Three layers. The epidermis is the top layer of skin. This layer is for making new skin cells, provides a waterproof barrier, gives skin its color and is your protective layer. The dermis which is responsible for supply blood to your skin, hair growth, and the production of sebum (oil) and sweat. Lastly, the hypodermis which is basically made of connective tissue and fat and good for regulating your body temperature (1, 2, 3).
As the race begins, all of your physiological support systems - the musculoskeletal, cardiovascular, respiratory, digestive, immune, nervous, ...
Answer:
The autonomic nervous system is in charge of controlling visceral effectors. Traditionally, it is described by its peripheral nervous components (ganglia, nerves and plexuses) and two divisions are distinguished: the sympathetic and the parasympathetic. Transmission of the excitatory stimulus through the synaptic cleft occurs by release of neurotransmitters; the neurotransmitters of the sympathetic and parasympathetic nervous system are mainly norepinephrine (NA) and acetylcholine (AC). The NA-secreting fibers are called adrenergic and those that secrete AC, cholinergic. All preganglionic neurons, both those of the sympathetic nervous system and those of the parasympathetic nervous system, are cholinergic. The neuron that releases the neurotransmitter is called a presynaptic neuron. The signal receptor neuron is called a postsynaptic neuron. Depending on the type of neurotransmitter released, postsynaptic neurons are either stimulated (excited) or de-stimulated (inhibited).
Explanation:
The autonomic nervous system is the part of the central and peripheral nervous system that is responsible for the regulation of the involuntary functions of the organism, the maintenance of internal homeostasis and the adaptive responses to variations in the external and internal environment and two divisions are distinguished: the sympathetic and the parasympathetic. Acetylcholine is the preganglionic neurotransmitter of both divisions of the S.N.A. (sympathetic and parasympathetic) and also of the postganglionic neurons of the parasympathetic. The nerves at whose endings acetylcholine are released are called cholinergic. Norepinephrine is the neurotransmitter of postganglionic sympathetic neurons. The nerves into which norepinephrine is released are called adrenergic. Within the efferent sympathetic impulses, the postganglionic neurons that innervate the eccrine sweat glands and some blood vessels that supply the skeletal muscles are of the cholinergic type. Both acetylcholine and norepinephrine act on the different organs to produce the corresponding parasympathetic or sympathetic effects. The peripheral nerve endings of the sympathetic form a reticulum or plexus from which the terminal fibers come in contact with the effector cells. All the norepinephrine in peripheral tissues is found in the sympathetic endings in which it accumulates in subcellular particles analogous to the chromaffin granulations of the adrenal medulla. The release of norepinephrine at nerve endings occurs in response to action potentials that travel through nerve endings. The receptor, when stimulated by catecholamines, sets in motion a series of membrane changes that are followed by a cascade of intracellular phenomena that culminate in a measurable response. There are two classes of adrenergic receptors known as alpha and beta. These two classes are again subdivided into others that have different functions and that can be stimulated or blocked separately. Norepinephrine primarily excites alpha receptors and beta receptors to a small extent. The neurotransmitter acetylcholine is synthesized at the axonal terminal and deposited in synaptic vesicles. Acetylcholine activates two different types of receptors, called muscarinic and nicotinic receptors. Acetylcholine (AC) synthesis takes place at presynaptic termination by acetylation of choline with acetyl-coenzyme A, a reaction catalyzed by acetylcholinetransferase. The energy required for the release of a neurotransmitter is generated in the mitochondria of the presynaptic terminal. Binding of neurotransmitters to postsynaptic membrane receptors produces changes in membrane permeability. The nature of the neurotransmitter and the receptor molecule determines whether the effect produced will be one of excitation or inhibition of the postsynaptic neuron.
Answer:B
Explanation:
The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.
Answer:
B) The mass of the reactants equals the mass of the products,
Explanation:
Given that the reaction is balanced, the mass of the reactants must equal to the mass of the products.
We know this by virtue of the law of conservation of mass.
The law of conservation of mass states that "in a chemical reaction, matter is neither created nor destroyed but atoms are rearranged".
Therefore, if the reaction is chemically balanced, the mass of reactants must be the same as the mass of the products in the reaction.
The second choice is the right one.
