📖 Physiology
Tissue conduction velocity
PhysiologyTissue conduction velocity (m/s)
SA node - 0.05
Atrial pathways - 1
AV node - 0.02- 0.05
Bundle of His - 1
Purkinje system - 4
Ventricular muscles -1
Neurons
PhysiologyNeurons :
Types of neurons based on structure:
a multipolar neuron because it has many poles or processes, the dendrites and the axon. Multipolar neurons are found as motor neurons and interneurons. There are also bipolar neurons with two processes, a dendrite and an axon, and unipolar neurons, which have only one process, classified as an axon.. Unipolar neurons are found as most of the body's sensory neurons. Their dendrites are the exposed branches connected to receptors, the axon carries the action potential in to the central nervous system.
Types of neurons based on function:
- motor neurons - these carry a message to a muscle, gland, or other effector. They are said to be efferent, i.e. they carry the message away from the central nervous system.
- sensory neurons - these carry a message in to the CNS. They are afferent, i.e. going toward the brain or spinal cord.
- interneuron (ie. association neuron, connecting neuron) - these neurons connect one neuron with another. For example in many reflexes interneurons connect the sensory neurons with the motor neurons.
Secretions into the duodenum and their actions
PhysiologyBile - produced in the liver and stored in the gallbladder, released in response to CCK . Bile salts (salts of cholic acid) act to emulsify fats, i.e. to split them so that they can mix with water and be acted on by lipase.
Pancreatic juice: Lipase - splits fats into glycerol and fatty acids. Trypsin, and chymotrypsin - protease enzymes which break polypeptides into dipeptides. Carboxypeptidase - splits dipeptide into amino acids. Bicarbonate - neutralizes acid. Amylase - splits polysaccharides into shorter chains and disaccharides.
Intestinal enzymes (brush border enzymes): Aminopeptidase and carboxypeptidase - split dipeptides into amino acids. Sucrase, lactase, maltase - break disaccharides into monosaccharides. Enterokinase - activates trypsinogen to produce trypsin. Trypsin then activates the precursors of chymotrypsin and carboxypeptidase. Other carbohydrases: dextrinase and glucoamylase. These are of minor importance.
Central Nervous System
Physiology
The Nervous System Has Peripheral and Central Units
- The central nervous system (CNS) is the brain and spinal column
- The peripheral nervous system (PNS) consists of nerves outside of the CNS
- There are 31 pairs of spinal nerves (mixed motor & sensory)
- There are 12 pairs of cranial nerves (some are pure sensory, but most are mixed)
The pattern of innervation plotted on the skin is called a dermatome
The Nervous System Has Peripheral and Central Units
- The central nervous system (CNS) is the brain and spinal column
- The peripheral nervous system (PNS) consists of nerves outside of the CNS
- There are 31 pairs of spinal nerves (mixed motor & sensory)
- There are 12 pairs of cranial nerves (some are pure sensory, but most are mixed)
The pattern of innervation plotted on the skin is called a dermatome