Biology 2 Flashcards
What is the purpose of the integumentary?
Provides a physical barrier to prevent the entrance of pathogens into the body
What consists of the integumentary in humans and animals?
In humans: hair, skin and nails
In animals: fur, hooves, scales, feathers, shell
What is the purpose of the skin?
Nonspecific defense mechanism that protects against pathogenic invasion
What is the pH of the skin?
4-6 in humans, decreases bacterial growth
What are some functions of sweat?
Evaporative cooling, has enzymes that help destroy bacterial cell walls
What are the layers of the skin and what connects them?
Two layers: Dermis and epidermis which are connected by the basement membrane
What does the dermis do?
Has the blood supply to the skin and most of the specialized cells
What does the epidermis do?
Has keratinocytes which differentiate into corneocytes which are protective, waterproof cells that don’t undergo any further replication and are routinely sloughed off and replaced
What is the purpose of hair?
Can direct sweat and waste away from the skin, help with evaporative cooling when body is hot or trap heat when body is cold, sensory organ and can detect nearby motion
What is the purpose of nails?
Protect tips of fingers and toes from injury and can be used as tools
What are the 2 major types of immunity?
Innate and adaptive
What is innate immunity?
The bodys intial, generalized defenses against pathogens
What are some non specific defense mechanisms?
inflammatory response, physiologic response (temperature and pH change), phagocytes cells (neutrophils and macrophages)
What occurs during inflammation?
During inflammation, injured cells release chemicals like histamine that dilate and increase the permeability of blood vessels, which increases white blood cell and immune cell to affected area
What is the purpose of a fever?
Fever increases the ability to fight infections by killing temperature dependent pathogens and speed up healing process
What do granulocytes do?
They are attracted to the site of injury where they phagocytize antigens and antigenic material
What are the types of granulocytes?
- Neutrophils are the most common type, first responders to sites of inflammation, attracted to cytokines, attract additional WBC to site, main component of pus, adapted to attack bacteria
- Eosinophils are less common, responsible for immune responses (e.g allergy or asthma)
- Basophils and mast cells are involved in allergic responses and parasite infections, often responsible for release of histamine
What are monocytes?
Immune cells that can differentiate into macrophages and dendritic cells
What do macrophages do?
Phagocytize dead cells and pathogens
What do dendritic cells do and where are they found?
Found in areas of body where contact with external environment is more common (skin, intestine etc) and focus on processing antigens and presenting them to other immune cells
What are antigen presenting cells (APC’s) and what are some examples?
Macrophages, dendritic cells and b lymphocytes; present antigens for recognition to mediate cell immune response
What are the types of adaptive immunity?
Cell mediated which is mediated by T lymphocytes or humoral which involves antibody production by b lymphocytes
How and where do T lymphocytes develop and mature?
T lymphocytes begin to develop in the bone marrow where there precursor cells are formed, then they travel through bloodstream to the thymus where they mature and once maturation is complete the T cells are released into the lymph to perform their immune function
True or False: Each T cell becomes reactive to only one specific antigen
True
What is the function of the major histocompatibility protein complex (MHC)?
The antigen from the pathogen will be presented by a major histocompatibility protein complex (MHC) on surface of the APC indicating that corresponding T cell should perform its function
What are the 2 major types of MHC?
Two major types of histocompatibility proteins are MHC 1 and MHC 2
What do cytotoxic T cells do?
Cytotoxic T cells (CD8+ T cells) recognize and respond to antigens presented by the MHC 1 complexes and signal the T cells to destroy the cells involved in viruses or developing tumors
What do T helper cells do?
T helper cells (CD4 + T cells) recognize and respond to antigens presented by the MHC 2 complexes and release cytokines to stimulate the immune response, causing white blood cells to mature and attack
What are memory T cells?
Memory T cells (once reaction has occurred) reactive to the same antigens are formed to allow a quicker and more targeted response
What are natural killer T cells?
Natural killer T cells behave similar to the other two types of T cells but respond to antigens presented by other types of cells
Where do B lymphocyte develop?
