Bio 14 Week 2 Nervous System Pt. 1

Lec 2

Nervous system

1. A main homeostatic control system that links sensory input from the environment with behavioral responses.

2. It also changes in response to experience (memory)

Nervous system characteristics

Input → Interpretation center → Output

Learning/memory formation

________ and _______ can alter the output due to changes in the interpretation center

Afferent neuron

The afferent neuron carries sensory information from sensory receptors (such as mechanoreceptors or photoreceptors) toward the central nervous system (CNS). It responds to an incoming stimulus, such as heat, pressure, or light, and transmits this information to the integrating center.

Input to integration center

What is the pathway of information for an afferent neuron?

Peripheral

Afferent neurons are generally part of the ______ nervous system because they connect sensory receptors in the periphery (e.g., skin, muscles, and organs) to the CNS (e.g., the brain and spinal cord).

Integrating center

Part of the CNS that receives and processes sensory input from afferent neurons, interprets that information, and then generates an appropriate response.

Interneuron

Type of neuron that transmits signals between other neurons within the central nervous system (CNS), specifically connecting afferent (sensory) neurons to efferent (motor) neurons

Integrating center

Interneurons are primarily found in the __________ of the nervous system, which include the brain and spinal cord. These centers are part of the central nervous system (CNS)

Sensory Receptors

Specialized cells or nerve endings that detect specific types of stimuli from the environment or the body and send signals via afferent neuron

Efferent Neuron

Motor neurons that transmit signals away from the central nervous system (CNS) to effector organs (such as muscles or glands) to produce a response (Part of PNS)

Effector organs

Tissues/organs that respond to signals from efferent neurons, the output part of the nervous system response, carrying out actions necessary to respond to stimuli/maintain homeostasis.

Dendrite

the bushy, branching extensions of a neuron that receive messages/conduct impulses toward the cell body

cell body (soma)

Main part of neuron that's responsible for integrating signals from dendrites and initiating the action potential that travels down the axon.

Axon

Long, slender projection of a nerve cell that conducts electrical impulses (action potentials) away from the cell body toward other neurons, muscles, or glands, responsible for signal conduction.

Myelin sheaths

The material that covers axons

Axon terminal

Very end of a neuron's axon, which forms synapses with other neurons, muscle cells, or glands. Responsible for transmitting signals across the synapse

Synapse

a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter

Invertebrates

Animal that does not possess a backbone or vertebral column, includes majority of animal species such as insects, worms, jellyfish, snails, and starfish.

Larger/easier

Invertebrates often have _____ neurons which are ______ for physiological examination (ex: squid, marine snails, leeches)

simpler circuits

Invertebrates often have ________ which helps understand the basics of neuron behavior

Evolutionary origins

Comparisons of nervous systems across animals can inform us about the _________ of our own nervous system

Artificial neural networks

Knowledge gained from animal nervous systems has contributed to the development of _______

Radial symmetry

Symmetry about a central axis

Bilateral Symmetry

Symmetry where organism can be divided by a single plane into two mirror-image halves

Cnidarians

Invertebrate animals characterized by radial symmetry, a sac-like body with a single opening (mouth/anus), and specialized stinging cells (nematocysts), they tend to be marine/predatory

Hydra, jellyfish, coral

Cnidarian that is a solitary, carnivorous jellyfish-like animal often found in freshwater environments and known for its regenerative abilities.

Radial

Cnidarians are examples of organisms with _____ symmetryNer

Nerve net

A diffuse, decentralized nervous system that consists of a network of interconnected neurons spread throughout the body, allowing for basic responses to stimuli but lacking a centralized brain or ganglia.

