Chapter 12: Human Physiology Flashcards
Digestion in Humans
Human digestive system has two functions: digestion and absorption.
Mouth
Tongue and teeth start the mechanical digestion. The salivary glands begin the chemical digestion of starch.
Esophagus
The epiglottis separates the windpipe and the esophagus, but no digestion occurs here.
Stomach
The stomach secretes gastric juice that starts the digestion of proteins.
Three types of cells assist in the digestion (chief cells and parietal cells).
Small Intestine
Digestion is completed here. Bile breaks down proteins, nucleus acid is hydrolysis by my leases, and lipase break down lipids. Has villi and lacteals.
Villi
Villi are fingerlike projections that absorb the nutrients from digestion. Contains lacteal, capillaries, and microvilli.
Lacteal: vessel of the lymphatic system.
Microvilli: greatly increase the rate of nutrient absorption by the villi
Large Intestine
Has three functions: egestion, vitamin production, and the removal of excess water.
Hormones of the Digestive System
Gastrin, secretin, and cholecystokinin.
Gastrin
Stimulates the secretion of gastric juice.
Secretin
Stimulates pancreas to release bicarbonate to neutralize acid in the duodenum.
Cholecystokinin
Stimulates pancreas to release pancreatic enzymes and gall bladder to release bile into the small intestine.
Respiration
The exchange of gasses: carbon dioxide and oxygen, through diffusion.
Gas Exchange in Humans
Air enters the naval cavity which moistens and filters it, which it then goes through the larynx to the bronchi, and the tiny bronchioles, and finally the alveoli where the gas exchange takes place.
Medulla and Gas Exchange
The medulla controls the breathing and sets the rhythm.. It monitors CO2 levels by sensing pH changes in the blood.
CO2 dissolves in the blood to become carbonic acid, so the higher the concentration of CO2, the lower the pH.
Hemoglobin
Carriers of oxygen in the blood stream. It is an allosteric molecule that exhibits cooperativity.
Hemoglobin is also sensitive to pH change. Because CO2 dissolves in the blood to make carbonic acid (making it have a lower pH), active muscles create a lot of CO2, which alerts the hemoglobin to go there and release oxygen/
Transport of Carbon Dioxide
Carbon dioxide is transported by plasma as part of the carbonic acid carbonate ion system, which keeps blood at the 7.4 pH.
Carbonic Acid Carbonate ion System
Bicarbonate ion is created in two steps:
- Carbon dioxide + H2O makes carbonic acid.
- Carbonic acid dissociates into a bicarbonate ion and a proton.
Closed Circulatory System
The human circulation system with arteries, veins, and capillaries.
Plasma
Liquid portion of blood, has clotting factors, hormones, antibodies, nutrients, dissolved gases, wastes.
Red blood cells
Carry hemoglobin and oxygen. Formed in the bone marrow and recycled in the liver.
White Blood Cells
Fight infection and formed in the bone marrow, as well as leukocytes produce antibodies.
Platelets
Cell fragments formed in the bone marrow that clot blood.
Arteries
Take blood away from the heart under great pressure, and made of thick, smooth muscle.
Veins
Take blood back to the heart under little pressure, and made of thin walls and valves to prevent back flow.
Capillaries
Allows for diffusion of nutrients and wastes, and only one cell thick.
Systolic Number
The measurement of the pressure when ventricles contract.
Diastolic Number
Measure of the pressure when the heart relaxes.
Coronary Circulation
Blood circulation through the heart.
Renal Circulation
Blood circulation through the kidneys.
Hepatic Circulation
Blood circulation through the liver.
Pulmonary Circulation
Includes the pulmonary artery, lungs, and pulmonary veins.
Regulatory System that Releases Chemicals
Endocrine and nervous.
Hormones
Produced in the ductless endocrine glands and move to target cells. They can have an immediate, short lived response, or alter the development of an entire organism.
Tropic Hormones
Cause other goods to release hormones, so have a far reaching affect.
