Neuroscience Chapter: Nerve Cell Functions

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Questions and Answers

What initiates the depolarization process in a nerve cell?

The closure of Na+ channels

The opening of Na+ channels (correct)

The movement of K+ into the cell

The opening of K+ channels

What happens to the voltage within the nerve cell during repolarization?

It remains at +40 mV

It falls below the resting potential (correct)

It decreases to -70 mV

It increases to +60 mV

What is the role of the Na+/K+ pump after hyperpolarization?

To prevent Na+ from entering the cell

To increase K+ concentration inside the cell

To maintain resting potential (correct)

To initiate depolarization

What characterizes the refractory period in a nerve cell?

Higher threshold required for action potential generation (A) Signup and view all the answers

How does saltatory conduction benefit nerve impulse transmission?

It allows impulses to jump between nodes of Ranvier (B) Signup and view all the answers

What mechanism in homeostasis reverses a variable to bring it back to balance?

Negative Feedback (A) Signup and view all the answers

Which of the following is typically NOT a factor that the body maintains in homeostasis?

Body shape (C) Signup and view all the answers

In the negative feedback system for blood glucose levels, which role does the pancreas play?

Effector (A) Signup and view all the answers

Which type of neuron is responsible for carrying signals away from the nerve cell body?

Motor Neuron (C) Signup and view all the answers

What is the function of the myelin sheath in a neuron?

To insulate the axon (C) Signup and view all the answers

Which type of feedback mechanism increases the change in a variable?

Positive Feedback (B) Signup and view all the answers

What structure within a neuron is primarily responsible for receiving signals?

Dendrite (C) Signup and view all the answers

Which cells are responsible for supporting and holding neurons in place?

Glial Cells (C) Signup and view all the answers

What is the primary function of sensory neurons?

To transmit impulses from the sensory receptors to the central nervous system (B) Signup and view all the answers

Which of the following brain structures is involved in autonomic nerve control?

Medulla oblongata (D) Signup and view all the answers

What is the role of interneurons in the central nervous system?

To connect sensory and motor neurons (D) Signup and view all the answers

Where is the corpus callosum located in the brain?

In the center connecting the left and right hemispheres (A) Signup and view all the answers

Which of the following correctly describes grey matter?

Contains the cell bodies and dendrites of neurons (C) Signup and view all the answers

Which structure is involved in regulating growth and metabolism?

Pituitary gland (B) Signup and view all the answers

What is the function of the hypothalamus?

To produce hormones regulating various physiological processes (D) Signup and view all the answers

Which part of the brain is primarily involved in motor activities and sensory information processing?

Cerebrum (B) Signup and view all the answers

What primarily forms the blood-brain barrier?

Tight junctions between endothelial cells (B) Signup and view all the answers

What is the role of the sodium-potassium pump in a nerve cell?

To maintain the resting potential of the nerve cell (A) Signup and view all the answers

What occurs to a nerve cell's potential during depolarization?

It becomes more positive as sodium channels open (A) Signup and view all the answers

Which component is NOT part of a neural circuit responsible for reflex actions?

Central nervous system (B) Signup and view all the answers

What happens to the charge inside a neuron when it is at resting potential?

It is negatively charged compared to the outside (C) Signup and view all the answers

What is the synaptic cleft?

The gap between terminal buds and dendrites of neurons (B) Signup and view all the answers

Which of the following ions primarily contributes to the depolarization phase of an action potential?

Sodium ions (Na+) (C) Signup and view all the answers

What function does the cerebral cortex serve?

It processes and integrates sensory information (D) Signup and view all the answers

Study Notes

Homeostasis

Homeostasis is a self-regulating process in biological systems to maintain balance for survival. This regulation occurs in a defined internal environment.
The body constantly tries to maintain a stable internal environment, including a temperature of 37°C, 100 mg/mL of glucose, and pH of 7.4.
A variety of organs and systems work together to achieve homeostasis.

Homeostasis Feedback Mechanisms

Negative Feedback: A mechanism in homeostasis where the output reverses the variable, bringing it back to a normal state of balance. An example is body temperature regulation.
Positive Feedback: A mechanism in homeostasis where the output strengthens and increases the change in the variable. This is often a rapid process used in specific circumstances, such as childbirth. Examples include childbirth, breastfeeding, and blood clotting.

Feedback Systems

When the internal environment changes, sensors (like nerve cells in skin and brain) detect the change.
Sensory information is relayed to the control center in the brain.
The control center sends signals to effectors (like sweat glands or blood vessels).
Effectors make necessary adjustments to maintain homeostasis.

Negative Feedback Example: Internal Temperature

Stimulus: Body temperature exceeds 37°C
Sensor: Nerve cells in the skin and brain
Control center: Temperature regulatory center in the brain
Effector: Sweat glands throughout the body
Response: Sweating cools the body, thus decreasing the body temperature

Negative Feedback Example: Blood Glucose Levels

Stimulus: Blood glucose level decreases.
Sensor: Beta cells in the pancreas
Effector: Insulin release into the blood
Response: Liver breaks down glycogen, releasing glucose into the bloodstream, increasing blood glucose levels

Positive Feedback Example: Childbirth

Stimulus: Head of the fetus pushes against the cervix.
Sensor: Nerve impulses from the cervix transmitted to the brain.
Control center: Brain stimulates the pituitary gland to secrete oxytocin.
Effector: Oxytocin stimulates uterine contractions.
Response: Uterine contractions increase, pushing the fetus toward the cervix, leading to childbirth.