Cephalization

Nerve tissues localize at the anterior (front) end of the body to form command center for the nervous system, typically associated with bilateral symmetry and directed movement

Invertebrates/vertebrates

Both ______ and _____ can have bilateral symmetry

Nerve cord

A major bundle of nerves that extends longitudinally through the body of many animals, serving to transmit signals between the brain (if present) and the rest of the body. In invertebrates, it is typically ventral, while in vertebrates, it is a dorsal, hollow structure (the spinal cord)

Ganglia

Clusters of nerve cell bodies that act as local processing centers

ganglia/nerve cord

In invertebrates with bilateral symmetry, the nervous system can present in _______ or _______

insects, flatworms, squid, leech

Examples of invertebrates with bilateral symmetry

fish, amphibians, reptiles, mammals

Examples of vertebrates with bilateral symmetry

brain/spinal cord/peripheral nerves

In vertebrates with bilateral symmetry, the nervous system usually presents as ______, ______, and _______

midbrain/smaller

In mammal brains, the _____ is _____ compared to other vertebrates

forebrain/cerebellum/larger

In mammal brains, the _____ and ________ is _____ compared to other vertebrates

Quadruped

an animal with four feet

Biped

an animal with two feet

anterior (ventral)

Refers to the front or belly side of the body. In humans, this is the forward-facing part of the body.

posterior (dorsal)

Refers to the back or spine side of the body. In humans, this term indicates structures located at the back or towards the back.

superior (cranial)

Refers to a position toward the head or upper part of the body. In humans, this term is used to describe structures that are located higher on the body.

Inferior (Caudal)

Refers to a position toward the feet or lower part of the body. In humans, this term indicates structures located below or toward the bottom of the body

Dorsal (For Quadrupeds)

Refers to the top side of an animal’s body (often the back), in animals that move on all fours (quadrupeds).

Ventral (For Quadrupeds)

Refers to the bottom or belly side of an animal’s body (again in quadrupeds).

Superior (brain)

Refers to a position above or toward the top of the brain. In humans, this would be the top part of the head.

Inferior (brain)

Refers to a position below or toward the bottom of the brain. For humans, this would be toward the base of the skull or spinal cord.

Anterior (brain)

Refers to a position toward the front of the brain (in humans, this is toward the face).

Posterior (brain)

Refers to a position toward the back of the brain (in humans, this is toward the back of the head).

Sagittal Plane

A vertical plane that divides the brain into left and right halves.

Coronal Plane

A vertical plane that divides the brain into front and back parts (also called a frontal plane). (like tiara/crown in a sense)

Horizontal Plane

A horizontal section that divides the brain into upper and lower parts.

central nervous system

the brain and spinal cord, acting as the body's main processing center for information/coordination

Peripheral Nervous System

the network of nerves that extends outside of the CNS, consists of cranial and spinal nerves, axons of efferent motor neurons and connects CNS to muscles, glands & sensory receptors

efferent/afferent

The two branches of the PNS are the ____ and _____ branch

Efferent Branch

This branch carries motor signals from the CNS to muscles and glands, responsible for actions such as muscle contraction

Afferent (Sensory) Branch

This branch carries sensory signals from sensory receptors to the CNS for processing, such as touch, pain, and temperature

Autonomic/motor

The two divisions of the efferent branch are the ____ and _____ division

Motor division

Component of the efferent branch that’s responsible for transmitting motor commands from the CNS to the muscles/glands. These commands initiate voluntary/involuntary actions, such as muscle movement/glandular secretion.

Autonomic division

Component of the efferent branch that controls involuntary bodily functions such as heart rate, digestion, respiration, pupil dilation, and glandular secretions

sympathetic/parasympathetic/enteric

the autonomic division is divided up into the _______, _______, and ______ divisions

Sympathetic Division

Division of the autonomic division that prepares the body for "fight or flight" responses, increasing heart rate and energy mobilization.

Parasympathetic Division

Division of the autonomic division that promotes "rest and digest" activities, lowering heart rate and stimulating digestion.

Enteric Division

Division of the autonomic division that regulates the function of the gastrointestinal system (movement of food through the gut), can be influenced by the other two systems

Gray matter

Composed of neuronal cell bodies. It is primarily involved in processing and integrating information within the CNS (brain and spinal cord)

White matter

Made up of myelinated axons. It is involved in the transmission of signals between different parts of the nervous system, allowing for rapid communication.

Spinal Nerves

These mixed nerves contain both sensory (afferent) and motor (efferent) fibers, allowing for communication between the CNS and PNS.

Dorsal Root Ganglion

This structure is part of the PNS and contains the cell bodies of sensory neurons. It transmits sensory information from the body to the CNS.

