Blood & Nervous Tissue BY: Jeremiah Peters, Brett Maggard, Miranda Asher, and Benjamin Oakes Blood Fluid within blood vessels Doesn t connect or give mechanical support Transports Nutrients, wastes, respiratory gasses Platelets are small blood cells Nervous Tissue Main component of the nervous system Brain Spinal cord Nerves 1
Continued.. Regulates body functions Neurons functional units of nervous system Stimuli An activation of sensory receptors Sensory receptors specialize to respond to changes in their environment Supporting cell non-conducting cells that support, insulate, and protect the delicate neurons. The 2 Major Parts of the Nervous System Central nervous system (CNS) Peripheral nervous system (PNS) Central Nervous System The Central Nervous System (CNS) is made up of the brain and spinal cord 2
Peripheral Nervous System The Peripheral Nervous System (PNS) is the nerves that communicate motor system and sensory signal between the central nervous system and the rest of the body The nerves in your body that tell your brain things about your environment. The 3 Types of Neurons There are 3 types of Neurons: Sensory, Motor, and Interneurons. Sensory Neurons A Neuron that receives the signal from your senses and they send the signal in the form of a chemical that the brain can interpret. 3
The Interneurons act as a bridge between sensory neurons and motor neurons. Interneurons The Motor Neurons stimulate effectors in motor cells. Causes movement Motor Neuron The Structure of a Neuron This is a picture of a Neuron cell (only a little prettier). This neuron shows what all Neurons have Dendrites, Cell Body, Axon Hillock, Terminal Branches, and a Axon. 4
The Dendrites of the Neuron The Dendrites of a neuron connect with the Synaptic Terminal of other Neurons. The Dendrites receive the signals first before it s passed on to the rest of the Neuron. The Neuron Cell Body The Neuron Cell is about the same as a regular blood cell. The only difference is that it s relatively bigger than normal. The Axon Hillock of a Neuron The Axon Hillock connects the Axon and Cell Body together ( the Axon Hillock is in red). 5
The Axon of the Neuron The Axon is the main place where the signals are transmitted to the Synaptic Terminals. The Schwann Cells The Schwann Cells are the support for the Neurons in the PNS. In the CNS they're called Oligodendrocytes. Both of them produce Myelin Sheath. The Myelin Sheath of a Neuron The Myelin Sheath insulates the Axons in the vertebrate nervous system. The Sheath is produced by the Schwann's and Oligodendrocytes. 6
Synaptic Terminal of a Neuron The Synaptic Terminals are what connects to the Dendrites of the next Neuron. They send the signal to the next Neuron. The Synaptic Cleft Of a Neuron The Synaptic Cleft is the gap between the Presynaptic Cell (the transmitting cell) and the Postsynaptic Cell (the receiving cell). Because the Neurons don t actually connect there is a gap between them called the Synaptic Cleft. The Neurons are not as connected as you might think. The Neurotransmitters of a Neuron The Neurotransmitters are in the Neuron s Vesicles. The Vesicles travel through the cell carrying the transmitters. The transmitters are released in the Terminal Branches. They then travel across the Synaptic Cleft to open Ion channels in the next Neurons Dendrites. That way the Sodium Ions outside the Neurons Can get in and start the Neural Signaling. 7
The process of Neural Signaling The signaling process involves multiple action potentials along the Axon. One action potential involves four steps: Resting State, Depolarizing Phase, Repolarizing Phase, And Undershoot. All this happens in what s called Nodes of Ranvier (the gaps between the Myelin Sheath). The resting state of Neurons is when the Potassium and Sodium channels are closed. Outside is positively charged and inside is negatively charged. Resting State Depolarization Phase Occurs when the Neurotransmitters open up the Sodium Ion channels. This allows the Sodium Ions to travels into the Neuron through it s channels causing a positive charge inside the Neuron. 8
Repolarization Phase The Potassium Ion channels open up allowing the Potassium Ions to leave the Neuron, because the Sodium Ion channels are now closed. Because the Potassium left now the Neuron is negatively charged inside. Undershoot The Potassium Ions keep leaving the Neuron, because the Potassium Ion channels take longer to close. Therefore too many Potassium Ions left the Neuron so the Neuron has become unbalanced. After a short time it returns to the Resting State. Action Potential Chart On Board/Handout 9
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