Circulatory System and Blood Composition

• The circulatory system distributes blood, oxygen, and nutrients throughout the body to organs, muscles, and tissues.
• The circulatory system removes waste products like carbon dioxide and other byproducts.

Blood Composition

• Blood is composed of two elements: blood plasma and blood cells.
• Blood plasma makes up 55% of blood, it is an extracellular matrix that contains nutrients, but has no oxygen.
• Blood cells make up 45% of blood, these absorb oxygen with hemoglobin and transport it throughout the body.
• Red blood cells (Erythrocytes): They have no nucleus, and transport oxygen via hemoglobin.
• White blood cells (Leukocytes): They have a nucleus, they are part of the body's immune response, and have memory.
• Platelets (Thrombocytes): They participate in blood clotting by attaching to broken blood vessels and creating a clot to stop bleeding.
• Blood cells are produced in bone marrow.

Blood Vessels

• Blood vessels are tubes through which blood flows, forming a network in a closed circuit.
• Blood always flows in the same direction through the blood vessels.
• Arteries: They transport blood from the heart to the organs and have high blood pressure.
• Capillaries: Responsible for carrying blood into specific parts of organs.
• Veins: They carry blood back to the heart to be filled with oxygen.

Heart Parts

• Veins and Arteries: They are the vessels connecting the heart with the rest of the body.
• Atria: The heart's two upper chambers, connected to large veins.
• Valves: They separate the heart's chambers and control blood flow direction when the heart contracts.
• Ventricles: The heart's lower chambers that pump blood out, connected to large arteries.

Circulation

• The first circulatory circuit is pulmonary circulation; blood rich in carbon dioxide flows from the heart to the pulmonary alveoli for gas exchange, then oxygen-rich blood flows back to the heart.
• The second circuit is systemic circulation; oxygen-rich blood flows from the heart to all organs and tissues, where cells absorb oxygen and release carbon dioxide, which the blood carries back to the heart.

Excretory System

• The excretory system filters blood to produce urine, which is stored in the bladder, and prevent toxins from harming our bodies.
• The urinary system removes wastes like urea.

Blood Filtering

• Unfiltered blood, containing salts, urea, water, and glucose, enters the kidneys through the renal artery for filtering.
• Primary urine is formed from the filtered waste products, while filtered blood returns via the renal vein.
• Nephrons: Units inside the kidneys where blood filtration occurs.
• Unfiltered blood enters, filtrate consists of nutrients, water, urea and salts to form primary urine.
• Primary urine exits the capsule to the tubule, where final filtration occurs with the renal vein.

Excretory System Parts

• Ureters: Tube like structures that direct urine to the bladder.
• Bladder: The hollow organ that stores urine.
• Urethra: The tube through which urine exits the body.

Interactions with the Environment

• Humans interact with their surroundings (the environment).
• The organism detects changes and responds to them in order to survive and reproduce.
• Interaction with the environment occurs in three stages: stimulus detection by receptors, relay and interpretation of the stimulus by coordination systems, and response by effectors.

Receptors

• Receptors detect stimuli, which are anything that causes a response in an organism (external or internal).
• Interoceptors: Collect information about the body’s internal conditions and respond to chemical stimuli.
• Exteroceptors: Provide information about the outside environment and are sense organs.
• Proprioceptors: Inform about the position and condition of muscles and are located in the inner ear and locomotive system.

Coordination

• Coordination is needed for cells, tissues, and organs to respond to changes.
• Coordinating systems receive information from receptors, interpret it, and activate organs for a response.

Coordinating Systems

• Includes the nervous system and endocrine system.
• The nervous system, consisting of nerves, the brain, and the spinal cord, generates fast, short-lived responses transmitted through nerve impulses.
• The endocrine system which is formed of endocrine glands use hormones in the blood and produces slower, long-lasting responses.

Responses

• Changes the human body experiences when stimuli are interpreted.
• Effectors: Organs, tissues, or cells that carry out responses.
• Motor responses involve movement and muscles.
• Secretory responses involve the production of substances by glands.