Pheromones
Carry a message between individuals of the same species.
The Hypothalamus
Send electrical signals to the adrenal gland to release adrenaline. Secretes GnRH from neurosecretory cells that stimulate the anterior pituary. Also is the body’s “thermostat” and regulate hunger and thirst.
Signals here travel to the posterior and anterior pituitary.
Feedback Mechanism
Self-regulating mechanism that increases or decreases the level of a particular substance.
Positive feedback
Enhances an already existing response, such as child birth that induces even more contracts.
Negative feedback
Maintains homeostasis, such as the body maintaining proper levels of thyroxin.
Lipid or Steroid Hormones
Diffuse right through the plasma membrane and bind to a nucleus receptor.
Protein or Peptide Hormones
Cannot diffuse through the plasma membrane, so they bind to a receptor on the cell’s surface. This triggers a secondary messenger such as cAMP, and converts the extracellular signal into a chemical signal.
Testosterone
Secreted by cells in the testes and travel through the blood to many cells. It passes through the cell membrane and binds to a receptor in the cytoplasm (only cells with testosterone receptors respond to testosterone).
it then enters the nucleus and acts as a transcription factor, turning on specific genes in the nucleus that contribute to male functions.
Epinephrine
Tells the liver to create glucose. Starts as epinephrine binds to the G protein membrane receptor on liver cells, and the G protein does shit to produce cAMP, which causes two reactions: 1) activates glycogen phophorlase to make glycogen turn into glucose. 2) inhibits glucose turning into glycogen.
Temperature Regulation
Because temperature on land fluctuates a lot, animals must learn to generate their own body heat, move to nice climate, or change their behavior.
Ectotherms
Generate most of their body heat from the environment. Have low metabolic rate and thus cannot generate much heat by themselves, so their internal temperature equates to the environment temperature. Examples include fish, reptiles, amphibians.
Endotherms
Use metabolic processes to create body heat. Examples include humans, other mammals.
North-South Cine
Anatomical difference in species across a geographic range. Examples include the jackrabbit who have big fluffy ears in warm southern regions (to dissipate heat), and small ears in cold weather.
Countercurrent Heat Exchange
Evolution in certain animals to help warm or cool extremities. An example includes polar bears having to reach into icy waters and catch fish to eat. Warm blood is flowing out to the paw which warms the cold water flowing back to the heart.
Osmoregulation
The management of the body’s water and solute concentration.
In marine environments, the ocean is a very dehydrating hypertonic place for its organisms. So, they produce little, concentrated urine and ingest lots of seawater.
Freshwater is opposite, as it is hypotonic, and fish excrete a lot of dilute urine and ingest little water.
Excretion
The removal of metabolic wastes, such as CO2 and H2O from respiration.
The Three Nitrogenous Wastes
Ammonia, Urea, and Uric Acid
Ammonia
Very toxic and soluble in water. Often produced by water-living organisms, like hydra and fish.
Urea
Not as toxic as ammonia. Secreted by humans, earthworms, and mammals (formed in the liver by ammonia).
Uric Acid
Pastelike, not soluble in water, and thus not very toxic. Secreted by birds, insects, reptiles.
Human Kidney
Functions as an osmoregulator and excretion mechanism. Filters many liters of blood per a day, as well as adjust both the volume and concentration of urine depending on how much fluid and salt the human has ingested in one day. If they ingest a lot of fluid and low salt, the kidney will produce lots of urine.
The Nephron
Has capillaries, glomerulus, the renal tubule. Does its job in four steps: filtration, secretion, reabsorption, and excretion.
Filtration: The kidney forces blood into the glomerulus in Bowman’s capsule, where specialized cells there will increase the rate of filtration. It is passive and nonselective, as the filtrate contains anything small enough to diffuse through the glomerulus Bowman’s capsule. Then it goes to the proximal tubule.
Secretion: Occurs in the proximal tubules. It is selective and active, as it picks out specific drugs and toxins to remove. It also releases ammonia to neutralize the acidic filtrate.
