Heart Rate
Also written as HR.
A 2-year-old child is brought to the emergency with a very high fever and a high heart rate.
What our notes say
- A 2-year-old child is brought to the emergency with a very high fever and a high heart rate. (Paediatrics end of 2nd semester exam (MBPE 4300): 5 October 2021, 50 MCQs)
- Mechanism: T4 is converted to T3, which binds nuclear thyroid hormone receptors and raises gene transcription, metabolic rate, heart rate and thermogenesis. (Integrated case paper: Medicine, Surgery, Gynaecology and Paediatrics (160 marks)
- A patient discharged on levothyroxine is re-admitted with heart rate 42, blood pressure 70/56, blood glucose 55 and body temperature 96.8°F. (Internal Medicine (MBIM 4100) main exam, Paper One: 3 July 2019)
- Infants with heart failure have a fast breathing rate and heart rate, a large liver and sweating, but ascites is rare. (Paediatrics end of fourth year main exam: 1 July 2019, Paper One, 99 of 100 MCQs)
- The heart rate is 160 beats per minute and the liver is 5 cm below the costal margin. (Paediatrics end of fourth year main exam: 1 July 2019, Paper One, 99 of 100 MCQs)
- Side effects: reduced appetite, insomnia, increased heart rate and blood pressure, slowed growth in children (monitor height and weight), potential for misuse. (Introduction to Psychopharmacology)
Study material on Heart Rate
- Cardiovascular system examination revised 2012
- CARDIOVASCULAR PATHOLOGY
- Medical Physiology Assorted SAQs — With Answers (Past Paper Study Guide)
- Medical Physiology Pp2 Year 2
- Junior Clerkship in Reproductive Health (MBOG 4200): end of year examination, 4 July 2019
- Paediatrics end of fourth year main exam: 1 July 2019, Paper One, 99 of 100 MCQs and essays
- Paediatric History Taking and Physical Examination
- CVS History, Physical Exam & ECG: Master Clinical Assessment
- LECTURE 6: Pancreatic and Adrenal Hormones
- cat 2 2014 — Source Paper Awaiting Edit
- Basic Pharmacology - Study Guide
- Basic Pharmacology - Study Guide
Practice questions on Heart Rate
Which autonomic receptor increases heart rate?
- Adrenergic α.
- Adrenergic β₁.
- Adrenergic β₂.
- Cholinergic muscarinic.
- Cholinergic nicotinic. ✅ Answer: B. Adrenergic β₁.
Answer: A. Adrenergic β₁. is the physiologically correct answer per standard MBChB-level teaching on this topic. ---
Mr. Kamau, 54, had a cardiac transplant 6 months ago. His current blood pressure is 120/70 mmHg and heart rate is 100 bpm. Which of the following drugs would have the least effect on Mr. Kamau's heart rate?
- Albuterol
- Epinephrine
- Phenylephrine
- Isoproterenol
Answer: C. A transplanted heart is denervated (no sympathetic or parasympathetic innervation). It responds only to circulating catecholamines via direct receptor stimulation. Phenylephrine is a selective α1 agonist with no direct cardiac effects. Any heart rate changes would be indirect (reflex bradycardia from vasoconstriction), but reflexes are absent in denervated hearts. --- ### AUTACOIDS ---
Mr. Kamau, 54, had a cardiac transplant 6 months ago. His current blood pressure is 120/70 mmHg and heart rate is 100 bpm. Which of the following drugs would have the least effect on Mr. Kamau's heart rate?
- Albuterol
- Epinephrine
- Phenylephrine
- Isoproterenol
Answer: C. A transplanted heart is denervated (no sympathetic or parasympathetic innervation). It responds only to circulating catecholamines via direct receptor stimulation. Phenylephrine is a selective α1 agonist with no direct cardiac effects. Any heart rate changes would be indirect (reflex bradycardia from vasoconstriction), but reflexes are absent in denervated hearts. --- ### AUTACOIDS ---
What happens to the heart rate when a person receives a high dose of pure Alpha-1 agonist like Phenylephrine intravenously?
- Tachycardia due to direct effect
- Reflex Bradycardia
- No change in heart rate
- Ventricular fibrillation
Answer: B. Phenylephrine causes intense vasoconstriction (inc BP), which triggers the baroreceptor reflex to slow the heart rate.
Which receptor subtype is found in the heart and increases heart rate when stimulated?
- Alpha-1
- Beta-1
- Beta-2
- M2 Muscarinic
Answer: B. Beta-1 adrenergic receptors are primarily located in the heart and increase rate and contractility.
Drugs that increase the heart rate have a __________ effect. ---
- Myogenic
- Negative inotropic
- Positive inotropic
- Negative chronotropic
- Positive chronotropic
Answer: A.