average blood pressure in adults?
What is the method of measuring blood pressure using a catheter called?
Signup and view all the answers
What is the usual method of measuring blood pressure?
Signup and view all the answers
What is the pulse rate usually equal to?
Signup and view all the answers
What happens to systolic and diastolic pressures with aging?
Signup and view all the answers
What is the blood pressure in a newborn?
Signup and view all the answers
Which of the following factors does not affect blood pressure?
Signup and view all the answers
In adults before 45 years, which of the following is true about blood pressure?
Signup and view all the answers
What happens to blood pressure during deep quiet sleep?
Signup and view all the answers
What is cardiac output?
Signup and view all the answers
What is the formula to calculate cardiac output?
Signup and view all the answers
What happens to blood pressure when cardiac output increases?
Signup and view all the answers
What is stroke volume?
Signup and view all the answers
What is the formula to calculate ejection fraction?
Signup and view all the answers
What is the normal heart rate in well-trained athletes at rest?
Signup and view all the answers
What is the effect of enhanced vagal activity on heart rate?
Signup and view all the answers
What is the intrinsic heart rate in adults?
Signup and view all the answers
What is the effect of blockade of both parasympathetic and sympathetic nerves on heart rate?
Signup and view all the answers
What is the effect of increased blood pressure on heart rate through the baroreceptor reflex?
Signup and view all the answers
What is the normal stroke volume?
Signup and view all the answers
What is the function of the precapillary sphincter in blood capillaries?
Signup and view all the answers
Which type of capillary is found in the kidneys?
Signup and view all the answers
What is the function of the skeletal muscle pump in veins?
Signup and view all the answers
What is the equation for calculating blood flow?
Signup and view all the answers
What is the purpose of the thoracic pump?
Signup and view all the answers
What is the site of highest resistance to blood flow?
Signup and view all the answers
What is the function of the endothelial cells lining the capillaries?
Signup and view all the answers
What is the term for the volume of blood contained in the arteries?
Signup and view all the answers
What is the purpose of the venous valves?
Signup and view all the answers
What happens to velocity of blood flow as vessel diameter increases?
Signup and view all the answers
Which nerve is involved in the Bainbridge reflex?
Signup and view all the answers
What is the name of the phenomenon where the strength of cardiac contraction increases with increasing frequency of stimulation of the myocardium?
Signup and view all the answers
What is the primary stimulus for the chemoreceptor reflex?
Signup and view all the answers
What is the term for the regulation of stroke volume by changes in the end-diastolic length of cardiac fibres?
Signup and view all the answers
Which of the following is NOT a factor that affects peripheral resistance?
Signup and view all the answers
What is the term for the measurement of cardiac output?
Signup and view all the answers
What is the main source of intrinsic regulation of cardiac output?
Signup and view all the answers
Which of the following is an extrinsic factor that regulates cardiac output?
Signup and view all the answers
Study Notes
Blood Vessels
- Arteries:
- Thick-walled, with extensive elastic tissue, smooth muscle, and connective tissue
- Under highest pressure
- Stressed volume: volume of blood contained in arteries
- Arterioles:
- Smallest branches of arteries
- Extensive smooth muscle in walls
- Site of highest resistance to blood flow
- Innervated by sympathetic adrenergic nerve fibers (α-Adrenergic receptors cause constriction, β2-Adrenergic receptors cause relaxation)
- Capillaries:
- Lined by a single layer of endothelial cells
- Site of exchange of nutrients, gases, water, and solutes between blood and tissues
- Lipid-soluble substances diffuse across capillary wall
- Water-soluble substances use pores to cross capillary wall
- Not all capillaries are perfused with blood at all times (selective perfusion)
- Venules and Veins:
- Venules: thin-walled
- Veins: modest amount of elastic tissue, smooth muscle, and connective tissue
- Large capacitance (capacity to hold blood)
- Contain largest percentage of blood in the cardiovascular system
- Unstressed volume: volume of blood contained in veins
Velocity of Blood Flow
- V = Q/A (velocity = flow / cross-sectional area)
- Changes in diameter alter velocity of flow:
- Increase in diameter: decrease in velocity
- Decrease in diameter: increase in velocity
- Blood flow at each level is the same
- Velocity of blood flow is highest in the aorta and lowest in capillaries (advantageous for exchange across capillary wall)
Blood Flow, Pressure, and Resistance
- Blood flow is determined by:
- Pressure difference (driving force) between two ends of a vessel
- Resistance of the vessel to blood flow
- Q = ΔP/R (blood flow = pressure difference / resistance)
- Major mechanism for changing blood flow is changing resistance in the arterioles
Pressure
- Blood flows from high pressure to low pressure areas
- Ejection of blood into the aorta by the left ventricle results in a characteristic aortic pressure pulse
- Peak of the aortic pressure pulse: systolic pressure (SP)
- Lowest pressure in the aorta: diastolic pressure (DP)
- PP = SP - DP (pulse pressure)
- Mean aortic pressure (MAP) is the average pressure during the aortic pulse cycle
Arterial Blood Pressure
- Characteristic changes occur in SP, DP, and MAP as the pressure pulse travels down the blood vessels
- Away from the heart, SP rises, and DP falls
- MAP slightly declines due to resistance in the arteries
- Arterial BP measured using a sphygmomanometer (blood pressure cuff) on the upper arm is slightly different from the pressure measured in the aorta or other distributing arteries
Measurement of Blood Pressure
- Direct method (invasive): most accurate means of measuring blood pressure directly within an artery using a catheter
- Indirect method (noninvasive): uses a sphygmomanometer (e.g., mercury-filled sphygmomanometer) to measure blood pressure in the brachial artery
- Measurement of blood pressure can be done by palpitation or auscultation
Physiological Factors Affecting Arterial Blood Pressure
- Age: BP increases with age
- Sex: differences in BP between males and females
- Race: differences in BP between different racial groups
- Gravity: BP in upper parts of the body is higher than in lower parts, especially during standing
- Meals: digestion increases BP
- Emotions and exercise: increase BP
- Sleep: deep quiet sleep decreases BP, while sleep with dreams increases BP
Factors that Affect Blood Pressure
- Cardiac output
- Peripheral resistance
- Vessel elasticity
- Blood volume
Cardiac Output
- Definition: volume of blood ejected by each ventricle per minute
- Normal cardiac output: 5L/min in adults
- Cardiac output is affected by:
- Heart rate
- Stroke volume
- Peripheral resistance
- Vessel elasticity
- Blood volume
Regulation of Heart Rate
- Autonomic influence: tonic influence of the autonomic nervous system (ANS) on the SA node
- Influence by higher centers: effects of reflexes on heart rate
- Baroreceptor reflex: ↑ BP → ↑ BR → ↑ vagal tone → ↓ HR
- Bainbridge reflex: venous engorgement of atria and great veins → ↑ HR
- Chemoreceptor reflex: ↓pO2, ↑pCO2, and ↓pH → ↑ CR → ↑ respiratory center → ↑ ventilatory drive
Regulation of Stroke Volume
- Nervous stimuli
- End-diastolic length of cardiac fibers (Starling's law of the heart)
Regulation of Cardiac Output
- Intrinsic regulation: changes in the end-diastolic length of myocardial fibers (Starling's law of the heart) and frequency-induced regulation (staircase or Treppe phenomenon)
- Extrinsic regulation: nervous control, humoral control, and blood gases
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the structure and function of blood capillaries, including their composition, types, and blood pressure. It also compares capillaries to arteries and veins.
