Untitled Flashcards Set

The nervous system is divided into 

• Central nervous system: Brain + Spinal cord

• Peripheral nervous system: Other nerves of the body 

Peripheral nervous

• All nerves found outside the brain +spinal cord 

• Sensory division: Afferent send impulses to the CNS

• Sympathetic division: Used in emergency situations (fight or flight)= Autonomic

• Parasympathetic division: reduces the sympathetic response and provides resting functions

• Motor division: efferent send impulses from the Cns to the muscle glands

The nervous system is the master control center for the body it works with the endocrine system

To do its job it uses

• Sensory input: detects stimuli inside and outside the body

• Integration- processing + interpreting information

• Response-activation of muscles (motor output) or glands

The 2 major types of nerve cells 

• Neurons: conduct impulses around the body (10%)

• Nueroglina: “nerve glue” supports, insulates, and protects neurons (90%)

Neurons have different structures but all have a main cell body process that extends outward

The cell body contains the nucleus cytoplasm and organelles

Processes are divided into 

dendrites- bring impulses toward the cell body 

Axons: send impulses away from the cell body

End in axon terminals which release neurotransmitters to pass the impulse to the next neuron

Neurons are classified by the number of processes extending from the cell body

Nuerons can also be classified by their function

• Afferent- carry impulses toward the CNS

• Efferent- carries impulses away from CNS

• Interneurons- connect afferent and efferent neurons

Axons are wrapped in myelin which is like a waxy insulation

To from the myelin, a Schwann cell a (type of neuroglia) wraps itself around the axon like a cel

The outer layers of the Shawn cell are called neurilemma

Myelin helps the nerve impulses travel more quickly 

Collectively, the myelin wrapping is called the myelin sheath. Since the myelin sheath is formed by many Schwan cells it has gaps called nodes of rainver 

Nuerogil cells are found in either the CNS or the PNS 

CNS: 

• Astrocytes support + anchor neurons to capillaries 

• Microglia: provide immune response to the CNS

• Ependymal cells: secrete + circulate cerebrospinal fluid

• Oligodendroctyes: provide myelin insulation to neurons

PNS: 

• Satellite cells: support + anchor neurons

• Schawn cells: provide myelin insulation

A nerve impulse is an electrical signal that travels along the neuron. It arises from the movement of ions causing a change in electrical charges

Process: 

At rest neurons, intracellular space is negatively charged and the extracellular space is positively charged. This is called the resting potential

When the neuron is stimulated (1) either by the environment or another neuron, sodium rushes into the neuron and quickly reverses the charges called depolarization (2). This depolarization is known as the action potential. This process quickly moves down the length of the down. As impulses pass potassium diffuses out of the neuron (repolarization) The sodium-potassium pump (4) then restores the ion concentration to normal and the resting potential returns (5)

When 2 neurons meet it is called the synapse 

The  2 neurons do not touch. The space between them is called synaptic clef

As the impulse reaches the axon terminal it can not cross the gap

The impulses stimulate vesicles to release neurotransmitters across the synaptic celf. These neurotransmitters cause channels to open in the next neuron, continuing the action potential from one neuron to the next

The brain and the spinal cord make up the CNS 

3 layers of connective tissues called meingies

• Dura mater- thick, tough layer

• Arachorid- thin, cobweb-like layer

• Pia mater- thin layer containing blood vessels

Between the arachnoid layer, the pia mater is the cerebrospinal fluid 

The CSF protects the brain by preventing it from contacting the skill and maintains the blood-brain barrier which controls homeostasis for the brain and prevents infection

CSF= produces in spaces called ventricles

There are 4 ventricles: 2 lateral, 3rd ventricle, 4th ventricle

The lateral ventricles are connected to the third ventricle by the thin interventricular foramen 

Clusters of capillaries in the ventures called choroid plexus secret CSF flow around the ventricles and then are absorbed by the arachnoid granulation into the blood

CSF is constantly being produced circulates and reboarded within these ventricles 

The cerebrum is the largest part of the brain

2 hemisphere= right and left hemispheres

These hemispheres are connected by a bundle of fibers called the corpus callosum The surface of the cerebrum is covered in ridges (Guri) and grooves (svlci)

Deeper grooves= fissures dived portion of the brain

Major layers (superficial to deep)

1. Cerebral cortex “gray matter” made of cell body + dendrites

2. Cerebral medulla “white matter” myelinated axons

3. Basal nuclei: islands of gray matter

Divided into 4 lobes based on their functions which are named after the part of the skull that protects them

Frontal lobe- voluntary movements, reasoning + decision making, memory, prediction of consequences, planning, Broca's area verbal communication

Parietal lobe- sensations, visual-spatial process, body position

Occipital lobe- visual processing-vison + memory of objects 

The temporal lobes are separated by the front lobe by the lateral sulcus 

Temporal lobe- memory, comprehension, pronunciation of words, smell, sound, emotional association of memories 

A region called the diencephalon 

It contains the thalamus, the hypothalamus,, and the pineal gland

The thalamus has 2 brain shapes halved in the center of the brain and relays sensory impulses to the cerebral cortex for processes and sorting

The pineal gland is posterior to the thalamus (part of the endocrine system) The tiny portion hypothalamus below the thalamus 

•  Responsible for autonomic processes (body temp, metabolism) 

• Controls hormones(signals to the pituitary gland)

• Part of the limbic system which regulates emotions, feelings, and pleasure 

The brain stem is located between the cerebrum and the spinal cord

3 regions: 

• Midbrain: menecephalon= relay into the cerebrum, controls body movement + posture 

• Pons: “bridge” while matter line cerebrum to cerebellum= carry into from one side of the brain to the other & controls breathing 

• Medulla oblongata: just above the spinal cord= transmits impulses between brain and spinal cord, Controls blood, pressure, heart rate, swallowing, coughing

The cerebellum is found near the back of the skull and is the second-largest 

• Coordinating movements directed by the cerebrum so they are graceful and efficient (involuntary)

• The cerebrum also aids in muscle memory 

The spinal cord extends from the medulla oblaganda to the lumbar vertebrae

Like the brain is covered by meninges for protection

The spinal cord relays impulses between the peripheral nervous system and the brain through 31 pairs of spinal nerves

A cross-section of the spinal cord has a butterfly of gray matter  surrounded by white matter

The dorsal horns receive impulses from different nerves and then pass the impulses through the ventral horns to the efforts of Nevers 

Doral + ventral contains the nerve fibers and join together to form a 2 - directional  spinal nerve 

Preprogrammed responses are called reflexes and the pathway travel is a reflex arc 

5 elements: receptor, sensory, neurons, integration, moto neurons, an effector 

Reflexes can be somatic involving skeletal muscle or autonomic involving smooth muscle

The eye is composed of 3 tissue layers: 

1. sclera: white of the eye, fibrous, protects  and shapes

2. Choroid: pigmented, vascular membrane (iris + pupil)

3. Retina: contains photo receptors that run light energy into nerve impulses 

The cornea is made of thick, transparent tissue and allows light into the eye 

The iris the colored part of the eye is located behind the cornea and works with the pupil to regulate light entering the eye

The pupil is the opening in the center of the iris through which light enters 

The lens is a semi-solid disc that directs light waves toward the retina

It is controlled by ciliary muscles and suspensory ligaments which bend or flatten the lens based on the distance of the image views 

In front of the lens is called the aqueous humor which nourishes the cornea and behind the lens is the vitreous humor which is a thick jelly-like fluid that reflects light and fills the space between the lens and retina