Human Physiology Flashcards
What’s in a healthy diet?
Carbohydrates (75%): used for cell resp, short term energy storage; not essential
Sources: monos in fruit; dis in sweet potato, bread; polys in whole grain, veggies
Fiber (is a carb): in cell wall, not for absorption, in unprocessed foods
Slows sugar absorption, stimulate bowel movement, limits bad bacteria
Fatty acids (15%): long term energy storage, membrane growth; omega-3 (leaves, fish) and omega-6 (seeds → corn) are essential Sources: saturated in animal products; unsaturated oils in fish/plants; trans fats, unnatural
Cholesterol: unessential; animal foods / sat fats; dietary excess → coronary heart disease
2 types: good low density (LDL) and bad high density (HDL)
Amino acids (10%): 10/20 are essential; in lean meats / fish / dairy, beans / lentils / nuts Health concerns cause developmental disabilities: phenylketonuria (pku) genetic mutation in enzyme, protein deficiency malnutrition causes few blood plasma proteins
Minerals (element), vitamins (organic compounds are water or fat soluble)
What are the types of malnutrition? How is appetite controlled?
Deficiency, excess, or imbalance of nutrients
Starvation: body breaks down tissue for energy (carb → fat → muscle)
Excess: obesity (high blood pressure, heart disease)
Hypothalamus makes us feel full when hormones arrive:
Small intestine (when food is there): PYY3-36
Pancreas (when blood glucose levels increase): insulin
Adipose tissue (when amount of stored eat increases): leptin
Describe the process of human digestion
Oral cavity: salivary amylase breaks down carbs, physical digestion of tongue and teeth
Esophagus: no new chemicals, peristalsis muscles move food
Stomach: holds 1 gallon of food 2-6 hours; rugae allow expansion, secretes hydrochloric acid to sterilize, lining replaced every 3 days, physical churning, pepsin for proteins, cardiac and pyloric sphincters
Small intestine: holds food 5-6 hours, 6m long, 250m2 surface area; duodenum starts, pancreas (secretes bicarbonate to up pH and enzymes) and liver/gall bladder (secrete and hold bile to coat lipids) at top; 25-30 enzymes to help digest; building blocks absorbed into blood by active transport, facilitated diffusion, exocytosis; villi in mucosa layer, then circular muscle layer, then longitudinal muscle layer
Intestinal villus: epithelial cells line microvilli in lumen; villus has capillary with large pores and lacteal to absorb lipoproteins (lipids with bile)
Large intestine: 12-24 hours, 90% of water reabsorbed, bacteria produce gas and vitamins
What is the circulatory system?
Transports nutrients, O2, CO2, hormones, antibodies, waste products, heat
No cells more than 2-3 cells away from capillary for diffusion
4-6 L of blood in average adult
55% plasma: liquid matrix with suspended cells, mostly water, electrolytes, plasma proteins, escorts for lipids, antibodies, pH buffers
Erythrocytes (red blood cell): 99.8% of blood
Biconcave shape, hemoglobin (protein with iron) carry oxygen to cells
Leukocytes (white blood cells): fewer and larger than RBC
Phagocytes: engulf foreign material
Lymphocytes: produce antibodies
Platelets: cell fragments aid in clotting with fibrin protein
What are the structures and functions of the human heart? (type of cells, problems)
Collects blood in atria → ventricles → pumped out
Valves prevent back flow
Cardiac muscle (smooth rather than striated / skeletal), thicker on left because it goes to the whole body
Coronary arteries supply heart muscle
Conduction fibers coordinate contraction of ventricle wall
Myogenic cells: contract without signal from brain/nerves
Sinoatrial node: top right atrium; pacemaker
Atrioventricular node: center top wall, medulla in brain signals; delays impulse between atria and ventricle contractions
Atherosclerosis: occlusion of coronary artery
Artery wall bulges into small lumen, can impede blood flow or rupture and clot
What are the parts of the not-heart circulatory system?
Heart → artery → arteriole → capillary → venule → vein → heart
Artery: thick / stiff with muscle fibers and elastin, high blood volume and pressure (even between pumps)
Capillary: thin, branching, permeable
Veins: thinner walls, low pressure, valves prevent backflow, flexible for muscle contractions to move blood
What are the structures in the respiratory system?
