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118 Cards in this Set
- Front
- Back
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Homeostasis
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Maintenance of steady internal conditions despite fluctuations in the external environment
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Examples of Homeostasis
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Thermoregulation
Osmoregulation Excretion |
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Thermoregulation
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The process by which animals maintain internal temperature within a tolerable range
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Ectothermic (animals)
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absorb heat from their surroundings, many fish, most amphibians, lizards, most invertebrates
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Endothermic (animals)
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derive body heat mainly from their metabolism, birds, mammals, a few replies and fish, many insects
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Five general categories of adaptations promote thermoregulation
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Increased metabolic heat production
Insulation Circulatory adaptions Evaporative cooling behavioral responses |
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Osmoconformers
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Have the same internal solute concentration as seawater
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Osmoregulators
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Control their solute concentrations
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In Osmoregulators Freshwater fish
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gain water by osmosis
excrete excess water pump salt across their gils |
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In Osmoregulators Saltwater fish
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lose water by osmosis
drink seawater pump out excess salt |
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In Osmoregulation land animals
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gain water by drinking and eating
lose water by evaporation and wast disposal conserve water using: kidneys, behavior adaptations, waterproof skin |
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Nitrogenous wast are
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toxic breakdown products of protein
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ways of disposal of nitrogenous wast in animals
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Ammonia (NH)
Urea |
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Uric acid
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dry waste used by some animals to preserve water
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Excretory system
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expels waste
regulates water balance regulates ion balance |
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Nephrons
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functional units of the kidneys
extract a filtrate from the blood refine the filtrate to produce urine |
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Urine
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ureters drain the kidneys
stored in the urinary bladder expelled through the urethra |
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The Urinary system
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Aorta
inferior vena cava renal artery and vein ureter urethra kidney urinary bladder |
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The Kidney
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Renal cortex
renal medulla renal pelvis ureter |
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Structure of a nephron
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Bowman's capsule
Arteriole form renal artery Arteriole from glomerulus Branch of renal vein Loop of Henle with capillary network Glomerulus Proximal tubule Capillaries Distal tubule From another nephron Collecting duct |
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Orientation of a nephron within the kidney
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Bowman's capsule
renal artery renal vein tubule collecting duct to renal pelvis Renal cortex Renal medulla |
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Filtration
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blood pressure forces water and many small solutes into the nephron
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Reabsorption
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valuable solutes are reclaimed from the filtrate
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secretion
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excess H+ and toxins are added to the filtrate
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Excretion
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The final product, urine, is excreted
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Reabsorption in the proximal and distal tubules removes
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nutrients
salt water |
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pH is regulated by
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reabsorption of HCO3-
Secretion of H+ |
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Antidiuretic hormone (ADH)
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regulates the amount of water excreted by the kidneys
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Compensating for kidney failure
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a dialysis machine
removes waste from the blood maintains its solute concentration |
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Endocrine disruptors
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environmental pollutants
interfere with the action of hormones some are estrogen mimics in the environment that may produce Demasculinized male alligators Bass with male and female characteristics Decrease in size and functioning of polar bears genitalia |
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Hormones
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chemical signals
usually carried in the blood cause specific changes in target cells secreted by Endocrine glands neurosecretory cells |
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Endocrine system
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consists of all hormone-secreting cells
works with nervous system to regulate body activities |
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The nervous system also
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communicates
regulates uses electrical signals via nerve cells |
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Comparing the endocrine and nervous systems
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Nervous system reacts faster
endocrine system responses last longer |
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Hormone signaling involves three key events
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reception
signal transduction response |
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Amino-acid-derived hormones
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are water soluble
include proteins, peptides, and amines bind to plasma-membrane receptors on target cells initiate a signal transduction pathway |
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Steroid Hormones
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Nonpolar lipids made from cholesterol
can diffuse through plasma membranes Bind to a receptor protein in the cytoplasm or nucleus Hormone-receptor complex carries out the transduction of the hormonal signal |
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The vertebrate endocrine system
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consists of more than a dozen glands
secretes more than 50 hormones |
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Glands
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Some are specialized for hormone secretion only
Some also do other jobs |
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Hormones
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some have a narrow range of targets and effects
some have numerous effects on many kinds of target cells |
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Hypothalamus
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Blurs the distinction between endocrine and nervous systems
Receives input from nerves about body conditions Responds by sending out appropriate nervous or endocrine signals Uses the pituitary glands to exert master control over the endocrine system |
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The pituitary gland consists of two parts
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Posterior pituitary
