Problem 29 - Biological Psychology

Question

What are the two kinds of stroke, and what causes each kind?

Step-by-Step Solution

Answer

The two kinds of stroke are ischemic and hemorrhagic, caused by blood clots and blood vessel ruptures, respectively.

Step 1: Define Stroke

A stroke occurs when the blood supply to a part of the brain is interrupted or reduced, preventing brain tissue from receiving oxygen and nutrients. This can result in brain cells beginning to die within minutes.

Step 2: Identify the Two Kinds of Stroke

There are two main types of stroke: ischemic stroke and hemorrhagic stroke.

Step 3: Explain Ischemic Stroke

An ischemic stroke occurs when a blood clot blocks or narrows an artery leading to the brain. The most common cause is atherosclerosis, where fatty deposits build up on artery walls, potentially leading to clot formation.

Step 4: Explain Hemorrhagic Stroke

A hemorrhagic stroke occurs when a blood vessel in the brain leaks or ruptures. Causes include high blood pressure, weak or thin blood vessel walls (aneurysms), or trauma.

Key Concepts

Ischemic Stroke

An ischemic stroke is the most common type of stroke, representing approximately 87% of all stroke cases. It happens when blood flow to the brain is obstructed by a blockage or narrowing of the arteries. This interruption means that the affected part of the brain does not get the essential oxygen and nutrients it needs, causing brain cells to die.

There are a few underlying causes for an ischemic stroke:

• Thrombotic Stroke: This occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. This is often due to plaques that have built up in the arteries, known as atherosclerosis.
• Embolic Stroke: In this case, a blood clot or other debris forms away from your brain, generally in the heart, and is swept through the bloodstream to lodge in narrower brain arteries.

Risk factors for ischemic strokes include high cholesterol, smoking, high blood pressure, diabetes, and existing cardiovascular problems. Recognizing these risks can help in preventive measures, thus reducing the incidence of stroke.

Hemorrhagic Stroke

Hemorrhagic strokes account for about 13% of all stroke cases and are characterized by bleeding either within the brain or in the space surrounding the brain. When a blood vessel bursts, it compromises the normal flow of blood and oxygen in the brain, leading to damage.

There are two primary types of hemorrhagic stroke:

• Intracerebral Hemorrhage: This is when a blood vessel inside the brain ruptures, causing bleeding into the brain itself. High blood pressure is a common cause because it weakens the blood vessel walls.
• Subarachnoid Hemorrhage: Here, bleeding occurs in the area between the brain's surface and the thin tissues covering it. This type of stroke is often due to a burst aneurysm, which is a weak area in a blood vessel wall.

Risk factors for hemorrhagic strokes include chronic hypertension (high blood pressure), smoking, excessive alcohol use, and having a history of aneurysms. Preventive measures such as managing blood pressure and avoiding smoking could lower the risk significantly.

Brain Function

Understanding brain function is crucial for grasping the impact of strokes. The brain is the control center of the body, responsible for regulating everything from sensations and movements to emotions and thought processes. It is divided into several parts, each with specific roles.

• Cerebrum: The largest part, responsible for voluntary actions such as speaking and thinking, and also involved in major sensory functions.
• Cerebellum: Responsible for coordination and balance, making your movements precise and smooth.
• Brainstem: Controls automatic functions like breathing, heart rate, and blood pressure.

When a stroke occurs, any part of the brain can be affected depending on where the blood flow disruption happens. This can lead to specific deficits, such as loss of motor skills, speech difficulties, or emotional instability, depending on the affected region. Rehabilitation and early intervention are key to recovery, as the brain adapts and attempts to regain lost functions through a process known as neuroplasticity.