Epiglottis open in larynx, trachea, bronchi, bronchioles
Alveoli: 100m2 surface area for gas exchange; high concentration gradient
Type 1 pneumocyte (95%) line inside; type 2 pneumocyte (5%) secrete water (surfocant) to help oxygen dissolve and prevent collapse
Pulmonary artery → capillaries around alveoli → pulmonary vein
Inhalation: external intercostal muscles and diaphragm contract, volume of thoracic cavity up
Exhalation: internal intercostal muscles contract, diaphragm relaxes, volume down
CO2 transport: 7% as dissolved, 23% bound to amine group on hemoglobin, 70% bicarbonate
How does exercise effect respiration?
Immediate: increased cell resp → increased blood pH → brain signals diaphragm and intercostal muscles
Long term: more efficient muscles, respiration, increased stroke and tidal volume, lower resting heart and ventilation rates
What is homeostasis? 2 examples
The steady state and physiological condition of the body
Blood pH, carbon dioxide and blood glucose concentration, body temp, water balance
Monitors levels of variable and changes via negative feedback loop
Nervous system: thermoregulation by hypothalamus
If temp increases: nerves activate sweat glands, dilate capillaries near skin → stops signal
It temp decreases: skin capillaries restrict, shiver contractions use energy (make heat) → stop
Short-term cold: red cheeks from blood heating
Cold: thyroid gland secretes thyroxin, increasing metabolic rate of cells
Endocrine system: blood glucose regulation
If increase: beta cells in pancreas secrete insulin into blood → liver pulls glucose to store as glycogen, body cells take glucose for cell resp → low glucose levels → no insulin
If low levels: alpha cells in pancreas secrete glucagon into blood → liver breaks down glycogen to glucose in blood → up glucose levels → alpha stops glucagon
What is diabetes?
Type 1: insulin dependent; 10%; appears in childhood
Autoimmune disorder, immune system destroys beta cells
Insulin injections
Type 2: non-insulin dependent; 90%; any age
Not enough insulin or target cells / receptors don’t respond to insulin
Control with diet, exercise, meds
What is the circadian rhythm?
Humans adapted to 24-hour cycle
Hypothalamus controls secretion of melatonin by pineal gland
High levels of melatonin → drowsiness
Falling levels of melatonin → wake up
What are the parts and functions of the nervous system?
Functions: sensory input, integration (with brain), motor output
Types of neurons
Sensory; info from environment to CNS, long axon
Relay: in spinal cord and brain, integrate information, short axon
Motor: impulse from CNS to effector cells, long axon
Neuron is the basic unit of nervous system
Nerve impulse in nerve cell body → through axon → to synapse / dendrite
Reflex arc: shortest route
Sensory neuron into goes to motor neuron and brain simulanteously
What is the cycle of nerve cell stimulation?
Starting at rest (NA+ out and K+ in by active transport); -70 mv
1) stimulus whacks dendrite → momentary change in permeability
2) sodium floods in → neurotransmitter out to synapse for next whack; 35 mv
3) potassium moves out in concentration gradient
4) sodium out, potassium in via active; -75 mv to -70 mv
5) back to resting; neurotransmitters back in
Depolarization: from negative to positive
Action potential: potassium leaves (peak)
Hyper polarization: down / bounce to rest
Threshold of -50 mv to fire; strong stimuli cause greater frequency of action potentials
What are myelin sheaths?
Wrap around axons to speed nerve impulse
Pump happens in gaps (nodes of ranvier); no depolarization
Jumps are faster and use less energy (saltory reconduction)
How do neurotransmitters and chemical synapses work?
1) action potential depolarizes membrane of presynaptic terminal (end of axon)
2) Na moving in causes Ca+2 to move in via facilitated diffusion
3) synaptic vesicles with neurotransmitters fuse with presynaptic membrane
4) neurotransmitters diffuse across synapse
5) neurotransmitter binds to channel in post-synaptic membrane → channel opens for something else to go through (may reach threshold)
6) neurotransmitter released from receptors → channels close
7) neurotransmitter degraded by enzyme, taken to presynaptic terminal in pieces
CNS integration: each neuron has many synaptic connections
Excitatory → toward threshold
Inhibitory → prevents firing
Neurotransmitter example: dopamine, serotonin
