Answer: they have week immune systems
Explanation:
that’s what happens when you get old
Answer: 1. Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. As the atrium contracts, blood flows from your right atrium into your right ventricle through the open tricuspid valve.
2. Plasma is the main component of blood and consists mostly of water, with proteins, ions, nutrients, and wastes mixed in. Red blood cells are responsible for carrying oxygen and carbon dioxide. Platelets are responsible for blood clotting. White blood cells are part of the immune system and function in immune response.
3.Within the bone marrow, all blood cells originate from a single type of unspecialized cell called a stem cell. When a stem cell divides, it first becomes an immature red blood cell, white blood cell, or platelet-producing cell.
4. Epinephrine and norepinephrine, hormones secreted by the adrenal medulla, raise blood pressure by increasing heart rate and the contractility of the heart muscles and by causing vasoconstriction of arteries and veins. These hormones are secreted as part of the fight‐or‐flight response.
Skill neck arms ribs hands leg foot
Answer:
The given statement is TRUE
Explanation:
Urinary bladder is the hollow, muscular and distensible (elastic) organ in the urinary system of a human. The urine enters the bladder through the ureters from the kidneys. The urine collected in the bladder expands it.
The urinary bladder is made up of transitional epithelium. Once the urinary bladder is expanded to a certain extent it stimulates the stretch receptors in the transitional epithelium for the excretion of urine through the urethra.
Therefore, when the urine is accumulated in the urinary bladder, the bladder distends or expands and stimulates the stretch receptors in the transitional epithelium for urine excretion.
Answer:
The answer is B: All the muscle cells innervated by a single motor neurorn.
Explanation:
It is called a motor unit, all muscle fibers that are innervated by a motor neuron cell. A motor neuron cell can establish contact with up to 150 muscle fibrils, which when activated causes their simultaneous contraction, therefore, all the muscle fibers of a motor unit contract and relax at the same time.