composed of nervous tissue Stores and secretes oxytocin and ADH Anterior pituitary synthesizes and secretes hormones that control the activity of other glands Is controlled by the hypothalamus Releasing hormones stimulate the anterior pituitary Inhibiting hormones inhibit the anterior pituitary |
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Thyroid gland hormones
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Thyroxine (T4) and Triiodothyronie (3)
regulate metabolism development Negative feedback maintain homeostatic levels of T4 and T3 in the blood |
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Thyroid imbalance can cause disease like
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Hyperthyroidism
too much T4 and T3 in blood Hypothyroidism to little T4 and T3 in the blood |
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Blood calcium level is regulated by a tightly balanced antagonism between
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calcitonin from the thyroid
parathyroid hormone (PTH) form the parathyroid glands |
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The pancreas secretes two hormones that control blood glucose
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Insulin
Glucagon |
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Diabetes mellitus results form
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a lack of insulin or a failure of cells to respond to it
Affects about 21 million americans |
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Two common types of diabetes mellitus
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Type 1 ( insulin-dependent)
Type 2 ( non-insulin-dependent) |
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Hormones from the __________help maintain homeostasis when the body is stressed
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adrenal glands
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Nerve signals from the hypothalamus stimulate the adrenal medulla to secrete
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epinephrine
norepinephrine these hormones quickly trigger the fight or flight responses |
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Adrenocorticotropic hormone (ACTH) from the pituitary causes the adrenal cortex to secrete
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Glucocorticoids
Mineralocorticoids These hormones boost blood pressure boost energy in response to long term stress |
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Steroid sex hormones
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estrogens, progestins, androgens
produced by the gonads in response to signals from hypothalamus pituitary |
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Estrogens and progestins
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stimulate the development of female characteristics
maintain the female reproductive system |
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Androgens
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such as testosterone
trigger the development of male characteristics |
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Asexual reproductions
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one parent produces genetically identically offspring
very rapid reproduction can proceed via budding fission fragmentation/regeneration |
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Sexual reproduction involves the fusion of gametes from two parents
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resulting in genetic variation among offspring
increased reproductive success in changing environments |
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Hermaphroditism
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one individual with male and female reproductive systems
easier to find a mate for animals less mobile or solitary |
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Sperm may be transferred to the female by
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external fertilization
internal fertilization |
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Ovaries contain follicles that
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nurture eggs
produce sex hormones |
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Testes
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produce sperm and male hormones
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Epididymis
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stores sperm as they develop further
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Several glands contribute to semen
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seminal vesicles
prostate bulbourethral |
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Ejaculation
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sperm is expelled from the epididymis
the seminal vesicles, prostrate, and glands secrete into the urethra semen is formed and expelled from the penis |
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Sperm production
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regulated by a negative feedback system of hormones
involves the hypothalamus, pituitary, and testes |
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Ovarian and menstrual cycles
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occur about every 28 days
Hypothalamus signals the anterior pituitary to secret follicle-stimulating hormone (FSH) and leuteinizing hormone (LH) which trigger growth of a follicle and ovulation |
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Oviducts convey eggs to the _______ where embryos develop
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uterus
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The uterus opens into the _____ through the cervix
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Vagina
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The Vagina
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receives the penis during sexual intercourse
forms the birth canal |
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Spinal cord injuries disrupt communication between
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the central nervous system (brain and spinal cord)
the rest of the body |
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The nervous system
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obtains sensory information
processes sensory information Sends commands to effector cells (muscles) that carry out appropriate responses |
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The central nervous system (CNS) consists of
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brain
spinal cord (vertebrates) |
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Peripheral nervous system (PNS)
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located outside the CNS
consists of nerves ganglia |
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Sensory neurons
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Conduct signals from sensory receptors
To the CNS |
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Interneurons in the CNS
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Integrate information
Send it to motor neurons |
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Motor neurons
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convey signals to effector cells
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Neurons are
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Cells specialized for carrying signals
The functional units of the nervous system |
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A neuron consists of
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A cell body
Two types of extensions (fibers) that conduct signals Dendrites Axons |
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Myelin sheaths
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Enclose axons
Form a cellular insulation Speed up signal transmission |
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At rest, a neuron’s plasma membrane
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Has potential energy—the membrane potential
Just inside the cell is slightly negative Just outside the cell is slightly positive Resting potential—voltage across the plasma membrane |
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The resting potential exists because of differences in ion concentration inside and outside a cell
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Inside a cell
K+ high Na+ low Outside a cell K+ low Na+ high |
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A stimulus
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Alters the permeability of a section of membrane
Allows ions to pass through Changes the membrane’s voltage |
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A nerve signal—an action potential
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A change in the membrane voltage
From the resting potential To a maximum level And back to the resting potential |
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Action potentials
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Are self-propagated in a one-way chain reaction along a neuron
