Nervous System Communication and Membrane Potential
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Questions and Answers

What is the average resting membrane potential of cells?

  • -30 mV
  • 0 mV
  • -70 mV (correct)
  • -90 mV

Which process is primarily responsible for maintaining the resting potential of a neuron?

  • Sodium potassium pump (correct)
  • Endocytosis
  • Facilitated diffusion
  • Passive transport

What occurs when the membrane potential reaches a threshold of -50 mV?

  • Sodium channels close
  • The neuron becomes hyperpolarized
  • An action potential is generated (correct)
  • Repolarization begins

During depolarization in action potential, which ion primarily floods into the neuron?

<p>Sodium ions (A)</p> Signup and view all the answers

What is the main function of the cerebrospinal fluid?

<p>To provide cushioning and protection to the brain (B)</p> Signup and view all the answers

What is hyperpolarization in the context of action potentials?

<p>Extra potassium channels open, making potential more negative (A)</p> Signup and view all the answers

Which protective layer under the skull is filled with cerebrospinal fluid?

<p>Dura (B)</p> Signup and view all the answers

Which event follows the closing of sodium channels during an action potential?

<p>Repolarization occurs (C)</p> Signup and view all the answers

What is the primary function of the somatic nervous system?

<p>Providing input to the central nervous system through sensory nerves (C)</p> Signup and view all the answers

Which of the following statements is true regarding the autonomic nervous system?

<p>It regulates involuntary functions such as heart rate and digestion. (A)</p> Signup and view all the answers

How are the sympathetic and parasympathetic nervous systems primarily different in their actions?

<p>Sympathetic stimulates fight or flight responses while parasympathetic promotes rest and energy conservation. (A)</p> Signup and view all the answers

In the autonomic nervous system, where do synapses typically occur in the parasympathetic division?

<p>In peripheral ganglia near the target tissue. (D)</p> Signup and view all the answers

What is the role of ganglia within the nervous system?

<p>Serve as mini processors that connect neuronal cell bodies. (C)</p> Signup and view all the answers

What is the function of astrocytes in the brain?

<p>Feed neurons and manage the environment (C)</p> Signup and view all the answers

Which part of the brain is primarily responsible for regulating homeostasis?

<p>Hypothalamus (D)</p> Signup and view all the answers

What is the primary function of microglia in the brain?

<p>Detect and engulf invading material (D)</p> Signup and view all the answers

Which lobe of the brain controls vision?

<p>Occipital lobe (C)</p> Signup and view all the answers

In terms of spinal cord anatomy, where does sensory input enter?

<p>Dorsal root (D)</p> Signup and view all the answers

What composes the grey matter in the spinal cord?

<p>Cell bodies and dendrites (D)</p> Signup and view all the answers

Which component of the nervous system is responsible for decision making and rational thinking?

<p>Cortex (B)</p> Signup and view all the answers

Which type of glial cell is responsible for wrapping neurons in myelin sheath?

<p>Oligodendrocytes (B)</p> Signup and view all the answers

What is the primary role of the ganglia in the peripheral nervous system?

<p>To serve as mini processors of neuronal cell bodies connected by synapses (D)</p> Signup and view all the answers

Which characteristic differentiates the autonomic nervous system from the somatic nervous system?

<p>It is not under conscious control, unlike the somatic system (D)</p> Signup and view all the answers

In the peripheral nervous system, where do sympathetic neurons typically synapse?

<p>In sympathetic ganglia located next to the spinal cord (A)</p> Signup and view all the answers

Which of the following describes the function of the enteric nervous system?

<p>It operates independently and specifically targets the intestines (A)</p> Signup and view all the answers

What happens to postganglionic neurons in the parasympathetic nervous system?

<p>They terminate directly on target tissues without synapsing in ganglia (D)</p> Signup and view all the answers

What is the main role of astrocytes in the brain?

<p>Regulate blood flow and nutrient exchange for neurons (C)</p> Signup and view all the answers

Which part of the brain acts as a relay station between the cortex and the rest of the nervous system?

<p>Thalamus (C)</p> Signup and view all the answers

What types of cells make up 95% of the brain's cellular composition?