Positive Feedback Example: Breastfeeding

Stimulus: Baby suckles at the nipple.
Sensor: Suckling impulses to the hypothalamus.
Control center: Hypothalamus signals posterior pituitary to release oxytocin.
Effector: Oxytocin released into the bloodstream stimulates the mammary gland.
Response: Milk is released and the baby continues to feed.

Positive Feedback Example: Blood Clotting

Stimulus: Damaged blood vessel
Sensor: Platelets
Effector: Formation of platelet plug; development of a clot
Response: Stops bleeding

The Nervous System

The nervous system includes the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS is comprised of the brain and spinal cord.
The PNS connects the CNS to the rest of the body.
Different types of neurons perform specialized functions.

Neuron Structure

Dendrite: Receives signals.
Soma: Cell body.
Axon: Carries signals away from the soma.
Node of Ranvier: Gaps in the myelin sheath.
Myelin Sheath: Insulation around the axon.
Axon Terminal: Releases neurotransmitters.
Schwann Cell: Produce myelin.

Types of Neurons

Glial Cells: Support and protect neurons.
Sensory/Afferent Neurons: Carry signals from sensory receptors to the CNS.
Motor/Efferent Neurons: Carry signals from the CNS to effectors (muscles or glands).
Interneurons: Relay signals between sensory and motor neurons within the CNS.

Neural Signalling

Afferent neurons carry signals from sensory receptors to the CNS.
Interneurons integrate and process information within the CNS.
Efferent neurons carry information from the CNS to effector organs.

Brain Hemispheres

Left Hemisphere: Analytical, detail-oriented, ordered, rational thought, verbal, cautious planning, math, science, right field vision.
Right Hemisphere: Intuitive, holistic, random, sequences, emotional thought, non-verbal, adventurous, impulsive, creative writing/art, left field vision.

Corpus Callosum

A structure that connects the left and right hemispheres of the brain.

The Brain (Central Nervous System)

The brain is the control center of the body, responsible for maintaining homeostasis, controlling emotions, thought, and relaying information from sensory neurons to effectors that respond effectively.
Main sections: Forebrain, Midbrain and Hindbrain

Brain Structures (detailed)

Medulla Oblongata: Connects spinal cord to cerebellum. Important in autonomic nerve control.
Cerebellum: Important for muscle movement and balance.
Pons: Transfers nerve signals between cerebellum and medulla.
Pituitary Gland: Regulates growth, metabolism, and reproduction through hormones produced.
Cerebrum: Involved in motor activities and sensory information.
Thalamus: Interprets sensory input and signals the cerebrum.
Hypothalamus: Produces hormones that regulate heart rate, body temperature, hunger, and sleep-wake cycle.
Blood-Brain Barrier: Protects brain from harmful substances by forming a barrier of endothelial cells in brain capillaries.

Brain - Lobes

Frontal Lobe: Motor functions, higher level reasoning, planning, personality
Parietal Lobe: General sensory functions
Temporal Lobe: Auditory, language processing, memory, facial recognition
Occipital Lobe: Visual processing

Neural Circuits

Neural circuit: Coordination of receptors, afferent neurons, interneurons, efferent neurons, and effectors in response to a stimulus.
Reflex arc: A neural circuit that travels through the spinal cord, not the brain, allowing for coordinated quick responses, such as withdrawing a hand from a hot stove.

Synaptic Transmission

Nerve cells don't transmit signals directly.
The signal is passed through a gap called the synapse via neurotransmitters from the presynaptic terminal to the postsynaptic receptors.

Chemical vs. Electrical Synapse

Chemical synapse: Neurotransmitters diffuse across the gap.
Electrical synapse: Signals transmit directly across gap junctions.

Transmitting Signals in the Nervous System (Details)

Resting potential: The cell is negatively charged (-70 mV) inside compared to the outside.
Action potential: The potential changes from negative to positive.
Depolarization: The inside of the nerve cell becomes positive, caused by the influx of Na+ions.
Repolarization: The inside of the nerve cell returns to being negative, caused by the effluxes of K+ ions.
Hyperpolarization: The potential dips briefly below resting potential.
Refractory period: A period after an action potential where it is difficult to initiate another action potential.
Ion channels and the Sodium-Potassium pump are important in maintaining resting potential.

Myelinated Nerve Impulses

Myelinated nerves impulses travel faster.
Saltatory conduction is the process by which action potentials "jump" between the nodes of Ranvier.

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Description

Test your understanding of nerve cell functions with this quiz focusing on processes like depolarization, repolarization, and the refractory period. Explore the role of the Na+/K+ pump and the advantages of saltatory conduction in nerve impulse transmission. Perfect for students studying neuroscience or biology.