Parasympathetic nervous
Parasympathetic nervous
system is known to be one of the two divisions of the autonomic nervous system
and it is responsible for the stimulation of rest and digest activities that
usually occur when the body is at rest after eating which includes salivation,
urination, sexual arousal and digestion.
 
        
                    
             
        
        
        
Genes and DNA of their parents i think its those two <span />
        
             
        
        
        
Ventricles need more, denser muscular tissue because they pump blood to either the whole body(aorta) or to lungs(pulmonary artery). Atria on the other hand pump blood straight to the ventricles so they do not need as much force and power to pump the blood. 
Hope this helps:)
        
             
        
        
        
Body systems include:
Circulatory-
INCLUDES: Heart, blood vessels, blood lymph nodes and vessels, lymph
FUNCTIONS: Transports nutrients, wastes, hormones, and gases
Digestive-
INCLUDES: Mouth, throat, esophagus, stomach, liver, pancreas, and small and large intestines.
FUNCTIONS: Extracts and absorbs nutrients from food; removes wastes; maintains water and chemical balances.
Endocrine-
INCLUDES: Hypothalamus, pituitary, pancreas, and many other endocrine glands.
FUNCTIONS: Regulates body temperature, metabolism, development, and reproduction; maintains homeostasis; regulates concentration of body fluids.
Excretory-
INCLUDES: Kidneys, urinary bladder, ureters, urethra, skin, lungs
FUNCTIONS: Removes wastes from blood; regulates conccentration of body fluids.
Immune-
INCLUDES: White blood cells, lymph nodes and vessels, skin.
FUNCTIONS: Defends against pathogens and disease.
Integumentary -
INCLUDES: Skin, nails, hair
FUNCTIONS: Protects against injury, infection, and fluid loss; helps regulate body temperature.
Muscular-
INCLUDES: Skeletal, smooth, and cardiac muscle tissues.
FUNCTIONS: Moves limbs and trunk; moves substances through body; provides structure and support.
Nervous-
INCLUDES: Brain, spinal cord, nerves, sense organs.
FUNCTIONS: Regulates behavior; maintains homeostasis; regulates other organ systems; controls sensory and motor fuctions.
Reproductive-
INCLUDES: Testes, penis(in males); Ovaries, uterus, breasts(in females)
FUNCTIONS: Produces gametes and offspring.
Repertory-
INCLUDES: Lungs, nose, mouth, trachea.
FUNCTIONS: Moves air into and out of lungs; controls gas exchange between blood and lungs.
Skeletal-
INCLUDES: Bones and joints.
FUNCTIONS: Protects and supports the body and organs; interacts with skeletal muscles, producs red blood cells, white blood cells, and platelets
HOPE THIS HELPS AND PUT AS BRAINLIEST ANSWER