Are all-or-none events |
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Synapses are junctions where signals are transmitted between
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Two neurons
Or between neurons and effector cells |
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Neurons communicate at synapses
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Electrical synapses
Electrical signals pass between cells Chemical synapses Sending (presynaptic) cell secretes a chemical signal, a neurotransmitter The neurotransmitter crosses the synaptic cleft The neurotransmitter binds to a receptor on the surface of the receiving (postsynaptic) cell |
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Some neurotransmitters
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Excite the receiving cell
Inhibit the receiving cell’s activity by decreasing its ability to develop action potentials |
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Chemical synapses make complex information processing possible
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A neuron may receive information
From hundreds of other neurons Via thousands of synaptic terminals The summation of excitation and inhibition Determines if a neuron will transmit a nerve signal |
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Many small, nitrogen-containing molecule serve as neurotransmitters
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Acetylcholine is a neurotransmitter
In the brain Between neurons and muscle cells Biogenic amines Important in the CNS Serotonin and dopamine affect sleep, mood, attention |
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The strength of the stimulus changes
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The frequency of action potentials
But not the strength of action potentials |
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A variety of small molecules function as neurotransmitters
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Amino acids important in the CNS
Some are excitatory Some are inhibitory Neuropeptides Substance P mediates perceptions of pain Endorphins decrease perception of pain Nitric oxide A dissolved gas Triggers erections |
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Many drugs act at chemical synapses
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Many psychoactive drugs
Act at synapses Affect neurotransmitter action Caffeine counts inhibitory neurotransmitters Nicotine acts as a stimulant Alcohol is a depressant |
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Radially symmetrical animals
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Nervous system arranged in a weblike system of neurons
Nerve net |
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Most bilaterally symmetrical animals exhibit
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Centralization—presence of a central nervous system
Cephalization—concentration of the nervous system in the head region |
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Vertebrate nervous systems are highly centralized and cephalized
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Central nervous system (CNS)
The brain and spinal cord Contains fluid-filled spaces In ventricles of the brain In the central canal of the spinal cord Surrounding the brain Peripheral nervous system (PNS) Nerves—cranial nerves and spinal nerves Ganglia |
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Two functional components of the PNS
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Somatic nervous system—mostly voluntary
Autonomic nervous system (ANS)—mostly involuntary |
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Somatic nervous system
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Carries signals to and from skeletal muscles
Mainly in response to external stimuli |
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Autonomic nervous system
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Regulates the internal environment
Controls Smooth muscle Cardiac muscle Organs of various body systems |
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Parasympathetic division of ANS
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Primes the body for activities that gain and conserve energy for the body
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Vertebrate nervous systems are
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Highly centralized
Cephalized |
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Sympathetic division of ANS
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Prepares the body for intense, energy-consuming activities
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The vertebrate brain evolved by the enlargement and subdivision of the
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Forebrain
Midbrain Hindbrain |
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In birds and mammals
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Size and complexity of the cerebrum
Correlates with their sophisticated behavior |
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The human brain
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More powerful than the most sophisticated computer
Composed of three main parts Forebrain Midbrain Hindbrain |
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Midbrain, subdivisions of the hindbrain, thalamus, and hypothalamus
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Conduct information to and from higher brain centers
Regulate homeostatic functions Keep track of body position Sort sensory information |
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Cerebrum
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Part of the forebrain
Largest and most complex part of the brain Most integrative power is in the cerebral cortex |
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Cerebral cortex
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About 5 mm thick
Accounts for 80% of brain mass Specialized integrative regions Somatosensory cortex Centers for vision, hearing, taste, and smell |
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The cerebral cortex is a mosaic of specialized, interactive regions
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Motor cortex—directs responses
Association areas Make up most of the cerebrum Higher mental activities Reasoning Language Right and left cerebral hemispheres Specialize in different mental tasks |
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fMRI scans can provide insight into brain structure and function
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A scanning and imaging technology used to study brain functions
Used on conscious patients Monitors changes in blood oxygen usage in the brain Correlates to regions of intense brain function |
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Sleep and arousal involve activity by the
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Hypothalamus
Medulla oblongata Pons Neurons of the reticular formation |
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Sleep
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Is essential for survival
Sleep is an active state Sleep may be involved in consolidating learning and memory |
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The limbic system
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Is a functional group of integrating centers in
Cerebral cortex Thalamus Hypothalamus Is involved in Emotions Memory Learning |
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Many neurological disorders can be linked to changes in brain physiology
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Schizophrenia
Depression Alzheimer’s disease Parkinson’s disease |
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Schizophrenia
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A severe mental disturbance
Characterized by psychotic episodes in which patients lose the ability to distinguish reality |
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Depression
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Two broad forms of depressive illness have been identified
Major depression Bipolar disorder—manic-depressive disorder Treatments may include selective serotonin reuptake inhibitors (SSRIs) |
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Alzheimer’s disease is characterized by
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Confusion
Memory loss |
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Parkinson’s disease
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Motor disorder
Characterized by Difficulty in initiating movements Slowness of movement Rigidity |
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Asexual reproduction results in the generation of genetically______
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identical offspring
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Sexual reproduction results in the generation of genetically _______
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unique offspring
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