Cell Membrane Ionic Balance

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Questions and Answers

What is the role of acetylcholine in the synaptic space?

To combine with acetylcholine receptors, increasing the permeability of the membrane to sodium ions (correct)

To release calcium ions from the sarcoplasmic reticulum

To inhibit muscle contraction

To decrease the permeability of the membrane to sodium ions

What is the name of the structure that the spinal cord extends to?

Lumbar vertebra

Coccyx (correct)

Atlas

Cervical vertebra

How many segments does the spinal cord have?

31 (correct)

What is the name of the part of the muscle fiber where acetylcholine receptors are found?

Sarcolemma Signup and view all the answers

What is the result of Na ion entry into the muscle fiber?

Depolarization of the membrane Signup and view all the answers

What is the name of the structure that stores neurotransmitters such as acetylcholine?

Synaptic vesicles Signup and view all the answers

How many pairs of spinal nerves arise from each segment of the spinal cord?

Two Signup and view all the answers

What is the site where the spinal cord lies?

Spinal canal Signup and view all the answers

What is the location of the cerebellum?

Behind the medulla oblongata and pons Signup and view all the answers

What is the appearance of the cerebellum's outer surface?

Contains many parallel grooves and protrusions Signup and view all the answers

Which of the following best describes the arrangement of gray and white matter in the cerebellum?

White matter inside, gray matter outside Signup and view all the answers

What is the function of the cerebellum?

Provides muscle tone and balance Signup and view all the answers

What is the name given to the white matter within the cerebellum due to its branching appearance?

Arbor vitae Signup and view all the answers

Which of the following structures is responsible for the secretion of cerebrospinal fluid (CSF)?

Plexus choroideus Signup and view all the answers

What is the name given to the spaces within the brain that contain cerebrospinal fluid?

Ventricles Signup and view all the answers

Which of the following statements accurately describes the connection between the third ventricle and the fourth ventricle?

The third ventricle opens into the fourth ventricle Signup and view all the answers

What is the primary ion present in excess outside the cell?

Sodium Signup and view all the answers

What is maintained during a cell's state of rest without excitation?

Electrochemical equilibrium Signup and view all the answers

How do ions generally diffuse across the cell membrane?

From a region of high concentration to low concentration Signup and view all the answers

What is the typical resting membrane potential in a nerve cell?

-90 mV Signup and view all the answers

What factor primarily influences the movement of ions across the cell membrane?

The permeability of the membrane Signup and view all the answers

What creates the intracellular negative potential in a resting cell?

Protein anions that cannot pass the membrane Signup and view all the answers

What is the term used to describe the combined effect of electrical and chemical forces on ion movement?

Electrochemical potential Signup and view all the answers

What happens to ion flow when electrochemical equilibrium is reached?

Ion flow stops between compartments Signup and view all the answers

What happens when a single peripheral nerve is cut?

No loss of sensation in the skin segment of that nerve. Signup and view all the answers

What is the primary difference between visceral sensations and somatic sensations?

Visceral sensations are poorly localized while somatic sensations are well localized. Signup and view all the answers

What is referred pain?

Pain that is felt in a different location from the actual source of the pain. Signup and view all the answers

What causes referred pain?

Overlapping sensory nerve pathways. Signup and view all the answers

How do nerve fibers from the skin and internal organs converge in the spinal cord?

Nerve fibers from both higher and lower sensory inputs converge at the same level of the spinal cord. Signup and view all the answers

Which of the following is NOT controlled by the autonomic nervous system?

Conscious movement. Signup and view all the answers

What type of muscle does the autonomic nervous system primarily control?

Both smooth and cardiac muscle. Signup and view all the answers

Which of the following is TRUE about the autonomic nervous system?

It operates independently, continuously, and involuntarily. Signup and view all the answers

What is the primary function of the spinal cord in relation to the central nervous system?

It transmits motor commands from the brain. Signup and view all the answers

Which structure connects the two hemispheres of the cerebrum?

Corpus callosum Signup and view all the answers

Which part of the brain is responsible for controlling the left side of the body?

Right hemisphere of the cerebrum Signup and view all the answers

What occurs when there is bleeding in one hemisphere of the brain?

It results in paralysis and sensory loss on the opposite side of the body. Signup and view all the answers

What structure is considered the largest part of the central nervous system?

Brain (encephalon) Signup and view all the answers

How are motor movements and sensory sensations represented in the brain?

