Human Biology: Blood, Excretion, Nutrition, and More
Human Biology: An Overview
Blood Composition and Function
Blood is composed of plasma and three types of cells:
- Erythrocytes: Red blood cells without a nucleus, responsible for oxygen transport.
- Leukocytes: White blood cells that defend the body against infections.
- Platelets: Involved in blood coagulation.
Diastole refers to the relaxation of the heart chambers, while systole refers to their contraction.
Excretion and the Kidneys
Excretion is the process of eliminating waste substances from the blood.
The kidney is the primary organ responsible for filtering blood. It is composed of nephrons, which consist of:
- Glomerulus
- Proximal tubule
- Distal tubule
- Collecting duct
The renal cortex contains the glomeruli, distal, and proximal tubules. The renal medulla contains the loops of Henle and collecting ducts. The renal pelvis consists of ducts that collect urine.
Urine is the liquid waste product containing toxic substances, formed in two phases:
- Blood is filtered in the glomerulus, and plasma enters the nephron.
- The filtered liquid passes through the rest of the nephron, where proteins, glucose, and water are reabsorbed.
Sweat is a liquid produced by filtering blood, which then reaches the skin.
Nutrition: Macro and Micronutrients
Nutrients are substances needed for energy. They are divided into macronutrients and micronutrients:
Macronutrients
- Glucids (Carbohydrates): Provide energy.
- Fiber: Aids in intestinal transit.
- Lipids (Fats): Provide energy.
- Proteins: Build the matter that forms our cells.
- Water: Essential for various bodily functions.
Food Groups
- Group 1 (Milk, Milk Derivatives, and Eggs): Sources of proteins, vitamins, and calcium.
- Group 2 (Meat, Poultry, and Fish): Provide proteins.
- Group 3 (Fats and Oils): Provide lipids.
- Group 4 (Cereals, Pulses, Potatoes, and Sugar): Provide proteins and glucids.
- Group 5 (Vegetables): Source of vitamins and fiber.
- Group 6 (Fruit): Provide glucids, vitamins, and fiber.
The Perfect Diet
A balanced diet should provide the right amount of energy, sufficient proteins, vitamins, and minerals, with careful consideration of the distribution of energy-providing foods.
Food Preservation Methods
Common methods of food preservation include drying, salting, and freezing.
Interaction and the Nervous System
Interaction is a set of processes through which a living being obtains information and makes decisions. The processes are:
- Obtaining information.
- Analyzing the information and elaborating a response.
- Executing a response.
Neurons
Neurons transport messages in the brain. They have three parts: the cell body, axon, and dendrites. There are three types of neurons: sensory, interneurons, and motor neurons.
Receptors
Receptors are specialized structures that capture external stimuli. Types include mechanoreceptors, thermoreceptors, chemoreceptors, photoreceptors, and nociceptors.
Brain Parts
- Cerebrum: The largest part of the brain, located in the front of the head, controls language and eating.
- Cerebellum: Located above the cerebrum, controls muscle movement and coordination.
- Brain Stem: Located at the bottom of the brain, controls automatic functions.
The Endocrine System
The endocrine system coordinates body organs and produces hormones that coordinate long-term processes in small quantities. Some endocrine glands include:
- Thyroid: Regulates metabolism.
- Adrenal Glands: Increase heart and breathing rate.
- Ovaries: Control development in women.
- Testes: Control development in males.
Reproduction
The male gamete is called sperm, and the female gamete is the ovum. These cells are formed by the testicles and ovaries.
Male Reproductive System
Consists of the testicles, epididymis, vas deferens, seminal vesicles, prostate, urethra, and penis.
Female Reproductive System
Consists of the ovaries, fallopian tubes, uterus, and vagina.
Fertilization and Birth
Fertilization is the union between the ovum and sperm to form a zygote.
Birth involves the dilatation of the uterine neck, expulsion of the fetus, and expulsion of the placenta.