Last week, I attended my last undergraduate anatomy and physiology lecture. To say that I’m excited would be a tremendous understatement. The class was two semesters long, jam-packed with information, and I was beyond ready for it to be over.
We talked about everything from immunity to the brain to reproduction in there, and if there’s one thing I learned in that class that I know I won’t forget, it’s that the complexity of the human body reveals the glory of God.
“For You created my inmost being; You knit me together in my mother’s womb. I praise You because I am fearfully and wonderfully made; Your works are wonderful, I know that full well. My frame was not hidden from You when I was made in the secret place, when I was woven together in the depths of the earth. Your eyes saw my unformed body; all the days ordained for me were written in Your book before one of them came to be. How precious to me are Your thoughts, God! How vast is the sum of them!” Psalm 139:13-18.
Now I’m sure that not all of you are scientifically-minded, but I think you’ll still enjoy today’s post. It’s fascinating and God-exalting, really, regardless of your interest (or lack thereof) in anatomy and physiology. Take a look below at nine topics from A&P that I think clearly display the glory of our Creator.
LOCATIONS OF DIFFERENT EPITHELIAL TISSUES
Many organs of the human body are lined with epithelial tissue – a collection of cells good for absorbing and secreting various substances. There is not merely one type of epithelial tissue, though. There’s simple squamous epithelium and ciliated columnar epithelium, stratified squamous epithelium and transitional epithelium – all of which are slightly different and specialize in different things.
The fascinating part is that the locations of the different epithelial tissues depend on their specialized function. For example, simple squamous epithelium is good for allowing materials to pass from one place to another via diffusion. Therefore, the alveoli of the lungs (the place where gas exchange occurs) are lined with simple squamous epithelium so that O2 and CO2 can diffuse across capillary walls. As for transitional epithelium, that’s a type of cell that allows its organs to stretch and expand, and that’s what lines the urinary bladder. Makes perfect sense, right?
MOVEMENT NOURISHES JOINTS
It’s pretty intuitive that the more sedentary an individual is, the more physical problems they’re likely to experience. This is especially true when it comes to one’s joints because movement nourishes our joints. Movement causes the cartilage in our joints to swell with synovial fluid (a slippery and viscous substance that allows joint movement to be friction free) and the joint compression that occurs with normal movement actually squeezes metabolic waste out of the cartilage. Without adequate amounts of movement, the cartilage in our joints deteriorates more quickly than it would with ample exercise. How incredible is it that God designed it so that something we do every day (move) nourishes our bodies from the inside out?
MYELIN SHEATHS ON NEURONS
Basically, myelin sheaths (also known as Schwann cells) are microscopic pillow-like structures located on the axons (tails) of neurons (cells in the nervous system). Neurons communicate via action potentials, directory impulses caused by chemical changes. The presence of myelin sheaths allows these action potentials to travel down the axon of one neuron and reach another neuron more quickly. Pretty neat, if you ask me! Myelin sheaths sometimes deteriorate with age, which helps explain why older adults sometimes don’t have the processing speed of a younger person. (They have a lot more wisdom though! Shout out to grandparents!)
HORMONAL CONTROL AT THE PITUITARY
Nine major hormones are directly controlled by the pituitary gland (and a host of other hormones are indirectly controlled by the pituitary gland), a pea-sized organ located in the medial region of the brain. The hormones directly controlled by the pituitary include GH (growth hormone), PRL (prolactin), ADH (antidiuretic hormone), and OXT (oxytocin). Respectively, those hormones allow developing children to grow, enable soon-to-be and new mothers to produce breast milk, assist in blood pressure regulation, and facilitate interpersonal bonding. All that and more from one pea-sized part of the brain…our God is amazing!
STRUCTURE OF ERYTHROCYTES
Erythrocytes (that’s just the fancy term for red blood cells) are biconcave (thick at the edges and thin in the middle) disc-shaped structures that carry oxygen through our bloodstreams. It’s their biconcave shape that allows them to hold oxygen, similar to how a bowl would hold water. Hence the theme of anatomy and physiology that structure determines function! When a person has Sickle Cell Anemia, their red blood cells lack this biconcave structure (the RBCs of an individual with Sickle Cell Anemia look more like a scythe), rendering them unable to carry oxygen properly. Personally, I think it’s pretty neat that God designed it so that oxygen would be carried through our blood by microscopic flexible “bowls.” Oh, and I can’t neglect to mention that you’ve got about 5 million of these little “bowls” in your blood vessels at any given time!
NATURAL KILLER CELLS
The immune system is among the more fascinating body systems, to be sure. Natural killer cells are a component of the immune system and if they don’t reveal intelligent design, I don’t know what does. Natural killer cells are specialized lymphocytes (white blood cells) that monitor our bodies for abnormal cells ranging from run-of-the-mill pathogens to cancerous cells. Upon finding abnormal cells, NK cells will release a protein called perforin, which will put holes in the membranes of those abnormal cells, inducing cell lysis, and therefore killing the abnormal cells. NK cells are like our bodies’ own God-given defense team. Crazy cool, if you ask me.
The glomerulus is a part of the kidney that functions in filtering blood for waste and monitoring blood ion levels. On average, people have about 5 liters of blood in their body, but the glomeruli in the kidneys filter approximately 180 liters of blood per day, meaning that all the blood in our bodies is filtered nearly 40 times per day. The kidneys are relatively small and the glomeruli are so small that they’re invisible to the human eye, but they’re always hard at work to maintain our homeostasis and ensure our health.
THE REPRODUCTIVE SYSTEM AND THE CAPACITY FOR PLEASURE
Sex is not merely for the purpose of furthering the human race. It is quite clear, from both Biblical and scientific points of view, that it is also meant to be a pleasurable experience. As Christians, we need to look no further than Song of Solomon for that truth. It is obvious from a purely scientific point of view too though. For example, the glans of the penis is highly innervated with nerves and the female clitoris exists for no purpose besides pleasure. And you remember that bonding hormone we talked about earlier, oxytocin? That’s released in copious amounts in both males and females upon orgasm. Just another reason sex ought to be saved for marriage (Hebrews 13:4)! It’s pretty remarkable in my opinion that when designing reproduction, our Lord took our joy into account. What a lavish God we serve!
NOURISHMENT AND REGULATION IN UTERO
Babies in the womb are nourished by a disc-shaped organ called a placenta that is attached to them via an umbilical cord. The placenta also functions in waste disposal, hormone secretion, and fetal cardiovascular function. For humans living outside the womb, blood is oxygenated at the lungs, sent throughout the body, and then returns, in a deoxygenated state, to the lungs to pick up more oxygen and start the journey all over again. For humans living inside the womb, however, this isn’t an option. Unborn babies’ lungs aren’t functional yet, so they cannot replenish blood oxygen levels. The placenta takes the place of the lungs in this regard, picking up oxygen from the mother and transferring it to her babies’ bloodstream via the umbilical vein. Pretty fancy, I’d say.
Wow, maybe I liked the class a little more than I thought. Looking back on all that, I think I might even miss it a little.
Even though I won’t be attending A&P lectures and filling out note packets and going to two-hour anatomy labs anymore, I’m thankful for the information I learned over the course of the last two semesters. And I’m even more thankful for the way all of it pointed to the glory of my Creator.
“Yet You, Lord, are our Father. We are the clay, You are the Potter; we are all the work of Your hands.” Isaiah 64:8.