The brain, heart and the skeleton are the integral parts of the nervous system, circulatory system and the skeletal system respectively. The nervous system is made of the brain and the spinal cord with neurons as the structural and functional units of it. The circulatory system is made up of the heart and its blood vessels. The skeletal system is made up of the bones and cartilages making the skeleton of the body.
The brain regulates the heart beat and the blood pressure. The heart nourishes the brain with oxygen and nutrients by pumping blood. The bone cells are nourished by the blood pumped by the heart. The bone marrow of the skeleton produces the new red blood cells which enter the blood circulatory system. Also the the ribs and the breast bone of the skeleton protects the heart, the cranium of the skeleton prtects the brain. The bones also provide calcium which is necessory for the functioning of the nervous system. The brain controls the skeletal movements of the body. The cerebellum of the brain controls the voluntary skeletal movements and the medulla controls the involuntary skeletal movements of the body. The blood brain barrier formed by the endothelial cells of the capillary walls located in the brain seperates the circulating blood from the brain and the extraclellular fluid in the central nervous system and acts as a selective semipermeable border.
I think the answer is B but I'm not sure sorry
Answer: Coelenterates as a whole are of little economic importance. Seldom used as food by man, they are eagerly devoured by certain fishes and by invertebrates such as the crown of thorns starfish. Certain corals used as ornaments and for the manufacture of jewelry have become rare because of exploitation.
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Answer:
b. Intrinsic rate of growth (r)
Explanation:
The per capita rate of increase in the population size makes its intrinsic growth rate. The maximum intrinsic growth rate is exhibited by a population when all the required resources are available and there are no negative ecological interactions such as competition. Each population has its specific innate capacity to increase its size that is represented by "r ".