<p>Glial cells (B)</p> Signup and view all the answers

Which lobe of the brain is primarily responsible for decision making and rational thinking?

<p>Frontal lobe (A)</p> Signup and view all the answers

What is the function of the cerebellum in the brain?

<p>Controlling motor coordination and balance (A)</p> Signup and view all the answers

In the spinal cord, which segment contains motor neurons?

<p>Ventral segment (A)</p> Signup and view all the answers

What structures are referred to as gyri in the outer view of the brain?

<p>Ridges that stick out on the brain surface (A)</p> Signup and view all the answers

Which type of glial cell is responsible for insulating neurons with myelin sheath?

<p>Oligodendrocytes (D)</p> Signup and view all the answers

What role does the sodium-potassium pump play in maintaining membrane potential?

<p>It pumps sodium ions out and potassium ions into the cell. (A)</p> Signup and view all the answers

Which statement best describes depolarization during an action potential?

<p>It occurs when sodium channels open and sodium floods into the neuron. (D)</p> Signup and view all the answers

When does hyperpolarization occur in the action potential process?

<p>It happens after repolarization due to the prolonged opening of potassium channels. (B)</p> Signup and view all the answers

What occurs when the membrane potential is more permeable to potassium?

<p>It reinforces the resting membrane potential. (A)</p> Signup and view all the answers

What is the significance of the voltage gradient created in the membrane potential?

<p>It determines the threshold value for action potential initiation. (C)</p> Signup and view all the answers

What triggers the generation of an action potential in a neuron?

<p>A depolarization that exceeds -50 mV. (B)</p> Signup and view all the answers

Which layer of protection surrounds the brain and spinal cord and contains cerebrospinal fluid?

<p>The arachnoid layer (B)</p> Signup and view all the answers

What is indicated by the spikes and dips seen in a graph of action potentials?

<p>The momentary change in electrical potential across the membrane. (B)</p> Signup and view all the answers

Flashcards

Membrane Potential

The voltage difference across a cell membrane at a given moment.

Resting Potential

The membrane potential of a cell when not actively transmitting signals; approximately -70mV.

Action Potential

A rapid, temporary change in membrane potential, a nerve impulse.

Sodium-Potassium Pump

Active transport that maintains the concentration gradients of sodium and potassium ions across the cell membrane.

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Depolarization

The membrane potential becomes less negative (more positive), usually caused by sodium influx.

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Repolarization

The membrane potential returns to its resting negative state.

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Threshold Value

The minimum membrane potential required to initiate an action potential (-50mV, example).

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Neurons

Electrically excitable cells that transmit signals with action potentials.

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Brain cell types

The brain contains two main types of cells: neurons and glial cells.

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Neuron structure

Neurons have dendrites, axons, and often a myelin sheath.

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Glial cell function

Glial cells, comprising about 95% of brain cells, support neurons.

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Astrocyte function

Astrocytes are star-shaped glial cells that nourish neurons and maintain the brain's environment.

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Oligodendrocytes function

Oligodendrocytes are glial cells that insulate neurons with myelin sheaths.

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Spinal cord segments

The spinal cord is divided into segments connected to specific body areas (dermatomes).

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Grey matter vs white matter

Grey matter contains cell bodies and synapses; white matter is composed of myelinated axons.

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Spinal cord roots

The sensory neurons are part of the dorsal root, while motor neurons are part of the ventral root of the spinal cord.

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Peripheral Nervous System

The part of the nervous system outside the brain and spinal cord, responsible for connecting the central nervous system to the rest of the body.

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Somatic Nervous System

The part of the peripheral nervous system responsible for voluntary control of skeletal muscles.

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Autonomic Nervous System

The part of the peripheral nervous system that controls involuntary bodily functions.

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Sympathetic Nervous System

The 'fight or flight' response system, prepares the body for stressful situations.

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Parasympathetic Nervous System

The 'rest and digest' response system, conserves energy and promotes relaxation.

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Hyperpolarization

The membrane potential becomes even more negative than the resting potential. This is due to extra potassium channels remaining open.

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Glial Cells

Cells that support and protect neurons, making up 95% of the brain's cells.

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Astrocytes

Star-shaped glial cells that nourish neurons and regulate the brain's environment.

