Human Physiology Flashcards
Digestion
Breaks down large molecules into smaller, usable molecules & absorbing these smaller molecules
Mouth
Where mechanical & chemical digestion begins
Salivary Amylase
Enzyme that begins starch digestion in saliva
Esophagus
No digestion, transports food from throat to stomach
Epiglottis
Keeps food away from windpipe
Stomach
Place for both mechanical & chemical digestion
Where protein digestion begins
It’s thick, muscular walls churns food & secretes gastric juice that contains hydrochloric acid & enzymes
Hydrochloric Acid
Begins breakdown of muscle (meat) & activates the inactive enzyme pepsinogen to become pepsin
Pepsin
Digests protein
Cardiac Sphincter
At top of stomach
Keeps acidified food in stomach from back up into esophagus
Pyloric Sphincter
At bottom of stomach
Keeps food in stomach long enough to be digested
Liver
Breaks down & recycles red blood cells
Detoxifies blood - removes alcohol & drugs
Produce cholesterol
Produce urea from protein metabolism
Produce bile
Bile
Emulsifies fats Neutralizes chyme (acidified food from stomach) entering small intestine
Small Intestine
Where all digestion is completed (in duodenum) & where nutrients are absorbed
Intestinal Enzymes
Amylase, protease, lipase, nuclease
Pancreatic amylase
Digests starch & is secreted into small intestine
Peptidases
Continue to break down proteins into amino acids
Nucleases
Hydrolyze nucleic acids into nucleotides
Lipases
Break down fats
Villi
Line small intestine & absorb all nutrients released from digested food
Pancreas
Produce enzymes that break down carbohydrates, proteins, lipids, nucleic acids & secretes them into small intestine
Produce hormones to control blood sugar levels
Produce sodium bicarbonate
Sodium bicarbonate
Produced in gallbladder
A base that neutralizes stomach acid, enabling intestinal enzymes to be effective as they require a basic environment
Large Intestine/Colon
Egestion - removal of undigested wastes
Vitamin Production - vit. K, B & folic acid
Reabsorption of Water
Rectum
Egestion, removal of undigested waste
Medulla in Gas Exchange
Sets breathing rhytm by monitoring carbon dioxide levels & by sensing changes in pH of blood
Artery
Carries blood away from heart
Enormous pressure
Vein
Carries blood back to heart
Little pressure
Capillary
Allows for diffusion of nutrients & wastes between cells & blood
Plasma
Liquid portion of blood, 90% water
Contains: clotting factors, hormones, antibodies, dissolved gases, nutrients, wastes
Red Blood Cells
Erythrocytes
Carry hemoglobin & oxygen, do not have oxygen
Live 120 days, formed in bone marrow & recycled in liver
White Blood Cells
Leukocytes
Fight infection, formed in bone marrow
Die fighting infection
Platelets
Thrombocytes
Clot blood
Cell fragments formed in bone marrow from megakaryocytes
Sinoatrial Node
Heart’s pacemaker
Sets timing of contractions of heart
Systolic
120
Measurement of pressure when ventricles contract
Diastolic
80
Measurement of pressure when heart relaxes
Pathway of Blood
Right atrium - right AV - Right ventricle - pulmonary semilunar valve - pulmonary artery - lungs - pulmonary vein - left atrium - left AV - left ventricle - aortic semilunar valve - aorta - all cells in body - vena cava
Endocrine System
Secretes hormones
Hormones
Produced in endocrine glands
Move through blood to specific target cell, tissue organ - produce short-lived or long-term response
Tropic Hormones
Stimulate other glands to release hormones - can have far reaching effect
Hypothalamus
Endocrine System
Bridge between endocrine & nervous systems in times of stress
It sends signals to adrenal gland to release adrenaline
Contains body’s homeostat & centers for regulating hunger/thirst
Growth Hormone (GH)
Anterior Pituitary
Stimulates growth of bones
Luteinizing Hormone (LH)
Anterior Pituitary
Stimulates ovaries & testes
Thyroid-Stimulating Hormone (TSH)
Anterior Pituitary
Stimulates thyroid gland
Adrenocorticotropic (ACTH) Hormone
Anterior Pituitary
Stimulates adrenal cortex to secrete glucocorticoids
Follice-Stimulating Hormone (FSH)
