Biology and human biology

• There are red blood cells
• Red blood cells are produced in the bone marrow
• Red blood cells carry gases such as oxygen
• The normal red blood cell count is 16
• Red blood cells


  • Biconcave shape which increases its surface area to carry more oxygen
  • Small in size and therefore can be transported easily
  • Flexible and therefore can enter into small blood vessels
  • Lack nucleus which creates room to transport oxygen
  • Lack nucleus
• Sperm cell


  The male gamete
• Sperm cell


  • Has haploid number of chromosomes (23)
  • Contains mitochondria which provide energy for the sperm
  • Has flagellum used for movement
  • Contains acrosome enzyme used to enter the egg cell
• Sperm cell components


  • Haploid nucleus
  • Cytoplasm
  • Mitochondria
  • Flagellum
  • Acrosome
• The main function of the endocrine system is to secrete hormones into the bloodstream, which then travel throughout the body.
• Endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands (including the adrenal medulla), pancreas, ovaries/testes, and pineal gland.
• Hormones are chemical messengers that regulate various physiological processes such as growth, metabolism, reproduction, and homeostasis.
• Skeletal muscles attach to bones via tendons and allow voluntary movement.
• Endocrine glands are specialized organs that produce and release hormones directly into the bloodstream.
• Examples of endocrine glands include the pituitary gland, thyroid gland, adrenal glands, pancreas, ovaries/testes, and hypothalamus.
• Each endocrine gland produces specific hormones that regulate various bodily functions such as growth, metabolism, reproduction, and stress response.
• Pituitary Gland - Located at the base of the brain, it secretes several important hormones such as growth hormone, prolactin, follicle-stimulating hormone, luteinizing hormone, thyrotropin, melanocyte-stimulating hormone, and antidiuretic hormone.
• Thyroid Gland - Located in the neck, it produces thyroxine and triiodothyronine, which regulate metabolism and other bodily functions.
• Examples of hormones produced by these glands include insulin, glucagon, testosterone, estrogen, progesterone, cortisol, epinephrine, norepinephrine, melatonin, and follicle-stimulating hormone (FSH).
• Cardiac muscle is found only in the heart and contracts rhythmically without conscious control.
• The hypothalamus secretes releasing factors and inhibiting factors that stimulate or suppress the release of hormones from other endocrine glands.
• Some hormones act locally on nearby tissues, while others circulate throughout the body.
• Endocrine glands secrete hormones directly into the bloodstream through their capillaries.
• Nervous tissue consists of neurons and neuroglia, with neurons being responsible for transmitting electrical impulses to other parts of the body.
• There are three types of tissue in animals: nervous tissue, muscular tissue, and connective tissue.
• Diabetes mellitus is a condition characterized by high blood sugar levels due to either insufficient production of insulin or resistance to its effects.
• Hormones are chemical messengers secreted by specialized cells called endocrine cells.
• Endocrine disorders are conditions where there is an overproduction or underproduction of certain hormones, leading to various health problems.
• Hormones can be classified based on their chemical structure and mode of action.
• Ovaries/Testes - Produce reproductive hormones like estrogen, progesterone, and testosterone.
• Hormones are chemical messengers secreted into the bloodstream to travel throughout the body and affect target organs.
• Pancreas - Produces both digestive enzymes and hormones like insulin and glucagon to control blood sugar levels.
• The nervous system consists of two main parts: the central nervous system (CNS) and peripheral nervous system (PNS).
• Pancreas - A large organ located behind the stomach, it contains both exocrine and endocrine tissues. The exocrine portion secretes digestive enzymes through ducts, while the endocrine portion consists of clusters of cells known as islets of Langerhans that produce insulin and glucagon.
• Ovaries/Testes - Produce estrogen and testosterone, respectively, which play crucial roles in sexual development and reproductive processes.
• Neurons have three main regions: dendrites, cell body, and axon.
• Dendrites receive signals from neighboring cells and transmit them towards the cell body.
• Connective tissue provides support, protection, and transportation functions in the body.
• Cell bodies contain the nucleus and are where most metabolic activity occurs.
• Muscle tissue allows movement by contracting and relaxing.
• Epithelial tissue covers surfaces and lines cavities, providing protection and absorption/secretion functions.