Diffusion and Osmosis in the Human Body

According to Fick’s first law of diffusion, smaller molecules diffuse through a cell membrane at a higher rate than larger molecules. Therefore, the rate of diffusion increases with a decrease in the size of the solute. A reduction in temperature (cold temperature) would reduce the rate of diffusion, while an increase in temperature (hot temperature) would increase the rate of diffusion.

Q 2

            A decrease in fluid volume increases osmotic pressure. That is because changes in the body-fluid volume affect the balance between fluid intake and loss, which is reflected in a change in osmotic pressure of the plasma space.

Q 3

            One of the situations that demonstrate diffusion in the human body is when oxygen diffuses from the alveolar space in the lungs into the blood circulating or moving around the lungs. One of the situations that demonstrate osmosis in the human body is when food nutrients get absorbed into the intestines and individual cells.

Q 4

            The tissue type that I think is most important in the human body is the muscle tissue. That is because it is responsible for all forms of body movement. In other words, there would be no movement of any body part without the muscle tissue.

Q 5

            Muscle tissue types: These include cardiac, smooth, and skeletal muscle tissues. Cardiac muscle tissues are under involuntary control, appear striated, and control various movements around the heart. Smooth muscle tissues are also under involuntary control, appear spindle-shaped, and control multiple body movements around hollow visceral organs, except the heart. Skeletal muscle tissues are under voluntary control, striated in appearance, and control the movement of body parts attached to the skeleton.

            Bone tissue types: These include compact and spongy bone tissues. Compact bone tissues have tightly packed Haversian system that forms a solid mass. The compact bone tissue forms the main structure for body support, movement, and protection. The spongy tissue is less dense and lighter than the compact bone tissue. It is filled with red bone marrow and helps in the production of blood cells.

Q 6

            Concentric muscle contraction: This is phase one of muscle contraction and involves the shortening of the muscles. Examples of activities that cause concentric muscle contraction include running uphill, sprints, climbing stairs, and cycling among others.

            Eccentric muscle contraction: This is the second phase of muscle contractions, and it involves lengthening of the muscles. The eccentric contraction occurs when one is walking downhill, in Pilates exercises, and braking while running.

            Isometric muscle contraction: This is the third phase of muscle contraction, and the muscles are usually static. Isometric muscle contraction occurs during exercises that do not cause joint movement, such as pushing against a wall.

Q 7

            During a muscle contraction to lift a 5Ib weight, the number of motor units involved will be less than the number of motor units involved during muscle contraction to lift a 50Ib weight. In other words, more motor units will be activated during a muscle contraction to lift a 50Ib weight than during muscle contraction to lift a 5Ib weight.

Q 8

            The synovial joints are surrounded by or covered with a layer of hyaline cartilage that functions to absorb shock by creating a slippery, smooth surface, thereby reducing the friction between the bones at the joints during movement.

Q 9

Using the picture of the man jumping as a reference, provide the correct answer to the questions below.

a. Name the articulation indicated by a circle. (Hint: It’s the name of the two main bones)

Answer: Patellofemoral articulation.

b. Name the action occurring at the hip joint.

Answer: Eccentric contraction.

c. Name the action occurring in the joint indicated by the square.

Answer: Concentric Contraction.

d. Name the muscle indicated by the arrow that points the ankle upwards.

Answer: tibialis anterior.

e. Name the muscle that flexes the right shoulder.

Answer: pectoralis major.