Stimulates gonads to produce sperm & ova
Oxytocin
Posterior Pituitary
Stimulates contractions of uterus + mammary glands
Antidiuretic Hormone (ADH)
Posterior Pituitary
Promotes retention of water by kidneys
Thyroxin
Thyroid
Controls metabolic rate
Calcitonin
Thyroid
Lowers blood calcium levels
Parathormone
Parathyroid
Raises blood calcium levels
Glucocorticoids
Adrenal Cortex
Raises blood sugar levels
Epinephrine (adrenaline)
Adrenal Medulla
Raises blood sugar level by increasing rate of glycogen breakdown by liver
Insulin
Pancreas
Lowers blood glucose levels
Glucagon
Pancreas
Raises blood sugar levels
Thymosin
Thymus
Stimulates T lymphocytes as part of immune response
Melatonin
Pineal
Involved in biorhythms
Estrogen
Ovaries
Stimulates uterine lining, promotes development & maintenance of primary & secondary characteristics of females
Progesterone
Ovaries
Promotes uterine lining growth
Androgens
Testes
Support sperm production & promote secondary sex characteristics
Feedback Mechanism
Self regulating mechanism that increase/decrease an action/level of a particular substance
Positive Feedback
Enhance existing response
Childbirth
Negative Feedback
Common in system that maintains homeostasis
Central Nervous System
Brain & Spinal Cord
Peripheral Nervous System
All nerves outside CNS
Sensory (PNS)
Conveys info from sensory receptors/nerve endings
Motor (PNS)
Stimulates voluntary & involuntary muscles & consists of 2 systems
Somatic System
Controls voluntary muscles
Autonomic System
Controls involuntary muscles
Resting Potential
The charge change across the membrane when a neuron is not firing (-70mV)
Action Potential
The charge change across the membrane when a neuron is firing (30mV)
Depolarization
The change from a negative resting potential to a positive action potential
Opening sodium channels
Repolarization
The change from a positive action potential back to a negative resting potential
Opening potassium channels
Nervous System
Secretes neurotransmitters
Cones
Photoreceptors in retina, distinguish different colors
Rods
Sensitive photoreceptors in retina
Do not distinguish different colors
Cornea
Tough, clear covering that protects eye & allows light to pass through
Humor
Fluids, maintain shape of cell
Iris
Colored part of eye
Controls how much light enters eye
Lens
Focuses light onto retina
Pupil
Small opening, middle of iris
Retina
Converts light into nerve impulses that are carried to the brain
Auditory Canal
Ear canal, where sounds enter
Cochlea
Fluid-filled part of inner ear
Sends nerve impulses to brain
Ear Bones
Hammer, anvil, stirrup; transmit vibrations from eardrum to oval window
Eustachian Tube
Equalizes pressure between environment & inner ear
Oval Window
Sends waves of pressure to cochlea
Semicircular Canals
Fluid-filled, helps maintain balance
Tympanum
Ear drum, vibrates as sound waves hit it
Excretion
Removal of metabolic wastes
Includes removing carbon dioxide & water from cell respiration, & nitrogenous wastes from protein metabolism
Organs of Excretion
Skin, Lungs, Liver, Kidney
Kidney
Filters about 1500L of blood per day & produce about 1.5L urine
Nephron
Basic functional unit of kidney
Carries out job in 4 steps; filtration, secretion, reabsorption, excretion
Smooth/Involuntary Muscles
Makes up walls of blood vessels & digestive tract under control of autonomic nervous system
Skeletal/Voluntary Muscles
Large & multinucleate, work in pairs; one muscle contracts & other relax
Bicep & tricep
Cardiac Muscle
Heart, generates its own action potential
Duodenum
First 10 inches of small intestine
Where all digestion is completed
Lacteal
Structures within villi that line the small intestine & that absorb fatty acids & glycerol into the lymphatic system
Alveoli
Microscopic air sacs in the lung where diffusion of the respiratory gases, oxygen & carbon dioxide, occurs
Serum
Plasma without clotting factors
Polarized
Condition of an axon of a nerve when it’s at rest, also resting potential
Na & K are pumped to opposite sides of the membrane
Wave of depolarization
The condition of an axon when an impulse is passing
Also action potential
