Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

19. The Blood Vessels

General Blood Vessel Structure

Anatomy & Physiology

19. The Blood Vessels

General Blood Vessel Structure

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1:49 minutes

Problem 23

Textbook Question

Describe neural and chemical (both systemic and local) effects exerted on the blood vessels when you are fleeing from a mugger. (Be careful, this is more involved than it appears at first glance.)

Verified step by step guidance

Step 1: Begin by understanding the 'fight or flight' response, which is activated by the sympathetic nervous system during stressful situations like fleeing from a mugger. This response prepares the body for rapid action by altering various physiological processes, including blood vessel behavior.

Step 2: Neural effects: The sympathetic nervous system releases norepinephrine, which binds to adrenergic receptors on blood vessels. This causes vasoconstriction in non-essential areas (e.g., digestive organs) to redirect blood flow to essential areas like muscles, heart, and lungs. Additionally, vasodilation occurs in skeletal muscles due to beta-adrenergic receptor activation.

Step 3: Systemic chemical effects: The adrenal medulla releases epinephrine (adrenaline) into the bloodstream. Epinephrine enhances the effects of norepinephrine, promoting vasodilation in skeletal muscles and vasoconstriction in non-essential areas. This systemic effect ensures efficient oxygen and nutrient delivery to tissues critical for fleeing.

Step 4: Local chemical effects: In active tissues like skeletal muscles, local factors such as increased carbon dioxide (CO₂), decreased oxygen (O₂), and elevated hydrogen ion concentration (lower pH) cause vasodilation. These local changes override systemic vasoconstriction to ensure adequate blood supply to the working muscles.

Step 5: Integrate the neural and chemical effects: The combined neural and chemical responses optimize blood flow distribution, ensuring that vital organs and muscles receive sufficient oxygen and nutrients while non-essential areas temporarily experience reduced blood flow. This coordination allows the body to respond effectively to the stressor.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Sympathetic Nervous System Activation

During a flight response, the sympathetic nervous system is activated, leading to the release of catecholamines like adrenaline. This activation causes vasoconstriction in non-essential blood vessels and vasodilation in muscles, optimizing blood flow to critical areas for immediate physical activity.

Hormonal Response

The hormonal response involves the release of stress hormones such as cortisol and epinephrine from the adrenal glands. These hormones enhance the body's ability to respond to stress by increasing heart rate, blood pressure, and energy availability, which are crucial for fleeing from danger.

Local Autoregulation of Blood Flow

Local autoregulation refers to the ability of blood vessels to adjust their diameter based on the metabolic needs of surrounding tissues. During a flight response, active muscles release metabolites that cause vasodilation, ensuring adequate blood supply to areas that require increased oxygen and nutrients for heightened physical activity.