Nervous System and The Brain The Nervous System

Nervous System and The Brain

The Nervous System � Subdivided � Central into two categories: Nervous System � Contains � Peripheral brain and spinal cord Nervous System � Nerves and ganglia outside of CNS � Reflexes �A hot stove

The Nervous System � The nervous system has a coordinating role where it receives, processes, stores, and transmits information that comes from the body and the outside world � The neuron is the basic unit (cell) of the nervous system � Impulses (signals) are carried throught the body by nerves

Neurons � Dendrite receives impulses � Axon propagates the impulses � Longest neuron in the body? Sciatic nerve which connects toes to spinal cord

Neurons � The neurons are the only cells that react to a stimulus � A stimulus is a change in the environment that results in nerve excitation � Ex. sun shining in your eyes or hearing a sound � Nerves are structures that help transmit information between the central nervous system and the various regions of the body � https: //www. youtube. com/watch? v=Ibzfwtdtong

Transmitting Signals � Neurons must pick up stimuli, transform them into nerve impulses and then transmit these impulses on to the next neuron � A nerve impulse is therefore any electric signal transmitted by a neuron � As signals move from one neuron to another, they must cross the synapse. This is the transition zone between two neurons (a very small gap)

Basic Tasks of the Nervous System � Sensory Input: Monitor both external and internal environments. � Integration: Process the information and often integrate it with stored information. � Motor output: If necessary, signal effector organs to make an appropriate response.

Nervous System � Composed � The of CNS and PNS central nervous system is made of the brain and the spinal cord

The Brain � Some brain myths… � http: //www. popsci. com/10 -brain-mythsbusted? image=0

The Brain � The brain controls everything in the body brain contains more than 100 billion neurons (nerve cells) and is the biggest part of the central nervous system

Size isn’t everything… � Neanderthal brains had more capacity devoted to vision and body control, with less left over for social interactions and complex cognition � Morton – racist brain size study �http: //www. smithsonianmag. com/science- nature/science-shows-why-youre-smarter-than-aneanderthal-1885827/ �

Parts of the Brain � The Brain has three main parts… � Cerebrum � Cerebellum � Medulla oblongata (brain stem)

Concussions � https: //www. youtube. com/watch? v=tg. Ch. Te. ALF 7 g � Fencing response

The Cerebrum � The � It largest part of the brain controls your: � Thinking � Memory � Speaking � Movement � Identifies info gathered by your sensory organs

Lobes of the Brain � The cerebrum is divided into several lobes, each of which is responsible for different tasks � The frontal lobes are responsible for problem solving and judgment and motor function.

Lobes of the Brain � The parietal lobes manage sensation, handwriting, and body position. � The temporal lobes are involved with memory and hearing � (short + long term) � The occipital lobes contain the brain's visual processing system. � (eyes + nostril ex)

The Cerebellum � Below and to the back of the cerebrum. � Controls your balance and posture � (along with inner ear)

Medulla Oblongata (Brain Stem) � Connects the brain to the spinal cord � Controls heartbeat, breathing and blood pressure � Responsible for certain reflexes: coughing, swallowing, hiccups, vomiting, and sneezing

Grey vs White Matter � The brain can be divided into two types of tissue

Grey Matter � The part of the brain controlled by nerve cell bodies and dendrites. � It is grey in appearance and is where the true processing occurs � Makes up 40% of the human brain and requires 94% of available oxygen

White Matter � Composed of axons � Found in the center of the brain and between the brain stem and cerebellum � Facilitates communication between the grey matter of the brain and between the brain and the rest of the body � Makes up 60% of the human brain

Spinal Cord � Connects the brain to the rest of the nervous system. � Sends messages to and from the brain. � The spinal cord is protected by small bones called vertebrae

Vertebrae

Peripheral Nervous System (PNS) � Consists of all the nerves that leave the spinal cord or brain reaching all parts of the body. � It has 2 types of nerves � Sensory nerves – sending info to CNS � Motor nerves – sending info to muscles

Types of Action � PNS has 3 types of actions: � Voluntary acts � Involuntary acts � Reflexes

Voluntary Acts � This system contains the skeletal muscles � Responsible for the conscious control of our movement � Signals from the brain effectuate contractions of the muscles

Involuntary Acts � An action that occurs without conscious thought or choice � Breathing, hiccups, digestion, coughing, sneezing

Reflex � https: //www. youtube. com/watch? v=qpw 31 bvo. Lpg � Is an involuntary automatic reaction that happens without thinking about it, due to an external stimulus �A reflex happens quickly in less than a second. � The difference between a reflex and an involuntary action is that a reflex requires a stimulus (external factor)

Reflex Arc

The brain is not involved in a reflex. Sensory Receptor (responds to a stimulus by producing a impulse) Sensory Neuron (axon conducts impulse) Integrating Center (Relay impulse from sensory to motor neurons) Motor Neuron (axon conducts impulse to effector) Effector (muscle that responds to A motor nerve impulse)