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Oligodendrocytes

Glial cells that wrap around neurons, forming a myelin sheath for insulation.

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Microglia

Immune cells in the brain that fight off infections and remove debris.

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Brain Lobes

Four major regions of the brain, each with specific functions: frontal (decision-making), parietal (sensory), temporal (hearing), and occipital (vision).

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Sulci and Gyri

Grooves (sulci) and ridges (gyri) on the brain's surface that increase its surface area.

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Study Notes

Nervous System Communication

  • Nervous system communication relies on adaptations of different cell types for immunity and nerve impulse generation.
  • Membrane potential is the electrical difference/voltage across a cell membrane at a given moment, constantly fluctuating.
  • Resting membrane potential averages -70mV, maintained by an imbalance of charged particles inside and outside the cell.

Membrane Potential

  • Resting potential is the electrical potential difference across a cell membrane when not actively firing.
  • Sodium-potassium pump plays a crucial, active transport role. It expels sodium ions from the cell and pumps potassium ions into the cell, creating an imbalance. This imbalance directly contributes to the resting membrane potential. (3 sodiums are pumped out for every 2 potassium ions pumped in.)
  • Membrane permeability differs for sodium and potassium ions at rest. The membrane is more permeable to potassium, allowing potassium ions to leak out, making the inside of the cell more negative, creating a substantial voltage gradient.
  • The concentration gradient pushes potassium ions out of the cell, further increasing the voltage gradient.
  • Sodium ions are drawn into the cell due to the voltage gradient, balancing the potential.
  • Equilibrium potential describes the point at which the concentration gradient and electrical forces balance out to prevent further net movement of ions.
  • Depolarization is an increase in membrane potential. It's caused by sodium channels opening, sodium floods in, and the membrane becomes more positive.
  • Repolarization occurs when sodium channels close, preventing sodium influx, decreasing membrane potential back towards resting potential.
  • Hyperpolarization (Slight increase) happens when extra potassium channels open causing potassium ions to leave the cell, making the membrane more negative than it was at rest.

Neurons

  • Neurons are electrically excitable cells, responding to inputs by transmitting electrical signals along their axons.
  • Action potentials are temporary reversals in the membrane potential. An axon that is depolarised above -50mV (threshold value) will initiate an action potential leading to a nerve impulse.
  • Action potentials are a momentary reversal of electrical potential.

Brain Structure and Function

  • The brain is protected by bone (skull) and vertebrae.
  • The brain is primarily composed of two types of cells: neurons and glial cells (95% glial cells, 5% neurons).
  • Three main types of glial cells: Astrocytes (star-shaped cells that feed neurons and manage the cellular environment), Oligodendrocytes (produce myelin sheaths insulating neurons), and Microlia (immune cells detecting and engulfing invaders).
  • Cortex (outer layer) of the brain is responsible for higher-level functions like memory, thinking, and control of the body.
  • Hypothalamus regulates homeostasis (stability), and the pituitary gland connects the nervous system and endocrine system.
  • The thalamus is a relay station for sensory information; the cerebellum controls motor movement.
  • Four main sections/lobes of the brain: Frontal (decision-making and thinking), Parietal (sensory processing), Temporal (hearing), and Occipital (vision).
  • Spinal cord contains sensory (Dorsal) and motor(Ventral) neurons and is organized into segments.
  • White matter, where neurons carry signals, consist of axons covered by myelin sheaths.
  • Grey matter consists of neurons, dendrites, and synapses.
  • The spinal cord is segmented, with each segment corresponding to a specific area of the body.
  • Each segment contains sensory and motor neurons linked to a distinct section/dermatome.
  • The spinal cord is further protected by layers of membrane, called the meninges (Dura, arachnoid and pia mater).
  • Spinal cord also has a central canal surrounded by Pia mater that contains cerebrospinal fluid (CSF).
  • The spinal cord is also structured in layers called Lamina/Rexed layers and contains nuclei to process information.

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Description

This quiz covers the fundamentals of nervous system communication, focusing on cell adaptations for immunity and nerve impulse generation. It also delves into membrane potential, including resting potential and the role of the sodium-potassium pump. Test your understanding of these key concepts in neurobiology.

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