Myosin
Myofilaments that make up the thick filaments in skeletal muscle
Actin
Protein that makes up the thin myofilaments in skeletal muscle
Capillary
Villus
Absorb amino acids, vitamins & monosaccharides directly into the bloodstream
Microvilli
Microscopic appendages
Further enhance the rate of absorption
Gallbladder
Stores bile produced in liver
Body can function without it
Constipation
Too much water is reabsorbed from the intestine into body
Diarrhea
An inadequate amount of water is absorbed back into body
Transport of Oxygen
Carried in blood by respiratory pigment hemoglobin
Combines loosely with oxygen to form molecule oxyhemoglobin
Transport of Carbon Dioxide
The by-product of cell respiration, is released from every cell & dissolves in the blood
Carbonic acid-bicarbonate ion system
Maintains the blood at a constant pH of 7.4
Blood Clotting
Mechanism that begins with the release of clotting factors from platelets & damaged tissue
Anticlotting Factors
Constantly circulate in the plasma to prevent the formation of a clot or thrombus
Can cause serious damage in the absence of injury
Pulmonary Artery
Carries deoxygenated blood
Pulmonary Vein
Carries oxygenated blood
Steroid Hormones
Lipids
Diffuse directly through the plasma membrane & bind to a receptor inside the cell that triggers the cell’s response
Nonsteroidal Hormone
Protein/Polypeptide
Cannot dissolve in the plasma membrane so they bind to a receptor on the surface of the cell, triggers a secondary messenger that converts extracellular chemical signal to a specific response inside the cell
Feedback Mechanism
Self-regulating mechanism that increases or decreases an action or the level of a particular substance
Positive Feedback
Enhances an already existing response
Childbirth
Negative Feedback
Maintains homeostasis
How body maintains proper levels of thyroxin
Neuron
Basic functional unit of the nervous system
Dendrites
Sensory
Receive incoming messages from other cells & carry the electrical signal to the cell body
Axons
Transmit an impulse from the cell body outward another cell
Sympathetic System
Fight/flight response Increase heart & breathing rate Liver convert glycogen to glucose Bronchi dilate & increase gas exchange Adrenaline raises blood glucose levels
Parasympathetic System
Calms the body
Decreases heart/breathing rate
Enhances digestion
Reflex Arc
Simplest nerve response
Inborn, automatic & protective
Ex: knee jerk
Membrane Potential
A difference in electrical charge between the cytoplasm (negative charge) & extracellular fluid (positive charge)
Refractory Period
Period of repolarization
Lasts few milliseconds during which neuron cannot respond to another stimulus
Ensures that an impulse moves along an axon in 1 direction only since impulse can move only to a region where membrane is polarized
Synapse
A junction between 2 nerve cells
Impulses pass by diffusion of a neurotransmitter
Homeostasis
Any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival
Neurotransmitters
Brain chemicals that communicate information through brain & body
Relays signals between neurons
Filtration
Nephron
Occurs by diffusion
It is passive & nonselective
Filtrate contains everything small enough to diffuse out of glomerulus into Bowman’s capsule
Glomerulus -> Bowman’s capsule -> loop of Henle -> collecting duct/tubule
Secretion
Nephron
Active, selective uptake of molecules that did not get filtered into Bowman’s capsule
In tubules of nephron
Reabsorption
Nephron
Process by which most water & solutes that initially entered the tubule during filtration are transported back into the capillaries & thus back to the body
Tubulue -> loop of Henle -> collecting tubule
Excretion
Nephron
Removal of metabolic wastes
Everything that passes into collecting tubule is excreted from the body
Myofibrils
Fibers within cytoplasm of each skeletal muscle cells that run parallel to length of the cell
Sliding Filament Theory
Muscles contract as thick (myosin) & thin (actin) filaments slide over each other
Peristalsis
Automatic process that moves food through the digestive system
