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Each tooth is made up of a crown, which is above the gum line and covered in enamel, and roots that anchor the tooth to the alveolar bone. [2] [6] Beneath the enamel, there are collagen fibres and inorganic hydroxyapatite, which together form dentin. [2] [6] Hydroxyapatite is the storage form of calcium found in the bone. [7]
A dog communicates by altering the position of its head. When the head is held in an erect position this could indicate that is approachable, attentive, curious, or aggressive. Turning the head away may indicate fear, but is also recognized as a calming signal. [13] A dominant dog will display an upright posture and/or stiff legs. [13]
The following is a list of the muscles in the dog, along with their origin, insertion, action and innervation. Extrinsic muscles of the thoracic limb and related structures: [4] Descending superficial pectoral: originates on the first sternebrae and inserts on the greater tubercle of the humerus. It both adducts the limb and also prevents the ...
Depiction of smooth muscle contraction. Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [1]
Tonic contractions are those contractions that are maintained from several minutes up to hours at a time. These occur in the sphincters of the tract, as well as in the anterior stomach. The other type of contractions, called phasic contractions, consist of brief periods of both relaxation and contraction, occurring in the posterior stomach and ...
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. [2] Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. In the neuromuscular system, nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles. [3]
Healthy gums fill and fit each space between the teeth, unlike the swollen gum papilla seen in gingivitis or the empty interdental embrasure seen in periodontal disease. Healthy gums hold tight to each tooth in that the gum surface narrows to "knife-edge" thin at the free gingival margin. On the other hand, inflamed gums have a "puffy" or ...
The flehmen response (/ ˈ f l eɪ m ən /; from German flehmen, to bare the upper teeth, and Upper Saxon German flemmen, to look spiteful), also called the flehmen position, flehmen reaction, flehmen grimace, flehming, or flehmening, is a behavior in which an animal curls back its upper lip exposing its front teeth, inhales with the nostrils usually closed, and then often holds this position ...