- B lymphocytes begin their development in bone marrow and is completed there
- When B cells are stimulated they create antibodies (immunoglobulins) that have a high affinity for antigens
What is the structure of immunoglobulin?
Immunoglobulin structure resembles a Y with antigen binding sites at either end of the top of the Y, each side of the Y has a light chain and a heavy chain which is held together with disulfide bonds, variable portion of structure is the antigen binding region
What is active immunity and what is passive immunity?
- Humoral immunity includes both active and passive immunity:
- Active immunity occurs as a result of an immune response (from exposure or vaccination)
- Passive immunity is acquired by the transfer of antibodies from one individual to another (can occur during pregnancy etc.), once antibodies are no longer circulating in immune system the effect of immunity is lost
What do immunosuppressive drugs do?
Immunosuppressive drugs are used to lower the immune response to transplant and decrease likelihood of rejection but makes patient immunocompromised since immune system is not functioning at full capacity
What is the lymphatic system?
The lymphatic system is a part of the immune system found in the extravascular space of most tissues
Where does lymph flow through?
Lymph flows through lymphatic vessels from lymph node to node; lymph nodes and spleen are reservoirs of white blood cells and filters for lymph, removing APC cells and foreign matter and activating immune system when necessary
What is the function of the nervous system and what is it composed of?
- Nervous system enable organisms to receive and respond to stimuli from their external and internal environments
- Composed of neurons (specialized nervous tissue) and neuroglia (cells that support and protect neurons)
What are the 2 divisions of the nervous system?
Two divisions: Central nervous system and peripheral nervous system
What is the primary function of the neuron?
Primary function to convert stimuli into electrochemical signals and conduct these signals throughout the body
What is the neuron composed of?
Has dendrites, a cell body and an axon
What are dendrites?
Dendrites are cytoplasmic extensions that receive information and transmit it toward the cell body
What is the function of the cell body of the neuron?
Cell body (soma) contains the nucleus and controls metabolic activity
What is the axon?
Axon is a long cellular process that transmits impulses (action potentials) away from cell body
What is the axon hillock?
Between axon and cell body is axon hillock where incoming signals from dendrites are summed
What is the function of myelin and what are nodes of ranvier?
- Myelin prevents leakage of signal from axons and allows for faster conduction of impulses
- Gaps between segments of myelin are nodes of ranvier, saltatory (hopping) conduction
What is myelin made by?
Myelin is produced by glial cells called oligodendrocytes in the CNS and by schwann cells in the PNS
What is resting membrane potential?
Potential difference at rest between the extracellular space and the intracellular space is resting potential and is typically -70 mv (inside of neuron more negative than the outside)
What does the Na/K pump pump?
Na+/K+ pump pumps 3 Na out of cell for every 2 K it pumps into cell; cell membrane more permeable to K+ (can flow out and make inside even more negative)
What is the threshold potential?
If membrane potential reaches the threshold potential of -55 mV, then voltage-gated Na+ channels open, triggering the action potential
What are the 3 phases of action potential?
3 phases of action potential: depolarization, repolarization, hyperpolarization
What occurs during action potential?
Depolarization occurs when a cell reaches threshold potential and voltage gated Na+ channels open to allow Na+ into the neuron, cell membrane potential reaches 35 mV and cell is depolarized, then voltage-gated K+ channels open and repolarization occurs, the opening and closing of K+ is slow process which causes hyperpolarization which results in a refractory period (period of time after action potential which new action potentials are difficult to initiate), and then resting potential reestablished
What is the purpose of refractory periods?
Refractory periods make the backward travel of action potentials impossible
How can nerve impulses travel faster?
The greater the diameter of the axon and the greater its myelination, the faster the impulses travel; larger diameter have greater cross sectional area and have less resistance to diffusion of ions and myelin increases conduction velocity by insulating segments of the acon so the membrane is permeable to ions only in nodes of ranvier
What is the synapse?