Sensory nerves cross before reaching the brain, leading to opposite representation. Signup and view all the answers

What are the main sections the brain is divided into?

Cerebrum, diencephalon, cerebellum, and brain stem. Signup and view all the answers

Which of the following functions is NOT attributed to the brain?

Producing hormones directly. Signup and view all the answers

Study Notes

Electrical Potential Difference between Inside and Outside the Cell

The main ions involved in the electrical potential difference between inside and outside the cell are sodium, potassium, and chlorine anions.
Sodium is present in excess outside the cell, while potassium is present inside the cell.
Ions are charged and cannot easily pass through the membrane, but they do so through their own channels.

Ionic Equilibrium: Electrochemical Potentials of Ions

Ions inside and outside the cell are at certain concentrations at rest.
The passage of ions from one medium to another depends on the permeability of the cell membrane and the type of electrical charge in the medium it will pass through.
The cell membrane has different permeability properties to each ion, which is why ions diffuse from the high side to the lesser side.
Both electrical and chemical potential play a role in the movement of an ion, and are together called electrochemical potentials.
The flow of an ion from one chamber to the other is from where the electrochemical potential of the ion is high to the lower direction.
When the ion flow stops between both compartments, the ion has reached electrochemical equilibrium.

Resting Membrane Potential

If electrodes are inserted into and out of the cell in a nerve cell and connected to a potentiometer, there is a potential difference of -90 mV at rest.
This potential difference arises from the different distribution of ions on both sides.
It is an intracellular negative potential due to protein anions that cannot pass the membrane inside the cell.

Nerve Impulse Transmission

When a nerve impulse from the brain and spinal cord reaches the end of the motor nerve extension, it causes acetylcholine, a neurotransmitter substance, to be released from the synaptic vesicles.
Acetylcholine in the synaptic space combines with acetylcholine receptors in muscle fiber sarcolemma, increasing the permeability of the membrane to sodium ions.
Na ion entry creates an action potential and depolarizes the membrane, leading to the release of calcium ions from the sarcoplasmic reticulum to the cytosol.
Thus, muscle contraction is initiated.

Central Nervous System

The central nervous system has two parts: the spinal cord (medulla spinalis) and the brain (encephalon).

Spinal Cord (Medulla Spinalis)

The spinal cord lies within the spinal canal (canalis vertebralis).
It is the continuation of the brain stem.
The lower end of the spinal cord is like a cone (conus medullaris).
The spinal cord has a transversally segmental structure, with 31 segments, and a pair of spinal nerves arise from each segment.

Brain (Encephalon)

The brain is the largest part of the central nervous system and is in the skull.
It can be divided into four major sub-sections: cerebrum (brain hemispheres), diencephalon (intermediate brain), truncus cerebri (brain stem), and cerebellum.
The cerebrum consists of two cerebral hemispheres separated by a deep cleft with a longitudinal course.
Each hemisphere controls the opposite side of the body.
The cerebellum is located behind the medulla oblongata and pons, and provides muscle tone and balance, and the harmony of the muscles.
Balance and proper posture are achieved with the senses coming from the muscles, joints, and hemisphere tracts.

Brain Cavities (Ventriculus Cerebri)

There are four cavities filled with cerebrospinal fluid (CSF) within the entire brain compartments.
These spaces, called ventricles, are lined with ependymal cells and are in contact with each other.
The plexus choroideus is responsible for the secretion of liquor cerebrospinalis (cerebrospinal fluid) and is found in all ventricles.

Visceral Sensations

Visceral sensations are the senses that come from internal organs.
The nerves that transmit the visceral senses enter the medulla of the spinal cord from the posterior root, just like the somatic nerves.
Visceral senses, unlike somatic senses, cannot be localized well (poor localization).

Referred Pain

Referred pain is pain perceived at a location other than the site of the painful stimulus/origin.
It is the result of a network of interconnecting sensory nerves that supplies many different tissues.
When there is an injury at one site in the network, it is possible that when the signal is interpreted in the brain, signals are experienced in the surrounding nervous tissue.

Autonomous Nervous System

The autonomic nervous system is a part of the peripheral nervous system and works independently, continuously, and involuntarily.
It controls the contraction of smooth muscles, the secretion of glands, and the regulation of heart rhythms.

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Description

This quiz tests your understanding of the ionic balance between the inside and outside of a cell, including the role of sodium, potassium, and chlorine ions in maintaining the electrical potential difference. Learn about the movement of ions through channels in the cell membrane and how it affects the cell's resting state.