Ventral Root

This structure carries motor information from the CNS to the muscles and glands, containing the axons of motor neurons.

gray matter/dorsal root ganglion/ventral root

The _______ of the spinal cord acts as the integrating center for sensory and motor information, and it's where the _______ and the _______ effectively "meet" and communicate

Cerebrum

Part of forebrain, contains cerebral cortex, basal ganglia, hippocampus, amygdala

Cerebral Cortex

This is the outermost layer of the cerebrum, involved in complex functions like conscious thought, perception, and motor control. (Grey matter)

Thalamus

Relays sensory information to the cerebral cortex.

Hypothalamus

Regulates homeostasis, including temperature, hunger, circadian rhythms, blood pressure, breathing

Amygdala

Involved in emotion processing, particularly fear and stress responses.

Hippocampus

Important for memory formation and spatial navigation. (Learning and long-term memory)

olfactory bulbs

Paired structures located in the forebrain of vertebrates that receive sensory information about smells directly from the olfactory receptor neurons in the nose. They process these signals before transmitting them to other brain regions.

Basal ganglia

A group of interconnected subcortical nuclei located deep within the cerebrum. They play a crucial role in the control of voluntary motor movements, procedural learning, habit formation, eye movements, cognition, and emotion.

Forebrain

The most anterior and largest part of the vertebrate brain, encompassing the cerebrum, thalamus, olfactory bulbs, and hypothalamus. It is responsible for a wide range of higher-level functions, including voluntary movement, sensory processing (except olfaction in its primary processing), learning, memory, emotion, and conscious thought.

Midbrain

acts as a relay station for information between the forebrain and hindbrain, and plays a role in motor control and sensory processing, contains superior/inferior colliculi

Superior colliculi

Part of the midbrain primarily involved in visual reflexes, such as directing eye movements and coordinating head movements in response to visual stimuli

Inferior colliculi

Part of the midbrain primarily that’s a key part of the auditory pathway, processing sound information and playing a role in auditory reflexes and sound localization

Hindbrain

posterior part of the brain and is crucial for controlling basic, life-sustaining functions such as breathing, heart rate, and motor control. (Medulla, pons, and cerebellum)

Medulla oblongata

located at the base of the brainstem, just above the spinal cord,

regulates autonomic functions like heart rate, breathing, blood pressure, and digestion. Essential for survival because it controls vital, involuntary functions.

Pons

• lies just above the medulla, in the brainstem.

• Relay station between spinal cord, cerebellum and cerebral cortex

• Breathing and blood pressure control

Cerebellum

• Located at the back of the brain, beneath the occipital lobes of the cerebrum.

• Integration of sensory information, coordination of movement, balance, fine motor skills

• Motor memory / learning

Lobes of the Cerebral Cortex

1. Frontal lobe

2. Parietal lobe

3. Temporal lobe

4. Occipital lobe

Frontal Lobe

• Reasoning and Decision Making: Involved in cognitive processes like thinking, problem-solving, and planning.

• Planned Actions and Movements: Includes the primary motor cortex, responsible for voluntary motor control.

• Speech (Broca's Area): Important for the production of speech. Damage here can result in difficulty speaking, although comprehension may remain intact.

Parietal Lobe

• Mechanosensory Processing: Processes tactile information like touch, pressure, and temperature (via the primary sensory cortex).

• Spatial Awareness: Helps in perceiving spatial relationships and navigating space.

Temporal Lobe

• Auditory Processing: The primary auditory cortex processes sounds.

• Speech Comprehension (Wernicke's Area): Important for understanding speech and language. Damage here can result in difficulties in comprehension, despite normal speech production.

Occipital Lobe

• Visual Processing: The primary visual cortex processes visual information (like shape, color, and movement).

Gyri

The bumps/ridges on the brain's surface that increase its surface area.

Sulci

The grooves/valleys between the gyri.

Sylvian Fissure

A major groove that separates the temporal lobe from the frontal and parietal lobes.

Broca's Area

region in the brain crucial for language production, particularly speech (frontal lobe)

primary motor cortex

Region in the frontal lobe responsible for voluntary motor control.

central sulcus

a prominent groove in the cerebral cortex that separates the frontal and parietal lobes, and also divides the primary motor cortex from the primary somatosensory cortex

Wernicke’s area

Located in left temporal lobe and plays a crucial role in language comprehension and speech production