The synapse is the gap between the axon terminal of one neuron (the presynaptic neuron) and the dendrites of the next neuron (post synaptic neuron)
What does the axon terminal have?
Axon terminal has thousands of membrane bound vesicles filled with neurotransmitters (chemical messengers)
How are neurotransmitters reused or degraded?
Neurotransmitter can be taken back up into the nerve terminal ( via protein called uptake carrier) where it can be reused or degraded, or it can be degraded by enzymes in the synapse or it can diffuse out of the synapse
What are afferent neurons?
Neurons that carry sensory information about the internal or external environment to the brain or spinal cord are called afferent neurons
What are efferent neurons?
Neurons that carry motor commands from the brain or spinal cord to various parts of the body are called efferent neurons
What are interneurons?
Interneurons participate in local circuits linking sensory and motor neurons in the brain and spinal cord
What are nerves?\
Nerves are bundles of axons covered with connective tissue
What is a plexus?
Network of nerve fibres is called a plexus
What are clustered neuronal cell bodies called in the PNS and in the CNS
Clustered neuronal cell bodies are called ganglia in the PNS and nuclei in the CNS
What do neuroglia do and what are the types in the CNS and PNS?
Neuroglia support and protect specialized neuronal cells: 4types in CNS and 2 in PNS SEE WRITTEN NOTES FOR FUNCTION
CNS: Astrocytes, oligodendrocytes, microglia and ependymal cells
PNS: Satellite cells and Schwann cells
What does the CNS consist of?
Brain and spinal cord
What is the brain?
Brain is a mass of neurons and interprets sensory information, forms motor plans and cognitive function (thinking)
What part of the brain is gray and white matter?
Brain has outer portion of cell bodies called gray matter and inner portion of myelinated axons called white matter
What are the 3 parts of the brain?
Forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon)
What does the forebrain consist of?
Forebrain (prosencephalon): consists of the telencephalon and diencephalon, major component of telencephalon is the cerebral cortex which processes and integrates sensory input and motor response (important for memory and creative thought) made of grey matter, telencephalon also has olfactory bulb which is important for smell, diencephalon has thalamus and hypothalamus, thalamus is a relay center for spinal cord and cerebral cortex, hypothalamus controls visceral functions like hunger, thirst sex drive etc. and controls temeprature, blood pressure and endocrine system
What does the cerebral cortex do?
cerebral cortex which processes and integrates sensory input and motor response (important for memory and creative thought)
What does the thalamus do?
thalamus is a relay center for spinal cord and cerebral cortex,
What does the hypothalamus do?
hypothalamus controls visceral functions like hunger, thirst sex drive etc. and controls temperature, blood pressure and endocrine system
What does the midbrain do?
Midbrain (mesencephalon): relay center for visual and auditory impulses, also plays a role in motor control
What is the hindbrain consisted of?
Hindbrain (rhombencephalon): consists of cerebellum, the pons and the medulla
What is the function of the cerebellum?
cerebellum important in maintaining balance, hand-eye coordination etc.
What is the function of the pons?
the pons is a relay center for communication between cortex and cerebellum,
What does the medulla oblongata do?
the medulla oblongata controls vital functions like heart rate, and breathing
What makes up the brain stem?
Midbrain, pons and medulla makeup the brain stem
Where is the white and grey matter in the spinal cord?
Outer white matter area with axons and inner gray matter area with nerve cell bodies
Where does sensory information enter and motor information leave the spinal cord?
Sensory information enters spinal cord through dorsal horn
All motor information exits the spinal cord through the ventral horn
What are the 2 divisions of the PNS?
Somatic and autonomic
What does the somatic nervous system do?
Somatic nervous system innervates skeletal muscles and is responsible for voluntary movement and reflex arcs
What does the autonomic nervous system do?
The autonomic nervous system regulates the body’s internal environment without the aid of conscious control, innervates smooth and cardiac muscle
What are the subdivisions of the autonomic nervous system and what do they do?
