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Human Biology

Lecture 4 [Endocrine/Nervous /Peripheral systems] -endocrine + nervous systems regulate [balance] animal physio [their body] KEY THOUGHTS:  Organization of nervous system  Evolution of nervous system  Neural communication = how the neurons are connected to each other + they send signals  Membrane potential = how NA goes iN and K comes out and they fix those chemical gradients Cells of the Nervous system ARE CALLED: Neurons AKA Excitable cells The reason for the name “excitable cells” is because they send INFORMATION when they are happy and excited [TURNED ON] The excitable cells [neurons] they send chemical + electrical signals BACK + FOURTH HOW IT WORKS:  We have a nervous system with two methods of input [afferent] + output [efferent]  In between both those methods, we have an integrating centre [the bridge] for the neuron to pass through from INPUT to OUTPUT.  Integrating centre is the brain which is in the CNS. The CNS has a cluster of nerves together.  Input + output mnethods are in the PNS [anything outside of the brain + spinal cord].  The input is SENSORTY organs. Ex. fingers are sensory organs like when you touch something HOT, your finger senses it + SENDS it to your brain. The brain sends the signal back to the output [efferent]. So the input is the sensors which sense the hotness in your fingers and travels down the bridge of the integrating centre and delivers the messages to the output aka the effectors. Deviation of the PNS + CNS EXAMPLE: Niegarians [jellyfish] : has ONE division[input + output region is in the SAME place] of all the nerves CONNECTED together in something caklled a NERVE NET. This means that information is going in TWO directions [no specific order] so the input + output neurons can travel quickly + randomly. Evolution of the BRAIN  HOWDOES IT LOOKS LIKE? It’s bilaterally symmetrical. Bilaterally symmetrical: We have a left side and a right side. Cephalization: It’s a PATTERN of LOCATING sensory + nervous integrating centres [brain] at the ANTERIOR [front] part of the body Example of Cephalization: JELLYFISH+ STARFISH [spongebob square pants] don’t have cephalization Ganglia: in the brain, its interconnected neural cells [cluster of cells] this is what is in the CNS. These are also grouped together in the INTERIOR end of the brain. The function of the ganglia is that it processes information to the CNS. Another fact is that ganglia can exist by itself like some animals don’t have a brain so instead they can have the ganglia. Veterbrate Nervous System - Have a high degree of Cephalization - Have unique dorsal nerves - Have CNS [brain + spinal cord] - Encased with cartilage + bones - Have PNS [nerves outside the body =everything else] CENTRAL NERVOUS SYSTEM HOW THE BRAIN IS BROKEN DOWN  Brain is broken down into sensory neurons [afferent –input] HOW IS THE SPINAL CORD BROKEN DOWN  The spinal cord is broken down into motor neurons [efferent-output] PERIPHERAL NERVOUS SYTEM  The sensory receptors which is in the PNS goes to the sensory neurons[in the BRAIN], and the brain sends signal to the spinal c
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