Senses

• A stimulus is detected by the sense organs

Eye

• Organ used to see light, contains photoreceptors that convert light to nerve impulses.
• Cornea: Focuses light rays and protects the pupil and iris.
• Iris: Regulates light entering the pupil by adjusting its size.
• Pupil: Opening for light to pass through.
• Crystalline lens: Converges light onto the retina and enables accommodation.
• Retina: Lines the inner surface of the eye, projects light rays, and contains two types of cells.
• Rods: They detect light intensity.
• Cones: They detect color.
• Optical Nerve: The nervous impulse is transmitted to the brain from here to be interpreted.

Nose

• Organ that allows us to smell particles in the air because of chemoreceptors in mucus.
  • Olfactory mucus has chemoreceptors to turn stimuli into electrical impulses.
  • Olfactory bulb collects impulses and directs them to the olfactory nerve.
  • Olfactory Nerve transmits impulses to the brain.

Ear

• Organ that detects vibrations via mechanoreceptor cells.
  • Outer Ear
  • Pinna captures sound waves and sends them through the ear canal.
  • Ear canal is a passage from the pinna to the eardrum.
  • Middle Ear
  • Eardrum vibrates when sound waves hit it.
  • Ossicles vibrate along with the eardrum (malleus, incus and stapes).
  • Inner Ear
  • Eustachian tube alleviates pressure in the eardrum.
  • The Vestibular System is responsible for balance.
  • Cochlea contains fluid and cilia, which receive sound vibrations and transform stimuli into nerve impulses.
  • Auditory nerve sends the nervous impulse.

Tongue

• Allows tasting substances in oral cavity, taste buds cover the surface.
  • Taste buds are tiny bumps that cover the surface of the tongue, they have nerve endings and taste receptors. -Receptors detect substances and turn them into electrical impulses. -Nerve endings receive impulses and send information to the the brain.

Skin

• Touch detects stimuli through changes in the environment.
  • Mechanoreceptors detect changes in pressure, like Meissner's corpuscles (light pressure) and Pacinian corpuscles (hard pressure).
  • Thermoreceptors detect change in temperature, Krause corpuscles (decrease) and Ruffini corpuscles(increase).
  • Nociceptors detect pain.
  • Free nerve endings detect pain.

Response

• The brain interprets the burn in your hand.
• The coordination systems, being nervous and endocrine based, send a response.
• Interoceptors detect internal changes with chemical stimuli.
• Exteroceptors detect external changes with physical stimuli, and the locomotor system carries out motor responses.
• Proprioceptors detect balance and changes in position.
• Motor actions cause movement.
• Secretory actions create gastric juices or hormones.

Nervous System (NS)

• Reacts quickly to stimuli and is divided into a central and peripheral section.
  • Central Nervous System
  • Brains consists hundred of millions of neurons, -Cerebellum controls muscle and balance, -Cerebrum controls critical thinking and movement, -Brainstem controls breathing and heart rate.
  • Spinal cord sends motor commands, sends information and coordinates reflexes. -Peripheral Nervous System -Autonomic controls involuntary movement, -Somatic controls voluntary movement.

Nerve Impulses

• Information that travels fast through nervous system as electrical signal. -Nerve impulses travel from 3m/s to 120/s. -Nerve impulses are transmitted between the main nerve cells.

Neurons:

• Neurons are specialized in producing and transmitting electrical nerve impulses. -Sensory neurons detect external stimuli. -Relay neurons have connection to create networks. -Motor neurons send responses from center to effectors.

Neurons Structure:

• Structure Cell body called SOMA with nucleus.
  • The extensions are Dendrites and Axons.
  • The connection point is synapse.
  • It includes Glial cells!

Endocrine System

• Glands and organs in charge of internal body stimuli.
• React slower but lasts longer.
• Secrete hormones into bloodstream to control the body:
• Metabolism, energy, reproduction, growth, and development.
• Hypothalamus controls the endocrine and the nervous systems.
• Pituitary gland is main gland.
• Pineal gland produces hormones.
• Thyroid controls metabolism and growth.
• Parathyroids regulate calcium.
• Adrenal glands secrete corticosteroids and adrenaline.
• Pancreas secreted insulin.
• Ovaries regulate estrogen and progestogen.
• Testes regulate testosterone.

Behavior

• Humans have varied responses to stimuli. -Innate behavior is what we are born knowing, like reflexes and instincts. -Learned behavior depends on the environment.

The circulatory system transports blood, oxygen, and nutrients. Blood contains plasma and cells, including red and white blood cells, and platelets. These components facilitate oxygen transport, immune response, and blood clotting throughout the body.