Reabsorption: Starts in the proximal tubules. It is passive, active, and selective. It gathers water and solutes to transport back to the capillaries and the body.
Excretion: Gathering of metabolic wastes (such as nitrogenous wastes) and excretes them from the body.
Hormone Control of the Kidney
As blood pressure falls, the ability of the nephron to filter blood at Bowman’s capsule is impaired, so the kidney must respond by increasing the blood pressure. Does this through three hormones: aldersterone, ADH, and renin.
Aldosterone
Released by the adrenal glands in response to a drop in blood pressure.
ADH
Released by the hypothalamus in response to dehydration, as the blood becomes too concentrated. ADH opens renal aquaporins, which allows more water to be reabsorbed.
Renin
Released by the kidneys, and converts an inactive protein to angiostenin. Stimulates the greater creation of aldosterone.
Nervous System
Divided into the central and peripheral nervous system.
Central Nervous System
Includes the brain and the spinal cord.
Peripheral Nervous System
Includes all the nervous not part of the CNS.
Sensory: conveys information from the nerve endings or sensory receptors.
Motor: somatic system controls the voluntary muscles. Autonomic system controls the involuntary muscles. Includes the sympathetic and parasympathetic systems.
Sympathetic: fight or flight, increase heart and breathing rate, stimulates glycogen to glucose production in liver, decreases digestion.
Parasympathetic: opposes the sympathetic system. Increases digestion and relaxation, decreases breathing and heart rate…
Neuron
Contains the cell body (with nucleus), dendrites, and axons.
Dendrites: sensory, as they receive information from other cells and carry it to the cell body.
Axons: transmit signals and impulses from one cell body to another cell.
Myelin Sheath
A coating that covers the axon, formed by the Schwann cells.
Sensory Neuron
Receives signals from a sensory organ, such as the eyes and ears, or from another neuron.
Motor Neuron
Stimulates effectors, such as muscles or glands.
Interneuron
Resides in the brain or spinal cord. Receives signals, and transfers it to motor neurons or the brain directly.
Membrane Potential
The difference in electrical change between the cytoplasm and extracellular fluid. The polarization in the neuron is maintained by the pumping of sodium and potassium ions across the membrane using the sodium potassium pump.
Gated-ion Channels
If a stimulus triggers the Na channels to open, the influx of Na+ in the membrane causes depolarization, which makes it easier and closer for the nerve to fire in to an action potential.
If a stimulus triggers the K channels to open, the influx of K+ causes the membrane to be hyper polarized, which makes it harder for the neuron to fire.
Action Potential
When the axon is stimulated past the threshold, an action potential occurs. The Na+ channels open, which the influx of Na+ causes a depolarization, as K+ leaves the membrane. After the action potential reaches its climax, the axon goes into repolarization, where the original states of Na+ and K+ return.
Refractory Period
The short period of repolarization in the axon during the action potential that the axon cannot respond to another stimulus.
The Synapse
The stimulus crosses the synapse chemically. The cytoplasm of the presynaptic neuron contains many vesicles that contain neurotransmitters. The depolarization of the presynaptic neuron causes the vesicles to bind with the membrane, releasing the neurotransmitters through exocytosis. The neurotransmitters bind to the postsynaptic membrane and creates a response by alerting the membrane potential of the postsynaptic. (Neurotransmitter is usually acetylcholine).
Cerebrum
Controls learning, emotion, perception. Has two left and right halves.
Cerebellum
Coordinates movement, balance, sensory information, and takes commands from the cerebrum.
Brainstem
Controls many homeostatic functions, sensory information, and transfers information from the PNS to other parts of the brain.
Eye Signal Transduction Pathway
Starts when the photons of light hit the eye lens, which is absorbed by photoreceptors. The rods and cones in the eye become embedded with retinal, and a change between cis to trans occurs. Rhodopsin becomes excited, and leads to the signal transduction pathway.
Three Types of Muscle
Smooth, skeletal, and cardiac.