ANS has 2 subdivisions: Sympathetic and parasympathetic
- Sympathetic: increases blood pressure and heart rate, increases blood flow to skeletal muscles, dilates bronchioles to increase gas exchange, uses norepinephrine as primary neurotransmitter
- Parasympathetic: acts to conserve energy and restore the body to resting activity levels, lowers heart rate and increases gut motility, innervates the vagus nerve (thoracic and abdominal viscera), uses acetylcholine as its primary neurotransmitter
What does the eye do?
Detects light energy (photons) and transmit information about intensity, color, and shape to the brain
What is the sclera?
Eyeball is covered by a thick, opaque layer called sclera (white part of eye)
What is the choroid layer and what is the choroid?
- Under the sclera is the choroid layer which helps supply the retina with blood
- Choroid is dark pigmented area that reduces reflection in the eye
What is the retina?
Innermost layer of the eye is the retina which contains photoreceptors that sense light
What does the transparent cornea do?
Transparent cornea at the front of the eye bends and focuses light rays
What does the pupil and iris do?
Light rays travel through opening called the pupil whose diameter is controlled by the iris
What does the ciliary muscles do?
The lens, the shape and focal length of which is controlled by the ciliary muscles, focuses the image onto the retina
What dos the vitreous humor do?
Vitreous humor is jelly material to help maintain eye shape and optical properties
What is the aqueous humor?
Aqueous humor is more watery substance that fills the space between the lens and the cornea
What are the 2 main types of photoreceptors and what do they respond to?
- The two main types of photoreceptors are cones and rods
- Cones respond to high intensity illumination and are sensitive to color while rods detect low-intensity illumination and are important in night vision
- Cones have 3 different pigments that absorb red, green and blue wavelengths while rod pigment rhodopsin only absorbs a single wavelength
- There are more rods than cones in the human eye
What is the macula and fovea?
Central section of the retina is the macula, has a high concentration of cones, center point of macula is called fovea and only has cones
How do photoreceptor cells generate action potentials?
Photoreceptor cells generate an action potential in response to light stimuli, the cells synapse onto bipolar cells which in turn synapse onto ganglion cells which group together to form optic nerve which takes information to the brain
What do amacrine and horizontal cells do?
Amacrine and horizontal cells also receive stimuli information from photoreceptors and process the information
What is myopia?
Myopia (nearsightedness) occurs when the image is focused in front of the retina
What is hyperopia?
Hyperopia (farsightedness) occurs when the image is focused behind the retina
What is astigmatism?
Astigmatism is caused by an irregularly shaped cornea
What are cataracts?
Cataracts develop when the lens becomes opaque, light can’t enter the eye and blindness results
What is glaucoma?
Glaucoma is an increase of pressure in the eye because of blocking of the outflow of aqueous humor, which results in optic nerve damage
What are the parts of the ear?
Divided into 3 parts: the outer, middle and inner ear
How does sound travel through the ear?
Sound wave first reaches the cartinalegenous pinna (sometimes called auricle) then sound is channeled into the external auditory canal which focuses the soundwave toward the tympanic membrane (eardrum) and the tympanic membrane vibrates with magnitude and frequency of incoming soundwave
What are the bones in the middle ear?
Middle ear contains 3 bones: malleus (hammer), incus (anvil), and stapes (stirrup); these bones collectively called ossicles
What do the ossicles do?
Ossicles vibrate with same frequency of tympanic membrane and transfer energy to oval window which is smaller and amplifies the vibration
What does the inner eat contain and what does it do?
- The inner ear begins after the oval window contains the cochlea and vestibule
- Vibration of oval window pushed against fluid called perilymph resulting in pressure waves that travel through fluid-filled cochlea, pressure waves detected by hair cells which transform mechanical stimuli into action potentials that travel down the auditory nerve and follows auditory pathway until it reaches the auditory cortex which processes auditory information
- Inner ear contains vestibule which is fluid filled and responsible for balance and acceleration detection of the organism
What is the function of the skeletal and muscular system?
The skeletal system provides physical support and locomotion while the muscular system generates force
What are the major components of the skeleton?
Two major components of the skeleton: cartilage and bone